Adsorbent For Arsenic Removal Research Articles

Role of Co and Ni ferrites in the fabrication of Saccharum officinarum bioadsorbents for removing As(III)

Removal of arsenic from drinking water is one of the most significant worldwide concerns. Adsorptive removal of arsenic is highly practical and efficient among the various methods. The green synthesis using sugarcane extract was eco-friendly, and cost-effective and resulted in adsorbents having magnetic behavior and a high capacity for arsenic. In the present study, activated carbon (ACs) of sugarcane and its surface, functionalized with nickel ferrite (AC/NFO) and cobalt ferrite (AC/CFO) were used as biosorbents for the removal of As(III) from aqueous medium. The functionalization was undertaken in a controlled hydrothermal method using Saccharum officinarum (sugarcane) extract as a green source. The morphology, functionality, thermal stability, structure, magnetic behavior, surface area and porosity of adsorbents were confirmed by SEM, FTIR, TGA, XRD, VSM, BJH and AFM. The sorption behavior was determined with the effect of pH, time, concentration, temperature and dose. Pseudo-second order and Langmuir models were found suitable to validate the sorption data. Thermodynamics of the sorption process and the desorption studies suggested that the governing mechanism is chemisorption. The adsorption capacities for AC2, AC2C2 and AC2N2 were 961 µg/g, 1103 µg/g and 1000 µg/g respectively. Among the studied samples, AC2C2 was found as a potential candidate due to its high adsorptive efficiency of 97 % for As(III).

Preparation and Characterization of Ferrihydrite: Application in Arsenic Removal from Aqueous Solutions

Arsenic pollution is a public health hazard in Burkina Faso due to its impact on human health and water resources. To mitigate this pollution, ferrihydrite material has been synthesized and characterized to be used as adsorbent for arsenic removal in aqueous solutions. This study aimed to contribute to improve of access to clean drinking water by removing arsenic from water using ferrihydrite. Arsenic species such as As(III) and As(V) were removed through batch adsorption. Experiments were carried out in batch mode using arsenic aqueous solutions. The characterization of ferrihydrite using Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDX), X-ray Diffraction (XRD), Infrared (IR), and Brunauer Emmett Teller (BET) showed that an amorphous and microporous 2-line ferrihydrite. The total specific surface area and pH at point of zero charge (pHpzc) were 184.518 m²/g and 9.41, respectively. The optimal adsorbent doses were 4 g/L for As (V) and 8 g/L for As (III). The optimum pH range for the adsorption of As (V) and As (III) was between 2 and 10, The maximum adsorption capacity was 15.07 mg/g for As(V) and 13.01 mg/g for As(III) with increasing concentration between 2 and 16 mg/L. Equilibrium time for As (V) and As (III) on ferrihydrite was found to be 720 min and 960 min, respectively. The adsorption of As(V) and As(III) was consistent with the Langmuir monolayer model on ferrihydrite. Arsenic adsorption was occurred according to spontaneous chemical reaction. Arsenic removal was occurred on a monolayer following the pseudo-second order kinetic.

Synthesized polyetheretherketone/polyvinylalcohol nanocomposite modified with zinc oxide nanoparticles: As an effective adsorbent for removal of arsenic (III) ion from wastewater

The applicability of Polyetheretherketone/Polyvinylalcohol nanocomposite modified with zinc oxide nanoparticles synthesis for the removal of arsenic (III) ion from wastewater. Identical techniques, including BET, FT-IR, pHzero, and SEM, have to characterize this unknown material. The investigation shows the applicability of adsorbent PEEK/PVA/ZnONPs, as an available, suitable, and low-cost adsorbent for properly removing of the arsenic (III) ion from wastewater. The impacts of variables, including arsenic (III) ion concentration, adsorbent, pH, and time (30 mgL−1, 50.0 mg, 7.0, and 60.0 min). The adsorption equilibrium and kinetic data were fitted with the Freundlich isotherm model, and pseudo-second-order kinetics (R2: 0.997), with the maximum adsorption capacity of the arsenic (III) ion for adsorbent PEEK/PVA/ZnONPs (35.5 mgg−1), respectively. Thermodynamic parameters (ΔG°: −121.06 kJ/mol, ΔH°: −42.17 kJ/mol, ΔS°: −138.38 kJ/mol K−1), also indicated arsenic (III) ion adsorption as feasible, spontaneous and exothermic. To evaluate the practical applicability of the prepared adsorbent for the removal of As (III) ion from wastewater (containing humic acid, and other ions), it was subjected to sorption experiments. The results indicated that novel sorbent showed great potential as an affordable and efficient adsorbent for treating wastewater.

