Search results for: ammonia hydrogen sulphide and removal

Authors: Abdulrazak Jinadu Otaru, Ahmed Almulhim, Hassan Alhassan, Mohammed Sabri

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Saudi Arabia is host to a state-owned oil and gas corporation, known as Saudi ARAMCO, that is responsible for the highest emissions of carbon dioxide (CO₂) due to the heavy reliance on fossil fuels as an energy source for various sectors such as transportation, aerospace, manufacturing, and residential use. Unfortunately, the detrimental consequences of CO₂ emissions include escalating temperatures in the Middle East region, posing significant obstacles in terms of food security and water scarcity for the Kingdom of Saudi Arabia. As part of the Saudi Vision 2030 initiative, which aims to reduce the country's reliance on fossil fuels by 50 %, this study focuses on designing a plant that will produce approximately 100,000 metric tons per year (MTPY) of green hydrogen (H₂) using brine as the primary feedstock. The proposed facility incorporates a double electrolytic technology that first separates brine or sodium chloride (NaCl) into sodium hydroxide, hydrogen gas, and chlorine gas. The sodium hydroxide is then used as an electrolyte in the splitting of water molecules through the supply of electrical energy in a second-stage electrolyser to produce green hydrogen. The study encompasses a comprehensive analysis of process descriptions and flow diagrams, as well as materials and energy balances. It also includes equipment design and specification, cost analysis, and considerations for safety and environmental impact. The design capitalizes on the abundant brine supply, a byproduct of the world's largest desalination plant located in Al Jubail, Saudi Arabia. Additionally, the design incorporates the use of available renewable energy sources, such as solar and wind power, to power the proposed plant. This approach not only helps reduce carbon emissions but also aligns with Saudi Arabia's energy transition policy. Furthermore, it supports the United Nations Sustainable Development Goals on Sustainable Cities and Communities (Goal 11) and Climate Action (Goal 13), benefiting not only Saudi Arabia but also other countries in the Middle East.

Keywords: plant design, electrolysis, brine, sodium hydroxide, chlorine gas, green hydrogen

Procedia PDF Downloads 49

Authors: Bessaha Hassiba, Bouraada Mohamed

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Layered double hydroxide with Zn/(Al+Fe) molar ratio of 3:1 was synthesized by co-precipitation method and their calcined product was obtained by heating treatment of ZAF-HT at 500°C. The calcined and uncalcined materials were used to remove weak acid dyes: indigo carmine (IC) and green bezanyl-F2B (F2B) in aqueous solution. The synthesized materials were characterized by XRD, SEM, FTIR and TG/DTA analysis confirming the formation of pure layered structure of ZAF-HT, the destruction of the original structure after calcination and the intercalation of the dyes molecules. Moreover, the interlayer distance increases from 7.645 Å in ZAF-HT to 19.102 Å after the dyes sorption. The dose of the adsorbents was chosen 0.5 g/l while the initial concentrations were 250 and 750 mg/l for indigo carmine and green bezanyl-F2B respectively. The sorption experiments were carried out at ambient temperature and without adjusting the initial solution pH (pHi = 6.10 for IC and pHi = 5.01 for F2B). In addition, the maximum adsorption capacities obtained by ZAF-HT and CZAF for both dyes followed the order: CZAF-F2B (1501.4 mg.g-1) > CZAF-IC (617.3 mg.g-1) > ZAF-HT-IC (41.4 mg.g-1) > ZAF-HT-F2B (28.9 mg.g-1). The removal of indigo carmine and green bezanyl-F2B by ZAF-HT was due to the anion exchange and/or the adsorption on the surface. By using the calcined material (CZAF), the removal of the dyes was based on a particular property, called ‘memory effect’. CZAF recover the pristine structure in the presence anionic molecules such as acid dyes where they occupy the interlayer space. The sorption process was spontaneous in nature and followed pseudo-second-order. The isotherms showed that the removal of IC and F2B by ZAF-HT and CZAF were consistent with Langmiur model.

Keywords: acid dyes, adsorption, calcination, layered double hydroxides

Procedia PDF Downloads 223

Authors: K. V. Kalinichenko, G. N. Nikovskaya

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The efficiency of heavy metals removal from sewage sludge in bioleaching with heterotrophic, chemoautotrophic (sulphur-oxidizing) sludge cenoses and chemical leaching (in distilled water, weakly acidic or alkaline medium) was compared. The efficacy of heavy metals removal from sewage sludge varied from 83 % (Zn) up to 14 % (Cr) and followed the order: Zn > Mn > Cu > Ni > Co > Pb > Cr. The advantages of metals bioleaching process at heterotrophic metabolism was shown. A new process for bioconversation of sewage sludge into fertilizer at middle temperature after partial heavy metals removal was developed. This process is based on enhancing vital ability of heterotrophic microorganisms by adding easily metabolized nutrients and synthesis of metabolites by growing sludge cenoses. These metabolites possess the properties of heavy metals extractants and flocculants which provide sludge flocks sedimentation and concentration. The process results in biomineral fertilizer with immobilized sludge bioelements with prolonged action. The fertilizer obtained satisfied the EU limits for the sewage sludge of agricultural utilization. High efficiency of the biomineral fertilizers obtained has been demonstrated in vegetation experiments.

