Role of Purged Air in the Synthesis of the Mesoporous NiO/C Composite and Its Application in Wastewater Treatment

Abstract

In this study, two methods were used to synthesize the NiO/C composite from agricultural waste. The mesoporous composite was successfully synthesized via a novel precipitation method in the presence of dissolved gases. The morphology of the composites was differentiated by using characterization techniques such as X-ray diffraction, the point of zero charge (pHpzc), field-emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy, energy-dispersive X-ray analysis (EDAX), and vibrating sample magnetometry (VSM). Then, the mechanism of synthesis was elucidated using the above experimental characterization data. Results of FESEM and EDAX analyses of Ni(OH)2–carbon composite clearly showed the role of dissolved gases in the synthesis. Both the composites were subjected as the adsorbent to remove the toxic Pb(II) ions from the wastewater. Batch adsorption experiments were carried out to compare the Pb(II) ion removal capability of both the composite materials. The parameters such as the effect of pH, the dosage of the adsorbents, and initial concentration were studied. At the optimized conditions, isotherm studies for each of the adsorbent were also carried out. The isotherm results revealed that the maximum removal capacity qe (mg/g) was 30.78 for PJNC and 43.48 for PJGNC. The VSM analysis confirmed that both the adsorbents were soft magnetic materials. Hence, they could be competently separated from salted/treated water using a magnetic field.