Sustainable Synthesis and Enhanced Photocatalytic Activity of Titanium Oxide-Clay Nanocomposite Toward Persistent Polychlorinated Biphenyl Degradation in Real Samples

This study presents the green synthesis of TiO2-clay nanocomposite using an eco-friendly method based on carbohydrates. Glucose and soluble starch function as the bioreductant and stabilizer agent during the reaction, respectively. The UV-vis analysis ascertained the formation of TiO2-clay nanocomposite presenting a distinctive absorption peak at 360 nm and an optical band gap of 4.3 eV. TEM and XRD results indicated the anatase phase of spherical TiO2-clay with a median crystallite size of 18.36 nm. EDX and XRF techniques revealed the presence of titanium, oxygen peaks, and TiO2 compound (58 wt%) along with the elemental composition of clay. The BET values of specific surface area, average pore diameter, and pore volumes are 47.48 m2g− 1, 17.39 nm, 0.19 cm3g− 1, respectively. The benign TiO2-clay nanocomposite demonstrated superior photocatalytic efficiency toward photodegradation of poly polychlorinated biphenyl pollutant in industrial wastewater with a removal rate of 98.32%, greater than untreated TiO2 NPs.

Evaluation of polychlorinated biphenyl degradation through refuse from Pleurotus ostreatus, Lentinula edodes and Agaricus bisporus production

White rot fungi (WRF) are known to have the ability to degrade organic pollutants with a structure similar to lignin. Because of this, the degradation of polychlorinated biphenyls (PCBs) congeners no. 28, 52, 101, 138, 153 and 180 by substrate before fruiting (substrate) and/or after fruiting (SMS) from cultivated mushrooms Pleurotus ostreatus, Lentinula edodes and Agaricus bisporus was examined. The experiment was carried out in four replications for each treatment using a mixture of substrate/SMS and sandy soil with PCBs at a concentration of each congener at 50 and 100 μg kg−1 soil DW. The results indicate that degradation was dependent on substrate/SMS addition, the concentration of PCBs and time of incubation. The efficiency of PCB degradation was generally reduced with the number of chlorine atoms in the structure of congeners: 28, 52, 101, 138, 153 or 180. In all combinations, degradation increased with incubation time. Degradation by SMS was lower in comparison to degradation by a substrate of the same mushroom. The degree of degradation of a single PCB after 12 weeks of incubation for A. bisporus ranged from 31.32 ± 1.52 to 83.91 ± 1.07%, while for P. ostreatus it was between 37.88 ± 2.54 and 78.29 ± 1.41%; for L. edodes it ranged from 17.38 ± 1.06 to 75.30 ± 1.46%. The best average degradation was confirmed for 20% SMS of A. bisporus at 50 μg kg−1 PCB.