Method For Removal Of Arsenic Research Articles

An Arsenic Removal Technology and Its Application in Arsenic-Containing Copper

The usage of copper (Cu) ores containing low or no arsenic (As) has reduced, and Cu ores containing high levels of As have emerged as vital mineral resources for Cu extraction and processing. The quality of the Cu ores has decreased from 1.6% to approximately 1.0%. The proportion of As to Cu in 15% of Cu resources currently reaches 1:5. However, during the extraction and processing of Cu ores, As presents significant environmental harm. Hence, safely and effectively removing As is paramount in Cu smelting and processing, holding substantial importance in fostering environmentally sustainable practices within the Cu extraction and processing industry. This article consolidates the resource distribution of As-containing Cu (ACC) ores, comprehensively and systematically evaluates the present advancements in extracting techniques for these minerals, and identifies the challenges inherent in pyrometallurgical and wet processes for treating ACC deposits. Pyrometallurgy is a simple primary roasting technique and has widespread applicability in the treatment of various ACC minerals. Its disadvantages are the emission of exhaust gas and the high treatment costs associated with it. The wet arsenic removal method boasts advantages including minimal air pollution and a high resource recovery rate, significantly aiding in Cu concentrate recovery; its major drawback is the production of As-containing wastewater. The hydrometallurgical removal of As from ACC mines involves extracting As through leaching. Recently, biometallurgy has presented innovative solutions using specialized microorganisms to bioleach or bioabsorb As, but large-scale industrial applications still lack specific practical implementation. This review explores the underlying causes of the challenges encountered in processing ACC minerals. Additionally, it highlights pyrometallurgical roasting coupled with high-temperature filtration as a pivotal advancement in the extraction and processing of ACC ores.

New Generation Nanoadsorbents and Conventional Techniques for Arsenic Removal from Waters

Nowadays, with excessive use due to rapid population growth, growing industry, and technological developments, environmental pollution is also increasing and is reaching a point where it threatens the health of humans. The alarming increase in environmental pollution is mostly seen in the form of water pollution. Water pollution has reached levels that threaten human health. There are difficulties in accessing clean water in many parts of the world as a result of restricting the use of natural water resources polluted by both human activities and natural causes. Therefore, intense efforts are made to remove especially heavy metals and other harmful substances that pollute water. Among these toxic heavy metals threatening the health of humans, arsenic is at the top of the list as the most dangerous one. In recent years, many methods and techniques have been developed in addition to classical methods for removing pollutants from water. In this study, conventional methods used in the treatment of arsenic-contaminated waters, the difficulties encountered in the removal process, and the advantages and disadvantages of the methods were critically reviewed in the light of current and past information. In addition, detailed comparative information is given about nano-sized adsorbents, which is an innovative approach used in the adsorption method, one of the arsenic removal methods.

Adsorption methods for arsenic removal in water bodies: a critical evaluation of effectiveness and limitations

The presence of arsenic in water bodies poses a significant risk to both human health and the environment. Arsenic (As) contamination in water sources is a global environmental concern caused by both natural processes and human activities. Due to its toxic and persistent nature, arsenic has detrimental effects on ecosystems and human wellbeing. This study aimed to elucidate the mechanisms behind arsenic accumulation in water bodies. In aquatic environments, arsenic concentrations in drinking water have been reported as high as 1,320 μg/L (Nicaragua), while groundwater levels exceeded 5,000 μg/L (Thailand), and wastewater contained up to 134,000 μg/L (landfill leachate in Brazil). Furthermore, bioaccumulation of arsenic (μg/g) in fish species ranges from 0.4 (catfish in the Paraná River Delta, Brazil) to 362 (Pteromylaeus bovinus, Northern Adriatic Sea). Recent research has predominantly focused on removing arsenic from aqueous solutions through adsorption methods. Notably, nanoparticle adsorbents and graphene-based adsorbents demonstrate a high capacity for arsenic removal from water bodies.

Influence of iron, phosphate, and silicate on arsenic removal from groundwater using a low-cost ceramic filter.

