High performance of carbon quantum dots-decorated-polymeric nanocomposite for enhanced microwave adsorption of vanadium (V) from water

Carbon quantum dots (CQDots), as a sorbent has been decorated via grafting onto polymer matrix (PHQFB) based on 8-hydroxyquinoline (HQ) and biuret using formaldehyde cross-linker for the construction of a novel nanosorbent (CQDots@PHQFB). The assembled material was characterized by different techniques. The SEM image of the prepared CQDots@PHQFB nanosorbent indicated its particle size in the range 17.6–24.1 nm and the average diameter of CQDots@PHQFB is 14.9 nm. The resultant BET pore volume (0.028 cm3 g−1), the mean pore diameter (11.3nm) and surface area (11.5 m2 g−1) were computed. Adsorption studies were accomplished to evaluate the V(V) removal by CQDots@PHQFB nanosorbent from aqueous solution by microwave irradiation technique. CQDots@PHQFB demonstrated excellent adsorption and selectivity for V(V) ions from acidic medium (91.2% for 5 mg L−1) at low pH conditions (pH 1–3). Therefore, three different mechanisms were proposed to account for such high extraction of V(V). The adsorption kinetics of V(V) was approved by the pseudo-second order with of R2 (1.0) for both concentrations (5 and 15 mg L−1). Furthermore, The values of qe(cal.) (18.3 mg g−1, 54.3 mg g−1 for 5, 15 mg L−1, respectively), were also confirmed to be very close to qe(exp.) (18.2 mg g−1, 54.2 mg g−1 for 5, 15 mg L−1, respectively), while the equilibrium isotherm results were evaluated by nonlinear models, viz. Langmuir, Freundlich, Liu and Temkin. The maximum capacity of adsorption from the Liu model was found 219mg g−1 at 346 K The computed parameters of thermodynamic approved endothermic and spontaneous nature of V(V) adsorption onto CQDots@PHQFB nanosorbent. V(V) ions removal values corresponding to 99.3% and 97.7% were achieved from sea water and wastewater, respectively. The collected results affirm that the designed CQDots@PHQFB nanosorbent is an excellent candidate adsorptive uptake of V(V) from aqueous medium. The extraordinary adsorption abilities with higher reusability features for adsorption of inorganic pollutant such as V(V) entrusts this CQDots@PHQFB as a potential economical adsorbent to alleviate water pollution problem.