Search results for: metals and vitamins

Authors: Hossein Hassani, Ali Rezaei

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Heavy metals are naturally occurring elements that have a high atomic weight and a density at least five times greater than that of water. Their multiple industrial, domestic, agricultural, medical, and technological applications have led to their wide distribution in the environment, raising concerns over their potential effects on human health and the environment. Environmental protection against various pollutants, such as heavy metals formed by industries, mines and modern technologies, is a concern for researchers and industry. In order to assess the contamination of soils the distribution and environmental behavior have been investigated. Jajarm bauxite mine, the most important deposits have been discovered in Iran, which is about 22 million tons of reserve, and is the main mineral of the Diaspora. With a view to estimate the heavy metals ratio of the Jajarm bauxite mine area and to evaluate the pollution level, 50 samples have been collected and have been analyzed for the heavy metals of As, Cd, Cu, Hg, Ni and Pb with the help of Inductively Coupled Plasma-Mass Spectrometer (ICP- MS). In this study, we have dealt with determining evaluation criteria including contamination factor (CF), average concentration (AV), enrichment factor (EF) and geoaccumulation index (GI) to assess the risk of pollution from heavy metals(As, Cd, Cu, Hg, Ni and Pb) in Jajarm bauxite mine. In the samples of the studied, the average of recorded concentration of elements for Arsenic, Cadmium, Copper, Mercury, Nickel and Lead are 18, 0.11, 12, 0.07, 58 and 51 (mg/kg) respectively. The comparison of the heavy metals concentration average and the toxic potential in the samples has shown that an average with respect to the world average of the uncontaminated soil amounts. The average of Pb and As elements shows a higher quantity with respect to the world average quantity. The pollution factor for the study elements has been calculated on the basis of the soil background concentration and has been categorized on the basis of the uncontaminated world soil average with respect to the Hakanson classification. The calculation of the corrected pollutant degree shows the degree of the bulk intermediate pollutant (1.55-2.0) for the average soil sampling of the study area which is on the basis of the background quantity and the world average quantity of the uncontaminated soils. The provided conclusion from calculation of the concentrated factor, for some of the samples show that the average of the lead and arsenic elements stations are more than the background values and the unnatural metal concentration are covered under the study area, That's because the process of mining and mineral extraction. Given conclusion from the calculation of Geoaccumulation index of the soil sampling can explain that the copper, nickel, cadmium, arsenic, lead and mercury elements are Uncontamination. In general, the results indicate that the Jajarm bauxite mine of heavy metal pollution is uncontaminated area and extract the mineral from the mine, not create environmental hazards in the region.

Keywords: enrichment factor, geoaccumulation index, heavy metals, Jajarm bauxite mine, pollution

Procedia PDF Downloads 259

Authors: A. A. Adebayo, A. O. Ogunkeyede, A. O. Adeigbe

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Digital globalisation and yarn of Nigeria society to overcome the digital divide have resulted in contamination of soil by heavy metals (HMs) from e-waste activities at Alaba international market, Lagos, Nigeria. The aim of this research was to determine the concentration of various metals {Cadmium (Cd), Chromium (Cr), Copper (Cu), and Lead (Pb)} and identify their ecological and health risks for the people within the study area. A total of 60 soil samples were collected at Alaba market study area. Two types of samples were collected from each sampling points: topsoil (0-15 cm), subsoil (15 -30 cm). The metal concentration results showed that the soils were heavily contaminated by HMs at topsoil and subsoil. The geoaccummulation and ecological risk indices revealed high pollution level from all studied site. The health risk assessment results suggested that there is high possibility of carcinogenic risk to humans because the carcinogenic risk via corresponding exposure pathways exceeded the safety limit of 10-6 (the acceptable level of carcinogenic risk for human). Furthermore, inhalation of soil particles is the main exposure pathway for Cr to enter the human body for all ages. Children in the vicinity are exposed more to ingestion of Pb since they tend to eat earth (pica) and repeatedly suck their fingers. This study provides basic information to create awareness for a need to introduce pollution control measures and the need to protect the ecosystem and human health within the study area at Alaba international market.

Keywords: contaminated soil, ecological risk, hazard index, risk factor, exposure pathways, heavy metals

Procedia PDF Downloads 223

Authors: Abdelkader T. Ahmed

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Phosphate Rocks (PR) are natural sediment rocks. These rocks contain several chemical compositions of heavy metals and radioactive elements. Mining and transportation these rocks beside or through the natural water streams may lead to water contamination. When PR is in contact with water in the field, as a consequence of precipitation events, changes in water table or sinking in water streams, elements such as salts and heavy metals, may be released to the water. In this work, the leaching properties of PR in Nile River water was investigated by experimental lab work. The study focused on evaluating potential environmental impacts of some constituents, including phosphors, cadmium, curium and lead of PR on the water quality of Nile by applying tank leaching tests. In these tests the potential impact of changing conditions, such as phosphate content in PR, liquid to solid ratio (L/S) and pH value, was studied on the long-term release of heavy metals and salts. Experimental results showed that cadmium and lead were released in very low concentrations but curium and phosphors were in high concentrations. Results showed also that the release rate from PR for all constituents was low even in long periods.

Keywords: leaching tests, Nile river, phosphate rocks, water quality

Procedia PDF Downloads 296

Authors: Masoud Ghermezi

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Studying the sheet metals is one of the most important research areas in the field of metal forming due to their extensive applications in the aerospace industries. A useful method for determining the forming limit of these materials and consequently preventing the rupture of sheet metals during the forming process is the use of the forming limit curve (FLC). In addition to specifying the forming limit, this curve also delineates a boundary for the allowed values of strain in sheet metal forming; these characteristics of the FLC along with its accuracy of computation and wide range of applications have made this curve the basis of research in the present paper. This study presents a new model that not only agrees with the results obtained from the above mentioned theory, but also eliminates its shortcomings. In this theory, like in the M-K theory, a thin sheet with an inhomogeneity as a gradient thickness reduction with a sinusoidal function has been chosen and subjected to two-dimensional stress. Through analytical evaluation, ultimately, a governing differential equation has been obtained. The numerical solution of this equation for the range of positive strains (stretched region) yields the results that agree with the results obtained from M-K theory. Also the solution of this equation for the range of negative strains (tension region) completes the FLC curve. The findings obtained by applying this equation on two alloys with the hardening exponents of 0.4 and 0.24 indicate the validity of the presented equation.

