Method For Removal Of Arsenic Research Articles

A continuous method for arsenic removal from groundwater using hybrid biopolymer‐iron‐nanoaggregates: improvement through factorial designs

AbstractBACKGROUNDDue to a variety of toxicological problems, the presence of As(V) in aquifers is a significant concern. Sorption using chitosan doped with iron nanoaggregates results in a green and cheap methodology for its elimination.RESULTSThe hybrid sorbent was characterized by SEM, EDS, TGA, XRD, and FTIR spectroscopy. Its stability against pH and time was determined by ICP‐MS, while conventional analytical techniques verified its Fe content. The sum of an individual As(V) removal capacity by chitosan and iron nanoaggregates was smaller than that of the hybrid sorbent, indicating the existence of synergy.CONCLUSIONThis study demonstrates the great capacity of the hybrid sorbent to eliminate As(V) working with a continuous system (columns). The additional use of a factorial design allows for determining of optimal operating values to optimize two responses. In other words, in this multi‐response system, column service time (tb) was minimized and, at the same time, it maximized the volumes of purified water obtained ([As(V)] <0.05 m L−1) using desirability function. © 2020 Society of Chemical Industry (SCI)

Review: Efficiently performing periodic elements with modern adsorption technologies for arsenic removal

Arsenic (As) toxicity is a global phenomenon, and it is continuously threatening human life. Arsenic remains in the Earth's crust in the forms of rocks and minerals, which can be released into water. In addition, anthropogenic activity also contributes to increase of As concentration in water. Arsenic-contaminated water is used as a raw water for drinking water treatment plants in many parts of the world especially Bangladesh and India. Based on extensive literature study, adsorption is the superior method of arsenic removal from water and Fe is the most researched periodic element in different adsorbent. Oxides and hydroxides of Fe-based adsorbents have been reported to have excellent adsorptive capacity to reduce As concentration to below recommended level. In addition, Fe-based adsorbents were found less expensive and not to have any toxicity after treatment. Most of the available commercial adsorbents were also found to be Fe based. Nanoparticles of Fe-, Ti-, Cu-, and Zr-based adsorbents have been found superior As removal capacity. Mixed element-based adsorbents (Fe-Mn, Fe-Ti, Fe-Cu, Fe-Zr, Fe-Cu-Y, Fe-Mg, etc.) removed As efficiently from water. Oxidation of AsO33- to AsO43-and adsorption of oxidized As on the mixed element-based adsorbent occurred by different adsorbents. Metal organic frameworks have also been confirmed as good performance adsorbents for As but had a limited application due to nano-crystallinity. However, using porous materials having extended surface area as carrier for nano-sized adsorbents could alleviate the separation problem of the used adsorbent after treatment and displayed outstanding removal performances.

Assessment of Arsenic and Iron Levels in Tube Wells of Government Run Institutions in a Block of Murshidabad District, West Bengal

Background: Murshidabad in West Bengal is considered as an endemic district for arsenic contaminated ground water. Iron is also a common inorganic material present in ground water which have ill effects on the body if beyond permissible limits. The present study was conducted to find out the level of arsenic and iron in the water samples in Government run institutions in one block of Murshidabad district. Methodology: In this descriptive observational study, water sample reports of 26 Government run institutions in an arsenic affected block were analysed. WHO and Bureau of Indian Standard permissible and acceptable values of both materials were considered for analysis. Results: As per Indian standards, only 26.9% of water samples in the study block were within acceptable limits for arsenic. If WHO recommended international standards were considered then more than 80% water samples were not safe as drinking water. In case of iron, only 7.7% water samples were within desirable limit as per Indian standards. While considering both arsenic and iron, only 1 water sample was seen to be within desirable limit. Conclusion: In spite of ongoing arsenic mitigation activity in West Bengal the arsenic level was found to be above permissible level in the Govt run tube wells. Awareness generation for repeated testing of arsenic, use of arsenic removal method at household level and use of safe water for both drinking and cooking at community level should be stressed upon.

