Sequestration of diclofenac and amoxycillin pharmaceutical compounds by thiourea modified poly(acrylonitrile-co-acrylic acid): parametric optimisation, kinetic and isotherm studies

Abstract

ABSTRACT It has been previously reported that thiourea modified poly(acrylonitrile-co-acrylic acid) (TMPAA) could successfully be employed as polymeric adsorbent for the sequestration of cationic dyes and nitro-phenol. In this research, parametric optimisation, kinetic and isotherm analyses on the sequestration of diclofenac (DCF) and amoxycillin (AMX)) by TMPAA were investigated for the first time. The central composite design (CCD) results revealed that the optimisation exhibited high significance and reliability. The analysis of variance (ANOVA) indicated that TMPAA dose, antibiotic concentration and adsorption time exhibited high significance effect on the DCF and AMX sequestration. The 3D response surface plots showed notable antagonistic interaction among the adsorption parameters. A maximum DCF uptake of 97.94% was achieved under optimum condition of 0.1 g TMPAA dose, 25 mg/L, and 54 min, while 94.06% AMX removal was obtained at 0.1 g sorbent dosage, 25 mg/L, and 34 min contact time. Predicted and experimental results confirmed the accuracy of the established optimal conditions for both antibiotics. It was discovered by adsorption analysis that the pseudo-second-order kinetic and Redlich-Peterson models agreed with the adsorption kinetic and isotherm data. The findings suggest that the synthesised TMPAA polymer is capable of removing DCF and AMX from aqueous solutions.