Adsorption Characteristics of Chromium(VI) Ions onto Fe(III)-Coordinated Amino-Functionalized Poly(glycidylmethacrylate)-Grafted TiO2-Densified Cellulose

An investigation was conducted with a newly developed adsorbent, iron(III)- coordinated amino-functionalized poly(glycidylmethacrylate)-grafted TiO₂-densified cellulose (Fe(III)-AM-PGDC) on the removal of chromium(VI) from aqueous solution. Batch experiments were performed under various conditions of time, pH, concentration, dose, ionic strength, and temperature. Adsorption of Cr(VI) on Fe(III)-AM-PGDC was dominated by ion exchange or outer-sphere complexation. The maximum adsorption capacity was found to be 109.76 mg g^?1. Thermodynamic study showed that adsorption of Cr(VI) onto Fe(III)-AM-PGDC is more favored. The complete removal of Cr(VI) from electroplating wastewater was achieved by the adsorbent. The adsorbent did not lose its adsorption capacity even after the fourth regeneration.     

Arsenic(III) Removal at Low Concentrations by Biosorption using Phanerochaete chrysosporium Pellets

As(III) removal from dilute aqueous solutions by biosorption onto pellets of the white rot fungus Phanerochaete chrysosporium was investigated. The As(III) uptake capacity was evaluated at low initial concentrations (0.2–1 mg/L) which revealed that the P. chrysosporium pellets were only slightly less efficient than the well studied adsorbent granular ferric hydroxide. Moreover, its performance was much more superior compared to anaerobic granular sludge, another cheaply available bacterial biosorbent. In the studied pH (5–9) and biomass concentration (0.25–1.5 g/L wet weight basis) ranges, no large differences in As(III) removal efficiency were observed. The influence of different ions, commonly present in groundwater, such as nitrate, fluoride, chloride, and Fe(III) on As(III) removal by the fungus was also examined by performing experiments as per the statistically valid two-level fractional factorial design of experiments. This showed a very good removal of only As(III) and Fe(III) (maximum 100%), the removal of the other ions in the mixture was very poor with the least well adsorbed being fluoride. A desorption efficiency exceeding 95% of the bound As(III) from the fungal biomass was achieved using sodium hydroxide (0.05–0.1 M) as desorbent.     

Selective Separation of Scandium(III) and Yttrium(III) from other Rare Earth Elements using Cyanex302 as an Extractant

Abstract

Liquid‐liquid extraction and selective separation of scandium(III) and yttrium(III) with Cyanex302 (bis(2,4,4‐trimethylpentyl)monothiophosphinic acid) has been carried out by controlling the aqueous phase pH. Scandium(III) and yttrium(III) were completely recovered from the organic phase using 5.0 M and 4.0 M nitric acid respectively and determined spectrophotometrically as their complexes with Arsenazo(III). The influence of extractant concentration, equilibration time, nature of diluents, stripping agents, and diverse ions on the extraction of scandium(III) and yttrium(III) was investigated. The extractability of scandium(III), yttrium(III), and other rare earth elements was exploited for sequential separation of scandium(III)‐yttrium(III)‐lanthanum(III) and other rare earth elements viz. lanthanum(III), cerium(IV), praseodymium(III), neodymium(III), gadolinium(III), dysprosium(III), and ytterbium(III) in binary mixtures. The method presented is simple and rapid for isolation of scandium(III) and yttrium(III) from associated elements and has been successfully applied for their selective separation from complex matrices of USGS standard soil GXR‐2 and Japanese standard stream sediment sample Jsd‐3.     

Preparation,characterization and application of iron (III)-loaded chitosan hollow fiber membranes as a new bio-based As (V) sorbent

Fe (III)-loaded chitosan (CS) hollow fibers (CS-Fe (III) HF) were successfully prepared according to the dry-wet spinning technique. The CS-Fe (III) HFs were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and thermal gravimetric analysis (TGA). Removal of pentavalent arsenic was studied through biosorption on CS-Fe (III) HF adsorptive membranes. The response surface methodology (RSM) was applied to investigate the influence of the main operating parameters such as contact time, pH, initial As (V) concentration and HFs dosage on the adsorption capacity of As (V). From the Pareto analysis, pH, [As (V)]_o, [CS-Fe (III) HF membranes] and squared effect of [As(V)]_o were found to produce the largest effect on biosorption of As (V). Kinetic studies showed that the pseudo-second-order kinetic model provides the best correlation to the experimental results. Equilibrium data fitted well with the Langmuir model with maximum adsorption capacity of 3,703 μg g^?1. A laboratory scale glass membrane module consisting of three CS-Fe(III) HFs has also been prepared and tested for biosorption of As (V) at a real scale. Permeability of As (V) ions through the CS-Fe (III) HF membranes was 0.145 μmol m^?2 h^?1 bar ^?1.     

