Green Adsorbents for Removal of Antibiotics, Pesticides and Endocrine Disruptors

Abstract

The increasing number of pollutants in the environment poses a threat to the safety and health of aquatic species and humans. Particularly, their adverse effects, such as hindering metabolic processes and occupying hormone receptors when consumed by aquatic species and humans is of concern. Here we present an overview on endocrine disruptors, pharmaceuticals, pesticides and hormones, with emphasis on their potential risk of exposure in water, occurrences and environmental fates. Special emphasis is directed to the adsorptive removal of these micropollutants. We review recent developments in raw and modified green adsorbents for adsorption of antibiotics, pesticides and endocrine disruptors from wastewaters. The major points are the following: several green adsorbents such as plant-based biochar, eggshells and waste fruit peels exhibit comparable adsorptive performance to most commercial adsorbents. Alkaline and acid modification of biochar increases its porosity for adsorption of organic micropollutants and oxyanions. Acid modification results in the abundance of carboxyl groups, while alkaline modification increases the hydroxyl groups of biochar. Particularly, nitric acid-modified garlic-based biochar removal capacity for quinolone antibiotics and hydrophobic pesticides, of 128-289 mg/g, was 15 times higher than the unmodified biochar, of 8.5-19.3 mg/g, and comparable with commercial activated carbon, of 32-263 mg/g. Alkaline-modified chicken bone ash exhibits remarkable adsorption (93%) of polar pesticides (carbaryl and oxamyl) compared to 75% removal recorded for hydrophobic pesticides azinphos-Me and chlorfenvinphos.