Adsorptive removal of Carbamazepine from synthetic wastewater using Moringa oleifera seed coat

Abstract

Biosorption has demonstrated effectiveness in eliminating contaminants of emerging concern (CECs) that lack inclusion in current water quality standards. These pollutants impede progress towards UN Sustainable Development Goals 6 and 14, pertaining to clean water accessibility and marine life preservation. This research investigated the adsorption potential of the persistent pharmaceutical pollutant, carbamazepine, using Moringa oleifera (MO) seed coat. This research investigated the adsorption potential of the persistent pharmaceutical pollutant, carbamazepine, using MO seed coat biochar. Acid hydrolysis and subsequent carbonization produced a biochar with superior properties for adsorption as confirmed by FTIR, SEM, EDX, CHNOS, and XRD analyses. The influence of agitation speed (200 rpm, 300 rpm, and 400 rpm), adsorption duration (0 to 180 min), and adsorption temperature (30 °C, 40 °C, and 50 °C) on CBZ removal in synthetic wastewater were studied. The quadratic regression model obtained from Box Behnken experimental design (BBD) with Response surface methodology (RSM) showed a strong predictive ability with R² = 0.9754 and adjusted-R² = 0.9015. Agitation speed significantly influenced the adsorption capacity as evidenced by a p-value of 0.02848. The optimum conditions for CBZ adsorption were 400 rpm, 30 °C, and 2.15 h at which a maximum adsorption capacity of 51.87 mg/g was anticipated. The adsorption behaviour was best described by pseudo-second order kinetics and the Temkin isotherm model. The study confirmed that MO seed coat biochar as a promising green adsorbent for pharmaceutical contaminant removal in wastewater treatment.

HIGHLIGHTS • Adsorption of carbamazepine (CBZ) by Moringa Oleifera seed coat biochar is presented. • Acid hydrolysis with 85 % H3PO4 followed by carbonisation increased the surface area from 1.160 m2/g in the raw biosorbent to 237.3 m2/g in the biochar. • 93.3 % of CBZ was removed from 50 ppm solution within 3 hours of agitation at 200 rpm. • Agitation speed significantly affected adsorption capacity for CBZ unlike adsorption temeprature and time • Pseudo second-order kinetics and Temkin isotherm model adequately described the adsorption of CBZ on MO.