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A novel activated carbon has been produced from pine cone, a sustainable resource, by phosphoric activation at 900 °C. The BET surface area of the activated carbon was 869 m2/g and the methylene blue isotherm area was 734 m2/g. The adsorption of two single-component acid azo dyes, Acid Blue 113 (AB113) and Acid Black 1 (AB1), onto this activated carbon was studied using fixed-bed adsorption. Breakthrough curves and equilibrium isotherms were obtained for the adsorption of these two dyes onto the prepared active carbon. The highest adsorption capacities achieved for AB113 and AB1 were 485 and 286 mg dye/g carbon, respectively. Two-column breakthrough curve models were applied to correlate the experimental adsorption breakthrough curves for each dye: the Thomas model, based on solid-phase internal diffusion, has been applied with considerable success; and the saturation isotherm model approach of Michaels was used with a reasonable degree of success. [ABSTRACT FROM AUTHOR]

Abstract: The adsorptive removal of toxic para-chlorophenol using activated carbon adsorption columns is a proven effective engineering process. This paper examined the possibility to stratify an adsorbent bed into layers, in order to enhance the adsorption process performance in terms of increased column service time and adsorbent bed saturation. Four different types of fixed-bed adsorption columns are used and compared under the same operating conditions, but with the variation of column geometry and activated carbon particle size stratification. The Type 3 column – a cylindrical column with particle stratification packing, is found to be the most efficient choice, as the extent of column service time and adsorbent bed saturation are the largest. This could eventually decrease the frequency of adsorbent replacement/regeneration and hence reduce the operating cost of the fixed-bed adsorption process. The Homogeneous Surface Diffusion Model (HSDM) was applied successfully to describe the dynamic adsorption of para-chlorophenol onto Filtrasorb 400 (F400) activated carbon in different types of columns. The Redlich-Peterson isotherm model equation, an experimentally derived external mass transfer correlation and a constant surface diffusivity are used in the HSDM. The optimised surface diffusivity of para-chlorophenol is found to be 1.20E-8 cm2/s, which is in good agreement with other phenolics/F400 carbon diffusing systems in literature. [Copyright &y& Elsevier]

Abstract: Novel Fe loaded activated carbons have been prepared from sugar beet pulp (BP) agricultural residues by direct steam activation followed by iron impregnation with or without previous oxidation. The corresponding activated carbons were: BP–H2O, BP–H2O–Fe, BP–H2O–H2O2–Fe and BP–H2O–MnO2–Fe. The textural characterization of these tailored activated carbons was based on nitrogen adsorption/desorption isotherms leading to BET surface area values between 741 and 821m2/g and total porous volumes between 0.58 and 0.79cm3/g. Elemental analysis and ash content showed that carbon content reached 78% for BP–H2O with 13.6% of ash and decreased to 50% in iron-based materials. BP–H2O and BP–H2O–Fe revealed a basic nature with pHPZC values of 9.8 and 9 respectively while BP–H2O–H2O2–Fe and BP–H2O–MnO2–Fe had acid pHPZC (5.1 and 3.6). Their surface chemistry has been investigated by XPS analysis and by the quantification of the surface chemical moieties based on Boehm’s approach. A clear relationship was found between the surface iron content and the strong acidic groups. Arsenic (As(V)) adsorption isotherms were performed and Langmuir, Freundlich, Redlich–Peterson models were used to describe the experimental data by non-linear regression. It was found that Redlich–Peterson isotherm provided the best fit and the Langmuir adsorption capacities confirmed that the iron-based activated carbons were highly attractive for As(V) removal with capacities up to 17mgg−1. Finally, it has been shown that the surface iron content determined by XPS analysis is very well correlated with Langmuir qm values (r 2 =0.982) and with the strong acidic moieties deduced from the Boehm’s method. [Copyright &y& Elsevier]

Abstract: Selective gold adsorption was investigated for the NH2-MCM-41 and SH-MCM-41 adsorbents prepared by grafting aminopropyl and thiolpropyl groups on the surface of the MCM-41 mesoporous silica. The single component adsorption of gold, copper and nickel from salt solutions, and the binary adsorption studies of Au3+/Cu2+ and Au3+/Ni2+ solutions were carried out for the two adsorbents. Gold adsorption from simulated gold mining solution and gold electroplating wastewater were also reported. The NH2-MCM-41 and SH-MCM-41 displayed strong affinity for gold in the solution and both exhibited 100% selectivity for the gold in the binary Au3+/Cu2+ and Au3+/Ni2+ solutions. The NH2-MCM-41 is more suitable for the gold mining solution, while SH-MCM-41 is efficient for gold adsorption from the electroplating waste containing high amount of organics. The gold was recovered as high purity salt solution by elution with mineral acid for NH2-MCM-41 and thiolsulfate for SH-MCM-41. The regenerated adsorbent remained selective to gold and exhibited the same adsorption capacity as the fresh adsorbent. Also, the regenerated adsorbent performed well even after several reuses. [Copyright &y& Elsevier]