The ceramic filter amended with iron (Fe) has proven to be a potential low-cost method for arsenic (As) removal from groundwater. The presence of Fe, phosphate (P), and silicate (Si) significantly affects the As removal efficiency of the ceramic filter, which has not been passably investigated. The present research aimed to examine the effect of Fe, P, and (or) Si presence as single or in combination on As (III) removal from synthetics groundwater by a low-cost iron amended ceramic filter (IACF). Laboratory-scale filtration experiments at different compositions of Fe, P, Si, and As (III) were conducted by the IACF fabricated with a ceramic candle and iron netting box. Fe (II) in synthetic groundwater positively impacted As (III) removal. At a concentration of 2mg/L of Fe (II), the As levels in the effluent decreased to less than the maximum contamination level (MCL) of 50 μg/L. Groundwater P concentration needed less than 3mg/L or Si concentrations required less than 35 mg/L to effectively reduce As (III) to below the MCL at 5mg/L of groundwater Fe (II). The cumulative effect of P and Si on As removal was found to be more significant than distinct contributions. The presence of 2mg/L P and 35 mg/L or higher Si in the groundwater cumulatively reduced the As removal performance from 92% to 63%, and the MCL was not met. The negative impact of P and Si on As (III) removal followed the order of (P + Si) > P > Si. P competed with As for adsorption sites during the process, while Si inhibited the Fe release and floc formation, significantly reducing As removal performance. The study findings can potentially contribute to optimizing IACF as a low-cost method for As removal from groundwater.

A critical analysis of various post-harvest arsenic removal treatments of rice and their impact on public health due to nutrient loss.

Rice (Oryza sativa L.) is particularly susceptible to arsenic (As) accumulation. Currently, to decrease the level of As accumulated in rice, various post-harvest methods, i.e., polishing, parboiling, pH-dependent soaking, washing, and cooking at different rice-to-water ratios (r/w), are being focused, because it removes significant amount of As from rice grain. Depending upon the rice variety and type, i.e., rough (with husk), husked (without husk/brown), or polished rice, these methods can remove 39-54% As by parboiling, 38-55% by polishing, 37-63% by soaking, and 6-80% by washing and cooking. Infants are highly vulnerable to As exposure; thus, these methods can be helpful for the production of rice-based infant foods. Although concern arises during the use of these methods that apart from decreasing the level of As in rice grain, they also lead to a significant loss of nutrients, such as macro- and micro-elements present in rice. Among these discussed methods, parboiling curtails 5-59%, polishing curtails 6-96%, soaking curtails 33-83%, and washing and cooking in different r/w reduce 8-81% of essential nutrients resulting in 2-90% reduction in contribution to the RDI of these nutrients through rice-based diet. Thus, these post-harvest arsenic removal methods, although reduce arsenic induced health hazard,but mayalso lead to malnutrition and compromised health in the population based on rice diet. There is a need to explore another way to reduce As from rice without compromising the nutrient availability or to supplement these nutrients through grain enrichment or by introducing additional dietary sources by changing eating habits; however, this may impose an extra economic burden on people.

Efficient removal of arsenate from water using electrospun polyethylenimine/polyvinyl chloride nanofiber sheets

Arsenic is a highly toxic pollutant affecting over 200 million people worldwide in >100 countries. Adsorption is an effective method for arsenic removal, and the development of efficient adsorbents for arsenic removal has received much attention. This study reports a regenerable electrospun polyethylenimine/polyvinyl chloride nanofiber sheet adsorbent with excellent adsorption performance for As(V). The adsorbent showed the highest As(V) uptake at pH 5. At the initial As(V) concentrations of 1, 10, and 100 mg/L, the adsorption equilibrium was reached in 10, 90, and 180 min, respectively. The maximal As(V) uptake on the adsorbent was 111.77, 115.79, 119.20, and 122.74 mg/g at the temperature of 15, 25, 35, and 45 °C, respectively, as calculated by the Langmuir model. The adsorption process was endothermic and spontaneous, as demonstrated by thermodynamic studies. Effects of competing anions on As(V) adsorption follow the order of SO42− > PO43− > CO32− ≈ NO3− ≈ F−. The main adsorption mechanisms were electrostatic attraction and coordination. The adsorbed As(V) can be eluted from the adsorbent with 0.2 M NaOH. The adsorption efficiency remained above 91% even after 5 reuse cycles. Overall, the sheets is a promising adsorbent for removing As(V) from water.