Keywords: fertilizer, heavy metals, leaching, sewage sludge

Procedia PDF Downloads 390

Authors: Rahim Shahrokhi, Junboum Park

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Per- and Polyfluoroalkyl Substances (PFASs) are environmentally persistent halogenated hydrocarbons that have been widely used in many industrial and commercial applications. Recently, contaminating the soil and groundwater due to the ubiquity of PFAS in environments has raised great concern. Adsorption technology is one of the most promising methods for PFAS removal. Chitosan is a biopolymer substance with abundant amine and hydroxyl functional groups, which render it a good adsorbent. This study has tried to enhance the adsorption capacity of chitosan by grafting more amine functional groups on its surface for the removal of two long (PFOA and PFOS) and two short-chain (PFBA, PFBS) PFAS substances from the aqueous phase. A series of batch adsorption tests have been performed to evaluate the adsorption capacity of the used sorbent. Also, the sorbent was analyzed by SEM, FT-IR, zeta potential, and XRD tests. The results demonstrated that both chitosan beads have good potential for adsorbing short and long-chain PFAS from the aqueous phase.

Keywords: PFAS, chitosan beads, adsorption, grafted chitosan

Procedia PDF Downloads 65

Authors: Neera Singh, Devendra Kumar, Om Parkash

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We have synthesized nanocrystalline Fe-Ni alloy powders where Ni varies as 10, 30 and 50 mole% by a wet chemical route (sol-gel auto-combustion) followed by reduction in hydrogen atmosphere. The ratio of citrate to nitrate was maintained at 0.3 where citric acid has worked as a fuel during combustion. The reduction of combusted powders was done at 700°C/1h in hydrogen atmosphere using an atmosphere controlled quartz tube furnace. Phase and microstructure analysis has shown the formation of α-(Fe,Ni) and γ-(Fe,Ni) phases after reduction. An increase in Ni concentration resulted in more γ-(Fe,Ni) formation where complete γ-(Fe,Ni) formation was achieved at 50 mole% Ni concentration. Formation of particles below 50 nm size range was confirmed using Scherrer’s formula and Transmission Electron Microscope. The work is aimed at the effect of Ni concentration on phase, microstructure and magnetic properties of synthesized alloy powders.

Keywords: combustion, microstructure, nanocrystalline, reduction

Procedia PDF Downloads 183

Authors: Eya Hentati, Mona Lamine, Jalel Bouzid

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In this study, a laboratory-scale was designed and fabricated to treat single house greywater in the north of Tunisia with a combination of physical and natural treatments systems. The combined system includes a bio-filter composed of LECA® (lightweight expanded clay aggregate) followed by a vertical up-flow constructed wetland planted with Iris pseudacorus and Typha Latifolia. Applied two hydraulic retention times (HRTs) with two different plants types showed that a bio-filter planted with Typha Latifolia has an optimum removal efficiency for degradation of organic matter and transformation of nitrogen and phosphate at HRT of 30 h. The optimum removal efficiency of biochemical oxygen demand (BOD), chemical oxygen demand (COD), and suspended solids (SS) ranged between 48-65%, between while the nutrients removal was in the range of 70% to 90%. Fecal coliforms dropped by three to four orders of magnitude from their initial concentration, but this steel does not meet current regulations for unlimited irrigation. Hence further improvement procedures are suggested.

Keywords: constructed wetland, greywater treatment, nutriments, organics

Procedia PDF Downloads 167

Authors: Rajalaxmi N., Padma Bhat, Pooja Garag, Pooja N. M., V. S. Hombalimath

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Microbial fuel cell (MFC) is the advancement of science that aims at utilizing the oxidizing potential of bacteria for wastewater treatment and production of bio-hydrogen and bio-electricity. Salt-bridge is the economic alternative to highly priced proton-exchange membrane in the construction of a microbial fuel cell. This paper studies the electricity generating capacity of E.coli and Clostridium sporogenes in microbial fuel cells (MFCs). Unlike most of MFC research, this targets the long term goals of renewable energy production and wastewater treatment. In present study the feasibility and potential of bioelectricity production from different wastewater was observed. Different wastewater was primarily treated which were confirmed by the COD tests which showed reduction of COD. We observe that the electricity production of MFCs decreases almost linearly after 120 hrs. The sewage wastewater containing Clostridium sporogenes showed bioelectricity production up to 188mV with COD removal of 60.52%. Sewage wastewater efficiently produces bioelectricity and this also helpful to reduce wastewater pollution load.

Keywords: microbial fuel cell, bioelectricity, wastewater, salt bridge, COD

Procedia PDF Downloads 538

Authors: Sudhanshu Kumar

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Electrical discharge machining, also known as EDM, process is one of the most applicable machining process for removal of material in hard to machine materials like superalloy metals. EDM process utilizes electrical energy into sparks to erode the metals in presence of dielectric medium. In the present investigation, superalloy, Inconel 718 has been selected as workpiece and electrolytic copper as tool electrode. Attempt has been made to understand the effect of size of tool with varying cavity depth during drilling of hole through EDM process. In order to systematic investigate, tool size in terms of tool diameter and cavity depth along with other important electrical parameters namely, peak current, pulse-on time and servo voltage have been varied at three different values and the experiments has been designed using fractional factorial (Taguchi) method. Each experiment has been repeated twice under the same condition in order to understand the variability within the experiments. The effect of variations in parameters has been evaluated in terms of material removal rate, tool wear rate and surface roughness. Results revel that change in tool diameter during machining affects the response characteristics significantly. Larger tool diameter yielded 13% more material removal rate than smaller tool diameter. Analysis of the effect of variation in cavity depth is notable. There is no significant effect of cavity depth on material removal rate, tool wear rate and surface quality. This indicates that number of experiments can be performed to analyze other parameters effect even at smaller depth of cavity which can reduce the cost and time of experiments. Further, statistical analysis has been carried out to identify the interaction effect between parameters.

