Sulfide remediation from wastewater using hydrothermally synthesized ?-MnO2/porous graphitic carbon as adsorbent

A facile hydrothermal assisted in-situ precipitation technique was employed for synthesizing highly efficient porous graphitic carbon/manganese dioxide (PGC/MnO2) nanocomposite adsorbent using calcium alginate as carbon precursor. Morphological and structural characterization using scanning electron microscopy equipped with energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction techniques confirmed the interconnected nanoporous architecture and birnessite (?) MnO2 polymorph evenly distributed on the PGC structure. The synergistic effect of PGC and MnO2 was exploited for enhanced sulfide removal from wastewater via adsorptive oxidation. The effect of different experimental parameters, including solution pH, initial sulfide concentration, adsorbent dosage, and contact time on removal efficiency was investigated. The equilibrium and kinetic data for sulfide adsorption by PGC/MnO2 nanocomposite fitted well with Langmuir isotherm and pseudo-second-order kinetic model, respectively. The maximum uptake capacity of sulfide by the nanocomposite was determined as 500 mg/g with complete sulfide removal. Further, it was estimated that a typical field application using the synthesized nanocomposite adsorbent would require 0.5?1 g/L per 200 mg/L of sulfide contaminated wastewater. Based on the experimental results, a schematic of the adsorptive oxidation mechanism of PGC/MnO2 nanocomposite is proposed.

Automated summary

A facile hydrothermal assisted in-situ precipitation technique was used to synthesize highly efficient porous graphitic carbon/manganese dioxide nanocomposite adsorbent for sulfide removal from wastewater. The synergistic effect of PGC and MnO2 facilitated enhanced sulfide removal, with the nanocomposite exhibiting a maximum uptake capacity of 500 mg/g and complete removal of sulfide. Experimental results also suggested the potential use of the synthesized nanocomposite adsorbent for field applications.