Efficient method of arsenic removal from water based on photocatalytic oxidation by a plasmonic–magnetic nanosystem

Arsenic is one of the most toxic elements in natural waters since prolonged exposure to this metalloid can cause chronic damage to health.

P-Arsanilic acid decontamination over a wide pH range using biochar-supported manganese ferrite material as an effective persulfate catalyst: Performances and mechanisms

Direct chemical oxidation and pure adsorption could not effectively remove p-Arsanilic acid (p-ASA) and the released inorganic arsenic. Herein, one novel biochar supported MnFe2O4 (MFB) was synthesized and adopted for p-ASA degradation and synchronous adsorption of the generated inorganic arsenic. The MFB/persulfate (PS) system could remain effective under a wide pH range (3.0–9.0), and the released arsenic could be removed simultaneously by MFB. Mechanism investigation revealed that the functional groups of MFB (i.e. O–C=O and C=O), Fe and Mn oxides on MFB all contributed to PS activation. O2·− and 1O2 were the main reactive oxygen species (ROS) responsible for p-ASA degradation, and 1O2 was the predominant ROS. Besides, the MFB possessed superior reusability. Therefore, it is expected to develop a potential method for organic arsenic contaminants removal via an oxidation-adsorption process, and the results could also shed light on the better understanding of the PS activation mechanisms.Graphical

Multi-roles of SO2 to enhance the removal of arsenic from wastewater in sulfidation processes

Sulfidation has been an efficient method for arsenic (As) removal from acid wastewater, yet it is inefficient under neutral and weak acid conditions. The higher pH values resulted in the formation of the unstable As-S precipitates, especially employing Na2S as the vulcanizing agent as it can increase the pH value dramatically. Here, we found that SO2 exhibited excellent multi-roles in As removal when applying H2S-sulfidation method. The acidification effect of SO2 lead to the decreasing of pH values, guaranteed the stable As-S precipitates formation. Through the SO2 pre-treatment method, the results indicated that the pH values decreased from 7 to 2.8, with the increased H2S utilization efficiencies for As(III) removal from 20.9% to 92.0%. Moreover, SO2 post-treatment not only increased the As(III) removal efficiency, but also eliminated the excessive sulfides in solution. The reaction mechanism analysis indicated that the liquid comproportionation reaction between SO2 and excessive sulfides plays a vital role. The generated nascent sulfur (N-S0) can adsorb arsenic species and promote the agglomeration of As(III)-S precipitates. Furthermore, the SO2 and H2S co-treatment exhibited excellent As(V) removal performance. This study provides a new alternative method to improve the H2S-sulfidation process with SO2 for As removal from wastewater.

Review on Application of Low-Cost Adsorbents for Arsenic Removal

Arsenic’s history in science, medicine and technology has been overshadowed by its notoriety as a poison in homicides. Arsenic is viewed as being synonymous with toxicity. Dangerous arsenic concentrations in natural waters, especially in ground water has become a worldwide problem and often referred to as a 20th–21st century calamity. The current regulation of drinking water standard has become more stringent and requires arsenic content to be reduced few parts per billion. There are numbers of arsenic removal methods, which include coagulation followed by view precipitation, membrane separation, anion exchange, adsorption etc. Some low-cost adsorbents are superior including Dry plants, red mud, fly ash, zeolites, blast furnace slag’s, hydrotalcites, hydroxides and various bio-adsorbents are include bio-char , methylated yeast biomass , fungal biomass , chicken feathers , alginate etc. The use of low-cost adsorbent obtained from an environmentally friendly materials, has been investigated as a replacement for the current expensive methods of removing arsenic from solution. Natural materials or waste products from certain industries with a high capacity for arsenic can be obtained, employed, and disposed of with little cost

Alkaline refining of crude lead: a method of arsenic removal and the behavior of arsenic in the process

In this work, the alkaline refining of arsenic in crude lead was studied with a mixture of sodium hydroxide and sodium carbonate as alkaline refining agents. Taking the arsenic removal rate as the research object, the effects of reaction temperature, holding time, Na2CO3:NaOH, the dosage of refining agent were investigated. The arsenic removal rate is 79.09% under the optimum experimental conditions as follows: reaction temperature 823 K, holding time 60 min, Na2CO3:NaOH 1:4, refining agent dosage 10%. The oxidation purification mechanism of arsenic was studied by XPS, SEM-EDS, XRD and FT-IR. The results show that arsenic in the crude lead is gradually oxidized by oxygen and lead oxide during arsenic removal process, and the arsenic trioxide is eventually converted into sodium arsenate (Na3AsO4) and lead arsenate (Pb2As2O7) in the slag.

