Development of novel biochar adsorbent using agricultural waste biomass for enhanced removal of ciprofloxacin from water: Insights into the isotherm, kinetics, and thermodynamic analysis
Bablu Alawa, Surya Singh, Sankar Chakma, Rupak Kishor, Cecilia Stålsby Lundborg, Vishal Diwan
Abstract
Increase in the antibiotic's usage and mis-management in antibiotics' disposal has led to the occurrence of antibiotic residues in the surface water bodies. These residues may pose considerable risks to the human as well as aquatic organisms owing to the enhancement in antimicrobial resistance among microbes. Hence, precautionary measures are need of the hour to curtail the occurrence of antibiotic compounds in water. In addition, rampant burning of agricultural waste in India causes considerable air pollution. Considering this, a novel adsorbent has been developed from agricultural waste biomass, viz . wheat straw (WS), through calcination (CWS), followed by chemical activation (AWS). These adsorbents were employed for the removal of ciprofloxacin (CIP) from water. Removal efficiency of 90% (for CWS) and 98% (for AWS) could be achieved at neutral pH in room temperature conditions. The maximum adsorption capacity of ciprofloxacin on synthesized adsorbent was evaluated as 14.51 mg g −1 . Experimental findings were further explored to get the insights of isotherm, kinetics, and thermodynamics involved in the process. It was found that Langmuir model (with R 2 value of 0.985) provided a better fit than the other isotherm models. Kinetics and thermodynamic studies revealed that adsorption process followed the pseudo second order linear kinetic model (with R 2 value of 0.999) with endothermic and spontaneous sorption of ciprofloxacin on developed adsorbent. Thus, wheat straw waste may suitably be used as adsorbent for the removal of antibiotics from water. • Removal of CIP from water was studied using agricultural waste derived biochar. • Activated biochar prepared from wheat straw was capable to remove ∼98% of CIP. • Interaction between activated biochar and CIP enhanced adsorption capacity by 36–44%. • Minimal effect of temperature was seen during adsorption of CIP using adsorbents. • Pore filling and surface adsorption mechanism prevail during CIP adsorption.