Application of response surface methodology (RSM) in optimisation of levofloxacin and ciprofloxacin removal by NH2/MOF: kinetics and isotherm study

Abstract

ABSTRACT Antibiotics used for human health, animal husbandry, and aquaculture all contribute to wastewater that contains harmful levels of the drugs. The pharmaceutical sector is responsible for producing dangerous and toxic wastewater. Therefore, the aim of this study was to investigate the adsorption behaviour of ciprofloxacin (CIP) and levofloxacin (LFX) on amine/metal-organic frameworks (MOFs). Initially, a composite of NH2/MOF was synthesised, and its properties were evaluated using SEM, TEM, XRD, and FTIR. Experiments were conducted to determine the impact of factors such as pH, contact time, adsorbent mass, and initial antibiotic concentration on the adsorption of CIP and LFX. Isotherm and kinetics studies were also carried out to gain a better understanding of the adsorption process. The effects of each variable were analysed using R software’s Response Surface Methodology (RSM). The results indicated that a pH value of 5 was optimal for the adsorption of both CIP and LFX. Equilibrium was reached after 30 minutes for LFX and 37 minutes for CIP. Under optimum conditions, maximum removal efficiencies of 95% for LFX and 94% for CIP were achieved. The adsorption data for both LFX and CIP followed the Langmuir isotherm model and pseudo-second-order kinetic model, respectively (R2 > 0.99 for both). The NH2/MOF composite proved to be an effective adsorbent for removing levofloxacin and ciprofloxacin from water supplies.