A systematic study on adsorptive removal of arsenic using low cost adsorbents with or without the presence of NOM

Arsenic is a toxic and bio-accumulating element in water bodies, especially in drinking water sources.One of the methods used to remove arsenic from drinking water is adsorption. NOM (natural organic matter), which is ubiquitous in natural aquatic environments, can inhibit arsenic adsorption by competing with arsenic for adsorbent surface sites. The main objectives of this study were to investigate the competitive adsorption between NOM and arsenic using low-cost adsorbents. For this purpose, batch adsorption experiments were carried out in synthetic and natural water using pumice, steel slag and red mud as low cost adsorbents.The highest arsenic removal efficiencies obtained with steel slag, pumice and red mud were 95, 95 and 50 %, respectively without the presence of NOM. The results showed that the presence of NOM caused a significant reduction in arsenic adsorption for all tested adsorbents and 20-30% less arsenic removal efficiency was obtained in natural water compared to the removal efficiencies obtained in synthetic water. The maximum adsorption capacities obtained in synthetic water with all tested adsorbents vary between 1.6 -3.05 mgAs/g, while the maximum adsorption capacities obtained in natural water vary between 0.9-1.2 mgAs/g. All these findings indicate that NOM can hinder the uptake of arsenic by all tested adsorbents. Moreover, the arsenic adsorption in natural water were modelled by Langmuir, Freundlich and modified Freundlich. The results showed that the arsenic adsorption data were well fitted by modified Freundlich isotherm with R2 values between 0.87 and 0.90.

Synthesis and characterization of maghemite submicron particles: novel adsorbent for arsenic removal

Synthesis and characterization of maghemite submicron particles: novel adsorbent for arsenic removal

Adsorption removal of arsenic from Aqueous solution by carboxy methyl Cellulose(CMC) modified with montmorillonite

In this research, CMC/MMT nano composite was prepared using the free radical polymerization method and evaluated as Arsenic ions removal adsorption from an aqueous solution. We used the Design expert (CCD) to remove Arsenic Ions optimally. SEM, XRD and FTIR analyses were used to determine the adsorbent properties. The experimental design was done with four time variables (25–40min), Arsenic concentration (0.5–2 ppm), adsorbent dose (0.05-2gr) and pH (4–8). The interaction and combined effects of the variables were evaluated by the analysis of variance (ANOVA) table. A quadratic polynomial regression equation was developed to predict the response under optimal conditions. The results of kinetic studies and adsorption isotherms present that the kinetics of Arsenic ion adsorption by CMS/MMT adsorbent follows the quadratic equation and the Langmuir isotherm with a better correlation coefficient than the Freundlich equation. Furthermore, under optimal conditions (pH = 5.6, t = 34 min), 1.9 ppm Arsenic is adsorbed per 0.09 g of the adsorbent with 85% efficiency which indicates that the carboxymethyl cellulose hydrogel modified with Montmorillonite is a suitable adsorbent to remove Arsenic ions from aqueous solution.

Synthesis and application of chicken manure biochar as an effective nanoporous adsorbent for removal of arsenic from wastewater: a cost-effective approach

Synthesis and application of chicken manure biochar as an effective nanoporous adsorbent for removal of arsenic from wastewater: a cost-effective approach

Adsorption removal of arsenic from aqueous solutions and groundwater by isomeric FeOOH.