Removal of Cu(II), Fe(III), and Cr(III) from Aqueous Solution by Aniline Grafted Silica Gel

Abstract

The aniline moiety was covalently grafted onto silica gel surface. The modified silica gel with aniline groups (SiAn) was used for removal of Cu(II), Fe(III), and Cr(III) ions from aqueous solution and industrial effluents using a batch adsorption procedure. The maximum adsorption of the transition metal ions took place at pH 4.5. The adsorption kinetics for all the adsorbates fitted better the pseudo second‐order kinetic model, obtaining the following adsorption rate constants (k₂): 1.233 · 10^?2, 1.902 · 10^?2, and 8.320 · 10^?3 g · mg^?1 min^?1 for Cr(III), Cu(II), and Fe(III), respectively. The adsorption of these transition metal ions were fitted to Langmuir, Freundlich, Sips, and Redlich‐Peterson isotherm models; however, the best isotherm model fitting which presented a lower difference of the q (amount adsorbed per gram of adsorbent) calculated by the model from the experimentally measured, was achieved by using the Sips model for all adsorbates chosen. The SiAn adsorbent was also employed for the removal of the transition metal ions Cr(III) (95%), Cu(II) (95%), and Fe(III) (94%) from industrial effluents, using the batch adsorption procedure.     

Modeling As(III) and As(V) Removal by an Iron Oxide Impregnated Activated Carbon in a Binary Adsorbate System

The adsorption behavior of As(III) as a function of pH on an iron oxide impregnated activated carbon (FeAC) at different adsorbate/adsorbent concentrations was modeled using the surface complexation modeling approach (SCM). The surface complexation constants developed from single sorbate experiments successfully predicted competition between As(V) and As(III) and the SCM predictions were verified experimentally. The monoprotic surface site representation described the experimental data better than the diprotic representation. Based on surface complexation modeling simulations, the effect of As(V) on As(III) removal was greater than As(III) on As(V) removal. As(III) → (As(V) was observed for the FeAC and the virgin carbon beginning at pH = 8.     

Separation and concentration processes of solutions of Co(II), Ni(II), Cr(III), Fe(III) and Mn(II) by extraction with toluene-dissolved rosin

The extraction and stripping of Co(II), Ni(II), Cr(III) and Fe(III) from aqueous solutions by rosin dissolved in toluene has been investigated. Results obtained show that rosin is better extractant than abietic or n-lauric acids under comparable conditions. From these results, and the data of Mn(II) solvent extraction studied previously under the same conditions, a separation and concentration process for these five cations in aqueous solutions has been designed. Saturated solutions of Fe(III), Cr(III), Mn(II) and finally Co(II) and Ni(II) have been obtained successively by extraction and stripping, by addition of ammonium hydroxide to obtain the appropriate pH value, and by modifying adequately the organic phase/aqueous phase volume ratio.     

Studies on extraction and permeation of lanthanum(III) and cerium(III) using cyphos IL 104 as extractant and ion carrier

ABSTRACT

This work shows application of Cyphos IL 104 (trihexyl(tetradecyl)phosphonium bis(2,4,4-trimethylpentyl)phosphinate) as the extractant and the ion carrier of Ce(III) and La(III) from aqueous solutions through polymer inclusion membranes (PIM). These membranes were used for separation of Ce(III) from solution containing La(III), Cu(II), Co(II) and Ni(II). The best results of the separation process were obtained for PIM containing: 20.0 wt.% CTA, 55.0 wt.% NPOE and 25.0 wt.% Cyphos IL 104 at pH 3.8 into 1 M H₂SO₄. The separation coefficients were found in order of S _Ce/La < S _Ce/Cu < S _Ce/Co < S _Ce/Ni.     