Keywords: EDM, Inconel 718, material removal rate, roughness, tool wear, tool size

Procedia PDF Downloads 217

Authors: Ammar Maziz, Prateek Gupta, Thiago Vasconcellos Birro, Benoit Gely

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Hydrogen as a sustainable fuel has the highest energy density per mass as compared to conventional non-renewable sources. As the world looks to move towards sustainability, especially in the sectors of aviation and automotive, it becomes important to address the issue of storage of hydrogen as compressed gas in high-pressure tanks. To improve the design for the efficient storage and transportation of Hydrogen, this paper presents the design and stress analysis of Dome Composite Overwrapped Pressure Vessels (COPVs) using the geodesic trajectory approach. The geodesic trajectory approach is used to optimize the dome design, resulting in a lightweight and efficient structure. Python scripting is employed to implement the mathematical modeling of the COPV, and after validating the model by comparison to the published paper, stress analysis is conducted using Abaqus commercial code. The results demonstrate the effectiveness of the geodesic trajectory approach in achieving a lightweight and structurally sound dome design, as well as the accuracy and reliability of the stress analysis using Abaqus commercial code. This study provides insights into the design and analysis of COPVs for aerospace applications, with the potential for further optimization and application in other industries.

Keywords: composite overwrapped pressure vessels, carbon fiber, geodesic trajectory approach, dome design, stress analysis, plugin python

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Authors: Deniz Sahin

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Growing concern for the presence and contamination of heavy metals in our water supplies has steadily increased over the last few years. A number of specialized technologies including precipitation, coagulation/flocculation, ion exchange, cementation, electrochemical operations, have been developed for the removal of heavy metals from wastewater. However, these technologies have many limitations in the application, such as high cost, low separation efficiency, Recently, numerous approaches have been investigated to overcome these difficulties and membrane filtration, advanced oxidation technologies (AOPs), and UV irradiation etc. are sufficiently developed to be considered as alternative treatments. Many factors come into play when selecting wastewater treatment technology, such as type of wastewater, operating conditions, economics etc. This study describes these various treatment technologies employed for heavy metal removal. Advantages and disadvantages of these technologies are also compared to highlight their current limitations and future research needs. For example, we investigated the applicability of the ultrafiltration technology for treating of heavy metal ions (e.g., Cu(II), Pb(II), Cd(II), Zn(II)) from synthetic wastewater solutions. Results shown that complete removal of metal ions, could be achieved.

Keywords: heavy metal, treatment methodologies, water, water treatment

Procedia PDF Downloads 171

Authors: A. Alhelfi, B. Sunden

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Cavitation in cryogenic liquids is widely present in contemporary science. In the current study, we re-examine a previously validated acoustic cavitation model which was developed for a gas bubble in liquid water. Furthermore, simulations of cryogenic fluids including the thermal effect, the effect of acoustic pressure amplitude and the frequency of sound field on the bubble dynamics are presented. A gas bubble (Helium) in liquids Nitrogen, Oxygen and Hydrogen in an acoustic field at ambient pressure and low temperature is investigated numerically. The results reveal that the oscillation of the bubble in liquid Hydrogen fluctuates more than in liquids Oxygen and Nitrogen. The oscillation of the bubble in liquids Oxygen and Nitrogen is approximately similar.

Keywords: cryogenic liquids, cavitation, rocket engineering, ultrasound

Procedia PDF Downloads 322

Authors: Vipan Kumar Sohpal

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Temperature effect on the adsorption of crystal violet dye (CVD) was investigated using a castor leaf powder (CLP) that was prepared from the mature leaves of castor trees, through chemical reaction. The optimum values of pH (8), adsorbent dose (10g/L), initial dye concentration (10g/L), time (2hrs), and stirrer speed (120 rpm) were fixed to investigate the influence of temperature on adsorption capacity, percentage of removal of dye and free energy. A central composite design (CCD) was successfully employed for experimental design and analysis of the results. The combined effect of temperature, absorbance, and concentration on the dye adsorption was studied and optimized using response surface methodology. The optimum values of adsorption capacity, percentage of removal of dye and free energy were found to be 0.965(mg/g), 93.38 %, -8202.7(J/mol) at temperature 55.97 °C having desirability > 90% for removal of crystal violet dye respectively. The experimental values were in good agreement with predicted values.

Keywords: crystal violet dye, CVD, castor leaf powder, CLP, response surface methodology, temperature, optimization

