Removal of Arsenic (III) and Chromium (VI) from The Water Using Phytoremediation and Bioremediation Techniques

Advancement in science and technologies parallel to industrial revolution has opened new vistas to exploit the inherent traits of natural resources including green plants and microorganisms to overcome the damage to the environment by pollutants. The present work was aimed to develop the phytoremediation potential of the aquatic plant Eichhornia crassipes for arsenic (III) and chromium (VI) from water. The accumulation, relative growth and bio-concentration factor of plant on treatment with different concentrations of arsenic(III) and chromium(VI) solution significantly increased (P<0.05) with the passage of time. Plants treated with 0.100 mg/L arsenic (III) accumulated the highest concentration of arsenite in roots (7.20 mg kg-1, dry weight) and shoots (32.1 mg kg-1, dry weight); while those treated with 4.0 mg/L of chromium (VI) accumulated the highest concentration of hexavalent chromium in roots (1320 mg/kg, dry weight) and shoots (260 mg/kg, dry weight) after 15 days. The plant biomass was characterized by SEM, EDX, FTIR and XRD techniques. Microwave-assisted extraction efficiency is investigated for extraction of arsenic from plant materials by comparison of the results by three extractant solutions: (i) 10% (v/v) tetramethylammonium hydroxide (TMAH) (ii) Deionized water and (iii) Modified protein extracting solution at different temperature and times. Extraction of chromium ions was carried by same procedure from plant materials using three extractant solutions: (i) 0.02 M ethylenediaminetetraacetic acid (EDTA), (ii) Deionized water and (iii) HCl solution at different temperature and times. Chromatograms are obtained for arsenic and chromium species in plant shoot biomass by using HPLC-ICP-MS. The biosorption of arsenic (III) and chromium (VI) from water is studied by living cells of Bacillus cereus biomass as bioremediation. Bacillus cereus biomass is characterized, using SEM-EDX, AFM and FTIR. Dependence of biosorption was studied with variation of various parameters to achieve the optimum condition. The maximum biosorption capacity of living cells of Bacillus cereus for arsenic (III) and chromium (VI) was found to be 32.42 mg/g and 39.06 mg/g at pH 7.5, at optimum conditions of contact time of 30 min, biomass dosage of 6 g/L, and temperature of 30 ± 2°C. Biosorption data of arsenic (III) chromium (VI) are fitted to linearly transformed Langmuir isotherm and pseudo-second-order model with R2 (correlation vi vii coefficient) > 0.99. Thermodynamic parameters reveal the endothermic, spontaneous, and feasible nature of sorption process of arsenic (III) chromium (VI) onto Bacillus cereus biomass. The arsenic (III) and chromium (VI) ions are desorbed from Bacillus cereus using both 1M HCl and 1M HNO3. The biosorption data of both arsenic (III) and chromium (VI) ions collected from laboratory scale experimental set up is used to train a back propagation (BP) learning algorithm having 4-7-1 architecture. The model uses tangent sigmoid transfer function at input to hidden layer whereas a linear transfer function is used at output layer. The removal of chromium (VI) from aqueous solutions by activated carbon prepared from the Eichhornia crassipes root biomass. The maximum removal capacity of activated carbon was found to be 36.34 mg/g for chromium (VI), at pH 4.5, contact time of 30 min, biomass dosage of 7 g/L, and temperature of 25 ± 2 °C. The adsorption mechanisms of chromium (VI) ions onto activated carbon prepared from the Eichhornia crassipes root biomass are also evaluated in terms of thermodynamics, equilibrium isotherm and kinetics studies. Column studies are also performed to know the breakthrough point with an initial concentration of 10 mg/L

The removal of chromium(VI) from water using functionalised Moringa oleifera leaves

