Design, Synthesis And Intelligent Prediction Of Tungstate And Heterojunctio

With the rapid development of social economy and the rapid development of industrialization,human beings have to face the two major problems of energy shortage and environmental pollution,because of energy shortage and serious environmental pollution.In recent years,semiconductor photocatalysis and sonocatalysis technology have been proved to be an effective green technology for the degradation of organic pollutants.However,the traditional single-phase semiconductor photocatalyst has some defects,such as low solar energy utilization rate,fast photoelectron-hole recombination and poor reusability.And the disadvantages of high energy consumption,low free radical production and low efficiency of single catalyst in the process of ultrasonic catalysis still hinder their practical application.In addition,the shortcomings of long cycle,high cost and great contingency in the research process of photocatalytic performance of actual materials,which can no longer meet the needs of research and development of modern materials.Artificial neural network has the advantages of self-learning and high-speed searching for optimal solutions,which can overcome the existing problems in the research of photocatalytic performance.Therefore,it is of great significance to research and develop new photocatalytic materials,sonocatalytic catalytic materials and catalyst modification methods to improve their catalytic efficiency and construct corresponding intelligent prediction algorithm.In this study,Co WO₄,Cu WO₄and non-metallic semiconductor photocatalyst graphite phase carbon nitride（g-C₃N₄）as the research object.The synthesis of Co WO₄/g-C₃N₄heterojunction material and their photocatalytic and sonocatalytic activities with different mass ratios were studied.In addition,the photoluminescence properties of Cu WO₄synthesized by polyacrylamide gel method were researched.Based on experimental data,artificial Neural Network（ANN）model was established,and Genetic Algorithm（GA）was used to optimize experimental operation parameters.The prediction of photocatalytic and sonocatalytic performance of Co WO₄/g-C₃N₄was realized,and the optimal experimental conditions and catalytic effects were predicted.Specific research contents are as follows:（1）CoWO₄/g-C₃N₄heterojunction was prepared by polyacrylamide gel method combined with a simple ultrasonic-assisted method.The photocatalytic experiments showed that the photocatalytic degradation rate of methylene blue（MB）by Co WO₄/g-C₃N₄heterojunction with a mass ratio of 1:2 could reach 94.5%after the reaction time of 100 min.The photocatalytic efficiency is 7.8 times and 1.5 times of that of pure Co WO₄and g-C₃N₄,respectively.The synergistic effect of Co WO₄and g-C₃N₄was the main reason for the enhancement of photocatalytic activity.Hydroxyl radical（·OH）is the main active species in the degradation of MB,and a possible photocatalytic mechanism of Co WO₄/g-C₃N₄heterojunction is proposed.ANN-GA results showed that the predicted value of photocatalytic degradation rate was consistent with the real value.The optimum experimental parameters（catalyst concentration 1.0000 g/L,dye concentration 10.0000mg/L,illumination time 95.3984 min,catalyst type 1:2 Co WO₄/g-C₃N₄,dye type MB）obtained by GA algorithm and photocatalytic degradation rate were 95.93%.These results are consistent with the actual photocatalytic results,indicating that the model has good predictive ability.（2）CoWO₄/g-C₃N₄composites with high ultrasonic catalytic activity were prepared by modified polyacrylamide gel method combined with grinding ultrasonic method.The degradation degree of Rhodamine B（Rh B）was evaluated for the sonocatalytic activity of the prepared composite.The ultrasonic catalytic degradation efficiency of 1 g/L Co WO₄/g-C₃N₄（7 wt%）composite and 10 mg/L Rh B solution reached 84.8%when treated with ultrasonic radiation（180 W,40 k Hz）for 180 min.The degradation efficiency of Rh B by Co WO₄/g-C₃N₄（7 wt%）ultrasonic catalyst was 6.6 times that of pure Co WO₄.The results showed that the degradation of Rh B by sonocatalysis was mainly caused by the production of superoxide radicals.A possible mechanism of sonodegradation was proposed based on sonocatalysis experiments.ANN-GA analysis showed that the prediction model of Co WO₄/g-C₃N₄sonocatalytic degradation rate had good performance,and the error of the sonocatalytic degradation rate was basically between-3%and 4%.The optimal experimental parameters（catalyst concentration 1.0000 g/L,dye concentration 10.0000mg/L,ultrasonic time 189.1675 min,catalyst type Co WO₄/g-C₃N₄-7 wt%）and the harmonic catalytic degradation rate（87.75%）were obtained.The results are similar to those of actual sonocatalytic activity analysis.（3）CuWO₄fluorescent materials were prepared by polyacrylamide gel method using Cu SO₄·5H₂O and H₂WO₄as metal sources.By XRD,XPS and FTIR characterization,it was confirmed that the pure phase Cu WO₄with triclinic crystal structure was obtained by calcined dry gel at 900°C.The results of transmission electron microscopy showed that Cu WO₄had high crystallinity.The UV-Vis absorption spectra show that the sample has significant light absorption in the near infrared region.The photoluminescence spectra show that Cu WO₄has an emission peak at 583 nm and excitation wavelength at 430 nm.The CIE color coordinates（x,y）of pure Cu WO₄phosphors are（0.5191,0.4800）compared to the CIE diagram,indicating that Cu WO₄phosphors have great potential in yellow light emitting devices.