Procedia PDF Downloads 135

Authors: E. Salem

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Combustion has been used for a long time as a means of energy extraction. However, in recent years, there has been a further increase in air pollution, through pollutants such as nitrogen oxides, acid etc. In order to solve this problem, there is a need to reduce carbon and nitrogen oxides through learn burning modifying combustors and fuel dilution. A numerical investigation has been done to investigate the effectiveness of several reduced mechanisms in terms of computational time and accuracy, for the combustion of the hydrocarbons/air or diluted with hydrogen in a micro combustor. The simulations were carried out using the ANSYS Fluent 19.1. To validate the results “PREMIX and CHEMKIN” codes were used to calculate 1D premixed flame based on the temperature, composition of burned and unburned gas mixtures. Numerical calculations were carried for several hydrocarbons by changing the equivalence ratios and adding small amounts of hydrogen into the fuel blends then analyzing the flammable limit, the reduction in NOx and CO emissions, then comparing it to experimental data. By solving the conservations equations, several global reduced mechanisms (2-9-12) were obtained. These reduced mechanisms were simulated on a 2D cylindrical tube with dimensions of 40 cm in length and 2.5 cm diameter. The mesh of the model included a proper fine quad mesh, within the first 7 cm of the tube and around the walls. By developing a proper boundary layer, several simulations were performed on hydrocarbon/air blends to visualize the flame characteristics than were compared with experimental data. Once the results were within acceptable range, the geometry of the combustor was modified through changing the length, diameter, adding hydrogen by volume, and changing the equivalence ratios from lean to rich in the fuel blends, the results on flame temperature, shape, velocity and concentrations of radicals and emissions were observed. It was determined that the reduced mechanisms provided results within an acceptable range. The variation of the inlet velocity and geometry of the tube lead to an increase of the temperature and CO2 emissions, highest temperatures were obtained in lean conditions (0.5-0.9) equivalence ratio. Addition of hydrogen blends into combustor fuel blends resulted in; reduction in CO and NOx emissions, expansion of the flammable limit, under the condition of having same laminar flow, and varying equivalence ratio with hydrogen additions. The production of NO is reduced because the combustion happens in a leaner state and helps in solving environmental problems.

Keywords: combustor, equivalence-ratio, hydrogenation, premixed flames

Procedia PDF Downloads 115

Authors: Xiaohua Jing

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Efficient extraction for separation of V and Cr in the leaching/aqueous solution is essential to the reuse of V and Cr in the V-Cr slag. Trioctylamine, a common tertiary amine extractant, with some good characters (e.g., weak base, insoluble in water and good stability) different from N1923, was investigated in this paper. The separation factor of Cr and V can be reached to 230.71 when initial pH of the aqueous solution is 0.5, so trioctylamine can be used for extracting Cr from the leaching/aqueous solution contained V and Cr. The highest extraction percentages of Cr and V were 98.73% and 90.22% when the initial pH values were 0.5 and 1.5, respectively. Via FT-IR spectra of loaded organic phase and trioctylamine, the hydrogen bond association mechanism of extracting V and Cr was investigated, which was the same with the way of extracting the two metals with primary amine N1923.

Keywords: selective extraction, trioctylamine, V and Cr, separation factor, hydrogen bond association

Procedia PDF Downloads 366

Authors: Nadia Allouache, Omar Rahli

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Many promising technologies have been developed to harness the sun's energy. These technologies help in economizing energy and environmental protection. The solar refrigerating systems are one of these important technologies. In addition to environmental benefits and energy saving, adsorption refrigerating systems have many advantages such as lack of moving parts, simplicity of construction and low operating costs. The work aimed to establish the main factors that affect the performances of an adsorption refrigerating system using different geometries of adsorbers and different adsorbent-adsorbate pairs. The numerical modeling of the heat and mass transfer in the system, using various working pairs, such as: activated carbon-ammonia, calcium chlorid-ammonia, activated carbon fiber- methanol and activated carbon AC35-methanol, show that the adsorber design can influence the system performances; The thermal performances of system are better in the annular configuration case. An optimal value of generating temperature is observed in annular adsorber case for which the thermal performance of the cooling system is maximal. While in the plate adsorber, above a certain value of generating temperature, the performance of the system remains almost constant. The environmental conditions such as solar radiation and pressure have a great influence in the system efficiency, and the choice of the working pair depends on the environmental conditions and the geometry of the adsorber.

Keywords: adsorber geometry, numerical modeling, optimal environmental conditions, working pairs.

Procedia PDF Downloads 79

Authors: R. Kerbachi , Y. Medkour, F. Sahnoune

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The integrated waste management is an important aspect in the implementation of sustainable development. Leachate generated by sanitary landfills is a high-strength wastewater that is likely to contain large amounts of organic and inorganic matter, with humic substances, as well as ammonia nitrogen, heavy metals, chlorinated organic and inorganic salts. Untreated leachates create a great potential for harm to the environment, they can permeate ground water or mix with surface water and contribute to the pollution of soil, ground water, and surface water. In Algeria, the treatment of landfill leachate is the weakest link in the solid waste management. This study focuses on the evaluation of the pollution load carried by leachate produced in a former sanitary landfill located to the west of Algiers and the implementation of advanced oxidation treatment (advanced oxidation process, AOP), Fenton, electro-Fenton etc. The characterization of these leachates shows that they have a high organic load, mineral and nitrogen. Measured COD reaches very high values of the order of 5000 to 20,000 mg O2 / L. On this non-biodegradable leachate, treatment tests have been carried out by the methods of coagulation-flocculation, Fenton oxidation, electrocoagulation and electro-Fenton. The removal efficiencies of pollution obtained for each of these modes of treatment are respectively 69, 80, 84 and 97%. The study shows that advanced oxidation processes are very suitable for the treatment of poorly biodegradable leachate.

Keywords: advanced oxidation processes, electrocoagulation, electro-Fenton, leachates treatment, sanitary landfill

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Authors: Sirirat Jangkorn, Pornsawai Praipipat

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Sugarcane bagasse ash of sugar factories is solid wastes that the richest source of silica. The alkali fusion method, quartz particles in material can be dissolved and they can be used as the silicon source for synthesizing silica-based materials such as zeolites. Zeolites have many advantages such as catalyst to improve the chemical reactions and they can also remove heavy metals in the water including lead. Therefore, this study attempts to synthesize zeolites from the sugarcane bagasse ash, investigate their structure characterizations and chemical components to confirm the happening of zeolites, and examine their lead removal efficiency through the batch test studies. In this study, the sugarcane bagasse ash was chosen as the silicon source to synthesize zeolites, X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF) were used to verify the zeolite pattern structures and element compositions, respectively. The batch test studies in dose (0.05, 0.1, 0.15 g.), contact time (1, 2, 3), and pH (3, 5, 7) were used to investigate the lead removal efficiency by the synthesized zeolite. XRD analysis result showed the crystalline phase of zeolite pattern, and XRF result showed the main element compositions of the synthesized zeolite that were SiO₂ (50%) and Al₂O₃ (30%). The batch test results showed the best optimum conditions of the synthesized zeolite for lead removal were 0.1 g, 2 hrs., and 5 of dose, contact time, and pH, respectively. As a result, this study can conclude that the zeolites can synthesize from the sugarcane bagasse ash and they can remove lead in the water.

