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February 24, 2022
Abstract
The heavy metal cadmium (Cd) is known to be a widespread environmental contaminant and a potential toxin that may adversely affect human health across the globe. Green nanotechnology has recently received a lot of attention for developing eco-friendly, low-cost renewable and sustainable materials for the efficient removal of persistent contaminants from wastewater, including heavy metals (HMs). The current study compared the ability of titanium dioxide nanoparticles (TiO 2 NPs) synthesized from Trianthema portulacastrum (A) and Chenopodium quinoa (B) extracts to remove Cd from wastewater. The washed biomass of both the plants was dried under shade for a few days and was ground into the fine particles in a blender. The powdered biomass of T. portulacastrum and C. quinoa was soaked separately in distilled water (@ 10 g/100 ml) for 36 h. The stock solution of titanium (0.3 M) was prepared from concentrated titanium tetraisopropoxide (TTIP) and was mixed with the plant extracts at 1:2 ratio of extract to TTIP solution with continuous stirring at room temperature. A light brown scum like TiO 2 -NPs were obtained at the bottom of china dish and calcined at 450 °C for 4 h. Finally, after natural cooling, the TiO 2 -NPs were collected and used for the sorption of Cd through wastewater. Sorption attributes of both TiO 2 NPs (A, B) were investigated over contact time, dosage of adsorbent, pH, and initial concentration of Cd. Maximum sorption was obtained (46 mgg −1 ) by TiO 2 NPs (A), followed by 44 mg Cd g −1 with TiO 2 NPs (B) at pH 4.2, an optimum adsorbent dosage 0.7 g L −1 , Cd initial level 30 mg L −1 , with contact time of 2 h. Pseudo-second-order kinetic model was suited for adsorption experimental data using both nanoparticles. These results validated the potential use of TiO 2 NPs to remove liquified cadmium at high concentrations from the industrial wastewater.