Keywords: sheet metal, metal forming, forming limit curve (FLC), M-K theory

Procedia PDF Downloads 336

Authors: Saima Nasreen, Uzaira Rafique, Shery Ehrman, Muhammad Aqeel Ashraf

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The release of heavy metals into the environment is a potential threat to water and soil quality as well as to plant, animal and human health. In current research work, organically functionalized mesoporous silicates (MSU-H) were prepared by the co-condensation between sodium silicate and oregano alkoxysilanes in the presence of the nonionic surfactant triblock copolymer P104. The surfactant was used as a template for improving the porosity of the hybrid gels. Synthesized materials were characterized by TEM, FT-IR, SEM/EDX, TG, surface area analysis. The surface morphology and textural properties of such materials varied with various kinds of groups in the channels. In this study, removal of some heavy metals ions from aqueous solution by adsorption process was investigated. Batch adsorption studies show that the adsorption capacity of metal ions on the functionalized silicates is more than that on pure MSU-H. Data shows adsorption on synthesized materials is a time efficient process, suggesting adsorption on external surface as well as the mesoporous process. Adsorption models of Langmuir, Freundlich, and Temkin depicted equal goodness for all adsorbents, whereas pseudo 2nd order kinetics is in best agreement with experimental data.

Keywords: heavy metals, mesoporous silica, hybrid, adsorption, freundlich, langmuir, temkin

Procedia PDF Downloads 244

Authors: Srinivasa Reddy Mallampati, Min Hee Park, Soo Mim Cho, Sung Hyeon Yoon

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One of the issues of End of Life Vehicles (ELVs) recycling promotion is technology for the appropriate treatment of automotive shredder residue (ASR). Owing to its high heterogeneity and variable composition (plastic (23–41%), rubber/elastomers (9–21%), metals (6–13%), glass (10–20%) and dust (soil/sand) etc.), ASR can be classified as ‘hazardous waste’, on the basis of the presence of heavy metals (HMs), PCBs, BFRs, mineral oils, etc. Considering their relevant concentrations, these metals and plastics should be properly recovered for recycling purposes before ASR residues are disposed of. Brominated flame retardant additives in ABS/HIPS and PVC may generate dioxins and furans at elevated temperatures. Moreover, these BFRs additives present in plastic materials may leach into the environment during landfilling operations. ASR thermal process removes some of the organic material but concentrates, the heavy metals and POPs present in the ASR residues. In the present study, Fe/Ca/CaO nanoparticle assisted ozone treatment has been found to selectively hydrophilize the surface of ABS/HIPS and PVC plastics, enhancing its wettability and thereby promoting its separation from ASR plastics by means of froth flotation. The water contact angles, of ABS/HIPS and PVC decreased, about 18.7°, 18.3°, and 17.9° in ASR respectively. Under froth flotation conditions at 50 rpm, about 99.5% and 99.5% of HIPS in ASR samples sank, resulting in a purity of 98% and 99%. Furthermore, at 150 rpm a 100% PVC separation in the settled fraction, with 98% of purity in ASR, respectively. Total recovery of non-ABS/HIPS and PVC plastics reached nearly 100% in the floating fraction. This process improved the quality of recycled ASR plastics by removing surface contaminants or impurities. Further, a hybrid ball-milling and with Fe/Ca/CaO nanoparticle froth flotation process was established for the recovery of HMs from ASR. After ball-milling with Fe/Ca/CaO nanoparticle additives, the flotation efficiency increased to about 55 wt% and the HMs recovery were also increased about 90% for the 0.25 mm size fractions of ASR. Coating with Fe/Ca/CaO nanoparticles associated with subsequent microbubble froth flotation allowed the air bubbles to attach firmly on the HMs. SEM–EDS maps showed that the amounts of HMs were significant on the surface of the floating ASR fraction. This result, along with the low HM concentration in the settled fraction, was confirmed by elemental spectra and semi-quantitative SEM–EDS analysis. Developed hybrid preferential hazardous plastics and metals separation process from ASR is a simple, highly efficient, and sustainable procedure.

Keywords: end of life vehicles shredder residue, hazardous plastics, nanoparticle froth flotation, separation process

Procedia PDF Downloads 255

Authors: Hai-Hong Gu, Yan-Jun Ai, Zheng Zhou

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Vanadium and titanium are rare metals with superior properties and are important resources in aerospace, aviation, and military. The vanadium/titanium magnetite are mostly ultra-lean ores, and a large number of tailings has been produced in the exploitation process. The tailings are characterized by loose structure, poor nutrient, complex composition and high trace metal contents. Returning green manure has been shown to not only increase plant biomass and soil nutrients but also change the bioavailability of trace metals and the microbial community structure. Fungi play an important role in decomposing organic matter and increasing soil fertility, and the application of organic matter also affects the community structure of fungi. The effects of green manure plants, alfalfa (Medicago sativa L.), returned to the tailings in situ on community structure of fungi, nutrients and bioavailability of trace metals in vanadium/titanium magnetite tailings were investigated in a pot experiment. The results showed that the fungal community diversity and richness were increase after alfalfa green manure returned in situ. The dominant phyla of the fungal community were Ascomycota, Basidiomycota and Ciliophora, especially, the phyla Ciliophora was rare in ordinary soil, but had been found to be the dominant phyla in tailings. Meanwhile, the nutrient properties and various trace metals may shape the microbial communities by affecting the abundance of fungi. It was found that the plant growth was stimulated and the available N and organic C were significantly improved in the vanadium/titanium magnetite tailing with the long-term returning of alfalfa green manure. Moreover, the DTPA-TEA extractable Cd and Zn concentrations in the vanadium/titanium magnetite tailing were reduced by 7.72%~23.8% and 8.02%~24.4%, respectively, compared with those in the non-returning treatment. The above results suggest that the returning of alfalfa green manure could be a potential approach to improve fungal community structure and restore mine tailing ecosystem.