Keywords: sugarcane bagasse ash, solid wastes, zeolite, lead

Procedia PDF Downloads 140

Authors: Jing Zhang, Yongqin Chang, Yongwei Wang, Xiaolin Li, Shaoning Jiang, Farong Wan, Yi Long

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Microstructural and hardening changes of Fe-0.2wt.%V alloy and pure Fe irradiated with 100 keV hydrogen ions at room temperature were investigated. It was found that dislocation density varies dramatically after irradiation, ranging from dislocation free to dense areas with tangled and complex dislocation configuration. As the irradiated Fe-0.2wt.%V samples were annealed at 773 K, the irradiation-induced dislocation loops disappear, while many small precipitates with enriched C distribute in the matrix. Some large precipitates with enriched V were also observed. The hardness of Fe-0.2wt.%V alloy and pure Fe increases after irradiation, which ascribes to the formation of dislocation loops in the irradiated specimens. Compared with pure Fe, the size of the irradiation-introduced dislocation loops in Fe-0.2wt.%V alloy decreases and the density increases, the change of the hardness also decreases.

Keywords: irradiation, Fe-0.2wt.%V alloy, microstructures, hardness

Procedia PDF Downloads 387

Authors: Bendjelloul Meriem, Elandaloussi El Hadj

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In this work, we studied the effectiveness of a lignocellulosic waste (wood sawdust) for the removal of cadmium Cd (II) in aqueous solution. The adsorbent material SBO-CH2-CO2Na has been prepared by alkaline pretreatment of wood sawdust followed by a chemical modification with sodium salt of chloroacetic acid. The characterization of the as-prepared material by FTIR has proven that the grafting of acetate spacer took actually place in the lignocellulosic backbone by the appearance of characteristic band of carboxylic groups in the IR spectrum. The removal study of Cd2+ by SBO-CH2-CO2Na material at the solid-liquid interface was carried out by kinetics, sorption isotherms, effect of temperature and thermodynamic parameters were evaluated. The last part of this work was dedicated to assess the regenerability of the adsorbent material after three reuse cycles. The results indicate that SBO-CH2-CO2Na matrix possesses a high effectiveness in removing Cd (II) with an adsorption capacity of 222.22 mg/g, yet a better value that those of many low-cost adsorbents so far reported in the literature. The results found in the course of this study suggest that ionic exchange is the most appropriate mechanism involved in the removal of cadmium ions.

Keywords: adsorption, cadmium, isotherms, lignocellulosic, regenerability

Procedia PDF Downloads 333

Authors: Tulika Malviya, Ritesh Chandra Shukla, Praveen Kumar Tandon

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Traditional methods of synthesis are hazardous for the environment and need nature friendly processes for the treatment of industrial effluents and contaminated water. Use of plant parts for the synthesis provides an efficient alternative method. In this paper, we report an ecofriendly and nonhazardous biobased method to prepare zerovalent iron nanoparticles (ZVINPs) using the liquor of commercially available tea. Tea liquor as the reducing agent has many advantages over other polymers. Unlike other polymers, the polyphenols present in tea extract are nontoxic and water soluble at room temperature. In addition, polyphenols can form complexes with metal ions and thereafter reduce the metals. Third, tea extract contains molecules bearing alcoholic functional groups that can be exploited for reduction as well as stabilization of the nanoparticles. Briefly, iron nanoparticles were prepared by adding 2.0 g of montmorillonite K10 (MMT K10) to 5.0 mL of 0.10 M solution of Fe(NO3)3 to which an equal volume of tea liquor was then added drop wise over 20 min with constant stirring. The color of the mixture changed from whitish yellow to black, indicating the formation of iron nanoparticles. The nanoparticles were adsorbed on montmorillonite K10, which is safe and aids in the separation of hazardous arsenic species simply by filtration. Particle sizes ranging from 59.08±7.81 nm were obtained which is confirmed by using different instrumental analyses like IR, XRD, SEM, and surface area studies. Removal of arsenic was done via batch adsorption method. Solutions of As(III) of different concentrations were prepared by diluting the stock solution of NaAsO2 with doubly distilled water. The required amount of in situ prepared ZVINPs supported on MMT K10 was added to a solution of desired strength of As (III). After the solution had been stirred for the preselected time, the solid mass was filtered. The amount of arsenic [in the form of As (V)] remaining in the filtrate was measured using ion chromatograph. Stirring of contaminated water with zerovalent iron nanoparticles supported on montmorillonite K10 for 30 min resulted in up to 99% removal of arsenic as As (III) from its solution at both high and low pH (2.75 and 11.1). It was also observed that, under similar conditions, montmorillonite K10 alone provided only <10% removal of As(III) from water. Adsorption at low pH with precipitation at higher pH has been proposed for As(III) removal.

