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Nanotechnology in Water and Wastewater Treatment || Application of Semiconductor Nanoparticles for Removal of Organic Pollutants or Dyes From Wastewater
摘要： Increasing demand and shortage of pure water sources due to the rapid development of industrialization, population growth and long-term droughts have become an issue world-wide. Industrial growth produces a great variety of organic products and frequently these substances are complex to degrade. Industrial wastewater contains various chemicals especially synthetic dyes. Example, Textile industry generate large amount of wastewater derived to different processes of color impregnation in textile fibers, which has a great amount of detergents, dyes, microfiber (cellulose, wool, and synthetic fibers), and inorganic salts. This residual water, with great load pollutants, generates the contaminations of natural waters bodies. Now a day, more than 50% of dyes used in the textile industry are monoazo, diazo, and triazo dyes, considering their chemical stability (recalcitrant) and negative influence on the ecological systems, the regulations of the removal color in the factory effluent is a current issue of discussion all over the world. The presence of even very low concentrations of dyes in effluent is highly visible and degradation products of these textile dyes are often carcinogenic. These effluent wastewaters have been recognized to have high color, high BOD and COD load, as well as high dissolve organic matter (DOM) concentration. Dyes are aromatic compounds which can absorb light in the visible wavelengths range (400–700 nm). The dye molecule is a combination of a chromophore which is a part of the molecule that can absorb light, that is, the color-absorbing coordination group and a conjugated system, and a structure with alternating double and single bonds. Chromophores are containing C=C and C=O (carbonyl), and azo group -N=N- or nitro group (-NO2). A complex mixture containing various organic materials, including carbohydrates or polysaccharides, amino acids or peptides or proteins, lipids, humic substances, and anthropogenic organic pollutants is known as Dissolved organic matter (DOM). It plays critical roles both in drinking water (DWTPs) and wastewater treatment plants (WWTPs) in determining the treatment performance and the distributed water quality and it is found in everywhere. The presence of DOM not only affects the current discharge standards, but also presents significant challenges in wastewater restoration.
关键词： Wastewater,ZnO,Dyes,Fe2O3,Photocatalysis,Semiconductor Nanoparticles,Organic Pollutants,TiO2
更新于2025-09-10 09:29:36
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Insight into photocatalytic activity, universality and mechanism of copper/chlorine surface dual-doped graphitic carbon nitride for degrading various organic pollutants in water
摘要： It is still a challenging work to realize the universality of photocatalytic materials for unselective removing various organic pollutants in water. Here a surface dual-doped Cu/Cl-g-C3N4 photocatalyst is firstly prepared, which exhibits much more superior photocatalytic performance for degrading multifarious persistent organic pollutants including tetracycline hydrochloride (TC-HCl), o-chlorophenol, bisphenol A and 2-mercaptobenzothiazole in water than pure g-C3N4. The high-efficiency and unselective photocatalytic degradation performance derives from the surface dual-doped effect of Cu/Cl elements on g-C3N4, which results in the extended visible light harvest range, elevated CB potential and improved the separation efficiency of charge carriers. The intermediate products, degradation pathway, degree of mineralization and reaction mechanism of representative TC-HCl pollutant over the surface dual-doped Cu/Cl-g-C3N4 photocatalyst are revealed in depth. This work makes an important development for treating the persistent organic pollutants in the water environments by exploiting new, low-cost and high-efficiency photocatalytic materials.
关键词： reaction mechanism,photocatalytic degradation,dual-doped Cu/Cl-g-C3N4,various organic pollutants,universality
更新于2025-09-10 09:29:36
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Design and Comparative Studies of Z-Scheme and Type II Based Heterostructures of NaNbO <sub/>3</sub> /CuInS <sub/>2</sub> /In <sub/>2</sub> S <sub/>3</sub> for Efficient Photoelectrochemical Applications
摘要： Here, we report the fabrication of a new Z-scheme based core/shell/shell heterostructure of NaNbO3/CuInS2/In2S3 (core/shell/shell) for photoelectrochemical (PEC) water splitting and also for degradation of organic pollutants. We have also performed a comparative study with a modified heterostructure of NaNbO3/In2S3/CuInS2 having Type II band alignment. The PEC measurements under visible light irradiation show increased photocatalytic performance for the NaNbO3/CuInS2/In2S3 heterostructures as revealed by a high current density of ～6.72 mA/cm2 at ?1.0 V versus Ag/AgCl and low photocurrent onset potential of ～?110 mV in comparison to the Type II system (～1.63 mA/cm2 and ?180 mV vs Ag/AgCl). Mott?Schottky plots confirmed the n?p?n type heterojunction formation in the NaNbO3/CuInS2/In2S3 heterostructure which reduces the charge carrier recombination (revealed by PL intensity and short lifetime). The Z-scheme based system also exhibits excellent degradation efficiency (～99.6%) of organic pollutants. This work shows that the Z-scheme charge separation mechanism in NaNbO3/CuInS2/In2S3 nanostructures is more efficient than the Type II based on NaNbO3/In2S3/CuInS2.
关键词： core/shell/shell heterostructure,photoelectrochemical water splitting,Type II band alignment,organic pollutants degradation,Z-scheme,NaNbO3/CuInS2/In2S3
更新于2025-09-09 09:28:46
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Application of BiOX Photocatalysts in Remediation of Persistent Organic Pollutants
摘要： Bismuth oxyhalides have recently gained attention for their promise as photocatalysts. Due to their layered structure, these materials present fascinating and highly desirable physicochemical properties including visible light photocatalytic capability and improved charge separation. While bismuth oxyhalides have been rigorously evaluated for the photocatalytic degradation of dyes and many synthesis strategies have been employed to enhance this property, relatively little work has been done to test them against pharmaceuticals and pesticides. These persistent organic pollutants are identified as emerging concerns by the EPA and effective strategies must be developed to combat them. Here, we review recent work directed at characterizing the nature of the interactions between bismuth oxyhalides and persistent organic pollutants using techniques including LC-MS/MS for the determination of photocatalytic degradation intermediates and radical scavenging to determine active species during photocatalytic degradation. The reported investigations indicate that the high activity of bismuth oxyhalides for the breakdown of persistent organic pollutants from water can be largely attributed to the strong oxidizing power of electron holes in the valence band. Unlike conventional catalysts like TiO2, these catalysts can also function in ambient solar conditions. This suggests a much wider potential use for these materials as green catalysts for industrial photocatalytic transformation, particularly in flow chemistry applications.
关键词： LC-MS/MS,persistent organic pollutants,BiOX,photocatalysis
更新于2025-09-09 09:28:46