Using grape pulp as a new alternative biosorbent for removal of a model basic dye

In the present study, grape pulp (GP), an agricultural waste available in large quantity in Turkey, was utilized as novel low‐cost biosorbent to remove model basic dye [methylene blue (MB)] from aqueous solution by biosorption. The effects of various parameters including solution pH, biosorbent dosage, initial dye concentration, contact time, temperature and ionic strength on the biosorption process were investigated. The biosorption kinetic data were modeled using the pseudo‐first‐order, pseudo‐second‐order and intraparticle diffusion kinetic equations. Batch kinetic experiments showed that the biosorption fitted the pseudo‐first‐order kinetic model well with correlation coefficients greater than 0.98 in the temperature range 20–60 °C. The equilibrium biosorption data were analyzed by Langmuir, Freundlich and Temkin isotherm models. The results indicated that the Langmuir model provided the best correlation with the experimental data. The maximum biosorption capacities of GP for MB determined with the Langmuir model ( q m ) were 78.74, 116.28 and 153.85 mg g −1 at temperatures of 20, 40 and 60 °C, respectively. The calculated thermodynamic parameters, namely, Δ G 0 (−5.33 to −7.17 kJ/mol), Δ H 0 (8.09 kJ/mol) and Δ S 0 (45.75 kJ/mol K), showed that the biosorption of MB on GP was spontaneous and endothermic under examined conditions. Results indicate that GP could be an alternative for more costly adsorbents used for MB removal.