Comparative profile of green and chemically synthesized nanomaterials from bio-hydrometallurgical leachate of e-waste on crystal violet adsorption kinetics, thermodynamics, and mass transfer and statistical models

In the present research, nano-sized copper oxide particles (CuO) were synthesized from the bio-hydrometallurgical leachate of electronic waste (e-waste) using chemical and green mediated approaches. Glycine nitrate precursor (GNP) method was adopted to synthesize cCuO and Eichhornia crassipes leaves extract was used to prepare gCuO. Further, to ensure their nano-sized forms, the optical and structural properties were examined. Then, a set of batch trials were planned to compare their removal efficiencies of the cationic dye, crystal violet (CV). The maximum percent removal of 93.8% and 91.3% were observed for gCuO and cCuO, respectively, at pH 0 of 8.0 with the initial concentration of 10 mg/L. The acquired batch trial data revealed the maximum adsorptive capacity for gCuO (200.00 mg/g) than cCuO (142.86 mg/g). This enhanced removal can be attributed due to the augmentation of surface functional moieties derived from the various phyto-constituents of E. crassipes . Also, the present study developed regression models predicting the CV adsorption process with high degree of statistical accuracy using artificial neural network (5-5-1 model; <0.5 MSE, R 2 >0.99) and response surface methodology (3-3 BBD model, p <0.05, C.I>95%). Conclusively, the desorption results showed that the nano-adsorbents can be efficiently regenerated for the minimum of three successive adsorption-desorption cycles. Graphical abstract