Wastewater Treatment by Enhanced H2O2 – Based Advanced Oxidation Process (AOP) Methods: A Review

The development of industries leads to large amount of organic wastewater that contains phenol and dyes. For the treatment of these pollutants, the applications of H2O2 based – AOP have advantages in less pollution, low costs and high efficiency. In order to promote the degradation effect of H2O2, researchers used several methods to strengthen the effect of H2O2 based – AOP. This article mainly reviews the development of catalysts of the strengthened Catalytic Wet Hydrogen Peroxide Oxidation (CWPO), Fenton-like and other assistant-H2O2 systems in the degradation of phenol and dyes recent years. Challenges and development directions concerning catalysts in the future are discussed.

Effect of Chemical Challenges on the Properties of Composite Resins

Objective. To evaluate the chemical degradation effect on microhardness and roughness of composite resins after aging. Materials and Methods. Specimens (n = 10) were used for Filtek Z350 XT (Z350), Filtek Bulk Fill (BULK), Micerium HRI (HRI), Micerium BIOFUNCION (BIO), and Vittra APS (VITTRA). Microhardness and roughness were performed before and after degradation with the followed solutions: citric acid, phosphoric acid, 75% alcohol, and distilled water. Samples were to a 180-day chemical cycling protocol. After degradation, one sample of each group was selected for scanning electron microscope evaluation. The data were analyzed with normal distribution (Kolmogorov–Smirnov) and similarities of variations for the Bartlett test. ANOVA (two-way) followed by Tukey’s test was performed considering treatment and composite resin P < 0.05 . Results. For microhardness and roughness, variations were noted to different solution and resin formulations. Z350 and HRI showed higher microhardness percentage loss, and it was more evident after storage in alcohol (−48.49 ± 20.16 and −25.02 ± 14.04, respectively) and citric acid (−65.05 ± 28.97 and 16.12 ± 8.35, respectively). For roughness, Z350 and VITTRA showed less delta values after alcohol storage (−0.047 ± 0.007 and −0.022 ± 0.009, respectively). HRI had the worst roughness for citric acid (−0.090 ± 0.025). All resins were not statistically different between each other in water and phosphoric acid. Conclusion. The formulations of restorative resin materials influenced in degree of surface degradation after 180 days of chemical degradation. Water was considered the solution that causes less degradation for microhardness and roughness evaluations. For microhardness, alcohol was considered the worst solution for Z350 and HRI. For superficial roughness, Z350 and VITTRA showed less degradation in alcohol and citric and phosphoric acid solutions.

Decomposition-Based Multistep Sea Wind Speed Forecasting Using Stacked Gated Recurrent Unit Improved by Residual Connections

Sea wind speed forecast is important for meteorological navigation system to keep ships in safe areas. The high volatility and uncertainty of wind make it difficult to accurately forecast multistep wind speed. This paper proposes a new decomposition-based model to forecast hourly sea wind speeds. Because mode mixing affects the accuracy of the empirical mode decomposition- (EMD-) based models, this model uses the variational mode decomposition (VMD) to alleviate this problem. To improve the accuracy of predicting subseries with high nonlinearity, this model uses stacked gate recurrent units (GRU) networks. To alleviate the degradation effect of stacked GRU, this model modifies them by adding residual connections to the deep layers. This model decomposes the nonlinear wind speed data into four subseries with different frequencies adaptively. Each stacked GRU predictor has four layers and the residual connections are added to the last two layers. The predictors have 24 inputs and 3 outputs, and the forecast is an ensemble of five predictors’ outputs. The proposed model can predict wind speed in the next 3 hours according to the past 24 hours’ wind speed data. The experiment results on three different sea areas show that the performance of this model surpasses those of a state-of-the-art model, several benchmarks, and decomposition-based models.

Degradation Effect of UV Synergistic Biomass Activated Carbon Materials on Phenol Pollutants in Water

The purpose of the study is to purify the water containing phenol pollutants. The degradation effect of phenol pollutants in water is studied through the combined action of UV and biomass-activated carbon. First, the phenol solution is prepared in the laboratory to simulate the polluted water. Second, the phenol adsorption effects of UV synergistic biomass activated carbon, biomass activated carbon and ordinary industrial activated carbon under different influencing factors are compared by experiments. Finally, the results are analyzed and the conclusions are drawn. The results show that the UV synergistic biomass activated carbon has the strongest degradation ability for phenol, and the highest removal rate is 66.5% when the shaking time is 65 minutes. The adsorption ability of the industrial activated carbon for phenol is the worst. When the initial concentration of phenol is 25mg/L, the maximum phenol removal rate is 96.8%. The maximum phenol removal rate of biomass activa ted carbon appears in the initial concentration of phenol and the phenol removal rate is 60 mg/L. The reaction temperature has little effect on the phenol removal rate of UV synergistic biomass activated carbon and biomass activated carbon. The phenol removal ability of UV synergistic biomass activated carbon and biomass activated carbon reaches the highest when the dosage of activated carbon is 2.0 g, and the rates are 96.4% and 91.1%, respectively. When the pH of the solution is 7, the removal rate of UV synergistic biomass activated carbon reaches a maximum of 97%. When the pH of the solution is 6, the removal rate of biomass-activated carbon reaches the maximum. When the pH of the ordinary industrial activated carbon is 7, the removal rate is the maximum. Due to different influencing factors, UV synergistic biomass activated carbon has the strongest phenol degradation ability. This study provides a reference for the purification of polluted water.

Synthesis of ZnWO4/Cu2O Composites and Efficient Catalytic Properties for 4-nitrophenol Removal

Preparation of ZnWO4/Cu2O composite materials by environmental protection experimental method. ZnWO4 nanorods were prepared by a simple hydrothermal method, and then ZnWO4/Cu2O composites were prepared by chemical precipitation method. The experimental method is simple and clean. Due to the unique structural characteristics of Cu2O, the wide band gap of ZnWO4 was improved and the ZnWO4/Cu2O composite with better catalytic performance was generated. Various tests show that the catalytic performance and stability of ZnWO4/Cu2O is not lower than that of ZnWO4. Among them, ZnWO4/Cu2O-5 has the best catalytic degradation effect. The Cu-H generated during the degradation of 4-nitrophenol (4-NP) prevents the oxidation of Cu+, and the neutral product 4-aminophenol (4-AP) is easier to fall off, which improves its recycling efficiency. These encouraging results show that the ZnWO4/Cu2O composites have great potential to degrade 4-NP.