Abstract: Please refer to full text to view abstract.M.Sc. (Nanoscience

Bromate and chromate removal from water by double layered hydroxides

To remove bromate and chromate from water, common methods include ion exchange, coagulation-flocculation processes, reductionprecipitation, etc., but these strategies can present some important disadvantages like incomplete removal, high cost, continuous use of reagents, and high energy costs. One of the most promising removal methods is the adsorption processes because of its high efficiency and low cost. In this study, double-layered hydroxides (DLH) of aluminum and magnesium were synthesized at different Mg/Al molar ratios with Cl- and CO3 -2 as the exchanging anions in order to remove bromate and chromate from water by adsorption processes. The synthesized materials were calcined at 400, 500, and 600°C to evaluate the effect of this treatment on the adsorption of the target pollutants. Contribution and Conclusions: Among all the tested adsorbents, DLH with a Mg/Al molar ratio of 3:1, with carbonate as the exchange anion, and calcined at 500 °C (identified as DLH31500) presented a maximum adsorption capacity for chromate and bromate of 248.9 and 134.1 mg/g at pH 6, respectively. In contrast, adsorption capacity onto granular activated carbon achieved 35.76 and 69.1 mg/g for chromate and bromate, respectively, which is seven times and two fold lower than DLH31500. When the activated carbon was modified with ammonia, bromate adsorption capacity decreased 12% in comparison with the raw activated carbon. Adsorption kinetics of chromate on DHL31500 was affected by the stirring type (mechanical, magnetic, intermittent, and oscillatory mixing), but the intermittent mode allowed the maximum chromate uptake as well as bubbling argon gas to the initial solution in order to displace the air in a closed vessel and to avoid carbon dioxide absorption along the experiment. The adsorption equilibrium was reached at 2880 min and the chromate adsorption capacity was 169.38 mg/g. In the same system, bromate adsorption equilibrium was reached at 5760 min, and the adsorption capacity was 110.38 mg/g. For continuous adsorption tests, a packed bed column with DLH31500 was built and chromate (20 mg/L) and bromate (5 mg/L) solutions were fed to the column. Chromate and bromate adsorption capacities of 104.66 and 45.77 mg/g were achieved, which successfully treated 7.85 and 13.73L, respectively. Finally, it was verified by X-Ray diffraction that DLH is mainly formed of layers, but after thermal treatment this structure is disassembled. Nevertheless, DLH layers reassemble after chromate adsorption, forming again the characteristic layers of a DLH (i.e. a memory effect). In conclusion, DLH is a promising adsorbent for the removal of bromate and chromate pollutants from aqueous solutions

Removal of various contaminants from water by renewable lignocellulose-derived biosorbents: a comprehensive and critical review

© 2019, © 2019 Taylor & Francis Group, LLC. Contaminants in water bodies cause potential health risks for humans and great environmental threats. Therefore, the development and exploration of low-cost, promising adsorbents to remove contaminants from water resources as a sustainable option is one focus of the scientific community. Here, we conducted a critical review regarding the application of pristine and modified/treated biosorbents derived from leaves for the removal of various contaminants. These include potentially toxic cationic and oxyanionic metal ions, radioactive metal ions, rare earth elements, organic cationic and anionic dyes, phosphate, ammonium, and fluoride from water media. Similar to lignocellulose-based biosorbents, leaf-based biosorbents exhibit a low specific surface area and total pore volume but have abundant surface functional groups, high concentrations of light metals, and a high net surface charge density. The maximum adsorption capacity of biosorbents strongly depends on the operation conditions, experiment types, and adsorbate nature. The absorption mechanism of contaminants onto biosorbents is complex; therefore, typical experiments used to identify the primary mechanism of the adsorption of contaminants onto biosorbents were thoroughly discussed. It was concluded that byproduct leaves are renewable, biodegradable, and promising biosorbents which have the potential to be used as a low-cost green alternative to commercial activated carbon for effective removal of various contaminants from the water environment in the real-scale plants

Wastewater Treatment and Reuse Technologies

This edited volume is a collection of 12 publications from esteemed research groups around the globe. The articles belong to the following broad categories: biological treatment process parameters, sludge management and disinfection, removal of trace organic contaminants, removal of heavy metals, and synthesis and fouling control of membranes for wastewater treatment

Development of New Environment Friendly Adsorption Media for the Removal of Hazardous Anions from Water.

