Iron-silver oxide nanoadsorbent synthesized by co-precipitation process for fluoride removal from aqueous solution and its adsorption mechanism

Fe-Ag magnetic binary oxide nanoparticles (Fe-Ag MBON) are prepared with co-precipitation of ferric and ferrous chloride solutions, and used for the adsorption of fluoride from aqueous solution. The surface morphology of the adsorbent was characterized by XRD, SEM, TEM, FTIR, XPS, EDX, BET, DLS and VSM techniques. Batch method was followed to optimize the conditions for the removal of fluoride. The results showed maximum removal occurred at pH 3.0 and adsorption equilibrium was achieved within 20 min. Chemical kinetics of the adsorption were well fitted by pseudo-second order models (R2 > 0.968) and the adsorption process followed the Langmuir isotherm model well (R2 > 0.976). The fluoride adsorption capacity of Fe-Ag MBON was 22.883 mg g-1, and decreased with increasing the temperature. Thermodynamic values revealed that the fluoride adsorption process was spontaneous and exothermic. Regeneration experiments were carried out for six cycles and the results indicate a removal efficiency loss of <22. © 2015 The Royal Society of Chemistry

Evaluation of basic violet 16 adsorption from aqueous solution by magnetic zero valent iron-activated carbon nanocomposite using response surface method: Isotherm and kinetic studies

Background and purpose: Increasing industrial activities and the subsequent discharge of untreated wastewater containing dye to aqueous environment can cause problems such as reducing the sun light penetration, creating anaerobic conditions, allergy and cancer. Adsorption is considered as one of the most efficient and effective methods for dye removal. The aim of this study was to magnetize the activated carbon with zero-valent iron and using it as an adsorbent for dye removal from aqueous solution. Materials and methods: In this study, co-precipitation method was used for synthesizing magnetic zero valent iron-activated carbon nanocomposite. Characteristics of absorbent were analyzed by SEM, TEM, EDX, XRD, and VSM techniques. We evaluated the effect of independent variables including contact time, solution pH, temperature, adsorbent dosage and the concentration of dyes on response performance (removal efficiency of Basic Violet dye) with response to surface methodology based on box-behnken design. ANOVA was applied to analyze the responses. Results: The optimum conditions for basic violet 16 dyes removal were obtained at pH= 3, contact time= 65 min, absorbent dose= 2 g/L and temperature= 45 C°. Investigating the isotherm and kinetic models showed that the experimental data were correlated with Langmuir adsorption isotherm model (R2>0.995) and pseudo-second order kinetic (R2>0.931). Conclusion: In optimal conditions, magnetic zero valent iron-activated carbon nanocomposite has the potential to remove violet 16 dyes. Also, its separation from the solution is more simple and faster due to its magnetism property. © 2015 Mazandaran University of Medical Sciences. All rights reserved

Performance, kinetic, and biodegradation pathway evaluation of anaerobic fixed film fixed bed reactor in removing phthalic acid esters from wastewater

Emerging and hazardous environmental pollutants like phthalic acid esters (PAEs) are one of the recent concerns worldwide. PAEs are considered to have diverse endocrine disrupting effects on human health. Industrial wastewater has been reported as an important environment with high concentrations of PAEs. In the present study, four short-chain PAEs including diallyl phthalate (DAP), diethyl phthalate (DEP), dimethyl phthalate (DMP), and phthalic acid (PA) were selected as a substrate for anaerobic fixed film fixed bed reactor (AnFFFBR). The process performances of AnFFFBR, and also its kinetic behavior, were evaluated to find the best eco-friendly phthalate from the biodegradability point of view. According to the results and kinetic coefficients, removing and mineralizing of DMP occurred at a higher rate than other phthalates. In optimum conditions 92.5, 84.41, and 80.39% of DMP, COD, and TOC were removed. DAP was found as the most bio-refractory phthalate. The second-order (Grau) model was selected as the best model for describing phthalates removal

Rapid and efficient magnetically removal of heavy metals by magnetite-activated carbon composite: a statistical design approach

This study investigates the efficiency of the magnetite-powder activated carbon (M-PAC) to removal of Ni2+, Co2+ and Cd2+ ions from the aqueous solution. Response surface methodology based on the Box�Behnken design was used to evaluate the effects of independent variables such as pH, contact time, adsorbent dosage, temperature and initial concentration of metal ions on the response function and prediction of the best response values. The adsorption fitted best to the Langmuir model indicating the presence of heterogeneous sites for Ni2+, Co2+ and Cd2+ ions adsorption. The kinetics results demonstrated the adsorption process well suited with pseudo-second-order model, indicating that it was involves the formation of valency forces through the exchange or sharing of electrons between metal ions and the binding sites of M-PAC. The intraparticle diffusion model showed a low linear relationship (R2 < 0.87), which suggests that pore diffusion is not the rate-limiting step in the adsorption process. The values of thermodynamic parameters (�G°, �S° and �H°) showed that the adsorption of all studied metal ions onto M-PAC was spontaneous, feasible and endothermic. Based on these findings, it is concluded that the M-PAC could be successfully employed for adsorption of heavy metals due to simple and rapid separation and high capacity. © 2015, Springer Science+Business Media New York

Synthesis and efficiency evaluation of magnetic nanocomposite of activated carbon- zero valent iron/silver (PAC-Feº/Ag) in phenol removal from aqueous solution

Background and Objectives: Phenol is one of priority pollutants produced through leather, paint, resin, and pharmaceutical industries and it can contaminate groundwater after entering to the environment. Hence, it is necessary to use a suitable method for its removal. The aim of this study was synthesize and efficiency evaluation of magnetic nanocomposite of activated carbon powder-zero valent iron/silver (PAC-Feo/Ag) in the removal of phenol from aqueous solution. Material & Methods: Reduction method was used for converting bivalent iron to zero valent iron and co-precipitation method for depositing of iron on activated carbon. For coating silver on nano zero valent iron, rapid mixing at high temperature was used. The adsorbent was characterized using SEM, TEM, and XRD techniques. Then, the impact of pH, contact time, agitation speed, temperature, adsorbent, and initial phenol concentration were evaluated and optimized by one factor at the time method. Reaction kinetics and isotherms were also determined. Results: It was found that PAC-Feo/Ag has cubic and intertwined structure and has a diameter in the range from 40 to 100 nm. The optimum conditions for phenol removal by PAC-Feo/Ag were as pH=3, 90 min contact time, 200 rpm agitating speed and adsorbent concentration equal to 1 g/l. Isotherm and kinetic equations showed that the experimental data of phenol adsorption onto PAC-Feo/Ag are correlated to the Langmuir (R2>0.969) and pseudo-second order (R2<0.965) models, respectively. Conclusion: Under optimum conditions, modified adsorbent by zero valent iron and silver with maximum efficiency of 97% has quickly and effectively ability in removal of phenol and it can be easily separated from the solution sample by magnet because of its magnetic properties