Fabrication of biochar from jarul (Lagerstroemia speciosa) seed hull for ultrasound aided sequestration of ofloxacin from water: Phytotoxic assessments and cost analysis

Abstract

Water pollution by pharmaceutical pollutants such as antibiotics are rising day by day and antibiotics are considered as emerging contaminants because of their eventual threats for both human health and aquatic ecology. Recently waste biomass derived biochar has drawn a lot of attention, especially as adsorbents, for antibiotics contaminated wastewater sequestration because of their high sorption capability, higher surface area, and microporosity. In this study, waste biomass (Lagerstroemia speciosa) seed coats were used to produce biochar (CLSHB) through a pyrolysis progression followed by chemical activation with NaOH for the effective removal of an antibiotic drug ofloxacin (OFL) from water. The surface area, and pore volume of CLSHB were assessed to be 82.192 m2/g, and 0.189 cm3/g, consecutively. The optimum removal percentage of OFL was obtained to be 91.43 % at solution pH 5.0, adsorbent dose of 1.0 g/L, OFL concentration of 20 mg/L, and sonication time of 90 min. The OFL adsorption data were well-fitted by the Langmuir isotherm model with uptake capacity of 34.60 mg/g, which depicts the monolayer adsorption of OFL onto the CLSHB surface. OFL adsorption kinetics results fit to the pseudo-second-order model, indicating that chemical sorption might be the main mechanism by which the pharmaceutical adhered to the CLSHB surface. The phytotoxicity assessment demonstrated that the treated OFL solution obtained in this process was deemed suitable for seed germination and the total synthesis cost of CLSHB was found to be only 8.7 $/kg. The OFL elimination efficacy with CLSHB decreases from 91.43 % to 73.26 % after fifth cycle of consecutive use, demonstrating the strong stability and reusability of CLSHB.