Over last three decades, the important thrust area among the researches are to provide uncontaminated drinking water and for other domestic uses. New technologies in field of water purification are developing steadily but it almost remains same in actual affected fields. In India, one of the main sources for domestic, industrial, agricultural and other purposes is the ground water. The ground water pollution with hazardous anions like fluoride, arsenate specifically, and other anions like nitrate, phosphate, sulphate, chromate etc. is a major issue that causes various adverse health effects. Many domestic purification processes are there in application, but not exactly applicable in rural area due to many factors like regular maintenance, cost and non-availability of electricity. So there is a huge research gap between technology available for water purification and its field application in actual affected area. In this project two specific ions fluoride and anions of arsenic are targeted for its removal from water environment. This dissertation focuses on the remediation of the above-mentioned anionic pollutants by designing suitable materials. Various techniques were applied for the removal of these anionic contaminants so far. Among them adsorption techniques with suitable adsorbent has been an efficient method. In this present research work, four different types of materials have been synthesized for adsorption of arsenic and fluoride from contaminated water separately. In the first project, we have prepared Fe-Al 6mixed oxide nanoparticle by precipitation method which was used as an adsorbing material to remove fluoride from synthetic aqueous solution. The results revealed that the Fe- Al mixed oxide nanoparticle results better affinity towards fluoride. The maximum adsorption capacity of the material for fluoride was found to be 103.9 mg g-1 with the optimum condition. (0.08 g of the adsorbent, pH 7 and temperature of 40°C). The experimental data are best fitted with Freundlich adsorption isotherm. The pseudo 2nd order kinetic model described the kinetics of adsorption process. In the same direction, in the second project, Chitosan encapsulated magnetic nanoparticle modified was synthesized via co-precipitation method and applied for de-fluoridation of water by adsorption. Experimental results showed that the prepared material works very well for practical purpose. The magnetic chitosan nano particle acts as a good adsorbent for fluoride ions due to interesting interactions of fluoride with amino functionalized Iron. The pseudo 2nd order kinetics is best fitted to the adsorption with a maximum removal capacity of 33.62 mg g-1 calculated from Langmuir isotherm model. In third project, Lanthanum incorporated Zirconium Phosphate mesoporous material was synthesized for remediation of fluoride by precipitation by followed by hydrothermal treatment. The mesostructured Zr-P compounds showed greater removal efficiency due to higher specific surface area. The maximum adsorption capacity of the material for fluoride was 83.90 mg g-1 with the optimum condition at adsorbent dose of 0.2 g, pH 6 and temperature of 60°C. The adsorption process was best suited to Langmuir adsorption isotherm model and the pseudo 2nd order kinetic model. In the fourth part of this work, Mg/Fe/carbonate layered double hydroxide was prepared for arsenic decontamination by simple precipitation method followed by heat treatment. Presence of the inter layer anions between two cationic layers, facilitates the ion-exchange mechanism for efficient As(V) removal. The maximum removal of arsenic was 271.00 mg g-1 at the optimum condition of 0.1 g of the adsorbent, pH of 7. The equilibrium data of As(V) were best described by Langmuir adsorption isotherm model and kinetics of adsorption followed the pseudo 2nd order kinetic model. To check the role of flow rate, initial concentration and bed volume on adsorption of fluoride ions using synthetic aqueous solution, fixed bed column study was conducted. The mechanism of adsorption process were studied by using analytical methods like SEM, EDX, TEM, XRD, FTIR, TGA-DSC and BET surface area before and after treatment. All the results suggested that the above said materials have a strong and specific affinity towards the anionic contaminants, and can be considered as excellent material for treatment of real contaminated water system