Systematic metronidazole adsorption performance onto montmorillonite clay: Parametric study, process modelling and RSM optimisation

Abstract

The aim of this study was to eliminate metronidazole in aqueous medium using clay material. The properties of adsorbent material collected in Cameroon were determined by BET, XRD, EDX-SEM, XRF, FTIR and zeta potential to provide its surface area, mineralogy, morphology, seize, functional groups and electrical charge. Batch adsorption experiment was used for metronidazole (MNZ) removal by considering several key operational parameters such as time, adsorbent dose and pH. Optimization process was done using full factorial experimental design. The rate of the reaction and mechanism was verified through linear and nonlinear isotherms, kinetics and statistical error analysis. Characterization of material have shown that it is a montmorillonite mineral clay with a specific surface area of 51.73 m²/g according to BET method. The calculated interlayer distance using Bragg law was d₀₀₁ = 10.18$\AA$. The optimum uptake capacity reached was 84.22 mg/g at a contact time of 20 min with adsorbent mass of 0.01 g at pH 7 using MNZ concentration of 80 mg/L. the second order kinetic model fitted best the experimental data and the reaction was controlled by Freundlich isotherm which indicate multilayer adsorption onto heterogeneous surface. The full factorial design also showed that mass and pH significantly influence adsorption process in view of surface response graph.