FeOOH as a naturally abundant, relatively low-cost and effective adsorbent have been gradually valued in wastewater field rich in arsenic pollution, which can make for environmental remediation. In this study, FeOOH samples included Gth1/Gth2 as goethite, Aka1/Aka2 as akaganéite, and Lep as lepidocrocite, were prepared and used as adsorbents, and adsorption kinetic and isotherm experiments of As(III) were analyzed. Meanwhile, the effects of pH, adsorbent content, arsenic initial concentration and electrolyte solutions on adsorption processes were also discussed in detail to study adsorption behaviors and mechanism. The results showed that As(III) could be effectively adsorbed on goethite, akaganéite and lepidocrocite, the adsorption equilibrium achieved after 24 h. When As(III) concentration ranged in 40 mg/L, the saturated adsorption amounts (mg/g) calculated by the Langmuir equation were 12.3 (Gth1), 7.50 (Gth2), 6.29 (Aka1), 23.4 (Aka2), and 17.7 (Lep). The increase of adsorbent and adsorbate levels was favorable to improve the adsorption capacities of As(III) within a certain range. Removal efficiency of As(III) with Na2SO4 and NaH2PO4 as electrolyte reduced by about 10% and 30%, respectively. Therefore, the appropriate parameters in the adsorption process for investigation were isomeric FeOOH of 1.0 g/L, pH 7.0 and NaNO3 as electrolyte. In simulated groundwater filter system initially with 200 μg/L of arsenic species at about pH 7.0, arsenic removal strength for five FeOOH adsorbents (0.8 g) was Aka2 > Aka1 and Gth1 > Lep and Gth2. Some differences were present in the infrared (IR) spectra of arsenic-loaded and original isomeric FeOOH. These outcomes could give the aim at seeking high efficient materials for the purification of arsenic contaminated groundwater and put out the suggestion.

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

Adsorption and Its Mechanism of Arsenate in Aqueous Solutions by Red Soil

The removal, and its mechanism, of arsenate from aqueous solutions was investigated using Yunnan red soil. A series of adsorption experiments was designed to disclose the effect of key factors (soil types, soil/solution rates, initial arsenate concentrations, and shaking speeds) on the adsorption capacity of Yunnan red soil for arsenate. The soil/solution ratio was optimized as 0.05 g/100 mL to balance the adsorption capacity and removal efficiency. The optimal shaking speed (225 rpm) not only ensured enough contact frequency between the Yunnan red soil and the arsenate, but also reduced the mass transfer resistance. The results from applying an orthogonal array method showed that the most significant factor affecting arsenate removal efficiency was soil type, followed by the soil/solution ratio, contact time, and shaking speed. The IR spectra of the precipitates further confirmed that the metal arsenide was settled by the Yunnan red soil, indicating that the arsenate ion existed on the red soil surface in the form of protonated bidentate surface complexation of –FeO2As(O)(OH)− and FeO2As(O)2−. These results indicate that Yunnan red soil is promising for the removal of arsenate from aqueous solutions; it may thus be suitable as a new adsorbent for arsenate removal during water treatment.

Adsorption and photocatalysis removal of arsenite, arsenate, and hexavalent chromium in water by the carbonized composite of manganese-crosslinked sodium alginate

The preparation of easily synthesized and cheap composite materials for the efficient removal of toxic oxoanions still remains challenging in sewage treatment. Herein, a new carbonized manganese-crosslinked sodium alginate (Mn/SA-C) was fabricated for the removal of arsenite (As(III)), arsenate (As(V)) and hexavalent chromium (Cr(VI)) in water. The results indicated that the Mn/SA-C pretreated with MnSO4 solution (Mn/SA-C-S) exhibited a rapid adsorption toward As(III) and As(V) with the removal efficiency of >98% within 10 min, and had a high adsorption capacity toward As(III), As(V), and Cr(VI) with the maximum value of 189.29, 193.29, and 104.50 mg/g based on the Langmuir model, respectively. The removal efficiency of As(III), As(V), and Cr(VI) could be further significantly enhanced by coupling a photocatalytic process. For example, the time in which >98% of Cr(VI) (10 mg/L) was removed dramatically shortened from 360 min (adsorption) to 45 min (adsorption-photocatalysis), and the removal efficiency of As(III) increased by ∼10% within initial 5 min. This was primarily attributed to the Mn-catalyzed production of the photocatalytic excitons for Cr(VI) reduction, and the superoxide (•O2−) and hydroxyl (•OH) radicals for As(III) oxidation. The adsorption removal of arsenic (As) was primarily ascribed to surface complexation with MnO and precipitation by MnS2, and oxidative adsorption because of Mn valence cycle. The removal mechanisms of Cr(VI) mainly contained reduction by MnO and MnS2, complexation with MnO and carboxyl/hydroxyl groups as well as Cr(OH)3 precipitation. Our research provides a promising Mn/SA-C-S material for rapid and efficient removal of As(III), As(V), and Cr(VI) in contaminated water through an adsorption-photocatalysis synergistic strategy.

