Arsenic Adsorption by Some Iron Oxide Minerals: Influence of Interfacial Chemistry (original) (raw)
Related papers
Desalination, 2011
In this paper, adsorption of arsenic (V) was studied under different physico-chemical conditions onto four commercial adsorbents: hematite, goethite, magnetite and zero-valent iron (ZVI). The reversibility of adsorption process was also studied using chlorides and phosphates as competing ions. Results show that arsenate adsorption is related to the iron content of adsorbents, and adsorption rate increases in the following order: goethite b hematite b magnetite b ZVI. The modeling of adsorption isotherms by empirical models show that arsenate adsorption is fitted by the Langmuir model for almost all adsorbents, suggesting a monolayer adsorption of arsenic onto adsorbents. Desorption experiments show that arsenic is strongly adsorbed onto hematite and ZVI. Among adsorbents, hematite appears to be the most suitable for removing arsenate in natural medium since it is effective over large ranges of pH and arsenic concentration.
Arsenic adsorption onto hematite and goethite
Comptes Rendus Chimie, 2009
Surface complexation reactions on mineral affect the fate and the transport of arsenic in environmental systems and the global cycle of this element. In this work, the sorption of As(V) on two commercial iron oxides (hematite and goethite) was studied as a function of different physico-chemical parameters such as pH and ionic strength. The main trend observed in the variation of the arsenic sorbed with the pH is a strong retention in acidic pH and the decrease of the sorption on both sorbents at alkaline pH values. The sorption experiments for these iron oxides show that there is no effect of the ionic strength on arsenate adsorption suggesting the formation of an inner sphere surface complex. At pH values corresponding to natural pH water, both hematite and goethite are able to adsorb more than 80% of arsenic, whatever the initial concentration may be. The iron oxides used in this work should be suitable candidates as sorbents for As(V) removal technologies. To cite this article: Y. Mamindy-Pajany et al., C. R. Chimie 12 (2009).
Adsorptive removal of arsenic from aqueous solutions by iron oxide coated natural materials
Arsenic in the environment, 2016
Magnetite nanosorbents are known with high sorption capacity and ease of solid phase separation from surrounding liquid by the imposed external magnetic field. In this study, magnetite nanoparticles (MNPs) and silica-coated magnetite nanoparticles (Si-MNPs) were prepared and used for the removal of arsenic (III) from aqueous solutions. The nanosorbents were characterized by transmission electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and vibrating sample magnetometer. The spherical Fe 3 O 4 nanoparticles in diameter of about 100 nm and SiO 2 shells of 12 nm were formed. The saturation magnetization was found to be 78 and 58 e mug-1 for MNPs and Si-MNPs, respectively. Under optimal conditions, both nanosorbents were very efficient for arsenite uptake (removal efficiency 99%). The highest removal percentage was obtained near PZC of nanosorbents where the net surface charge was zero. The MNPs exhibited higher sorption capacities in comparison with Si-MNPs although they tended to be agglomerated in higher applied doses. The kinetic of experiments indicated the best fit to the pseudo-second order model. Furthermore, the experimental data were best described by the Langmuir model. This study demonstrated the effectiveness of bare and silica coated magnetic nanoparticles to remove trace concentrations of arsenic (III) in water environment. V C
Frontiers in Environmental Science, 2023
Arsenic decontamination is a major worldwide concern as prolonged exposure to arsenic (>10 µg L-1) through drinking water causes serious health hazards in human beings. The selection of significant, cost-effective, and affordable processes for arsenic removal is the need of the hour. For the last decades, iron-oxide nanomaterials (either in the magnetite or bimetallic form) based adsorptive process gained attention owing to their high arsenic removal efficiency and high regenerative capacity as well as low yield of harmful by-products. In the current state-of-the-art, a comprehensive literature review was conducted focused on the applicability of iron-based nanomaterials for arsenic removal by considering three main factors: (a) compilation of arsenic removal efficiency, (b) identifying factors that are majorly affecting the process of arsenic adsorption and needs further investigation, and (c) regeneration capacity of adsorbents without affecting the removal process. The results revealed that magnetite and bimetallic nanomaterials are more effective for removing Arsenic (III) and Arsenic (V). Further, magnetite-based nanomaterials could be used up to five to six reuse cycles, whereas this value varied from three to six reuse cycles for bimetallic ones. However, most of the literature was based on laboratory findings using decided protocols and sophisticated instruments. It cannot be replicated under natural aquatic settings in the occurrence of organic contents, fluctuating pH and temperature, and interfering compounds. The primary rationale behind this study is to provide a comparative picture of arsenic removal through different iron-oxide nanomaterials (last twelve yearsof published literature) and insights into future research directions.
Water Pollution X, 2010
Drinking water has been identified as one of the major sources of arsenic exposure by the general population. A variety of treatment processes has been studied for arsenic removal from water. One of the most used methods is adsorption. The most efficient adsorbent materials are those with iron content considering the affinity of arsenic towards iron. Relatively limited information is available regarding the impact of temperature on the arsenic (As) (III) adsorption kinetic and equilibrium capacities on iron oxide. In this paper we studied the possibility of using iron oxide as an adsorbent for the removal of As (III) from aqueous solutions. The iron oxide was obtained through annealing of iron oxalate at 550°C. The effects of contact time, initial concentration of the solutions and temperature on the removal of As (III) were investigated in order to explain the adsorption mechanism. The kinetic of As (III) adsorption can be described well by the pseudo-second-order models. The equilibrium adsorption data were fitted using Freundlich and Langmuir isotherm equations and the corresponding parameters were calculated and discussed in detail. An increase in temperature increases the values of the overall adsorption reaction rate constant. An examination of thermodynamic parameters shows that the adsorption of As (III) by iron oxide is an endothermic process and is spontaneous at the specific temperature investigated.