Keywords: fungal community, green manure returning, vanadium/titanium magnet tailings, trace metals

Procedia PDF Downloads 37

Authors: Lydia Andrade, Kumar M. R. Bhat

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Heavy metals, especially lead, is considered to be a multi-organ toxicant. However, such heavy metals, are used in the preparation of traditional medicines. Nagabhasma is one of the traditional medicines. Lead is the metal used in its preparation. Lead is converted into a health beneficial, organometallic compound, when subjected to various traditional methods of purification. Therefore, this study is designed to evaluate the effect of such processed lead in various stages of traditionally prepared Nagabhasma on the histological structure of kidneys. Using the human equivalent doses of Nagabhasma, various stages of its preparation were fed orally for 30 days and 60 days (short term and long term). The treated and untreated rats were then sacrificed for the collection of kidneys. The kidneys were processed for histopathological study. The results show severe changes in the histological structure of kidneys. The animals treated with lead acetate showed changes in the epithelial cells lining the bowman’s capsule. The proximal and distal convoluted tubules were dilated leading to atrophy of their epithelial cells. The amount of inflammatory infiltrates was more in this group. A few groups also showed pockets of inter-tubular hemorrhage. These changes, however, were minimized as the stages progressed form stages 1 to 4 of Nagabhasma preparation. Therefore, it is necessary to stringently monitor the processing of lead acetate during the preparation of Nagabhasma.

Keywords: heavy metals, kidneys, lead acetate, Nagabhasma

Procedia PDF Downloads 121

Authors: Roberta Guerra, Juan Pablo Pozo Hernandez

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Surface sediments from the coastal lagoon of Pialassa Piomboni in the NW Adriatic Sea were collected and analysed and the potential ecological risks in the area were assessed based on the acid-volatile sulphide (AVS) model. The AVS levels are between 0.03 and 8.8 µmol g-1, with the average at 3.1 µmol g-1. The simultaneously extracted metals (∑SEM), which is the molar sum of Cd, Cu, Ni, Pb, and Zn, range from 0.3 to 6.6 µmol g-1, with the average at 1.7 µmol g-1. Most of the high ∑SEM concentrations are located in the southern area of the lagoon. [SEM]Zn had the comparatively high mean concentration (1.4 µmol g-1), and a maximum value of 6.1 µmol g-1, respectively. Concentrations of [SEM]Cd, [SEM]Cu, [SEM]Ni, and [SEM]Pb were consistently lower, with maximum values of 0.007 µmol g-1, 1.4 µmol g-1, 0.3 µmol g-1 and 0.2 µmol g-1, respectively. Compared to other metals, [SEM]Zn was the dominant component in all samples and accounted for approximately 31 - 93% of the ∑SEM, whereas the contribution of Cd – the most toxic metal studied – to ∑SEM was no more than 1%. According to the USEPA evaluation method, the sediment samples can be divided into the three following categories: category 1, adverse biological effects on aquatic life may be expected when ([SEM]–[AVS])/fOC > 3000; category 2, adverse effects on aquatic life are uncertain when ([SEM]–[AVS])/fOC = 130 to 3,000; and category 3, no indication of adverse effects when ([SEM]–[AVS])/fOC < 130. Most of the surface sediments of the Pialassa Piomboni lagoon (>90%) had no adverse biological effects according to the criterion proposed by the USEPA; while adverse effects were uncertain in few stations (~2%).

Keywords: sediment quality, heavy metals, coastal lagoon, bioavailability, SEM, AVS

Procedia PDF Downloads 375

Authors: R. Ravisankar, Tholkappian A. Chandrasekaran, Y. Raghu, K. K. Satapathy, M. V. R. Prasad, K. V. Kanagasabapathy

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The coastal areas of Tamilnadu are assuming greater importance owing to increasing human population, urbanization and accelerated industrial activities. sIn the present study, sediment samples are collected along the east coast of Tamilnadu for assessment of heavy metal pollution. The concentration of 13 selected heavy metals such as Mg, Al, Si, K, Ca, Ti, Fe, V, Cr, Mn, Co, Ni and Zn determined by Energy dispersive X-ray fluorescence (EDXRF) technique. In order to describe the pollution status, Contamination factor and pollution load index are calculated and reported. This result suggests that sources of metal contamination were mainly attributed to natural inputs from surrounding environments.

Keywords: sediments, heavy metals, EDXRF, pollution contamination factors

Procedia PDF Downloads 313

Authors: E. D. Paul, H. Otanwa, O. F. Paul, A. J. Salifu, J. E. Toryila, C. E. Gimba

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The concentration levels of six heavy metals (Cd, Cr, Fe, Ni, Pb, and Zn) and two mineral elements (Ca and Mg) were determined in soil samples collected from the vicinity of two auto mechanic workshops in Sabon-Gari, Kaduna state, Nigeria, using Atomic Absorption Spectrometry (AAS), in order to compare the gradation of their concentrations with distance and depth of soil from the workshop sites. At site 1, concentrations of lead, chromium, iron, and zinc were generally found to be above the World Health Organization limits, while those of Nickel and Cadmium fell within the limits. Iron had the highest concentration with a range of 176.274 ppm to 489.127 ppm at depths of 5 cm to 15 cm and a distance range of 5 m to 15 m, while the concentration of cadmium was least with a range of 0.001 ppm to 0.008 ppm at similar depth and distance ranges. In addition, there was more of calcium (11.521 ppm to 121.709 ppm), in all the samples, than magnesium (11.293 ppm to 21.635 ppm). Similar results were obtained for site II. The concentrations of all the metals analyzed showed a downward gradient with an increase in depth and distance from both workshop sites except for iron and zinc at site 2. The immediate and remote implications of these findings on the biota are discussed.