Enhancing the plants growth and arsenic uptake from soil using arsenite-oxidizing bacteria

Plants, that naturally inhabit arsenic-contaminated areas may be used for effective arsenic-uptake from soil. The efficiency of this process may be increased by the reducing arsenic phytotoxicity and stimulating the activity of indigenous soil microbiota. As we showed, it can be achieved by the bioaugmenting of soil with arsenite-oxidizing bacteria (AOB). This study aimed to investigate the influence of soil bioaugmentation with AOB on the structure, quantity, and activity of the indigenous soil microbiota as well as to estimate the effect of such changes on the morphology, growth rate, and arsenic-uptake efficiency of plants. Plants-microbes interactions were investigated using the effective arsenites oxidizer Ensifer sp. M14 and the native plant alfalfa. The experiments were performed both in potted garden soil enriched with arsenic and in highly arsenic polluted, natural soil. The presence of M14 strain in soil contributed to the increase both in plants growth intensity and arsenic-uptake efficiency with regard to the soil without M14. After 40 days of plants culture, their average biomass increased by about 60% compared to non-bioaugmented soil, while the arsenic accumulation increased more than two times. The soil bioaugmentation contributed also to the increase in the quantity and activity of soil microorganisms without disturbing the natural microbial community structure. In the bioaugmented soil, the noticable increase in the quantity of heterotrophic, denitrifying, nitrifying and cellulolytic bacteria as well as in the activity of dehydrogenases and cellulases were observed. Soil bioaugmentation with M14 enables the application of native and commonly occurring plant species for enhancing the treatment of arsenic-contaminated soil. This in situ strategy may constitute a valuable alternative both to the chemical and physical methods of arsenic removal from soil and to the biological ways based on the arsenic hyperaccumulating plants and/or the arsenic mobilizing bacteria.

Mechanisms of arsenate removal and membrane fouling in ferric based coprecipitation–low pressure membrane filtration systems

Ferric based coprecipitation–low pressure membrane filtration is a promising arsenic (As) removal method, however, membrane fouling mechanisms are not fully understood. In this study we investigated the effect of feed water composition and membrane pore size on arsenate [As(V)] removal and membrane fouling. We observed that As removal efficiency was independent of the membrane pore size because the size of the Fe(III) particles was larger than the pore size of the membranes, attributed to a high calcium concentration in the feed water. Arsenic coprecipitation with Fe(III) (oxyhydr)oxides rapidly reached equilibrium before membrane filtration, within 1 min. Therefore, As removal efficiency was not improved by increasing residence time before membrane filtration. The removal of As(V) was strongly dependent on feed water composition. A higher Fe(III) dose was required to reduce As(V) to sub-µg/L levels for feed water containing higher concentration of oxyanions such as phosphate and silicate, and lower concentration of cations such as calcium. Cake-layer formation was observed to be the predominant membrane fouling mechanism.

High-efficiency As(III) oxidation and electrocoagulation removal using hematite with a charge−discharge technique

Arsenite (As(III)) is generally removed by adsorption or coprecipitation after being oxidized to arsenate (As(V)). Electrocoagulation is regarded as an effective and environment-friendly method for arsenic (As) removal from wastewater. However, some disadvantages including the passivation of electrode and high energy consumption limit its wide application. Herein, a multi-cycle galvanostatic charge−discharge technique was employed to remove aqueous As(III) using hematite prepared through a microwave-assisted hydrothermal reaction. When charge−discharge experiments were conducted at the potential window of −0.8–0 V (vs. SCE) in As(III) solution with NaCl as the background electrolyte, ClO− intermediates and the counter electrode at high potential contributed much to As(III) oxidation. As(V) was adsorbed on ferrihydrite generated from the re-oxidation of released Fe2+, forming FeAsO4 precipitate. A higher removal ratio of As(T) was achieved at initial pH 7.0 compared with that at initial pH 5.0 and 9.0. When the hematite mass was 4, 10 and 15 mg, the removal ratio of As(T) reached 55.2%, 79.6% and 98.6% after 600 cycles of charge−discharge. The periodic redox reactions of hematite electrodes occurred in each charge−discharge process, effectively avoiding the passivation of electrode. Additionally, the electrochemical system can be used as a supercapacitor for power output. The present work provides a novel strategy for high-efficiency As(III) immobilization and removal from aqueous solution.