Arsenic Adsorption on Iron-Modified Montmorillonite: Kinetic Equilibrium and Surface Complexes
Environmental Engineering Science, 2019
As(V) adsorption mechanisms on an iron-modified montmorillonite (Fe-Mt) were studied by analysis from kinetic and equilibrium perspectives, and applicability of Fe-Mt for As(V) removal from groundwater was evaluated. Iron-modified montmorillonite was characterized by Small Angle X-Ray Scattering (SAXS), Wide Angle X-Ray Scattering (WAXS) and scanning electron microscopy technique and an excellent performance for As(V) removal, even at neutral and basic pH values and high conductivity conditions, was determined. Moreover, As(V) adsorption was higher with the increasing of ionic strength of the solution. Both Langmuir and Freundlich models provided a suitable fit to the experimental data, and the maxima adsorption capacity was 6.3 g/kg. Kinetic studies indicated that about 99% of As(V) was removed in the first 30 min of time from a starting concentration of 3 mg/L following a pseudo-second order kinetic. Formation of inner-sphere complexes of As(V) at the surface of Fe-Mt was stated by evaluation of As(V) adsorption in the presence of Cl-, NO 3-, and PO 4 3ions and of the zeta potential versus pH curves.
Adsorption and removal of arsenic from water by iron ore mining waste
Water Science and Technology, 2009
There is a global need to develop low-cost technologies to remove arsenic from water for individual household water supply. In this study, a purified and enriched waste material (treated magnetite waste, TMW) from the Trai Cau's iron ore mine in the Thai Nguyen Province in Vietnam was examined for its capacity to remove arsenic. The treatment system was packed with TMW that consisted of 75% of ferrous-ferric oxide (Fe3O4) and had a large surface area of 89.7 m2/g. The experiments were conducted at a filtration rate of 0.05 m/h to treat groundwater with an arsenic concentration of 380 μg/L and iron, manganese and phosphate concentrations of 2.07 mg/L, 0.093 mg/L and 1.6 mg/L respectively. The batch experimental results show that this new material was able to absorb up to 0.74 mg arsenic/g. The results also indicated that the treatment system removed more than 90% arsenic giving an effluent with an arsenic concentration of less than 30 μg/L while achieving a removal efficiency of ...
ARSENATE ADSORPTION ONTO ALUMINIUM AND IRON (HYDR)OXIDES AS AN ALTERNATIVE FOR WATER TREATMENT
2007
The geochemical fates of iron and arsenic are so closely correlated that methods of arsenic removal from water are in general based on the high adsorptive affinity of this metalloid with iron (hydr)oxides. Under anoxic conditions, however, reductive dissolution of iron (hydr)oxides can take place, and arsenic may be released into the surrounding environment. The purpose of this study was to investigate the potential of Al-substituted goethites in adsorbing arsenic compared with other Fe and Al (hydr)oxides. Hematite (Hm), goethite (Gt), 2-line ferrihydrite (Fh), gibbsite (Gb), aluminium hydroxide, and three Al-substituted goethites (AlGt) were synthesized and characterized by X-ray powder diffraction (XRD), particle size analysis, and diffuse reflectance (DR) spectroscopy. Adsorption isotherms were obtained after shaking the samples with increasing concentrations of arsenate (40 -1600 mg L -1 ) in a 10 mmol L -1 CaCl 2 solution for 24 hours. The adsorption envelope was measured at pH ranging from 3 to 9. The As(V) adsorption maxima decreased in the following order: Al(OH) 3 > Fh > AlGt-15 > AlGt-25 > AlGt-35 > Hm > Gb > Gt. No relationship was observed between particle diameter and maximum adsorption, suggesting that re-aggregation could have taken place, or possibly that imperfections on the surface of the particles increased their surface net charge, resulting in high adsorption density. The behaviour of all samples was strongly dependent on pH, and the maximum adsorption was achieved in slightly acidic conditions. In general, Al-substituted goethites showed promising results for their potential use as an adsorbent to remove arsenic from water.
Journal of Environmental Science for Sustainable Society, 2009
This work aims to investigate the removal of arsenic from the simulated groundwater by batch adsorption using Iron (ZVI) and Iron[III] Oxide (IO). The effect of initial arsenic concentration, adsorbent dose and pH were investigated. Adsorption equilibrium and its kinetics were also studied. The results showed that both ZVI and IO have a high efficiency for adsorption of arsenic from groundwater. Langmuir isotherm described well the adsorption equilibrium and the pseudo-second order kinetic model gave the best fit with the experimental kinetic data for both ZVI and IO.
Effect of competing solutes on arsenic(V) adsorption using iron and aluminum oxides
Journal of Environmental Sciences, 2007
The study focused on the effect of several typical competing solutes on removal of arsenic with Fe 2 O 3 and Al 2 O 3 . The test results indicate that chloride, nitrate and sulfate did not have detectable effects, and that selenium(IV) (Se(IV)) and vanadium(V) (V(V)) showed slight effects on the adsorption of As(V) with Fe 2 O 3 . The results also showed that adsorption of As(V) on Al 2 O 3 was not affected by chloride and nitrate anions, but slightly by Se(IV) and V(V) ions. Unlike the adsorption of As(V) with Fe 2 O 3 , that with Fe 2 O 3 was affected by the presence of sulfate in water solutions. Both phosphate and silica have significant adverse effects on the adsorption of As(V) adsorption with Fe 2 O 3 and Al 2 O 3 . Compared to the other tested anions, phosphate anion was found to be the most prominent solute affecting the As(V) adsorption with Fe 2 O 3 and Al 2 O 3 . In general, Fe 2 O 3 has a better performance than Al 2 O 3 in removal of As(V) within a water environment where multi competing solutes are present.