Synthesis and characterization of humic acid and lignosulphonate based adsorbents for removal of pollutants from textile effluents

Abstract

Effluents containing dyes have become a big problem because of the ineffective and uneconomic treatment methods used by industries. There is no single treatment system that is adequate for the degradation of dyes. Currently, several chemical and physical degradation protocols for the remediation of dyes in wastewater are being used. Also, researchers have detected nitro-aromatic compounds in wastewater and these toxic compounds are detrimental to flora and fauna present in water bodies. Our aim was to prepare new materials and assess their potential as adsorbents as well as synthesis of new catalysts for the reduction of selected dyes and nitro-aromatic compounds. Two new composites were synthesised from starting materials lignosulphonate, humic acid, maleic anhydride and Kraft lignin. The novel nanocomposites were characterized by various spectroscopic techniques such as Fourier-Transform Infra-red Spectroscopy (FTIR), X-Ray Powder Diffraction (XRD), Brunauer-Emmett-Teller (BET), Scanning Electron Microscopy (SEM), Energy Dispersive X-ray Spectroscopy (EDS) and Transmission Electron Microscopy (TEM). Furthermore, the synthesized nanocomposite material was used either as an adsorbent for the dyes such as Reactive Blue 222 (RB), Reactive Red 195 (RR), and Reactive Yellow 145 (RY) or as a heterogeneous catalyst for the reduction of several nitro-anilines and selected dyes. UV-vis spectroscopy was used to assess the potential of the composite as adsorbents or be reductants. Adsorption isotherms, and adsorption kinetics of the new composite were studied. The overall advantage of this investigation is the raw material of the composite is cheap as it is obtained as waste material and is easily available.