Keywords: AAS, heavy metals, mechanic workshops, soil, variation

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Authors: K. Menad, A. Faddeg

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Zeolites are a family of mineral compounds. With special properties that have led to several important industrial applications. Ion exchange has enabled the first industrial application in the field of water treatment. The exchange by aqueous pathway is the method most used in the case of such microporous materials and this technique will be used in this work. The objective of this work is to find performance materials for the recovery of heavy metals such as cadmium. The study is to compare the properties of different ion exchange zeolite Na-X, Na-A, their physical mixture and the composite A (LTA) / X (FAU). After the synthesis of various zeolites X and A, it was designed a model Core-Shell to form a composite zeolite A on zeolite X. Finally, ion exchange studies were performed on these zeolite materials. The cation is exclusively tested for cadmium, a toxic element and is harmful to health and the environment.

Keywords: zeolite A, zeolite X, ion exchange, water treatment

Procedia PDF Downloads 406

Authors: Simon Mensah Ofosu

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Illicit surface mining activities pollutes agricultural lands and water bodies and results in accumulation of heavy metals in vegetables cultivated in such areas. Heavy metal (HM) accumulation in vegetables is a serious food safety issues due to the adverse effects of metal toxicities, hence the need to investigate the levels of these metals in cultivated vegetables in the eastern region. Cocoyam leaves, cabbage and cucumber were sampled from selected farms in mining areas (Atiwa District) and non -mining areas (Yilo Krobo and East Akim District) of the region for the study. Levels of Cadmium, Lead, Mercury and Arsenic were investigated in the vegetables with Atomic Absorption Spectrometer, and the results statistically analyzed with Microsoft Office Excel (2013) Spread Sheet and ANOVA. Cadmium (Cd) and arsenic (As) were the highest and least concentrated HM in the vegetables sampled, respectively. The mean concentrations of Cd and Pb in cabbage (0.564 mg/kg, 0.470 mg/kg), cucumber (0.389 mg/kg, 0.190 mg/kg), cocoyam leaves (0.410 mg/kg, 0.256 mg/kg) respectively from the mining areas exceeded the permissible limits set by Joint FAO/WHO. The mean concentrations of the metals in vegetables from the mining and non-mining areas varied significantly (P<0.05). The Target Hazard Quotient (THQ) was used to assess the health risk posed to the human population via vegetable consumption. The THQ values of cadmium, mercury, and lead in adults and children through vegetable consumption in the mining areas were greater than 1 (THQ >1). This indicates the potential health risk that the children and adults may be facing. The THQ values of adults and children in the non-mining areas were less than the safe limit of 1 (THQ<1), hence no significant health risk posed to the population from such areas.

Keywords: food safety, risk assessment, illicit mining, public health, contaminated vegetables

Procedia PDF Downloads 59

Authors: G. Petruzzelli, F. Pedron, M. Grifoni, A. Pera, I. Rosellini, B. Pezzarossa

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The addition of lime as Ca(OH)2 to sewage sludge to destroy pathogens (Escherichia coli), was evaluated also in relation to heavy metal bioavailability. The obtained results show that the use of calcium hydroxide at the dose of 3% effectively destroyed pathogens ensuring the stability at high pH values over long period and the duration of the sewage sludge stabilization. In general, lime addition decreased the total extractability of heavy metals indicating a reduced bioavailability of these elements. This is particularly important for a safe utilization in agricultural soils to reduce the possible transfer of heavy metals to the food chain.

Keywords: biological sludge, Ca(OH)2, copper, pathogens, sanitation, zinc

Procedia PDF Downloads 401

Authors: Muhammad Dildar Gogi, Muhammad Arshad, Muhammad Ahsan Khan, M. Sufian, Ahmad Nawaz, Mubashir Iqbal, Muhammad Junaid Nisar, Waleed Afzal Naveed

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Larvae of silkworm (Bombyx mori) exhibit very high mortality when reared on mulberry leaves collected from mulberry orchards which get contaminated with metallic/nonmetallic compounds through either drift-deposition or chemigation. There is need to screen out such metallic compound for their toxicity at their various concentrations. The present study was carried out to assess toxicity of metals in different instars of silkworm. Aqueous solutions of nine heavy-metal based salts were prepared by dissolving 50, 100, 150, 200, 250, 300, 350 and 400 mg of each salt in one liter of water and were applied on the mulberry leaves by leaf-dip methods. The results reveal that mortality in 1st, 2nd, 3rd, 4th and 5th instar larvae caused by each heavy metal salts increased with an increase in their concentrations. The 1st instar larvae were found more susceptible to metal salts followed by 2nd, 3rd, 4th and 5th instar larvae of silkworm. Overall, Nickel chloride proved more toxic for all larval instar as it demonstrated approximately 40-99% mortality. On the basis of LC2 and larval mortality, the order of toxicity of heavy metals against all five larval instar was Nickel chloride (LC₂ = 1.9-13.9 mg/L; & 15.0±1.2-69.2±1.7% mortality) followed by Chromium nitrate (LC₂ = 3.3-14.8 mg/L; & 13.3±1.4-62.4±2.8% mortality), Cobalt nitrate (LC₂ = 4.3-30.9; &11.4±0.07-54.9±2.0% mortality), Lead acetate (LC₂ =8.8-53.3 mg/L; & 9.5±1.3-46.4±2.9% mortality), Aluminum sulfate (LC₂ = 15.5-76.6 mg/L; & 8.4±0.08-42.1±2.8% mortality), Barium sulfide (LC₂ = 20.9-105.9; & 7.7±1.1-39.2±2.5% mortality), Copper sulfate (LC2 = 28.5-12.4 mg/L; & 7.3±0.06-37.1±2.4% mortality), Manganese chloride (LC₂ = 29.9-136.9 mg/L; & 6.8±0.09-35.3±1.6% mortality) and Zinc nitrate (LC₂ = 36.3-15 mg/L; & 6.2±1.2-32.1±1.9% mortality). Zinc nitrate @ 50 and 100 mg/L, Barium sulfide @ 50 mg/L, Manganese chloride @ 50 and 100 mg/L and Copper sulfate @ 50 mg/L proved safe for 5th instar larvae as these interaction attributed no mortality. All the heavy metal salts at a concentration of 50 mg/L demonstrated less than 10% mortality.