Keywords: arsenic removal, montmorillonite K10, tea liquor, zerovalent iron nanoparticles

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Authors: Karan R. Chavan, Paula Saavalainen, Kumudini V. Marathe, Riitta L. Keiski, Ganapati D. Yadav

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Co-contamination of groundwaters by arsenic in different forms is often observed around the globe. Arsenic is introduced into the waters by several mechanisms and different technologies are proposed and practiced for effective removal. The assessment of three prominent technologies, namely, adsorption, ion exchange and nanofiltration was carried out in this study based on lifecycle methodology. The life of the technologies was divided into two stages: cradle to gate (C-G) and gate to gate (G-G), in order to find out the impacts in different categories of environmental burdens, human health and resource consumption. Life cycle inventory was estimated by use of models and design equations concerning with the different technologies. Regeneration was considered for each technology and over the course of its full lifetime. The impact values of adsorption technology for the C-G stage are greater by thousand times (103) and million times (106) compared to ion exchange and nanofiltration technologies, respectively. The impact of G-G stage of the lifecycle is the major contributor of the impact for all the 3 technologies due to electricity consumption during the operation. Overall, the ion Exchange technology fares well in this study of removal of As (V) only.

Keywords: arsenic, nanofiltration, lifecycle assessment, membrane technology

Procedia PDF Downloads 246

Authors: Yew Mun Yip, Dawei Zhang

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Proteins are the biological machinery that executes specific vital functions in every cell of the human body by folding into their 3D structures. When a protein misfolds from its native structure, the machinery will malfunction and lead to misfolding diseases. Although in vitro experiments are able to conclude that the mutations of the amino acid sequence lead to incorrectly folded protein structures, these experiments are unable to decipher the folding process. Therefore, molecular dynamic (MD) simulations are employed to simulate the folding process so that our improved understanding of the folding process will enable us to contemplate better treatments for misfolding diseases. MD simulations make use of force fields to simulate the folding process of peptides. Secondary structures are formed via the hydrogen bonds formed between the backbone atoms (C, O, N, H). It is important that the hydrogen bond energy computed during the MD simulation is accurate in order to direct the folding process to the native structure. Since the atoms involved in a hydrogen bond possess very dissimilar electronegativities, the more electronegative atom will attract greater electron density from the less electronegative atom towards itself. This is known as the polarization effect. Since the polarization effect changes the electron density of the two atoms in close proximity, the atomic charges of the two atoms should also vary based on the strength of the polarization effect. However, the fixed atomic charge scheme in force fields does not account for the polarization effect. In this study, we introduce the polarized structure-specific backbone charge (PSBC) model. The PSBC model accounts for the polarization effect in MD simulation by updating the atomic charges of the backbone hydrogen bond atoms according to equations derived between the amount of charge transferred to the atom and the length of the hydrogen bond, which are calculated from quantum-mechanical calculations. Compared to other polarizable models, the PSBC model does not require quantum-mechanical calculations of the peptide simulated at every time-step of the simulation and maintains the dynamic update of atomic charges, thereby reducing the computational cost and time while accounting for the polarization effect dynamically at the same time. The PSBC model is applied to two different β-peptides, namely the Beta3s/GS peptide, a de novo designed three-stranded β-sheet whose structure is folded in vitro and studied by NMR, and the trpzip peptides, a double-stranded β-sheet where a correlation is found between the type of amino acids that constitute the β-turn and the β-propensity.

Keywords: hydrogen bond, polarization effect, protein folding, PSBC

Procedia PDF Downloads 270

Authors: Harshita Raj, Joydeep Ghosh, Rakesh L. Tanna, Prabal K. Chattopadhyay, K. A. Jadeja, Sharvil Patel, Kaushal M. Patel, Narendra C. Patel, S. B. Bhatt, V. K. Panchal, Chhaya Chavda, C. N. Gupta, D. Raju, S. K. Jha, J. Raval, S. Joisa, S. Purohit, C. V. S. Rao, P. K. Atrey, Umesh Nagora, R. Manchanda, M. B. Chowdhuri, Nilam Ramaiya, S. Banerjee, Y. C. Saxena

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Efficient gas fueling is a critical aspect that needs to be mastered in order to maintain plasma density, to carry out fusion. This requires a fair understanding of fuel recycling in order to optimize the gas fueling. In Aditya tokamak, multiple gas puffs are used in a precise and controlled manner, for hydrogen fueling during the flat top of plasma discharge which has been instrumental in achieving discharges with enhanced density as well as energy confinement time. Following each gas puff, we observe peaks in temporal profile of Hα emission, Soft X-ray (SXR) and chord averaged electron density in a number of discharges, indicating efficient gas fueling. Interestingly, Hα temporal profile exhibited an additional peak following the peak corresponding to each gas puff. These additional peak Hα appeared in between the two gas puffs, indicating the presence of a secondary hydrogen source apart from the gas puffs. A thorough investigation revealed that these secondary Hα peaks coincide with Hard X- ray bursts which come from the interaction of runaway electrons with vessel limiters. This leads to consider that the runaway electrons (REs), which hit the wall, in turn, bring out the absorbed hydrogen and oxygen from the wall and makes the interaction of REs with limiter a secondary hydrogen source. These observations suggest that runaway electron induced recycling should also be included in recycling particle source in the particle balance calculations in tokamaks. Observation of two Hα peaks associated with one gas puff and their roles in enhancing and maintaining plasma density in Aditya tokamak will be discussed in this paper.

