Functionalized graphite into hydrophilic activated carbon: Synthesis, characterization, and adsorption studies

Functionalization of graphite by alkali activation and oxidation by chemical treatment has not been explored. The hydrophobic nature of carbon poses a particular challenge when used as an agent in water treatment applications in particular. Modification with hydrophilic groups on carbon makes carbon a promising material because of its good properties and used in various sectors. This study focused on the synthesis of hydrophilic activated carbon (HAC) from graphite by activation using sodium hydroxide (NaOH) and hydrophilization with ammonium persulfate (APS). The effects of functionalization on the surface chemical properties, wettability, and morphology were evaluated using various techniques. Fourier transform infrared (FTIR) analysis confirmed the functionalization results with the appearance of hydroxyl groups. X-ray photoelectron spectroscopy (XPS) analysis confirmed the carbon surface properties by total survey scan, showing the presence of N 1s and S 2p peaks on HAC. Contact angle values showed an increase in hydrophilicity from 88 ± 1.5° to 39 ± 1.0° for graphite and HAC, respectively. The absorption time also showed that HAC has active hydrophilic groups that can absorb water droplets in less than 0.60 s. The scanning electron microscopy (SEM) results also showed an increase in the number of pores on HAC. The methylene blue (MB) adsorption study showed that HAC had an adsorption capacity of 49.399 mg/g with a removal percent of 98.798 % at optimum conditions with an initial MB concentration of 50 mg/L, contact time of 240 minutes, and adsorbent dose of 0.1 g/100 mL. The adsorption kinetics of MB, AC, and HAC fitted well with the pseudo-second-order model. The Langmuir model provided the best fit to the experimental data, indicating a homogeneous and monolayer adsorbent surface. Accordingly, the synthesized HAC can effectively and reliably remediate wastewater contamination with organic pollutant.