Keywords: heavy-metals, larval-instars, lethal-concentration, mortality, silkworm

Procedia PDF Downloads 185

Authors: Mariam Aljumaa

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Industrial wastewater has been increased rapidly in the last decades, however, the generated wastewater is not treated properly on site before transfer it to the treatment plant. In this study, the most common industries (dairy, soft drinks, detergent, and petrochemical) has been studied in term of wastewater quality. The main aim of this study is to characterize and evaluate the quality of the most common industrial wastewater in Kuwait. Industrial wastewater samples were collected from detergents, dairy, beverage, and petrochemical factories. The collected wastewater samples were analyzed for temperature, EC, pH, DO, BOD, COD, TOC, TS, TSS, volatile suspended solids (VSS), total volatile solids (TVS), NO2, NO3, NH3, N, P, K, CaCO3, heavy metals, Total coliform, Fecal coliform, and E.coli bacteria. The results showed that petrochemical industry has the highest concentration of organic and nutrients, followed by detergents wastewater, then dairy, and finally, soft drink wastewater. Regarding the heavy metals, the results showed that dairy wastewater had the highest concentration, specifically in Zinc, Arsenic, and Cadmium. In term of biological analysis, the dairy industry had the highest concentration of total coliform, followed by soft drinks industry, then shampoo industry, and finally petrochemical industry.

Keywords: industrial wastewater, characterization, heavy metals, wastewater quality

Procedia PDF Downloads 59

Authors: Tengfei He, Mengjie Zhang, Baosheng Jin

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In this study, the low-cost halloysite (Hal) was utilized for the first time to enhance the solid-phase enrichment and stability of heavy metals (HMs) during solid waste pyrolysis through experimental and theoretical methods, and compared with kaolinite (Kao). Experimental results demonstrated that Hal was superior to Kao in improving the solid-phase enrichment of HMs. Adding Hal reduced the proportion of HMs in the unstable fraction (F1+F2), consequently lowering the environmental risk of biochar and the extractable state of HMs. Through Grand canonical Monte Carlo and Density Functional Theory (DFT) simulations, the adsorption amounts and adsorption mechanisms of Cd/Pb compound on Hal/Kao surfaces were analyzed. The adsorption amounts of HMs by Hal were significantly higher than Kao and decreased with increasing temperature, and the difference in adsorption performance caused by structural bending was negligible. The DFT results indicated that Cd/Pb monomers were stabilized by establishing covalent bonds with OH or reactive O atoms on the Al-(0 0 1) surface, whereas the covalent bonds with ionic bonding properties formed between Cl atoms and unsaturated Al atoms played a crucial role in stabilizing HM chlorides. This study highlights the potential of Hal in stabilizing HMs during pyrolysis without requiring any modifications.

Keywords: heavy metals, halloysite, density functional theory, grand canonical Monte Carlo

Procedia PDF Downloads 48

Authors: Monu Verma, Hyunook Kim

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Heavy metals and organic dyes are the major sources of water pollution. Herein, a trifunctional β−cyclodextrin−ethylenediaminetetraacetic acid−chitosan (β−CD−EDTA−CS) polymer was synthesized using an easy and simple chemical route by the reaction of activated β−CD with CS through EDTA as a cross-linker (amidation reaction) for the removal of inorganic and organic pollutants from aqueous solution under different parameters such as pH, time effect, initial concentration, reusability, etc. The synthesized adsorbent was characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, field scanning electron microscopy, energy dispersive spectroscopy, Brunauer-Emmett-Teller (BET), thermogravimetric analyzer techniques to investigate their structural, functional, morphological, elemental compositions, surface area, and thermal properties, respectively. Two types of heavy metals, i.e., mercury (Hg²⁺) and cadmium (Cd²⁺), and three organic dyes, i.e., methylene blue (MB), crystal violet (CV), and safranin O (SO), were chosen as inorganic and organic pollutants, respectively, to study the adsorption capacity of β-CD-EDTA-CS in aqueous solution. The β-CD-EDTA-CS shows a monolayer adsorption capacity of 346.30 ± 14.0 and 202.90 ± 13.90 mg g−¹ for Hg²⁺ and Cd²⁺, respectively, and a heterogeneous adsorption capacity of 107.20 ± 5.70, 77.40 ± 5.30 and 55.30 ± 3.60 mg g−¹ for MB, CV and SO, respectively. Kinetics results followed pseudo-second order (PSO) kinetics behavior for both metal ions and dyes, and higher rate constants values (0.00161–0.00368 g mg−¹ min−¹) for dyes confirmed the cavitation of organic dyes (physisorption). In addition, we have also demonstrated the performance of β-CD-EDTA-CS for the four heavy metals, Hg²⁺, Cd²⁺, Ni²⁺, and Cu²⁺, and three dyes MB, CV, and SO in secondary treated wastewater. The findings of this study indicate that β-CD-EDTA-CS is simple and easy to synthesize and can be used in wastewater treatment.