Alginate-based biotechnology: a review on the arsenic removal technologies and future possibilities

Abstract The alginate-based adsorption technologies have emerged as potential methods for arsenic removal from drinking water. The adsorbents (iron oxide, hydroxide, nano zero valent iron (nZVI), industrial waste, minerals, magnetite, goethite, zirconium oxide, etc.) are impregnated into alginate beads to produce the media. The biocompatibility, rough surface with large area, and amorphous and high water permeable bead structure improve arsenic adsorption efficiency while the regeneration process is simpler than the conventional adsorbents. In recent years, studies have reported laboratory-scale applications of alginate beads, encapsulated and impregnated with adsorbents, for arsenic removal from drinking water. The arsenic removal efficiencies were reported to be over 95% with a wide range of concentrations (10–1,000 parts per billion) and pH (3.0–7.5). However, commercial- and/or mass-scale applications have not been reported yet, due possibly to overall cost, complexity, reusability, and arsenic waste-laden sludge management. In this paper, research achievement on arsenic removal using alginate-based adsorbents has been reviewed. The review was performed in context to alginate bead development, adsorbent encapsulation and impregnation, application, performance, and regeneration. The advantages and limitations of the methods were analyzed and the scopes of future research were identified for mass scale domestic and industrial applications.

Arsenic removal and biomass reduction of As-hyperaccumulator Pteris vittata: Coupling ethanol extraction with anaerobic digestion

Improper disposal of arsenic-rich biomass and the lack of efficient methods to treat it may cause contamination in the environment. We developed an efficient method for arsenic (As) removal and biomass reduction of As-rich biomass of the As-hyperaccumulator Pteris vittata by coupling ethanol extraction with anaerobic digestion. This study assessed As partitioning among the three phases (gas, liquid and solid) after anaerobic digestion of P. vittata biomass. Biomass with and without As was first extracted with ethanol. Ethanol extraction removed ~93% As, with remaining As concentration at 197 mg kg−1. The extracted biomass was then digested at 35 °C under anaerobic conditions for 35 d. Arsenic in the digested biomass was reduced by 89%, with remaining As concentration at 60 mg kg−1. In addition, anaerobic digestion reduced the biomass by 64–71% and decreased the volatile solids content from 94 to 15–18%. Methane production was 145 and 160 LNCH4/kgVS after 35 d for As-rich and control biomass, respectively. As a final step, As concentration in anaerobic digestate supernatant was reduced to 0.26 mg L−1 by As-Mg precipitation. Overall, coupling ethanol extraction with anaerobic digestion decreased As concentration in P. vittata biomass from 2665 to 60 mg kg−1, or by 98%. At this level (<100 mg As kg−1), P. vittata biomass can be considered a safe material based on USEPA regulations. Effective As removal from P. vittata biomass prior to disposal improves the phytoremediation process and lowers biomass transport and landfill disposal costs.

Density Functional Theory Study of Arsenic Adsorption on the Fe2O3 (001) Surface

Iron-based sorbent addition is a promising method for arsenic removal from coal-fired flue gas, but the adsorption process and surface active site that are responsible for arsenic adsorption remain...

Separation of arsenic(V) by composite adsorbents of metal oxide nanoparticles immobilized on silica flakes and use of adsorbent coated alumina tubes as an alternative method

This study investigates the arsenic(V) removal capacities of composite adsorbents made of silicate flakes of zirconium oxide and titanium oxide nanoparticles, which are then coated onto alumina tubes as an alternative method for arsenic(V) removal. As part of the study, the adsorption isotherms, interference of coexisting ions, stability of adsorbents and recovery of arsenic(V) were examined. The adsorbent containing zirconium oxide reveals a quite fast adsorption; through which 92% of the arsenic(V) was removed within 5 min. The both adsorbents containing zirconium oxide and titanium oxide reveal good stability and removal performance at neutral pH. The both adsorbents were arsenic(V) selective in presence of coexisting anions; however, the adsorbent containing zirconium oxide exhibits higher selectivity for arsenic(V) in presence of cations. The adsorption capacities were found to be 1.2 mmol g−1 (305 mg g−1) for zirconium oxide and 0.5 mmol g−1 (125 mg g−1) for titanium oxide, and finally 0.52 mmol g−1 (129 mg g−1) for zirconium oxide in case of tube-coating. The test results indicate that, although the both adsorbents are suitable for arsenic(V) removal, the adsorbent containing zirconium oxide has superior properties owing to its rapid adsorption, higher capacity and selectivity. Additionally, it is demonstrated that coating alumina tubes with adsorbents could serve as an alternative method for arsenic(V) removal.

