Adsorptive removal capacities of renewable and highly available Chaetophora elegans algae have been investigated in this study. To assess the use of this soft water algae to remove organic pollutants ...from aqueous solution, Methylene blue (MB) dye was used as a model molecule. The effect of dye concentrations, pH, adsorbent mass, temperature, and particle size have been evaluated. The algal biomass showed quite interesting adsorption capacity under optimized operating conditions (333 mg of dye per gram of biomass at 30 °C). Pseudo-first and pseudo-second order kinetic models were applied to the adsorption dynamic data. Pseudo second order model was well in line with the experimental data, therefore suggesting a probable chemically-based adsorption process. Several isotherm models were investigated to monitor the adsorption behavior. The Langmuir-Freundlich isotherm model fitted the experimental data best. The adsorption thermodynamic parameters ΔG°, ΔH° and ΔS° were calculated. The maximum uptake is independent of temperature. From the values of the thermodynamic parameters, we concluded that the adsorption is exothermic, more ordered and spontaneous.
The adsorption of two textile dyes onto a low-cost and unexploited marine biomass, Posidonia oceanica (L.), was investigated in batch mode. The biosorption process was studied as a function of ...contact time, initial pH and temperature. The highest dye adsorption capacities attained at 30°C were 3.081 mg/g at pH 2 for the Direct dye and 4.252 mg/g at pH 5 for the Reactive dye. The Freundlich, Langmuir and Redlich–Peterson adsorption models were used to determine the parameters of the equilibrium data and, under the operating conditions studied, the best fit to the experimental curves was obtained using the Freundlich model. The thermodynamic constants of the adsorption process (i.e. ΔG 0 , ΔH 0 and ΔS 9 ) were evaluated as −6.36 kJ/mol, 57.80 kJ/mol and −103.45 J/(mol K), respectively, for the Direct dye and as −3.22 kJ/mol, 84.10 kJ/mol and −225.55 J/(mol K), respectively, for the Reactive dye. Consequently, the adsorption of dyes onto P. oceanica biomass was favourable, endothermic and spontaneous.
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