Keywords: adsorption isotherms, adsorption mechanism, amino-β-cyclodextrin, heavy metal ions, organic dyes

Procedia PDF Downloads 79

Authors: Mozhgan Bahadory, Gholam-Hossein Rostami

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Over the next quarter of a century, the US government and the private sector will spend billions of dollars annually to clean the contaminated sites from pollution such as petroleum products, heavy metals, and solvents organic compounds. During the past three decades, almost 750,000 sites that require remediation have been reported to the United States federal and state agencies. Out of these contamination sites, approximately 300,000 are still in need of remediation. In these sites, the most widespread forms of contamination are petroleum products and heavy metals. At least half of US Department of Defense, US Department of Energy, Superfund sites, and Resource Conservation and Recovery Act (RCRA) sites have been reported to contain heavy metals. Heavy metals most often found in the contaminated water are lead, mercury, chromium, cadmium, arsenic, and zinc. This investigation emphasizes the elimination of arsenic and cadmium from aqueous solution. During the past several years, we developed a novel material called Alkali-Activated fly ash Material Permeable Reactive Barrier (AAM-PRB), which includes fly ash, fine aggregates, coarse aggregates, activating chemicals, and water. AAM can be produced with high permeability, 10-1 cm/s, then crushed into pelletized form. Laboratory experiments showed that water containing 10 ppm, 100 ppm, and 1000 ppm of arsenic and cadmium ion passing through AAM-PRB reduced to less than 0.1 ppm. However, water containing 10,000 ppm arsenic ion passing through AAM- PRB shows that the breakthrough was achieved. The removal of the mixture of arsenic and cadmium from aqueous solutions was also tested by using AAM-PRB. The results indicate that the efficiency of AAM-PRB for simultaneous removal of arsenic and cadmium from 10 ppm, 100 ppm, and 1,000 ppm were marginally below that of arsenic alone. Still, it was significantly lower for cadmium from the aqueous solution. The basic science behind removing heavy metal and microstructural investigation AAM-PRB will be the focus of our future work.

Keywords: arsenic, cadmium, contaminated water, fly ash, permeability, reactive barrier

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Authors: Soumita Mitra, Santosh Kumar Sarkar

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Hooghly river estuary (HRE), situated at the north eastern part of Bay of Bengal has global significance due to its holiness. It is of immense importance to the local population as it gives perpetual water supply for various activities such as transportation, fishing, boating, bathing etc. to the local people who settled on both the banks of this estuary. This study was done to assess the dissolved and particulate trace metal in the estuary covering a stretch of about 175 Km. The water samples were collected from the surface (0-5 cm) along the salinity gradient and metal concentration were studied both in dissolved and particulate phase using Graphite Furnace Atomic Absorption Spectrophotometer (GF-AAS) along some physical characteristics such as water temperature, salinity, pH, turbidity and total dissolved solids. Although much significant spatial variation was noticed but little enrichment was found along the downstream of the estuary. The mean concentration of the metals in the dissolved and particulate phase followed the same trend and as follows: Fe>Mn>Cr>Zn>Cu>Ni>Pb. The concentration of the metals in the particulate phase were much greater than that in dissolved phase which was also depicted from the values of the partition coefficient (Kd)(ml mg-1). The Kdvalues ranged from 1.5x105 (in case of Pb) to 4.29x106 (in case of Cr). The high value of Kd for Cr denoted that the metal Cr is mostly bounded with the suspended particulate matter while the least value for Pb signified it presence more in dissolved phase. Moreover, the concentrations of all the studied metals in the dissolved phase were many folds higher than their respective permissible limits assested by WHO 2008, 2009 and 2011. On the other hand, according to Sediment Quality Guidelines (SQGs), Zn, Cu and Ni in the particulate phase lied between ERL and ERM values but Cr exceeded ERM values at all the stations confirming that the estuary is mostly contaminated with the particulate Cr and it might cause frequent adverse effects on the aquatic life. Multivariate statistics Cluster analysis was also performed which separated the stations according to the level of contamination from several point and nonpoint sources. Thus, it is found that the estuarine system is much polluted by the toxic metals and further investigation, toxicological studies should be implemented for full risk assessment of this system, better management and restoration of the water quality of this globally significant aquatic system.

Keywords: dissolved and particulate phase, Hooghly river estuary, partition coefficient, surface water, toxic metals

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Authors: Sandra H. Fukurozaki, Andre L. N. Silva, Joao B. F. Neto, Fernando J. G. Landgraf

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Nowadays, the rare earth (RE) metals play an important role in emerging technologies that are crucial for the decarbonisation of the energy sector. Their unique properties have led to increasing clean energy applications, such as wind turbine generators, and hybrid and electric vehicles. Despite the substantial media coverage that has recently surrounded the mining and processing of rare earth metals, very little quantitative information is available concerning their subsequent life stages, especially related to the metallic production of didymium (Nd-Pr) in fluoride molten salt system. Here we investigate a gate to gate scale life cycle assessment (LCA) of the didymium electrolysis based on three different scenarios of operational conditions. The product system is modeled with SimaPro Analyst 8.0.2 software, and IMPACT 2002+ was applied as an impact assessment tool. In order to develop a life cycle inventories built in software databases, patents, and other published sources together with energy/mass balance were utilized. Analysis indicates that from the 14 midpoint impact categories evaluated, the global warming potential (GWP) is the main contributors to the total environmental burden, ranging from 2.7E2 to 3.2E2 kg CO2eq/kg Nd-Pr. At the damage step assessment, the results suggest that slight changes in materials flows associated with enhancement of current efficiency (between 2.5% and 5%), could lead a reduction up to 12% and 15% of human health and climate change damage, respectively. Additionally, this paper highlights the knowledge gaps and future research efforts needing to understand the environmental impacts of Nd-Pr electrolysis process from the life cycle perspective.

Keywords: didymium electrolysis, environmental impacts, life cycle assessment, rare earth metals

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Authors: Linus O. Asuquo

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Mining in Nigeria and development effort of metallurgical technologies at National Metallurgical Development Centre Jos has been addressed in this paper. The paper has looked at the history of mining in Nigeria, the impact of mining on social and industrial development, and the contribution of the mining sector to Nigeria’s Gross Domestic Product (GDP). The paper clearly stated that Nigeria’s mining sector only contributes 0.5% to the nation’s GDP unlike Botswana that the mining sector contributes 38% to the nation’s GDP. Nigeria Bureau of Statistics has it on record that Nigeria has about 44 solid minerals awaiting to be exploited. Clearly highlighted by this paper is the abundant potentials that exist in the mining sector for investment. The paper made an exposition on the extensive efforts made at National Metallurgical Development Center (NMDC) to develop metallurgical technologies in various areas of the metals sector; like mineral processing, foundry development, nonferrous metals extraction, materials testing, lime calcination, ANO (Trade name for powder lubricant) wire drawing lubricant, refractories and many others. The paper went ahead to draw a conclusion that there is a need to develop the mining sector in Nigeria and to give a sustainable support to the efforts currently made at NMDC to develop metallurgical technologies which are capable of transforming the metals sector in Nigeria, which will lead to industrialization. Finally the paper made some recommendations which traverse the topic for the best expectation.