Application of Mn-Fe Layered Double Hydroxide as an Adsorbent for the Removal of Arsenic from Synthetic Acid Mine Drainage

The Mn-Fe layered double hydroxide using chloride in the interlayer anion was successfully synthesized using chemical co-precipitation methods. The Mn-Fe LDH was then applied as adsorbent for arsenic removal from synthetic acid mine drainage. The adsorbent characterizations of SEM and XRD analysis showed that the Mn-Fe LDH had many different functional groups and a high specific surface area for the adsorption processes. The morphological structure of Mn-Fe LDH by the SEM-EDS analysis method shows a round shape structure with a particle size of about 1 μm, and the XRF analysis method shows that the Mn and Fe elements dominate more than other components. Batch adsorption experimental conducted using the Mn-Fe LDH with the interlayer anion of chloride as an adsorbent to study the effect of contact time, equilibrium pH, and temperature on the arsenic removal. The Mn-Fe LDH showed high adsorption uptake capacity and selectivity for the arsenic in the synthetic acid mine drainage. The adsorption and ion exchange between interlayer chloride anions in Mn-Fe LDH and As (V) solution was the main adsorption mechanism. Therefore, the Mn-Fe LDH can be used as an adsorbent in water and wastewater treatment. In contrast, this research has the potential to be processed and developed into advanced materials.

Review on heterogeneous oxidation and adsorption for arsenic removal from drinking water

The long term exposure of arsenic via drinking water has resulted in wide occurrence of arsenisim globally, and the oxidation of the non-ionic arsenite (As(III)) to negatively-charged arsenate (As(V)) is of crucial importance for the promising removal of arsenic. The chemical oxidants of ozone, chlorine, chlorine dioxide, and potassium permanganate may achieve this goal; however, their application in developing countries is sometimes restricted by the complicate operation and high cost. This review paper focuses on the heterogeneous oxidation of As(III) by solid oxidants such as manganese oxide, and the adsorption of As(V) accordingly. Manganese oxide may be prepared by both chemical and biological methods to achieve good oxidation performance towards As(III). Additionally, manganese oxide may be combined with other metal oxides, e.g., iron oxide, to improve the adsorption capability towards As(V). Furthermore, manganese oxide may be coated onto porous materials of metal organic frameworks to develop novel adsorbents for arsenic removal. To achieve the application in engineering works, the adsorbents granulation may be achieved by drying and calcination, agglomeration, and the active components may also be in situ coated onto the porous materials to maintain the oxidation and adsorption activities as much as possible. The novel adsorbents with heterogeneous oxidation and adsorption capability may be carefully designed for the removal of arsenic in household purifiers, community-level decentralized small systems, and the large-scale drinking water treatment plants (DWTPs). This review provides insight into the fundamental studies on novel adsorbents, the development of innovative technologies, and the demonstration engineering works involved in the heterogeneous oxidation and adsorption, and may be practically valuable for the arsenic pollution control globally.

