Biosorptive removal of toxic nitrate ion from wastewater using Albizia lebbeck seed pods: Isotherm and equilibrium studies

Abstract

A major environmental issue that contaminates drinking water and endangers human health is nitrate pollution. In this study, goethite, citric acid, tartaric acid was employed to modify Albizia lebbeck seed pod for the biosorption of nitrate ion. The developed unmodified Albizia lebbeck (UALB), citric acid modified Albizia lebbeck (CALB), tartaric acid modified Albizia lebbeck (TALB), and goethite acid modified Albizia lebbeck (GALB) were characterized using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR), and point of zero charge (pH_pzc) to determine the structural morphology, functional group, and adsorbent surface charge. The adsorption nitrate ion onto the biosorbents was found to be dependent on the operating parameters. The findings revealed that the maximum percentage removal of nitrate ion was 80.8 % at pH 7 for UALB, 80.3 % at pH = 4.0 for CALB, 70.30 % at pH = 3.0 for TALB and 76 % at pH 7 for GALB. The adsorption experimental data for nitrate ion adsorption onto ULAB, CALB, TALB, and GALB were best described by the Langmuir isotherm model. The UALB exhibited the highest Langmuir monolayer adsorption capacities with a value of 344.827 mg/g. Therefore, the unmodified form of Albizia lebbeck (UALB) which is economical, and sustainable provides an efficient alternative method for nitrate removal in aqueous environment.