Abstract
The recent excessive industrial usage and applications of nanomaterials and quantum dots (QDs) will lead to high abundance of wastes that will be exposed to the environment causing contamination and risk for human health especially when they reach to water resources. Thus, the main objective in this work is devoted to remove silver quantum dots (Ag-QDs) by an efficient fibrous composite (COSB@DETA@delta-FeOOH@DETA@NC) prepared on the basis of crosslinking reaction of Corchorus olitorius stalks biochar (COSB) with feroxyhyte (delta-FeOOH) and natural cotton (NC) via diethylenetriamine (DETA). SEM, TEM, EDX, XRD, FTIR, and XPS have been manipulated to characterize the fibrous composite. Coagulative adsorprtion of Ag-QDs from water onto COSB@DETA@delta-FeOOH@DETA@NC fibrous composite was monitored and optimized under different conditions of stirring time, composite mass, initial Ag-QDs concentration, pH, electrolyte concentration and temperature. The coagulative removal process was confirmed to take place in few minutes giving rise to 100% recovery via an efficient reaction of Ag-QDs onto COSB@DETA@delta-FeOOH@DETA@NC. The adsorption equilibrium of Ag-QDs was clarified via pseudo-second-order kinetics (R-2 = 0.999) and Freundlich isotherm (R-2 = 0.947 and Q(max) = 163.93 mg g(-1)). The coagulative adsorption and removal mechanism of Ag-QDs was interpreted via four interaction modes, e.g., charge neutralization, metal-ligand interaction, van der Waal forces and bridging function due to high N and O contents in the composite structure. The fibrous composite achieved excellent regeneration performance and superior efficiency in Ag-QDs recovery values (> 93%) from real samples such as tap, sea and wastewater from 10 to 50 mg L-1.