Effective Removal of Arsenic in Drinking Water Using Facile Synthesized Fe2O3 Coated N-Doped TiO2 Nanoparticles

Arsenic contamination of water in the Red River and Mekong deltas brings the largest mass poisoning calamity in human history because drinking of arsenic contaminated water can cause cancers of the skin, lungs, bladder and kidney and other harmful diseases. In general, the arsenic exists in difference oxidation states such as –3, 0, +3, and +5, among which As(+3) has been considered as the most dangerous contaminant in the water. Synthesis of nature friendly and low cost, portable, and effective adsorbent for removal of arsenic in contaminated water is very essential for many countries where development of large industrial setup is difficult. In this work, we introduce a facile method for preparation of Iron Oxide (Fe2O3) coated N-doped Titanium Oxide (TiO2) nanoparticles (FNT NPs) towards effective removal of As(III) from drinking water. The FNT NPs were synthesized by a scalable low temperature, solution based hydrothermal method using as Iron(III) chloride (FeCl3), and N‑doped TiO2 NPs as starting materials. The prepared FNT NPs were characterized by Scanning electron microscopy (SEM), Energy-Dispersive X-Ray (EDS), and Transmission electron microscopy (TEM), whereas the As(III) adsorption studied were done using Inductively coupled plasma mass spectrometry (ICP) analysis. Results pointed out that the high quality FNT NPs were successfully synthesized by a low temperature hydrothermal method with uniform size and shape. The adsorption test confirmed that the prepared FNT NPs can effectively remove the As from the water. The results shows 99.34% As(III) form water was adsorbed using the prepared FNT NPs within 60 min. The results shows synthesized FNT NPs, could provide large specific surface area for effective adsorption sites for capturing and removal of As(III) in the water.

Synthesis and characterization of gold nanoparticles (AuNPs) and ZnO decorated zirconia as a potential adsorbent for enhanced arsenic removal from aqueous solution

In this study, gold nanoparticles (AuNPs) and ZnO-decorated zirconia (AuNPs/ZnO-ZrO2) were synthesized through co-precipitation and hydrolysis coupled with heat treatment, and explored as a novel adsorbent for arsenic removal from aqueous solution. The effects of synthesis parameters were examined, such as support type, Zn/Zr mole ratio, co-precipitation method and calcination temperature. X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and N2 adsorption were used to investigate the enhancement of arsenic adsorption on the hybrid composites. It was found that the adsorption property of AuNPs/ZnO-ZrO2 was strongly dependent on support type, Zn/Zr mole ratio, co-precipitation method and calcination temperature. The optimized AuNPs/ZnO-ZrO2 exhibited the best adsorption capacity for arsenic at lower concentrations (less than 8 mg L−1), compared with ZnO-decorated zirconia (ZnO-ZrO2) and bare zirconia (ZrO2). The enhanced adsorption of arsenic by AuNPs/ZnO-ZrO2 was ascribed to the larger specific surface area, abundant hydroxyl groups and co-existance of ionic gold (Au(OH)2+) and gold clusters (Auδ+) highly dispersed on the surface which could act as smart scavengers for low-concentration arsenic from water. The adsorption equilibrium of arsenic on AuNPs/ZnO-ZrO2 fitted to the Langmuir, Brunauer–Emmett–Teller (BET) and Gunary models well and the Gunary model gave the best fit. Isotherm analysis results showed that the adsorption of arsenic on AuNPs/ZnO-ZrO2 occurred dominantly through monolayer formation but was a non-ideal Langmuir type adsorption. However, ZnO-ZrO2 showed much higher adsorption capacity for arsenic than that of ZrO2, which was mainly attributed to the formation of basic zinc carbonate (BZC) with rich structural hydroxyl groups and to the improvement in surface properties of zirconia. Significant multilayer adsorption was able to proceed on the surface at higher arsenic concentrations (more than 8 mg L−1), obeying the BET isotherm.