Keywords: fusion, gas fueling, recycling, Tokamak, Aditya

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Authors: Ana C. Ramos Valdivia, Ileana Vera-Reyes, Ariana A. Huerta-Heredia

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The conditions of biotic and abiotic stress in plants can lead to the generation of high amounts of reactive oxygen species (ROS), which leads through a signaling cascade and second messengers to different antioxidant defense responses including the production of secondary metabolites. A limited number of species of plants like Uncaria tomentosa (cat claw) typical of the Amazon region produce monoterpenoid oxindole alkaloids (MOA) such as isopteropodine, mitraphylline, rhynchophylline and its isomers. Moreover, in cultivated roots, the glucoindole alkaloid 3α-dihydrocadambine (DHC) is also accumulated. Several studies have demonstrated that MAO has antioxidant properties and possess important pharmacological activities such as antitumor and immunostimulant while DHC, has hypotensive and hypolipidemic effects. In order the study the regulatory concerns operating in MAO production, the links between oxidative stress and antioxidant alkaloid production in U. tomentosa root cultures were examined. Different amount of hydrogen peroxide between 0.2 -1.0 mM was added to 12 days old roots cultures showing that, this substance had a differential effect on the production of DHC and MOA whereas the viability remained in 80% after six days. Addition of 0.2 mM hydrogen peroxide increased approximately 65% MAO and DHC production (0,540 ± 0.018 and 0.618 ± 0.029 mg per g dry weight, respectively) relative to the control. On contrast, after the addition of 0.6 mM and 1 mM hydrogen peroxide, DHC accumulation into the roots gradually decreased to 53% and 93% respectively, without changes in MAO concentration, which was in relation to a twice increase of the intracellular hydrogen peroxide content. On the other hand, concentrations of DHC (0.1, 0.5 and 1.0 mM in methanol) demonstrated free-radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. The calculated IC50 for all tested concentrations was 0.180 mg per ml (0.33 mM) while the calculated TE50 was 276 minutes. Our results suggest that U. tomentosa root cultures both MAO and DHC have antioxidant capacities and respond to oxidative stress with a stimulation of their production; however, in presence of a higher concentration of ROS into the roots, DHC could be oxidized.

Keywords: monoterpenoid indole alkaloid, oxidative stress, root cultures, uncaria tomentosa

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Authors: Anas Rao, Hao Duan, Fanhua Ma

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The dependency on the fossil fuels can be minimized by using the hydrogen enriched compressed natural gas (HCNG) in the transportation vehicles. However, the NOx emissions of HCNG engines are significantly higher, and this turned to be its major drawback. Therefore, the study of NOx emission of HCNG engines is a very important area of research. In this context, the experiments have been performed at the different hydrogen percentage, ignition timing, air-fuel ratio, manifold-absolute pressure, load and engine speed. Afterwards, the simulation has been accomplished by the quasi-dimensional combustion model of HCNG engine. In order to investigate the NOx emission, the NO mechanism has been coupled to the quasi-dimensional combustion model of HCNG engine. The three NOx mechanism: the thermal NOx, prompt NOx and N2O mechanism have been used to predict NOx emission. For the validation purpose, NO curve has been transformed into NO packets based on the temperature difference of 100 K for the lean-burn and 60 K for stoichiometric condition. While, the width of the packet has been taken as the ratio of crank duration of the packet to the total burnt duration. The combustion chamber of the engine has been divided into three zones, with the zone equal to the product of summation of NO packets and space. In order to check the accuracy of the model, the percentage error of NOx emission has been evaluated, and it lies in the range of ±6% and ±10% for the lean-burn and stoichiometric conditions respectively. Finally, the percentage contribution of each NO formation has been evaluated.

Keywords: quasi-dimensional combustion , thermal NO, prompt NO, NO packet

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Authors: Mejri Achref

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This paper proposes an energy management strategy for an electrical hybrid vehicle which is composed of a Proton Exchange Membrane (PEM) fuel cell and a supercapacitor storage device. In this paper, the mathematical model for the proposed power train, comprising the PEM Fuel Cell, supercapacitor, boost converter, inverter, and vehicular structure, was modeled in MATLAB/Simulink. The proposed algorithm is evaluated for the Highway Fuel Economy Test (HWFET) driving cycle. The obtained results demonstrate the effectiveness of the proposed energy management strategy in reduction of hydrogen consumption.

Keywords: proton exchange membrane fuel cell, hybrid vehicle, hydrogen consumption, energy management strategy

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Authors: M. Abd elfattah, M. Ossman, Nahla A. Taha

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The present work explored the use of Egyptian rice straw, an agricultural waste that leads to global warming problem through brown cloud, as a potential feedstock for the preparation of activated carbon by physical and chemical activation. The results of this study showed that it is feasible to prepare activated carbons with relatively high surface areas and pore volumes from the Egyptian rice straw by direct chemical and physical activation. The produced activated carbon from the two methods (AC1 and AC2) could be used as potential adsorbent for the removal of Fe(III) from aqueous solution contains heavy metals and polluted water. The adsorption of Fe(III) was depended on the pH of the solution. The optimal Fe(III) removal efficiency occurs at pH 5. Based on the results, the optimum contact time is 60 minutes and adsorbent dosage is 3 g/L. The adsorption breakthrough curves obtained at different bed depths indicated increase of breakthrough time with increase in bed depths. A rise in inlet Fe(III) concentration reduces the throughput volume before the packed bed gets saturated. AC1 showed higher affinity for Fe(III) as compared to Raw rice husk.

