Synthesis and characterization of L-Arg-polypyrrole@g-C3N4 nanocomposite for highly efficient removal of orange G dye: Mechanistic insights and RSM@BBD optimization

Abstract

Dye pollution, specifically orange G dye (OG dye) has been substantial threat owing to its poisonous to both human health and ecosystems. Thus, developing adsorbents with high stability, strong adsorption efficiency, easy separation, and excellent regenerability remains a challenge. In the present research, L-Arg-PPy@g-C3N4 nanocomposite was crafted through an interfacial polymerization process. OG adsorption onto L-Arg-PPy@g-C3N4 was optimized in batch mode using response surface methodology coupled with box-Behnken design (RSM@BBD) to assess the adsorbent dose, pH and initial OG concentration. The developed composite proficiently eliminates 94.87 % of OG dye molecules at 1 g·L−1 with a reaction time approaching 60 min, with high uptake efficacy of 23.31 mg·g−1. The Langmuir isotherm and pseudo-second-order kinetic models effectively describe the adsorption process in both aqueous solution and wastewater. Based on XPS/FT-IR analysis, the OG dye mechanism is mainly driven by π-π interactions, hydrogen bonding and electrostatic attractions. The adsorbent efficacy achieved 88.3 % removal in real wastewater treatment. This slight detriment was explained by the individual study of co-interfering ions. Reusability tests confirmed the adsorbent’s excellent regeneration capability for purifying wastewater containing OG dye molecules maintaining 73.8 % removal capacity during 4 cycles. These findings confirm the potential of the developed L-Arg-PPy@g-C3N4 as an effective filter for OG removal from wastewater.