Fabrication of chitosan/graphene oxide-gadolinium nanorods as a novel nanocomposite for arsenic removal from aqueous solutions

Chitosan-graphene oxide-gadolinium oxide (CGO-Gd) nanocomposite was prepared to adsorption removal of arsenic(V) from water. The CGO-Gd nanocomposite were characterized through X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), N2 adsorption/desorption isotherms, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Thermal gravimetric analysis (TGA), and Raman spectroscopy analyses. The 50 nm long rods were found to possess a crystalline morphology with highly active oxygenated functional groups (OH−, COO−, C–O–C, and Gd2O3), which aid in the adsorptive removal of arsenic. Batch experiments, including pH, adsorption kinetics, and equilibrium isotherms studies were performed to evaluate arsenic adsorptive removal using prepared CGO-Gd. The efficacy of CGO-Gd for arsenic removal was found to be high in the range of pH 3 to 7, and then decline above pH >7. However, the removal capacity for As(V) was 252.12, and 128.20 mg/g for 0.1 and 0.3 g/L of CGO-Gd, respectively, obtained at pH 6.0. Moreover, the CGO-Gd can be reused up to five times for As(V) removal that demonstrates the feasibility and cost-effectiveness of the material. Further evaluated the applicability of developed method for real water samples treatment that results demonstrates that the CGO-Gd can reduce the quantity of As(V) in water to the regulatory standards required for drinking water (10 μg/L) stipulated by environmental protection agencies. Moreover, the loaded Gd2O3 not only enhanced the adsorption ability of CGO but also improve the separation and stability of the CGO-Gd. Thus, the prepared CGO-Gd has a latent for As(V) removal from various real water effluents.

Preparation and Adsorption Characteristics of Novel Molecular Sieve for High Efficiency Arsenic Removal

In order to enhance the adsorption performance of 4A molecular sieve for arsenic in aqueous solution,using MS as a carrier,iron-loaded molecular sieves(FMS)and iron-manganese molecular sieves(FMMS)were prepared as adsorbents for arsenic removal by impregnation method.The MS and FMS were characterized by SEM,FT-IR and BET,and carried out batch experiments to investigate the adsorption and removal effects of FMS and FMMS for pentavalent arsenic(As^5+)and trivalent arsenic(As^3+).The adsorption kinetics,isothermal adsorption test and adsorption thermodynamics of the FMS adsorption process were performed.The results show that the specific surface area of FMS is significantly increased and the surface structure of the material is improved.The specific surface area and pore volume of the FMS increased from^27.38 m^2 g and 0.068 cm^3 g to 281.25 m^2 g and 0.16 cm^3 g,respectively.Meanwhile,the average pore size decreased from 9.93 nm to 2.21 nm.This could cause the dense coarse particles to become an adsorbent with loose porous microstructure.FT-IR analysis shows that iron oxide formed in the iron salt impregnation process is mainly combined with O-H,Al-O and Si-O in the molecular sieve structure.The results of batch experiments with 4 mg L As^5+indicate that the removal rate increases by about 70%after the material modification.Moreover,the adsorption process is in accordance with the quasi second-order adsorption kinetics,and the correlation coefficient(R 2)is 0.99,indicating that the chemical adsorption plays an important role in the adsorption process.The Freundlich isotherm adsorption model fits the adsorption data well with a correlation coefficient(R 2)is 0.98,and the maximum adsorption capacity is calculated to be 9.9 mg g.Furthermore,the calculation of thermodynamic parametersΔG,ΔH andΔS find that temperature increase is favorable for adsorption,and the disorder degree between solid and liquid on the surface of the material increases during the reaction.Compared with FMS,FMMS can effectively improve the removal performance of As^3+.The initial concentrationof coexistence conditions wereρ(As^3+As^5+)=2.0,4.0,6.0 mg L,the removal rate of FMMS is increased by about 26.34%,28.06%and 28.09%,respectively.The research shows that the use of iron salt impregnation method to modify MS can effectively increase the adsorption capacity of As^5+and As^3+,and can give full play to the practical application value of the material.

Removal and Oxidation of As(III) from Water Using Iron Oxide Coated CTAB as Adsorbent.