Keywords: rice straw, activated carbon, Fe(III), fixed bed column, pyrolysis

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Authors: Vibha Sinha, Sumedha Chakma

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Arsenic (As) contamination in drinking water is a serious concern worldwide resulting in severe health maladies. To tackle this problem, several hydrogel based matrix which selectively uptake toxic metals from contaminated water has increasingly been examined as a potential practical method for metal removal. The major concern in hydrogels is low stability of matrix, resulting in poor performance. In this study, the potential of hybrid hydrogel-biochar matrix synthesized from natural plant polymers, specific for As removal was explored. Various compositional and functional group changes of the elements contained in the matrix due to the adsorption of As were identified. Moreover, to resolve the stability issue in hydrogel matrix, optimum and effective mixing of hydrogel with biochar was studied. Mixing varied proportions of matrix components at the time of digestion process was tested. Preliminary results suggest that partial premixing methods may increase the stability and reduce cost. Addition of nanoparticles and specific catalysts with different concentrations of As(III) and As(V) under batch conditions was performed to study their role in performance enhancement of the hydrogel matrix. Further, effect of process parameters, optimal uptake conditions and detailed mechanism derived from experimental studies were suitably conducted. This study provides an efficient, specific and a low-cost As removal method that offers excellent regeneration abilities which can be reused for value.

Keywords: arsenic, catalysts, hybrid hydrogel-biochar, water purification

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Authors: Ghodsieh Isapour Toutizad, Aiyong Wang, Joonsoo Han, Derek Creaser, Louise Olsson, Magnus Skoglundh, Hanna HaRelind

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Nitrous oxide (N2O), which is generally formed as a byproduct of industrial chemical processes and fossil fuel combustion, has attracted considerable attention due to its destructive role in global warming and ozone layer depletion. From various developed technologies used for lean NOx reduction, the selective catalytic reduction (SCR) of NOx with ammonia is presently the most applied method. Therefore, the development of catalysts for efficient lean NOx reduction without forming N2O in the process, or only forming it to a very small extent from the exhaust gases is of crucial significance. One type of catalysts that nowadays are used for this aim are zeolite-based catalysts. It is owing to their remarkable catalytic performance under practical reaction conditions such as high thermal stability and high N2 selectivity. Among all zeolites, copper ion-exchanged zeolites, with CHA, MFI, and BEA framework structure (like SSZ-13, ZSM-5 and Beta, respectively), represent higher hydrothermal stability, high activity and N2 selectivity. This work aims at investigating the effect of the zeolite framework structure on the formation of N2O during NH3-SCR reaction conditions over three Cu-based zeolites ranging from small-pore to large-pore framework structure. In the zeolite framework, Cu exists in two cationic forms, that can catalyze the SCR reaction by activating NO to form NO+ and/or surface nitrate species. The nitrate species can thereafter react with NH3 to form another intermediate, ammonium nitrate, which seems to be one source for N2O formation at low temperatures. The results from in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) indicate that during the NO oxidation step, mainly NO+ and nitrate species are formed on the surface of the catalysts. The intensity of the absorption peak attributed to NO+ species is higher for the Cu-CHA sample compared to the other two samples, indicating a higher stability of this species in small cages. Furthermore, upon the addition of NH3, through the standard SCR reaction conditions, absorption peaks assigned to N-H stretching and bending vibrations are building up. At the same time, negative peaks are evolving in the O-H stretching region, indicating blocking/replacement of surface OH-groups by NH3 and NH4+. By removing NH3 and adding NO2 to the inlet gas composition, the peaks in the N-H stretching and bending vibration regions show a decreasing trend in intensity, with the decrease being more pronounced for increasing pore size. It can probably be owing to the higher accumulation of ammonia species in the small-pore size zeolite compared to the other two samples. Furthermore, it is worth noting that the ammonia surface species are strongly bonded to the CHA zeolite structure, which makes it more difficult to react with NO2. To conclude, the framework structure of the zeolite seems to play an important role in the formation and reactivity of surface species relevant for the SCR process. Here we intend to discuss the connection between the zeolite structure, the surface species, and the formation of N2O during ammonia-SCR.

Keywords: fast SCR, nitrous oxide, NOx, standard SCR, zeolites

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Authors: Harikrishna Yadav Nanganuru, Narasimhulu Korrapati

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Over the past many years, many sites in the world have been contaminated with heavy metals, which are the largest class of contaminants. Lead is one of the toxic heavy metals contaminated in the environment. Lead is not biodegradable, that’s why it is accumulated in the human body and impacts all the systems of the human body when it has been taken by humans. The accumulation of lead in the water environment has been showing adverse effects on the public health. So the removal of lead from the water environment by the biosorption process, which is emerged as a potential method for the lead removal, is an efficient approach. This work was focused to examine the removal of Lead [Pb (II)] ions from aqueous solution and effluent from battery industry. Lead contamination in water is a widespread problem throughout the world and mainly results from lead acid battery manufacturing effluent. In this work, isolated bacteria from wastewater of lead acid battery industry has been utilized for the removal of lead. First effluent from the lead acid battery industry was characterized by the inductively coupled plasma atomic emission spectrometry (ICP – AES). Then the bacteria was isolated from the effluent and used it’s immobilized dead mass for the biosorption of lead. Scanning electron microscopic (SEM) and Atomic force microscopy (AFM) studies clearly suggested that the Lead (Pb) was adsorbed efficiently. The adsorbed percentage of lead (II) from waste was 97.40 the concentration of lead (II) is measured by Atomic Absorption Spectroscopy (AAS). From the result of AAS it can be concluded that immobilized isolated dead mass was well efficient and useful for biosorption of lead contaminated waste water.

Keywords: biosorption, ICP-AES, lead (Pb), SEM

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