Keywords: mining, minerals, technologies, value addition

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Authors: Souhila Terfi, Fatma Hassaine-Sadi

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In the present study, wet digestion with HCl and HNO3 mixture was used to extract the heavy metals (copper (Cu), chromium (Cr), zinc (Zn), lead (Pb) and cadmium (Cd)) from the leaves, the stems and the roots of Malva sylvestris L., which were subsequently analyzed by AAS. The samples (soil and parts of species) were collected from different sites: the industrial area (IA) (Rouiba), the rubbish dump area (RDA) (Boudouaou), the residential area (RA) with large open fields and construction activities (Blida), the Montaigne area (MA) (Chrea) and the high plateau area (HPA) (Berouaguia). The study showed differences in metal concentrations according to the analysed parts and the different sampling locations. In the contaminated site of the industrial area (IA), high content of the toxic heavy metals (Cd: 3.18 µg/g DW and Pb: 34.48 µg/g DW) were found in the leaves of Malva sylvestris L. This finding suggests that the consumers of this species could be exposed to a risk associated with this higher level of these toxic metals. It was found that Malva sylvestris L. is rich by Zn and Cu in some sites, which are considered to be the essential elements for the human health. The obtained results with the control site (Montaigne area) suggest that this species can be applicable in both the health and food, feasible alternatives as medicinal plant without any risk.

Keywords: Malva sylvestris L., toxic heavy metal, medicinal plant, impact on human health

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Authors: N. Cetinkaya, F. Erdem

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Juncus acutus (Juncaceae) is a perennial wetland plant and it is commonly known as spiny rush or sharp rush. It is the most abundant plant in Kizilirmak grassland, Samsun, Turkey. Heavy metals are significant environmental contaminants in delta and their toxicity is an increasing problem for animals whose natural habitat is delta. The objective of this study was to evaluate heavy metal concentrations mainly As, Cd, Sb, Ba, Pb and Hg in stem and seed of Juncus acutus for grazing animals and birds in delta. The Juncus acutus stem and seed samples were collected from Kizilirmak Delta in July, August and September. Heavy metal concentrations of collected samples were analyzed by Inductively Coupled Plasma – Mass Spectrometer (ICP-MS). The obtained mean values of three months for As, Cd, Sb, Ba, Pb and Hg of stem and seed samples of Juncus acutus were 0.11 and 0.23 mg/kg; 0.07 and 0.11 mg/kg; 0.02 and 0.02 mg/kg; 5.26 and 1.75 mg/kg; 0.05 and not detectable in July respectively. Hg was not detected in both stem and seed of Juncus acutus, Pb concentration was determined only in stem of Juncus acutus but not in seed. There were no significant differences between the values of three months for As, Cd, Sb, Ba, Pb and Hg of stem and seed samples of Juncus acutus. The obtained As, Cd, Sb, Ba, Pb and Hg results of stem and seed of Juncus acutus show that seed and stem of Juncus acutus may be safely consumed for grazing animals and birds regarding to heavy metals contamination in Kizilirmak Delta.

Keywords: heavy metals, Juncus acutus, Kizilirmak Delta, wetland

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Authors: Akanimo Emene, Robert Edyvean

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In developing countries, a low cost method of wastewater treatment is highly recommended. Adsorption is an efficient and economically viable treatment process for wastewater. The utilisation of this process is based on the understanding of the relationship between the growth environment and the metal capacity of the biomaterial. Luffa cylindrica (LC), a plant material, was used as an adsorbent in adsorption design system of heavy metals. The chemically modified LC was used to adsorb heavy metals ions, lead and cadmium, from aqueous environmental solution at varying experimental conditions. Experimental factors, adsorption time, initial metal ion concentration, ionic strength and pH of solution were studied. The chemical nature and surface area of the tissues adsorbing heavy metals in LC biosorption systems were characterised by using electron microscopy and infra-red spectroscopy. It showed an increase in the surface area and improved adhesion capacity after chemical treatment. Metal speciation of the metal ions showed the binary interaction between the ions and the LC surface as the pH increases. Maximum adsorption was shown between pH 5 and pH 6. The ionic strength of the metal ion solution has an effect on the adsorption capacity based on the surface charge and the availability of the adsorption sites on the LC. The nature of the metal-surface complexes formed as a result of the experimental data were analysed with kinetic and isotherm models. The pseudo second order kinetic model and the two-site Langmuir isotherm model showed the best fit. Through the understanding of this process, there will be an opportunity to provide an alternative method for water purification. This will be provide an option, for when expensive water treatment technologies are not viable in developing countries.

Keywords: adsorption, luffa cylindrica, metal-surface complexes, pH

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Authors: Brahim Merdas, Abdelhak Boutaleb

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Polymetallic mineralizations with Zn, Sb, Pb boxed in miopliocene limestones of Hammam N’bails’s basin are regarded as the youngest mineralizations of North East of Algeria and are characterized by the presence of rather rare mineral phases throughout the world such as nadorite and flajolotite. Mineralization seems to have a bond with thermal springs emergent within the basin and with the faults which limit the basin. The comparison between mineralizations and similar ore deposits known in the world and which are characterized by the presence of the noble metals such as gold and the discovery of traces of this metal (1.4g/t) enables us to start again the problems of the noble metals of the type “low sulfidation” related to the thermal springs in the area in particular and in all Algerian North generally.