Iron oxides such as magnetite and maghemite coated with cetyltrimethylammonium bromide (CTAB) are very promising materials for wastewater treatment because iron oxide can be easily separated from solutions using the magnetic separation procedure Iron oxide (IO) coated CTAB was synthesized by an adapted co-precipitation method. In the present study, the IO-CTAB was used for removing arsenic from water for the first time. In the present study, the performance of iron oxide coated CTAB biocomposites as an adsorbent for arsenic removal from aqueous solutions was examined. X-ray diffraction (XRD) analysis and the results revealed a cubic phase Fd-3 m of Fe3O4 with lattice a = 8.40 Å and average crystal size equal to 17.26 ± 3 nm. The mean particle size calculated from transmission electron microscopy (TEM) was 19.86 ±1.7 nm. The results of the adsorption batch experiments and the data determined using the Langmuir and Freundlich models emphasized that IO-CTAB nanoparticles were favorable for the adsorption of As(III) ions from aqueous solutions. Ultrasound measurements have shown that IO-CTAB is a cost-effective biocomposite for removing arsenic from contaminated solutions. Moreover, x-ray photoelectron spectroscopy (XPS) has shown that during the process of arsenic absorption, there is oxidation from As(III) to As(V), which leads to a decrease in toxicity during this process. The results of the cytotoxic assays confirmed that the IO-CTAB nanoparticles did not induce any morphological changes in the HeLa cells and did not affect their proliferation after 24 h of incubation.

Fabrication and adsorption properties of magnetic graphene oxide nanocomposites for removal of arsenic (V) from water

In this work, magnetic graphene oxide nanocomposites were synthesized by co-precipitation method and used as an adsorbent for removal of arsenic (V) ions from water. The structure and morphology of magnetic graphene oxide nanocomposites were studied by X-ray diffraction, Fourier transform infrared spectroscopy, transmission electron microscopy, Brunauer–Emmett–Teller specific surface area, and vibrating sample magnetometry. Fourier transform infrared spectroscopy, X-ray diffraction, and transmission electron microscopy results of magnetic graphene oxide presented that the Fe3O4 nanoparticles in the size range of 10–25 nm were decorated on graphene oxide nanosheets. The adsorption properties of magnetic graphene oxide nanocomposites for arsenic (V) from water were investigated to study the effects of magnetic graphene oxide mass ratio, contact time, pH, and initial concentration. The suitable magnetic graphene oxide mass ratio of nanocomposites for arsenic (V) adsorption was determined to be 4:1 (FG2). The adsorption process on FG2 followed a pseudo-second-order kinetic and well fitted in to Langmuir isotherm model with the maximum adsorption capacity of 69.44 mg/g at pH 3. Accordingly, FG2 could be used as an effective adsorbent for removal of arsenic (V) from water.

Remediation of carcinogenic arsenic by pyroaurite-based green adsorbent: isotherm, kinetic, mechanistic study, and applicability in real-life groundwater

The removal of the harmful carcinogen arsenic from drinking water by a green technology is a major concern in the field of environmental engineering. The sorptive profile of arsenic remediation by calcined Mg-Fe-layered double hydroxide, fabricated by a one-pot synthesis technique, was investigated to delineate its applicability in real-life water. The physicochemical properties of adsorbent, as demonstrated from spectroscopy and microscopy, which described the existence of amorphous material with significant surface roughness possess selectivity towards arsenic. The isotherm and kinetic along with thermodynamic modeling exhibited the occurrence of spontaneous (ΔG0 value=- 8.084kJ/mol to - 10.942kJ/mol), endothermic (ΔH0 value=12.135kJ/mol), and physisorption reactions (Ead=4.103-5.832kJ/mol, Ea=11.546kJ/mol, S*=0.0005<<1, and ΔHx=9.23-16.29kJ/mol) with high uptake rate and adsorption potential of adsorbent. The isotherm and kinetics were demonstrated by Temkin (R2=0.944-0.969) and Elovich (R2=0.996-0.998) models, respectively, with high statistical significance. The intraparticle diffusion model which established the rate-limiting step is the combination of both film and pore diffusions. The applicability of layered double hydroxide (LDH) material in the real-life water was confirmed by isotherm and kinetic modeling along with the regeneration/reuse potential. The adsorptive removal of arsenic by the LDH material exhibited to be a promising technique without creating any secondary hazard.