Green and eco-friendly synthesis of TiO<sub>2</sub> nanoparticles and their application for removal of cadmium from wastewater: reaction kinetics study
Muhammad Atif Irshad, Muhammad Bilal Shakoor, Rab Nawaz, Tahira Yasmeen, Muhammad Arif, Muhammad Rizwan, Muhammad Zia‐ur‐Rehman, Sajid Rashid Ahmad, Maria Latif, Iqra Nasim, Shafaqat Ali
Abstract
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.