Keywords: Nadorite, galana, gold, dolomitisation, epigenétic, hot springs, , miopliocene, Hammam N’bails, algeria

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Authors: Grace O. Akinlade, Danjuma D. Maza, Oluwakemi O. Olawolu, Delight O. Babalola, John A. O. Oyekunle, Joshua O. Ojo

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The Mokuro area of Ile-Ife, South West Nigeria, was well known for gold mining in the past (about twenty years ago). However, the place has since been reclaimed and converted to residential area without any environmental risk assessment of the impact of the mining tailings on the environment. Soil, water, and plant samples were collected from 4 different locations around the mine-turned-residential area. Soil samples were pulverized and sieved into finer particles, while the plant samples were dried and pulverized. All the samples were digested and analyzed for As, Pb, Cd, and Zn using atomic absorption spectroscopy (AAS). From the analysis results, the hazard index (HI) was then calculated for the metals. The soil and plant samples were air dried and pulverized, then weighed, after which the samples were packed into special and properly sealed containers to prevent radon gas leakage. After the sealing, the samples were kept for 28 days to attain secular equilibrium. The concentrations of 40K, 238U, and 232Th in the samples were measured using a cesium iodide (CsI) spectrometer and URSA software. The AAS analysis showed that As, Pb, Cd (Toxic metals), and Zn (essential trace metals) are in concentrations lower than permissible limits in plants and soil samples, while the water samples had concentrations higher than permissible limits. The calculated health indices (HI) show that HI for water is >1 and that of plants and soil is <1. Gamma spectrometry result shows high levels of activity concentrations above the recommended limits for all the soil and plant samples collected from the area. Only the water samples have activity concentrations below the recommended limit. Consequently, the absorbed dose, annual effective dose, and excess lifetime cancer risk are all above the recommended safe limit for all the samples except for water samples. In conclusion, all the samples collected from the area are either contaminated with toxic metals or they pose radiological hazards to the consumers. Further detailed study is therefore recommended in order to be able to advise the residents appropriately.

Keywords: toxic metals, gamma spectrometry, Ile-Ife, radiological hazards, gold mining

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Authors: Vesna Karapetkovska Hristova, M. Ayaz Ahmad, Julijana Tomovska, Biljana Bogdanova Popov, Blagojce Najdovski

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The average total concentrations of heavy metals; (cadmium [Cd], copper [Cu], nickel [Ni], lead [Pb], and zinc [Zn]) were analyzed in soil and vegetables samples collected from the different region of Macedonia during the years 2010-2012. Basic soil properties such as pH, organic matter and clay content were also included in the study. The average concentrations of Cd, Cu, Ni, Pb, Zn in the A horizon (0-30 cm) of agricultural soils were as follows, respectively: 0.25, 5.3, 6.9, 15.2, 26.3 mg kg-1 of soil. We have found that neural networking model can be considered as a tool for prediction and spatial analysis of the processes controlling the metal transfer within the soil-and vegetables. The predictive ability of such models is well over 80% as compared to 20% for typical regression models. A radial basic function network reflects good predicting accuracy and correlation coefficients between soil properties and metal content in vegetables much better than the back-propagation method. Neural Networking / soft computing can support the decision-making processes at different levels, including agro ecology, to improve crop management based on monitoring data and risk assessment of metal transfer from soils to vegetables.

Keywords: soft computing approach, total concentrations, heavy metals, agricultural soils

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Authors: W. E. Igwegbe, B. C. Okoro, J. C. Osuagwu

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The study was aimed at assessing the effectiveness of reducing the concentrations of heavy metals in waste water using Pawpaw (Carica papaya) wood as a bio-sorbent. The heavy metals considered include; zinc, cadmium, lead, copper, iron, selenium, nickel, and manganese. The physiochemical properties of carica papaya stem were studied. The experimental sample was obtained from a felled trunk of matured pawpaw tree. Waste water for experimental use was prepared by dissolving soil samples collected from a dump site at Owerri, Imo state in water. The concentration of each metal remaining in solution as residual metal after bio-sorption was determined using Atomic absorption Spectrometer. The effects of ph, contact time and initial heavy metal concentration were studied in a batch reactor. The results of Spectrometer test showed that there were different functional groups detected in the carica papaya stem biomass. Optimum bio-sorption occurred at pH 5.9 with 5g/100ml solution of bio-sorbent. The results of the study showed that the treated wastewater is fit for irrigation purpose based on Canada wastewater quality guideline for the protection of Agricultural standard. This approach thus provides a cost effective and environmentally friendly option for treating waste water.

Keywords: biomass, bio-sorption, Carica papaya, heavy metal, wastewater

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Authors: Derin Ureten

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Plastic pollution does not disappear, it gets smaller and smaller through photolysis which are caused mainly by sun’s radiation, thermal oxidation, thermal degradation, and biodegradation which is the action of organisms digesting larger plastics. All plastic pollutants have exceedingly harmful effects on the environment. Together with the COVID-19 pandemic, the number of plastic products such as masks and gloves flowing into the environment has increased more than ever. However, microplastics are not the only pollutants in water, one of the most tenacious and toxic pollutants are heavy metals. Heavy metal solutions are also capable of causing varieties of health problems in organisms such as cancer, organ damage, nervous system damage, and even death. The aim of this research is to prove that microplastics can be used in wastewater treatment systems by proving that they could adsorb heavy metals in solutions. Experiment for this research will include two heavy metal solutions; one including microplastics in a heavy metal contaminated water solution, and one that just includes heavy metal solution. After being sieved, absorbance of both mediums will be measured with the help of a spectrometer. Iron (III) chloride (FeCl3) will be used as the heavy metal solution since the solution becomes darker as the presence of this substance increases. The experiment will be supported by Pure Nile Red powder in order to observe if there are any visible differences under the microscope. Pure Nile Red powder is a chemical that binds to hydrophobic materials such as plastics and lipids. If proof of adsorbance could be observed by the rates of the solutions' final absorbance rates and visuals ensured by the Pure Nile Red powder, the experiment will be conducted with different temperature levels in order to analyze the most accurate temperature level to proceed with removal of heavy metals from water. New wastewater treatment systems could be generated with the help of microplastics, for water contaminated with heavy metals.

Keywords: microplastics, heavy metal, pollution, adsorbance, wastewater treatment

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