Graphitic carbon nitride modified by molybdenum trioxide (g-C3N4/MoO3) as a nanohybrid was synthesized by co-precipitation method. Here, g-C3N4/MoO3 nanohybrid was used for the first time as an adsorbent for the pharmaceutical drug, diclofenac, (an aqueous micropollutant) from water to mitigate its possible environmental toxic effects. Compared to pristine components, the nanohybrid exhibited better adsorptive removal of diclofenac. Adsorption was enhanced with increment in MoO3 content from 1 to 3 wt %; however further increment in MoO3 content resulted in lower adsorption capacity due to agglomeration of MoO3 particles over g-C3N4. 162 mg g-1 adsorption capacity was achieved for 300 mg L-1 diclofenac in solution with 1 g L-1 adsorbent at pH = 6. Adsorption of diclofenac over g-C3N4 /MoO3 followed pseudo 2nd order kinetics. Temkin, Langmuir, Dubinin Radushkevich and Freundlich isotherm models were applied on the experimental results concluding that diclofenac adsorption over g-C3N4/MoO3 followed the Langmuir isotherm. The adsorption mechanism could be explained by the π-π interaction between aromatic rings of diclofenac and g-C3N4/MoO3 (3%) nanohybrid, which is also evident by the FTIR results. This study presents the facile fabrication of a 2nd generation adsorbent for the treatment of diclofenac contaminated water that may as well help achieve the removal of other micropollutants form water.
Keywords: diclofenac sodium; efficient adsorbent; g-C3N4; micropollutants; nanohybrid.