NiO-biomass microcomposite for the phytoremediation of methylene blue from wastewater

Modification of adsorbent with nanomaterials has become a widely adopted method to improve their surface morphology and adsorption capacity. In the present study, <i>Bauhinia tomentosa</i> seedpod (BTSP) was modified with unary NiO nanoparticle to form NiO-BTSP adsorbent for the removal of methylene blue (MB) from water. The functional, optical, and morphological properties of the synthesized adsorbent was characterized by Fourier transform infrared spectroscopy, UV-Vis Spectroscopy, Energy Dispersive X-Ray, and Scanning electron microscopy. Results showed formation of agglomerated particles with pore spaces that were loaded with dye molecules after adsorption. Adsorption studies revealed formation of multiple layers of dye molecules on the adsorbent at an optimum pH of 12 and maximum monolayer capacity of 357.14 mg/g. Kinetics modeling of the adsorption data showed that adsorption occurred through chemical interaction between the adsorbent and dye molecules to reach equilibrium in 60 min. Desorption experiments using different organic and inorganic acids and bases further revealed the reusability potential of the adsorbent with optimal regeneration obtained using as low as 0.01 M acetic acid. The consistent release of toxic dye effluents to water bodies remains an international problem that threatens both aquatic and terrestrial life. It is, therefore, important to develop effective, low-cost, and eco-friendly materials to remove these pollutants. This study develops a novel adsorbent produced by modifying a low-cost and readily available environmental waste with NiO nanoparticle, to effectively remove methylene blue, an emerging and highly toxic water pollutant, from wastewater.