Bioaccumulation and biosorption of copper(II) and chromium(III) from aqueous solutions by Pichia stipitis yeast

BACKGROUND: Bioaccumulation and biosorption by Pichia stipitis yeast has not yet been explored. This paper evaluates, for the first time, the use of both viable and nonviable P. stipitis yeast to eliminate Cu(II) and Cr(III) from aqueous solutions. The effect of Cu(II) and Cr(III) ions on the growth and bioaccumulation properties of adapted and nonadapted biomass is investigated as a function of initial metal concentration. Binding capacity experiments using nonviable biomass are also performed as a function of temperature. RESULTS: The addition of Cu(II) and Cr(III) had a significant negative effect on the growth of yeast. Nonadapted cells could tolerate Cu(II) and Cr(III) ions up to a concentration of 75 ppm. The growth rate of nonadapted and adapted cells decreased with the increase in Cu(II) and Cr(III) concentration. Adapted P. stipitis biomass was capable of removing Cu(II) and Cr(III) with a maximum specific uptake capacity of 15.85 and 9.10 mg g⁻¹, respectively, at 100 ppm initial Cu(II) and Cr(III) concentration at pH 4.5. Adsorption data on nonviable cells were found to be well modeled by the Langmuir and Temkin isotherms. The maximum loading capacity of dry biomass predicted from Langmuir isotherm for Cu(II) and Cr(III) at 20 °C were 16.89 and 19.2 mg g⁻¹, respectively, at pH 4.5. Biosorptive capacities were dependent on temperature for Cu(II) and Cr(III) solutions. CONCLUSION: Cu(II)‐ and Cr(III)‐adapted cells grow and accumulate these ions at high ratios. On the other hand, nonviable P. stipitis was found to be an effective biosorbent for Cu(II) and Cr(III) biosorption. Copyright © 2008 Society of Chemical Industry     

Use of deep eutectic solvent as extractant for separation of Fe (III) and Mn (II) from aqueous solution

In this work, we used deep eutectic solvent (DES) composed of decanoic acid and lidocaine, which is characterized as a green solvent, for separation of Fe (III), which is the most-used metal in the world, and Mn (II), which is currently being used in many industries. We found that the pH of the initial metal solution strongly influenced the extraction mechanism. Fe (III) can be extracted at pH 1.0–2.0 due to the ion pair reaction between Fe³⁺ and decanoic anion, while at higher pH, the extraction mechanism cannot be evaluated due to formation of precipitation at the aqueous phase. In the case of Mn (II), the ion pair reaction occurred at pH of lower than 2.2 and higher than 3.5, while from pH 2.2 to 3.5, the cation exchange between Mn²⁺ and lidocaine cation probably dominated the extraction process. The DES concentration needed to reach the complete separation of Fe (III) was about 25 g/L, while Mn (II) was completely extracted using about 300 g/L of DES. The selectivity of this method was very high when was applied in the separation of Fe (III) from Mn (II).     

Highly selective solvent extraction of Zn(II) and Cr(III) with trioctylmethylammonium chloride ionic liquid

This study investigates the recovery of Zn(II) and Cr(III) from aqueous solutions based on solvent extraction with trioctylmethylammonium chloride [TOMA⁺][Cl-], commercialy named Aliquat 336. Single metal solutions and binary mixtures of both metals were considered. The effect of relevant operating conditions such as pH, contact time, initial concentration, O/A phase volumetric ratio, and temperature were evaluated. Additionally, loading capacity and stripping studies were performed. Results showed that [TOMA⁺][Cl^?] is an effective extracting agent for Zn(II), reaching maximum removal capacity at pH 1.8 and demonstrating fast extraction kinetics. Extraction efficiencies above 99% were achieved at 0.5, 0.75, and 1.00 O/A volumetric phase ratios for 0.1 g/L initial Zn(II) concentration. At 1 g/L and 10 g/L concentration, for the same O/A ratios, approximately 88% of the initial Zn(II) was extracted. In contrast, it was found that negligible amounts of Cr(III) were transferred to the [TOMA⁺][Cl^?] phase at the 1-5 pH range. Selectivity studies showed that Zn(II) removal is boosted in the presence of Cr(III), although no Cr(III) is extracted. [TOMA⁺][Cl^?] exhibited a high Zn(II) storage capacity, since after 25 loading cycles with 1 g/L, the loading capacity reached approximately 13.5 g/L, and after five loading cycles with 5 g/L, the capacity reached 19.4 g/L. Stripping tests revealed that NaOH is an efficient agent for the removal of Zn(II) from the ionic liquids, reaching 98.5% removal after two cycles, whereas HNO₃ is not a suitable agent, reaching less than 40% removal after three cycles. [TOMA⁺][Cl^?] revealed high potential for separating Zn(II) from Cr(III).     

