Coconut shells based MrGO@CMC adsorbent for the chromium (VI) ion removal from contaminated water through batch adsorption method

Abstract

The chromium (III) ion is necessary for biological function and the chromium (VI) ion (Cr (VI)) induces toxicity to humans and animals. From the sources of industries, the contaminated Cr (VI) is an important issue to remove from the solution. Here, we synthesized magnetic reduced graphene oxide @ carboxymethyl cellulose (MrGO@CMC) adsorbent for the removal of Cr (VI) from aqueous solution. The fabricated adsorbent was characterized through XRD, FT-IR, SEM, EDX, BET, VSM, and TGA. Adsorption studies were conducted various parameters and the optimized contact time, dosage and concentration was fixed such 60 min and 10 mg L−1 respectively. By the MrGO@CMC adsorbent almost 93% efficiency Cr (VI) was removed from the aqueous solution at 40 min, 25 mg, 10 mg L−1, and neutral pH. The zero point charge (pHzpc) of the adsorbent was observed at pH-6.3. The MrGO@CMC adsorbent followed Langmuir isotherm model at achieving a maximum adsorption capacity of 625.8 mg g−1 and it indicates chemisorption dominated monolayer adsorption and the system follows pseudo-second-order kinetics model indicating a bimolecular system. Thermodynamic analysis revealed that the adsorption process was endothermic and spontaneous reaction. The adsorbent regeneration and reusability studies demonstrated that MrGO@CMC retained over 70.90% efficiency in removing Cr (VI) ions even after five recovery cycles compare with other graphene oxide-based adsorbent, the current adsorbent have potential removal efficiency, since the proposed adsorbent shows excellent adsorbent for Cr (VI) ions from industrial wastewater.

Keywords

• Chromium (VI) ion
• Coconut shells
• Graphene oxide
• Magnetic iron nanoparticle
• Carboxymethyl cellulose