Arsenic in the Wiśniówka acid mine drainage area (south-central Poland) – Mineralogy, hydrogeochemistry, remediation

This paper summarizes different aspects of arsenic mineralogy and geochemistry in the Wiśniówka acid mine drainage (AMD) area, south-central Poland. The basic source of this metalloid in AMD water bodies is micro-grained pyrite that forms two different mineralized zones within the Upper Cambrian rock formation. Due to specific textural and geochemical characteristics, this mineral undergoes rapid oxidation on exposed quarry walls and unvegetated tailings piles, thus contributing to elevated arsenic concentrations in acid pit lakes and ponds, and locally intermittent pools. The latter were highlighted by the highest As levels reaching even 370 mg/L. Of the three AMD large reservoirs, the Podwiśniówka (eastern) lake revealed distinctly raised As concentrations varying from 7.02 to 22.2 mg/L. Another interesting water body is the Marczakowe Doły acid pond showing diverse seasonal As concentration patterns in colloids and a water column. Results of geochemical modeling showed that the saturation indices (SI) of hematite and goethite exhibited the highest values (range of 6.96 to 12.84 and 2.47 to 5.39, respectively) tending to precipitate in all the water bodies examined. In addition, the positive SI values of nanosized ε-Fe2O3 (1.64 to 4.13) and schwertmannite (0.90 to 2.10) were found only in the Wiśniówka Duża and Marczakowe Doły acid waters. Laboratory experiments revealed that the best chemical and cost-effective method (out of the limited number of options) of arsenic removal from the AMD waters examined was the use of high-grade powdered limestone (fraction 0.0–0.09 mm) or more effective although more expensive limewater (calcium hydroxide). The positive SI values of hematite, goethite, ε-Fe2O3 and schwertmannite of neutralized solutions suggest that these minerals should precipitate. Due to diverse concentrations in the examined rock series, arsenic has been used for fingerprinting “hot” places within the mining and neighboring areas, as well as for predicting the directions and effects of strip mining for quartzites. The As signature can also be applied to monitor a detrimental AMD impact on local surface and underground waters.

Arsenic removal methods for drinking water in the developing countries: technological developments and research needs.

Arsenic pollution of drinking water is a concern, particularly in the developing countries. Removal of arsenic from drinking water is strongly recommended. Despite the availability of efficient technologies for arsenic removal, the small and rural communities in the developing countries are not capable of employing most of these technologies due to their high cost and technical complexity. There is a need for the "low-cost" and "easy to use" technologies to protect the humans in the arsenic affected developing countries. In this study, arsenic removal technologies were summarized and the low-cost technologies were reviewed. The advantages and disadvantages of these technologies were identified and their scopes of applications and improvements were investigated. The costs were compared in context to the capacity of the low-income populations in the developing countries. Finally, future research directions were proposed to protect the low-income populations in the developing countries.

Combined Electrosorption and Chemisorption of As(V) in Water by Using Fe-rGO@AC Electrode

A novel method of arsenic removal from water, combined electrosorption and chemisorption (CEC), has been presented in this work in order to deeply eliminate arsenic in water. This method was proposed using a mixture of activated carbon (AC) and reduced graphene–iron composite (Fe-rGO) as the electrode (Fe-rGO@AC). The results showed that the AC had a better electrosorption performance, while Fe-rGO was more suitable for chemisorption of As(V). The Fe-rGO@AC electrode combined the electrosorption with chemisorption. It was confirmed that the combination accelerated the adsorption rate of Fe-rGO. The AC on the electrode accelerated the mobility of arsenic ions and concentrated them in the electrical double layer (EDL) by means of electrostatic force underpotential. Meanwhlie, the concentrated As(V) ions reacted with Fe-rGO, contributing to a higher arsenic chemisorption on Fe-rGO. Therefore, the combination of electrosorption with chemisorption was an effective process for arsenic removal.

