Hybrid amino-terminated lignin microspheres loaded with magnetite and manganese oxide nanoparticles: An effective hazardous oxyanions adsorbent

Abstract

Highly effective lignin-based microspheres were prepared by inverse copolymerization of lignin (kraft) from suspension, with poly(ethylene imine) and amino-functionalized magnetite nanoparticles (A-LMS_Fe3O4) or manganese(IV)oxide nanoparticles (A-LMS_MnO2). The XRD, FTIR, SEM, BET, TEM techniques, including the porosity determination, were performed to analyze morphological and structural properties of synthesized microspheres. The effect of pH, the adsorbent dosage, temperature and contact duration on a batch-mode adsorption efficiency of arsenate and chromate (oxy)anions removal was tested. Spontaneous adsorption was found to be feasible, reaching the adsorption capacities of Cr(VI) (62.9 mg g−1), As(V) (47.8 mg g−1) by A-LMS_Fe3O4, and of Cr(VI) (73.9 mg g−1), As(V) (62.5 mg g−1) using A-LMS_MnO2 adsorbent. Fast removal rates were confirmed via kinetic study, using pseudo-second order, the Weber-Morris and the single resistance mass-transfer model, with a limiting step of the diffusion transport through pores. The correlation of fixed-bed-column results with Bohart–Adams, Thomas, Yoon–Nelson and Dose Response models displayed that breakthrough behavior was influenced by flow rate and the inlet concentration. Significant potential of produced bio-adsorbent is further confirmed by the pore surface diffusion modeling, desorption study and adsorption from multi-component system using artificial water.