Studying Of Ultrasonic Catalysis Of Carbon-based Piezoelectric Reinforced Composites

Ultrasonic catalysis,photocatalysis and piezoelectric catalysis are commonly used for the degradation of organic pollutants in water.These methods acting alone suffer from many shortcomings such as secondary pollution,poor effectiveness,large cost,and inability to be applied on a large scale.Their combination produces a synergistic effect that significantly increases the catalytic activity,resulting in efficient degradation efficiency.In this thesis,ultrasonic catalysis,photocatalysis and piezoelectric catalysis were combined to enhance the catalytic performance of the composites by using the piezoelectric effect of Na Nb O₃(NNO)and Sr Ti O₃(STO)under the action of ultrasound.At the same time,this thesis investigates the stability of the composite material by conducting repeated experiments for large-scale applications.(1)Activated carbon is used as the base material and modified by nitric acid solution.Six composites,NNO-Co₃O₄/AC,NNO-NiO/AC,NNO-CuO/AC,STO-Co₃O₄/AC,STO-NiO/AC,and STO-CuO/AC,were prepared by hydrothermal and static methods,and the prepared samples were characterized by XRD,Raman,SEM and EDS tests.The results showed that the prepared composites were said to be of high purity and good crystallinity.(2)The catalytic properties of NNO-Co₃O₄/AC,NNO-NiO/AC,and NNO-CuO/AC were investigated using methyl orange and methylene blue as the target contaminants.The composites improved the catalytic activity by coupling both semiconductor oxides and the piezoelectric effect of NNO in the presence of ultrasound to hinder the complexation of electron-hole pairs.The degradation rates of NNO-Co₃O₄/AC,NNO-NiO/AC,and NNO-CuO/AC for methyl orange reached85.94%,86.6%,and 90.84%at 25 min,respectively,under the action of ultrasonic waves;the degradation rates of methylene blue reached 91.8%,93.74%,95.12%for methylene blue.(3)The catalytic performance of STO-Co₃O₄/AC,STO-NiO/AC,and STO-CuO/AC was investigated with methyl orange and methylene blue as the target pollutants.88.59%,91.33%,and 91.84%degradation rates were achieved at 25 min for methyl orange by STO-Co₃O₄/AC,STO-NiO/AC,and STO-CuO/AC,respectively;the degradation rates for methylene blue reached 94.8%,97.4%,95.72%at 25 min,respectively.The degradation rate of STO-type composites is higher than that of NNO-type composites for methyl orange and methylene blue.This may be attributed to the fact that STO is an n-type nanosemiconductor oxide,which is able to form p-n heterojunctions with three p-type semiconductor oxides,Co₃O₄,NiO,and CuO,leading to the effective separation of carriers at the junction interface and enhancing the catalytic activity.After three repeated experiments,all six composites have certain stability,which is relevant for the application of catalysts.