Mechanism of zero-valent lead reduction for removing high concentration of arsenic from waste acid of lead smelting system

Lead metal smelting waste acid containing high concentrations of arsenic and sulfuric acid threaten human health and pose huge potential environmental risks due to its possible leakages during storage and disposal. In order to remove arsenic in smelting waste acid, a new method for arsenic removal by adding zero-valent lead and CuSO4 is proposed. The substitution reaction between zero-valent lead and CuSO4 to generate Cu0, and form a Pb-Cu galvanic cell system with zero-valent lead. Through the reduction of zero-valent lead, As(III) was reduced to As(0) and reacted with Cu0 to produce Cu3As precipitation. As the pH of waste acid changed, AsO2- will produce As2O3. When the molar ratio of Pb to As (Pb/As) was 6, CuSO4 concentration was 7 g/L, 25 °C, and 240 min, the arsenic concentration sharp decreased from 4706.4 mg/L to 35.21 mg/L, arsenic removal efficiency reached 99.25%. The arsenic removal process could be described by the shrinking core model which was controlled by a diffusion process. XRD, SEM-EDS, and XPS were used to characterize the phase, morphology, and elemental valence of the arsenic-containing precipitates. Based on the above analysis and combined with thermodynamic analysis, the mechanism of arsenic removal by zero-valent lead combined with CuSO4 was revealed.

Specifically designed magnetic biochar from waste wood for arsenic removal

Arsenic is a carcinogenic substance, with many cases of poisoning related to arsenic pollution in groundwater. In Taiwan arsenic in groundwater caused the notorious Blackfoot disease. Methods for arsenic removal from water include precipitation, membrane processes, ion exchange, and adsorption, but these processing technologies suffer from high investment costs and complex operations. The traditional adsorption method cannot be used for arsenic removal due to its high operating costs, difficulties in recovery, and low adsorption capacity. To address these issues, this study designed an adsorption material based on biochar for arsenic removal with higher adsorption properties and easy recovery. Biochar sources are readily available from waste wood as a cheap and environmentally friendly material. The efficiency of As (III) removal is also promoted by FeCl3 and KMnO4. The objectives of this research are to obtain optimum operation conditions by assessing the effects of different iron and manganese contents, different doses, different pH and different initial concentration. The adsorption mechanism between As (III) and biochar was studied by adsorption isotherms and the kinetic model. X-ray diffraction, energy-dispersive X-ray spectroscopy and elemental analyzer analysis results show that modified biochar has major elements of Fe and Mn. There is greater magnetism, 40 emu g− 1, in the modified biochar. The maximum adsorption efficiency of 81% and 0.72 mg g− 1 capacity occurs when the ratio of Mn, Fe and C is 4:1:1. The adsorption capacity is high under higher pH with pristine biochar and 1FeC under lower pH with 1Fe2MnC. The reaction mechanism is divided into four pathways. The first pathway is the attachment of As (III) ions into the pore of biochar via physical adsorption. In the second pathway, biochar can connect with As (III) through hydrogen bonding from the function group -OH in the biochar and the As (III) itself. In the third pathway, they can contact each other by electron force when the biochar surface is filled with a positive charge. In the fourth pathway, the compounds of manganese have strong oxidizability to oxidize As (III) to As(V). The iron ions then act as a bridge connecting the biochar and the As (III), resulting in the formation of new complex compounds.

