Selected pharmaceutical pollutant recovery from wastewater by an agro-byproduct Laurus nobilis-based adsorbent: Theoretical and experimental studies

Abstract

Background

Residues generated from essential-oils extraction are steadily increasing, causing a major disposal and environmental problem that must be properly handled and used for environmental remediation.

Method

In this study, powdered Laurus nobilis leaves were converted into an efficient adsorbent via simultaneous treatments using CaCl₂ 20% and 40% as an impregnant and pyrolysis in the muffle furnace at 600 °C as a heating step, resulting in CA-20 and CA-40 samples respectively, in order to remove pharmaceutical pollutant from aqueous media.

Significant findings

Characterization methods, such as FTIR analysis, pH_zpc, SEM microscopy, Raman, XRD, BET surface area, and available porosity, were explored for physicochemical characteristics of the as-prepared material prior to its use in removing Salicylic acid from simulated wastewater. Effects of conventional parameters were also evaluated through batch experiments (dose of 0.02¹, pH=2, stirring time of 90 min). Among adsorption isotherm models used and based on R² and error analysis values, Sips better describes experimental data from which an adsorption capacity of 45.42 mg/g is reached. The Pseudo-second order (PSO) kinetic model best fits the experimental data, indicating the adsorption process is chemically controlled. Thermodynamics confirms the spontaneous adsorption process (∆G⁰ ranging from -27.633 to -26.024 kJ/mol) and its endothermicity (∆H⁰ = -57.907(kJ/mol). Laurus nobilis leaves residue were successfully and easily converted into an efficient adsorbent and used for lowering concentration of salicylic acid from wastewater.