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15 pages, 2145 KiB

Open AccessArticle

Optimizing the Flocculation Effect of Cationic Polyacrylamide Prepared with UV-Initiated Polymerization by Response Surface Methodology

by Chaochen Fu, Zhengan Zhang, Yuying Li, Lin Li, Hongtian Wang, Shaobo Liu, Xia Hua and Bailian Li

Water 2023, 15(6), 1200; https://doi.org/10.3390/w15061200 - 20 Mar 2023

Cited by 2 | Viewed by 2560

Abstract

Cationic polyacrylamide (CPAM) is a commonly used flocculant for water treatment. Factors that affect the flocculation effect and can be controlled manually include the type and dosage of CPAM, wastewater pH, stirring time and settling time, and their reasonable setting is critical to [...] Read more.

Cationic polyacrylamide (CPAM) is a commonly used flocculant for water treatment. Factors that affect the flocculation effect and can be controlled manually include the type and dosage of CPAM, wastewater pH, stirring time and settling time, and their reasonable setting is critical to the flocculation effect of CPAM. In this paper, the optimal flocculation conditions of a novel CPAM were studied. First, single-factor tests were conducted to preliminarily explore the optimal range of factors that influence CPAM flocculation, and then response surface methodology (RSM) tests were performed to accurately determine the optimums of the influencing factors. The results showed that the flocculation effect was better when the intrinsic viscosity was larger or the cationic degree of CPAM was higher. The CPAM dosage, wastewater pH and stirring time significantly impacted the flocculation effect, and inflection points were observed. A model that could guide CPAM-8.14-40.2 flocculation was obtained by RSM tests. The model optimization showed that the optimal flocculation conditions of CPAM-8.14-40.2 for treating wastewater prepared with kaolin were as follows: the CPAM dosage, wastewater pH and stirring time were 5.83 mg·L⁻¹, 7.28, and 5.95 min, respectively, and the turbidity of the treated wastewater was reduced to 6.24 NTU. Full article

(This article belongs to the Special Issue Physicochemical Technology for Wastewater Treatment: Theory, Methods and Applications)

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22 pages, 5952 KiB

Open AccessFeature PaperArticle

Synthesis and Investigation of TiO₂/g-C₃N₄ Performance for Photocatalytic Degradation of Bromophenol Blue and Eriochrome Black T: Experimental Design Optimization and Reactive Oxygen Species Contribution

by Fadimatou Hassan, Pierre Bonnet, Jean Marie Dangwang Dikdim, Nadege Gatcha Bandjoun, Christophe Caperaa, Sadou Dalhatou, Abdoulaye Kane and Hicham Zeghioud

Water 2022, 14(20), 3331; https://doi.org/10.3390/w14203331 - 21 Oct 2022

Cited by 9 | Viewed by 2946

Abstract

Graphitic carbon nitride (g-C₃N₄) based photocatalyst was synthesized and the photocatalytic performance was investigated for the removal of Eriochrome Black T (EBT) and Bromophenol Blue (BPB) under UV irradiation. The prepared materials were characterized by SEM-EDX, XRD, Raman, FTIR [...] Read more.

Graphitic carbon nitride (g-C₃N₄) based photocatalyst was synthesized and the photocatalytic performance was investigated for the removal of Eriochrome Black T (EBT) and Bromophenol Blue (BPB) under UV irradiation. The prepared materials were characterized by SEM-EDX, XRD, Raman, FTIR and DRS. Higher degradation efficiency for the same initial concentrations of EBT and BPB in presence of TiO₂/g-C₃N₄ have been achieved within 160 min of irradiation. The kinetic study showed that the photodegradation of BPB by TiO₂/g-C₃N₄ follows pseudo-first-order kinetics with an R2 value of 0.98. The addition of persulfate (PS) in BPB solution improved the degradation yield from 8.81% to 80.14% within 20 min of UV light irradiation. A Box-Behnken model was developed from three factors and Response surface methodology (RSM) was employed to identify the optimum conditions for the treatment of BPB solution by TiO₂/g-C₃N₄. The experimental values of degradation of BPB agreed with predicted values obtained from central composite design (CCD) analysis with an R² value of 0.9999. The scavenger study revealed that superoxide radical anion (O₂^•−) plays a key role (68.89% of contribution) followed by OH^• and h⁺ with 22.40% and 15.55% of contribution, respectively. This study has obviously exhibited the potential of TiO₂/g-C₃N₄ composite as a promising catalyst for photocatalytic purposes. Full article

(This article belongs to the Special Issue Physicochemical Technology for Wastewater Treatment: Theory, Methods and Applications)

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Review

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20 pages, 1315 KiB

Open AccessReview

The Socio-Environmental and Human Health Problems Related to the Use of Pesticides and the Use of Advanced Oxidative Processes for Their Degradation: Brazil

by Anna Karla Santos Pereira, Lívia Fernandes Silva, Gustavo Antonio Figueredo Barbosa, Thaynara Guimarães Miranda, Rayane Reis Sousa, Renato Almeida Sarmento, Nelson Luís Gonçalves Dias Souza, Douglas Henrique Pereira and Grasiele Soares Cavallini

Water 2023, 15(8), 1608; https://doi.org/10.3390/w15081608 - 20 Apr 2023

Cited by 2 | Viewed by 2270

Abstract

The present study reviews the quantitative data on the use of pesticides and their relationship to environmental and human health problems in Brazil. The detection of residual concentrations of pesticides in food and water consumed by humans has raised questions regarding the overuse [...] Read more.

The present study reviews the quantitative data on the use of pesticides and their relationship to environmental and human health problems in Brazil. The detection of residual concentrations of pesticides in food and water consumed by humans has raised questions regarding the overuse of pesticides and their consequences. This global concern was registered as the second goal of sustainable development by the United Nations, which refers to sustainable agriculture and alternatives to pesticides. However, besides recognizing the harmful effects of these contaminants on the environment and human health, there is also a need to understand treatment techniques that can remedy the existing conditions and thus alleviate the problems that affect water treatment plants. In this context, this study compiles information pertinent to the use of pesticides and highlights the prospects for the degradation of these persistent pollutants with emphasis on Brazilian data, one of the countries that had the greatest increase in the consumption of pesticides in the world. Full article

(This article belongs to the Special Issue Physicochemical Technology for Wastewater Treatment: Theory, Methods and Applications)

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