Removal of Cu(II) and Fe(III) from aqueous solutions by dead sulfate reducing bacteria

The biosorption properties of dead sulfate reducing bacteria (SRB) for the removal of Cu(II) and Fe(III) from aqueous solutions was studied. The effects of the biosorbent concentration, the initial pH value and the temperature on the biosorption of Cu(II) and Fe(III) by the SRB were investigated. FTIR analysis verified that the hydroxyl, carbonyl and amine functional groups of the SRB biosorbent were involved in the biosorption process. For both Cu(II) and Fe(III), an increase in the SRB biosorbent concentration resulted in an increase in the removal percentage but a decrease in the amount of specific metal biosorption. The maximum specific metal biosorption was 93.25 mg?g^–1 at pH 4.5 for Cu(II) and 88.29 mg?g^–1 at pH 3.5 for Fe(III). The temperature did not have a significant effect on biosorption. In a binary metal system, the specific biosorption capacity for the target metal decreased when another metal ion was added. For both the single metal and binary metal systems, the biosorption of Cu(II) and Fe(III) onto a SRB biosorbent was better represented by a Langmuir model than by a Freundlich model.     

Removal of Chromium(VI) and Chromium(III) from Aqueous Solution by Grainless Stalk of Corn

Abstract

Grainless stalk of corn (GLSC) was tested for removal of Cr(VI) and Cr(III) from aqueous solution at different pH, contact time, temperature, and chromium/adsorbent ratio. The results show that the optimum pH for removal of Cr(VI) is 0.84, while the optimum pH for removal of Cr(III) is 4.6. The adsorption processes of both Cr(VI) and Cr(III) onto GLSC were found to follow first-order kinetics. Values of k _ads of 0.037 and 0.018 min^?1 were obtained for Cr(VI) and Cr(III), respectively. The adsorption capacity of GLSC was calculated from the Langmuir isotherm as 7.1 mg g^?1 at pH 0.84 for Cr(VI), and as 7.3 mg g^?1 at pH 4.6 for Cr(III), at 20°C. At the optimum pH for Cr(VI) removal, Cr(VI) reduces to Cr(III). EPR spectroscopy shows the presence of Cr(V) + Cr(III)-bound-GLSC at short contact times and adsorbed Cr(III) as the final oxidation state of Cr(VI)-treated GLSC. The results indicate that, at pH ≈ 1, GLSC can completely remove Cr(VI) from aqueous solution through an adsorption-coupled reduction mechanism to yield adsorbed Cr(III) and the less toxic aqueous Cr(III), which can be further removed at pH 4.6.     

Is the Coagulation-Filtration Process with Fe(III) Efficient for As(III) Removal from Groundwaters?

The coagulation–filtration process using Fe(III) salts is the most frequently practiced technology for As(V) removal in full scale water treatment plants. The co-existing As(III) is usually oxidized to As(V) prior to removal. Nonetheless, research studies applying high As(III) initial concentrations showed significant As(III) removal capacities, however, the efficiency of the process for initial As(III) concentrations commonly encountered in drinking water, i.e., 10-100 μg/L is not sufficiently investigated. The experimental results of this study indicated that the coagulation–filtration process using Fe(III) can safely meet the drinking water regulation limit of 10 μg/L, only when the initial As(III) concentration is < 25 μg/L and the Fe(III) dose ≥ 5 mg/L, for experiments performed with NSF challenge water. The limitations for efficient As(III) removal are attributed to the fact that As(III), under circumneutral pH values is mostly present with the uncharged H₃AsO₃ form, which is not efficiently adsorbed onto iron oxy hydroxides (FeOOH), the product of Fe(III) hydrolysis. Adsorption isotherms data were best fitted to BET model, indicating multi-layer adsorption and low affinity of As(III) for Fe(III) hydroxides.     

Optimizing adsorption of arsenic(III) by NH2-MCM-41 using response surface methodology

Response surface methodology (RSM) was used to optimize process parameters for arsenic (As(III)) removal from aqueous solution using amine-functionalized MCM-41 (NH₂-MCM-41). Four independent variables such as pH, initial metal concentration, temperature and adsorbent dosage were investigated. The optimal conditions to remove As(III) by NH₂-MCM-41 was found to be pH 5.62, initial As(III) concentration 5.00 mg/L, temperature 20 °C and NH₂-MCM-41 dosage 5.00 g/L. XRD, FTIR and SEM analyses testified to the obvious change of the surface morphology and the presence of metal on the sorbent after adsorption.     