Safe and ecological performance of mining and processing industry

Mineral mining and processing activities result in highly toxic arsenic-bearing waste water discharged in natural water bodies. The promising methods of arsenic removal from waste water use adsorption at natural sorbents and oxidizers. The tests of arsenic removal by adsorption at magnesium- and manganese-bearing minerals show that the use of these natural raw materials can greatly enhance efficiency of the environmental activities in the mining and processing industry.

In situ X-ray absorption spectroscopic studies of photocatalytic oxidation of As(III) to less toxic As(V) by TiO2 nanotubes.

Arsenic in groundwater caused the black-foot disease (BFD) in many countries in the 1950-1960s. It is of great importance to develop a feasible method for removal of arsenic from contaminated groundwater in BFD endemic areas. Photocatalytic oxidation of As(III) to less toxic As(V) is, therefore, of significance for preventing any arsenic-related disease that may occur. By insitu synchrotron X-ray absorption spectroscopy, the formation of As(V) is related to the expense of As(III) disappearance during photocatalysis by TiO2 nanotubes (TNTs). Under UV/Vis light irradiation, the apparent first-order rate constant for the photocatalytic oxidation of As(III) to As(V) is 0.0148 min-1. Itseems that As(III) can be oxidized with photo-excited holes while the not-recombined electrons may be scavenged with O2 in the channels of the well defined TNTs (an opening of 7 nm in diameter). In the absence of O2, on the contrary, As(III) can be reduced to As(0), to some extent. Cu(II) (CuO), as an electron acceptor, was impregnated on the TNTs surfaces in order to gain a better understanding of electron transfer during photocatalysis. It appears that As(III) can be oxidized to As(V) while Cu(II) is reduced to Cu(I) and Cu(0). The molecular-scale data are very useful in revealing the oxidation states and interconversions of arsenic during the photocatalytic reactions. This work has implications in that the toxicity of arsenic in contaminated groundwater or wastewater can be effectively decreased via solar-driven photocatalysis, which may facilitate further treatments by coagulation.

Mechanism of As(V) adsorption from aqueous solution by chitosan-modified diatomite adsorbent

Arsenic poses severe threats to human and ecosystem health. Various methods for arsenic removal, including the use of different adsorbents, have been employed. Herein, an adsorbent using refined diatomite as the matrix and chitosan as the modifying agent was evaluated. For effective design of adsorption systems, the structural changes during adsorbent modification and the adsorption process were investigated. The adsorbent was analyzed and characterized using scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). The feasibility of using chitosan-modified diatomite was explored by utilizing the batch equilibrium technique with varying experimental parameters, including the adsorbent dose, initial concentration of As(V), temperature, pH, and time. Additionally, chitosan-modified diatomite adsorption isotherms and adsorption kinetics were studied. The ability of the adsorbent to remove As(V) from an aqueous solution before and after modification was investigated via a static adsorption experiment. No change was found in the diatomite matrix after modification; however, the adsorption peaks of the functional groups changed. The organic phase peak revealed by XRD disappeared, whereas a nitrogen phase peak appeared. During modification, open chains of chitosan were grafted effectively onto the diatomite surface. Chitosan-modified diatomite can be used to coordinate an adsorption reaction with arsenate through surface –NH2. The optimum conditions for adsorption at an initial As(V) concentration of 2 mg/L were a pH of 5, temperature of 25 °C, reaction time of 60 min, and an adsorbent dose of 3 g/L. Chitosan-modified diatomite can remove As(V) from aqueous solutions significantly better than unmodified diatomite.

Arsenic removal through bio sand filter using different bio-adsorbents

Arsenic is one of the most harmful pollutants in groundwater. In this paper, the Nepali bio sand filter (BSF) was modi-fied with different bio-adsorbents, and proved to be an efficient method for arsenic removal from groundwater. Three dif-ferent bio-adsorbents were used to modify the Nepali BSF. Iron nails and biochar BSF, ~96% and ~93% arsenic removal was achieved, within the range of WHO guidelines. In iron nails, BSF and biochar BSF ~15 dm3∙h–1 arsenic content water was treated. In the other two BSFs, rice-husk and banana peel were used, the arsenic removal efficiency was ~83% of both BSFs. Furthermore, the efficiency of rice-husk and banana peel BSFs can be increased by increasing the surface area of the adsorbent or by reducing the flow rate.

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.