Examination of the Effects of Activated Carbon Produced from Coal Using Single-Step H3PO4/N2+H2O Vapor Activation on the Adsorption of Bovine Serum Albumin at Different Temperatures and pH Values

Abstract

This study examined protein adsorption equilibrium and kinetics on activatedcarbon (AC) that we obtained from coal by single-step H3PO4 activation under N2+H2Ovapor at 800 °C. Surface properties, pore size distribution, and volumes of AC weredetermined using volumetric method with N2 adsorption at 77 K. Also, the texturalproperties were characterized by SEM-EDAX and XRD. The zeta potential values weremeasured to elucidate the electrostatic interactions between the protein and AC. Theobtained AC discrete system was also used as an adsorbent for adsorbing bovine serumalbumin (BSA) from aqueous solution. The effects of pH (4.0, 5.0, and 7.4) andtemperatures (20, 30 and 40 °C) on the adsorption of BSA on AC were examined. Thesurface area, micropore, mesopore and total pore volumes of AC were found to be 1175m2/g, 0.477 cm3/g, 0.061 cm3/g and 0.538 cm3/g, respectively. The optimum temperaturefor AC in BSA adsorption was found to be 40 °C and the pH was found to be 4.0. Thehighest BSA adsorption was found to be 159 mg/g and pH to be 4.0. The experimentalequilibrium data were compared with the Langmuir and Freundlich models and found to becompatible with both models. The adsorption process is best described by the pseudo-firstorderkinetic model. As a result, it was found out that AC obtained by single stepH3PO4/N2+H2O vapor activation is an effective adsorbent for the adsorption of BSA fromaqueous solution.