Removal of chromium(III) from tannery effluents,using a system of packed columns of zeolite and activated carbon

The removal of chromium(III) in packed columns of zeolite and activated carbon has been studied. The process of Cr(III) exchange in 13X zeolite was optimized using mass transference parameters. In addition, the effects of pH, the presence of interfering ions and the anion associated with the chromium in the solution were studied. It was found that particle diameter controls the Cr(III) exchange in the zeolite, indicating that particle diffusion predominantly controls the process of Cr(III) exchange in 13X zeolite. A mixed system of zeolite and activated carbon columns increased the efficiency of chromium removal from diluted wastewater. This effect occurred due to the reduction of the organic matter (chemical oxygen demand), adsorption of chromium, and interfering ions on the activated carbon column. The activated carbon + zeolite column system emerges as an alternative method in Cr(III) removal from tannery effluents. Copyright © 2005 Society of Chemical Industry     

Chemically Modified CaO/Fe3O4 Nanocomposite by Sodium Dodecyl Sulfate for Cr(III) Removal from Water

A CaO/Fe₃O₄ nanocomposite was modified by sodium dodecyl sulfate (SDS) and used for Cr(III) removal from aqueous solution. The physical and surface characteristics of the adsorbent were studied by different analysis techniques. The effects of key parameters such as pH, contact time, temperature, initial concentration of Cr(III) ions, and adsorbent dose were investigated at a fixed mixing rate. Parameters were optimized to attain the best possible removal efficiency of Cr(III) ions. The maximum adsorption capacities obtained from the Langmuir model were determined. The results of equilibrium and kinetic studies indicate that the adsorption process follows the Langmuir isotherm model and the pseudo‐second‐order kinetic model. The thermodynamic study demonstrated that the adsorption process was suitable, spontaneous, and exothermic.     

Synthesis of the cotton cellulose based Fe(III)-loaded adsorbent for arsenic(V) removal from drinking water

A novel macroporous bead adsorbent, Fe(III)-loaded ligand exchange cotton cellulose adsorbent [Fe(III)LECCA], is synthesized for selective adsorption of arsenate anions [As(V)] from drinking water in batch and column systems. As(V) adsorption on Fe(III)LECCA was independent of pH, especially in drinking water pH range. Film diffusive control mechanism will benefit As(V) exchange with Fe(III)LECCA whether in batch or in column experiments. When treating the tap water at 26.0 BV/h, the column still preserves 83% of the original saturation adsorption capacity of the As(V) aqueous solution. These results have indicated that Fe(III)LECCA has the potential to act as an adsorbent for the removal of As(V) from drinking water considering its availability, nontoxicity and cost-effectiveness.     

CR(III) removal by macroreticular chelating ion exchange resins

The poly(styrene-co-divinylbenzene) beads were synthesized by suspension polymerization using benzoylperoxide as an initiator and i -octane as a diluent. The copolymer beads with a particle size range of 32-60 mesh were selected. Chloromethylation was performed with chloromethylether at 0°C using tetrachloroethane as swelling agent and AlCl 3 as catalyst. The phosphorylation of copolymer beads (RS) and its chloromethylated derivative (RCS) was carried out using a mixture of PCl 3 and AlCl 3 under the reflux. The phosphorylated resins (RSP) were further oxidized using concentrated HNO 3 to obtain the oxidized form of RSP resins (RSPO). The removal of Cr(III) by the resins RSP, RSPO, and RCSP containing phosphinic, phosphonic, and methylenephosphonic groups, respectively, was investigated by batch and column methods. The results were compared with that of Diaion CRP-200 resin having methylenephosphonic functional groups. These resins exhibited a high affinity for Cr(III). The percent removal of Cr(III) reached a plateau with almost a 100% of removal at pH range between 2 and 2.5. The breakthrough capacity decreased in the order RCSP>RSPO>Diaion CRP-200>RSP.     

Selective Competitive Biosorption of Au(III) and Cu(II) in Binary Systems by Magnetospirillum gryphiswaldense

The biosorption of Au(III) and Cu(II) ions in both single and binary systems by Magnetospirillum gryphiswaldense (MSR-1) was investigated. For comparison with the selective reinforced competitive biosorption process in a binary system, the experimental research first explored the biosorption of Au(III) and Cu(II) in a single system under various conditions. The biomass exhibited the highest single Au(III) and Cu(II) ion adsorption yields at room temperature (25°C), pH values of 2.5 and 5.0, respectively, and a biomass concentration of 10 g · L^?1 (3.83 g · L^?1, dry basis). The experimental data from the single component system for the two metallic ions fitted well to a Langmuir isotherm and a pseudo second-order kinetic models. In the Au(III)-Cu(II) binary system, the coexistence of Cu(II) cations promoted the adsorption of Au(III) within a certain range of ratios. A new sigmoidal Cu(II) biosorption isotherm was determined specifically to reveal the Cu(II) adsorption behavior in this case.