Simultaneous removal of arsenic, iron and manganese from groundwater by oxidation-coagulation-adsorption at optimized pH

Abstract The method based on oxidation-coagulation-adsorption at optimized pH (OCOP) using NaHCO3, KMnO4 and FeCl3 as pH conditioner, oxidant and coagulant, respectively, is an efficient and low-cost method for removal of arsenic from groundwater that has been gaining popularity in India. In a recent modification of OCOP, coexisting ferrous iron of water was utilized in order to lower the dose of FeCl3 and hence to lower the cost of the treatment of water containing both arsenic and iron. Here we present how the OCOP method can be effectively and economically used for simultaneous removal of arsenic, iron and manganese ions from water containing all three contaminants. For this we have optimized the required doses of NaHCO3, KMnO4 and FeCl3 by response surface methodology and used the optimized doses in a field trial with 11 domestic units of 20 L capacity in batch mode. Arsenic, iron and manganese were removed simultaneously by the present modification of the OCOP method to below 1 μg/L, 0.03 mg/L and 0.009 mg/L from initial concentrations of 100 μg/L, 1–8 mg/L and 0.5–5.0 mg/L, respectively, with a reduced cost.

Synthesis and application of Friedel’s salt in arsenic removal from caustic solution

Conventional way to remove arsenic from caustic solution is neutralization-precipitation process, which costs a large amount of acidic reagents while huge wastes are generated. This study proposed a method for arsenic removal from caustic solution using Friedel’s salt as an adsorbent. Friedel’s salt was synthesized by coprecipitation in different feeding ways and characterized by XRD, FESEM, DSC-TGA and FT-IR techniques. The Friedel’s salt synthesized in forward feeding way showed smallest crystallite size and exhibited the highest adsorption capacity of As(V). The As(V) adsorption properties of Friedel’s salt was evaluated in detail under the effects of contact time, temperature, OH− concentration and adsorbent dosage. Kinetic experiments were done and the data was well predicted by pseudo-second-order model, indicating the adsorption process is controlled by the chemisorption. Temperature shows positive effect on As(V) adsorption, which indicated an endothermic interaction between As(V) and Friedel’s salt. The adsorption process could be well described by Langmuir isotherm model, with a maximum adsorption capacity of 172.41mg·g−1 at 70°C. Moreover, the adsorption mechanism was elucidated with the characterizations of the Friedel’s salt after adsorption.

REACTOR DESIGN FOR EXTRACTION OF TRIVALENT ARSENIC BY SULFIDE TECHNOLOGY

The accumulation of arsenic in solid, liquid and gaseous waste of metallurgical production is an acute problem. Deposition of arsenic by sodium hydrosulfide is an effective and fast method of arsenic removal from solutions. The paper proposes a reactor design procedure for extraction of As (III) using the sulfide technology from washing solutions for wet gas scrubbing in sulfuric acid production. The paper takes into consideration the optimum parameters for removal of arsenic from solutions: the specific consumption of sulfide sulfur per1 kgof arsenic, the concentration of As (III) ions in the solution, the rate of sodium hydrosulfide feeding into the solution, and the hydrodynamic regime of the reactor. The obtained results are useful for design of experimental-industrial reactors used in dearsenication of solutions.

Mesoporous Magnesium Oxide Hollow Spheres as Superior Arsenite Adsorbent: Synthesis and Adsorption Behavior.

