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Abstract: Graphene was prepared using a modified Hummers’ method. The physico-chemical properties of graphene were characterized by TEM, BET specific surface area, FTIR, Raman and XRD measurements. The effect factors including pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto graphene were investigated. The experimental data of isotherm followed the Langmuir isotherm model better than the Freundlich model. The maximum adsorption capacity obtained from Langmuir isotherm equation at 293K was 153.85mg/g, indicating graphene is a good adsorbent for the adsorption of MB. The kinetic study illustrated that the adsorption of methylene blue onto graphene fit the pseudo second-order model. The thermodynamic parameters indicated that the adsorption of methylene blue onto graphene was an endothermic and spontaneous process. [Copyright &y& Elsevier]

Abstract: Graphene oxide has been used as an adsorbent in wastewater treatment. However, the dispersibility in aqueous solution and the biotoxicity to human cells of graphene oxide limits its practical application in environmental protection. In this research, a novel environmental friendly adsorbent, calcium alginate immobilized graphene oxide composites was prepared. The effects of pH, contact time, temperature and dosage on the adsorption properties of methylene blue onto calcium alginate immobilized graphene oxide composites were investigated. The equilibrium adsorption data were described by the Langmuir and Freundlich isotherms. The maximum adsorption capacity obtained from Langmuir isotherm equation was 181.81mg/g. The pseudo-first order, pseudo-second order, and intraparticle diffusion equation were used to evaluate the kinetic data. Thermodynamic analysis of equilibriums indicated that the adsorption reaction of methylene blue onto calcium alginate immobilized graphene oxide composites was exothermic and spontaneous in nature. [Copyright &y& Elsevier]

Abstract: Enteromorpha prolifera was pyrolyzed to prepare activated carbon using chemical activation by zinc chloride. The effect of activation parameters such as activation temperature, weight ratio (Enteromorpha prolifera to ZnCl2), and activation time was investigated. The BET results showed that the surface area and pore volume of activated carbons were achieved as high as 1722m2/g and 1.11cm3/g, respectively, in the optimal activation conditions. Batch adsorption studies were carried out to study the adsorption properties of cationic red X-GRL onto activated carbon by varying the parameters like initial solution pH, contact time, and temperature. The kinetic studies showed that the adsorption data followed a pseudo second-order model. The isotherm analysis indicated that the adsorption data could be represented by the Langmuir isotherm model. The Langmuir monolayer adsorption capacity of cationic red X-GRL was estimated as 263.16mg/g at pH 6.0. [Copyright &y& Elsevier]

Abstract: A new adsorbent manganese oxide coated graphene oxide (MOGO) was synthesized and characterized by TEM, XRD, FTIR, and BET analysis. The effects of different parameters such as pH, adsorbent dose, contact time and temperature were studied to understand the adsorption behavior of the adsorbent under various conditions. Adsorption studies revealed that optimum removal of fluoride occurred in a pH range of 5.5–6.7. The Langmuir isotherm model demonstrated that the maximum fluoride adsorption capacity of MOGO was 11.93mg/g and 8.34 times higher than that of GO. The kinetic adsorption data were analyzed using the pseudo first-order model, the pseudo second-order model and the intra-particle diffusion model. Thermodynamic adsorption results showed that adsorption of fluoride by MOGO was a spontaneous and endothermic process. [Copyright &y& Elsevier]

Abstract: A batch adsorption system was applied to investigate the adsorption of fluoride from aqueous solution by graphene. The adsorption capacities and rates of fluoride onto graphene at different initial pH, contact time, and temperature were evaluated. The experimental results showed that graphene is an excellent fluoride adsorbent with an adsorption capacity of up to 17.65mg/g at initial fluoride concentration of 25mg/L and temperature of 298K. The isotherm analysis indicated that the adsorption data can be well described by Langmuir isotherm model. Thermodynamic studies revealed that the adsorption reaction was a spontaneous and endothermic process. [Copyright &y& Elsevier]