Arsenic contamination in natural water has posed a significant threat to global health due to its toxicity and carcinogenity. Adsorption technology is an easy and flexible method for arsenic removal with high efficiency. In this Article, we demonstrated the synthesis of mesoporous MgO hollow spheres (MgO-HS) and their application as high performance arsenite (As(III)) adsorbent. MgO-HS with uniform particle size (∼180 nm), high specific surface area (175 m(2) g(-1)), and distinguished mesopores (9.5 nm in size) have been prepared by hard-templating approach using mesoporous hollow carbon spheres as templates. An ultrahigh maximum As(III) adsorption capacity (Qmax) of 892 mg g(-1) was achieved in batch As(III) removal study. Adsorption kinetic study demonstrated that MgO-HS could enable As(III) adsorption 6 times faster as a commercial MgO adsorbent. The ultrahigh adsorption capacity and faster adsorption kinetics were attributed to the unique structure and morphology of MgO-HS that enabled fast transformation into a flower-like porous structure composed of ultrathin Mg(OH)2 nanosheets. This in situ formed structure provided abundant and highly accessible hydroxyl groups, which enhanced the adsorption performance toward As(III). The outstanding As(III) removal capability of MgO-HS showed their great promise as highly efficient adsorbents for As(III) sequestration from contaminated water.

Study on thermal decomposition and arsenic removal of a silver bearing copper ore

By thermodynamic calculation and analysis, a hypothesis is suggested and provided that tennatite gets easily converted to Cu3As which exists in slag in the traditional pyrometallurgy process. Due to the formation of Cu3As, the economic value of high-arsenic silver bearing copper ore is greatly reduced, and the copper recovery ratio declines. Arsenic in the silver bearing copper ore is a punitive element in a trade. It is verified that arsenic could be removed from tennantite and most of sulfur is retained satisfactorily at low oxygen pressure.Investigation has been carried out for arsenic removal from a silver bearing copper ore. The copper ore was roasted in nitrogen atmosphere (>99%) at temperatures ranging from 923.15K to1123.15K. By suitably adjusting the main reaction conditions, nearly 98% arsenic was removed at 1053.15K for 3h in nitrogen atmosphere, while most of the sulfur was particularly retained in the copper ore. After the arsenic removal, the arsenic content was reduced from 7.81% to 0.13% and the copper ore could be used for feeding the smelter. Compared with the traditional method of arsenic removal from copper ore by roasting in oxygen, our proposed method of arsenic removal in nitrogen atmosphere at temperature of 1053.15K is more effective.

Utilization of co-existing iron in arsenic removal from groundwater by oxidation-coagulation at optimized pH

Oxidation-coagulation at optimized pH (OCOP) using NaHCO3, KMnO4 and FeCl3 is an efficient and low-cost arsenic removal method for domestic to large community scale applications. In this method, a high dose of the oxidant is used when the groundwater contains high concentration of coexisting iron for oxidising all ferrous and arsenate ions. A fixed dose of 25mg/L of FeCl3 is also employed as coagulant despite the formation of ferric ions from the coexisting ferrous ions. The present study aimed at utilization of the coexisting iron for the coagulation purpose and reducing the coagulant dose. Response Surface Methodology was employed to optimize the doses of the oxidant and the pH conditioner. A field trial at various arsenic affected rural habitations has shown that the present modified OCOP method to be more efficient and economical than the OCOP method reducing both arsenic and coexisting iron concentrations to less than 2μg/L and 0.1mg/L, respectively, at a lower cost. The modified OCOP method is useful especially with high concentration of coexisting iron.

Enhanced Removal of Arsenite from Ground Water by Adsorption onto Heat-Treated Rice Husk

The effect of heat treatment for rice husk was investigated on the removal of arsenite in ground water by the adsorption onto the rice husk surface. The heat treatment was performed at the temperature from 80oC to 300oC in the closed system under anoxic environment. The continuous adsorption column method was applied for the removal of arsenite. The removal efficiency (75%) with rice husk treated at 150oC was better compared to those (54%) obtained with untreated rice husk. Therefore, the heat treatment of rice husk at relatively low temperature was effective for the enhancement of arsenic removal from water. The treatment conditions of As removal from aqueous solution were optimized. The developed treatment technique was applied into the real ground water sample in Bangladesh. The As concentration in sample water after treatment was approximately 18 and 8 μg/L, which was below the WHO guideline value of maximum admissible level of arsenic in ground water for Bangladesh (50 μg/L). The developed technique might become a potential avenue for simple and low cost arsenic removal methods.