Papers by Keyword: Organic Pollutant

Abstract: Photocatalytic technology is one of the promising technologies for wastewater treatment. Herein, zinc oxide/multi-walled carbon nanotubes (ZnO/CNTs) photocatalyst was successfully prepared by hydrothermal method with combining in-situ synthesis technology. The micro-morphology, crystalline structure, surface chemical elements, and optical properties were characterized by SEM, TEM, XRD, FTIR, UV-Vis, and DRS technologies. The ZnO/CNTs photo-catalyst exhibited enhancement photo activity for degradation of organic pollutants under simulated light irradiation. Specifically, the photo-catalytic activity of the ZnO/CNTs catalysts improved with the rise of CNTs content in the composites. Investigation on the photo-degradation mechanism verified that the presence of CNTs in the catalyst not only optimized the band structure of ZnO semiconductor but also contributed to the transfer of photo-generated electrons and reducing the recombination of electron-hole pairs due to its excellent conductivity. Moreover, the active radical groups such as superoxide radical (O-2), hole (h⁺), and hydroxyl radical (·OH) played the dominated role for the pollutants degradation under the simulated sunlight irradiation. In addition, ZCT20 catalysts and light irradiation had synergistic effects on antibacterial activity, whose antibacterial rates against E. coli and S. aureus were up to 99.96% and 99.94%, respectively. Investigation on antibacterial mechanisms revealed that the existence of ROS and the continuous release of Zn²⁺ played an important role for improving the antibacterial activity of the ZCT20 catalyst under the simulated sunlight irradiation.

Abstract: A novel and convenient approach for the fabrication of vinyl functionalized multiwalled carbon nanotube (MWCNT) as a sorbent for organic pollutant is described in this article. In this method, the purified MWCNT is functionalized via a non-covalent strategy using 9-vinyl anthracene, fluorescent active species. The synthesised nanotube was characterised using various techniques such as Fourier transform infrared spectroscopy (FT-IR), UV-Vis. spectroscopic analysis, scanning electron microscopy (SEM), X-ray diffraction technique (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM) and Raman spectroscopy. Effects of concentration, pH and time for the functionalization of MWCNTs were investigated through photoluminescence (PL) studies. The resulting vinyl functionalized MWCNT will act as a promising adsorbent for organic pollutants like p-chlorobenzoic acid.

Abstract: The paper reports the results of QSPR analysis of several problems of coloration of textiles, including light fastness of azo benzothiazole and indigoid dyes, ionization of hydroxyl groups in mordant dyes forming complexes with polyvalent metal ions and rate reactions of organic substances with OH radical during catalytic oxidizing of pollutants. Multiple linear regression models are built with the use of fragment descriptors. The role of different molecular fragments is discussed emphasizing the mechanism of the phenomena and ways of application in coloration technology.

Abstract: Heavy industrialization, specifically in the developing countries, has generated several unwanted environmental pollution. A variety of toxic organic compounds is produced in chemical and petroleum industries, which have resulted in collectively hazardous effects on the environment that needs immediate attention for remediation. Degradation of these pollutants has been tried through the various mechanism, out of which photocatalytic degradation seems to be one of the most promising approaches to reduce environmental pollution specifically in waste water treatment. Photocatalytic degradation has potential for the effective decomposition of organic pollutants due to efficiency to convert light energy into chemical energy. Additionally, the photocatalytic oxidation process is an advanced technique as it offers high degradation and effective mineralization at moderate temperature and specific radiation wavelength. Among various known photocatalysts, TiO₂ is regarded as the one of the potential photocatalysts because of its hydrophilic property, high reactivity, reduced toxicity, chemical stability and lower costs. Therefore, the present chapter focuses on the role of TiO₂ as the photocatalyst for the degradation of organic pollutants. The general mechanism of degradation of organic pollutants along with properties of TiO₂ as the photocatalyst, existing mechanism of degradation via TiO₂ was explained. The possible approaches to enhance degradation via TiO₂ nanoparticle along with existing bottlenecks have been also discussed.

Abstract: Polychlorinated naphthalene (PCNs) is similar structure and toxicity of dioxin (PCDD/Fs), it can be detected in the global environmental and biological samples. This paper introduces the main source of PCNs in the environment and environmental fate, sludge PCNs pollution level in 1.48~28.21 ng/g (dry weight), PCN-TEQs content is in 0.11~2.45 pg/g (dry weight), far below the content of other areas in foreign countries. The results showed that the sources of wastewater, sewage treatment plant is an important factor affecting the level of polychlorinated naphthalene pollution. Discussion on the distribution characteristics of sludge in polychlorinated naphthalene congeners, found that the distribution of PCNs congeners in all of the samples is largely the same, it is mainly two chloride and three chloro naphthalene, it showed that the pollution source has a certain resemblance. Research shows that, polychlorinated naphthalenes city sludge mainly comes from industrial pollution sources; in addition, an important source of waste incineration, burning heat treatment process is caused by polychlorinated naphthalene pollution.

Abstract: In this study, the Fe₃O₄ magnetic nanoparticles (MNPs) were synthesized as heterogeneous catalysts to effectively degrade methyl orange. The coulping method of microwave irradiation and Fenton-like reaction was used for degradation of methyl orange waste water. The effects of Fe₃O₄ dosage, initial H₂O₂ concentration, catalyst cycles, reaction temperature and so on were assessed systematically. The experimental results showed that the microwave-assisted Fenton-like process using H₂O₂/Fe₃O₄ was the most effective treatment process compared with other traditional methods. According to degradation of methyl orange, it has been found that the oxidation by Fenton-likes reagent is dependent on Fe₃O₄ dosage, H₂O₂ dosage, reaction temperature. The results indicate that under the optimal conditions, the removal rate of methyl orange could reach nearly 100%. Moreover, six cyclic tests for methyl orange degradation showed that the magnetic catalyst was very stable, recoverable, highly active, and easy to separate using an external magnet. Hence, the coulping method of microwave irradiation and Fenton-like reaction with magnetic nanomaterials of Fe₃O₄ as the catalyst has potential use in organic pollutant removal.

Abstract: In recent years, more and more attention has been paid to environmental application of biochar because its great potential in mitigating global warming and remedying contaminated soils. In this review, long-term carbon sequestration and environmental immobilization of biochar were discussed. It indicated that the synthesis of biomass into biochar not only helps in the CO₂ fixation, suppress the emission of green gases, but also represent the suitable candidate for contaminated soil remediation due to its cheap cost and large mount of raw materials.

Abstract: BiVO₄ composited with TiO₂ (BVO-T) nanoparticles was sensitized by tetrakis(4-carboxy phenyl)porphyrin (TCPP) dye (BVO-T/P) to efficiently utilize visible light in the photodegradation reaction. To investigate the photoactivity of this catalyst, its photocatalytic efficiency was compared to the pure TiO₂, pure BiVO₄, and BiVO₄ composited with TiO₂ in the destruction of methyl orange in the visible light. Furthermore, the kinetic of the MO degradation as well as the stability of BVO-T/P photocatalyst was investigated.

Abstract: For the first time antimony vanadium oxide-TiO₂ (SbV-T) nanocomposite was synthesized via sol-gel method to improve the photocatalytic efficiency of TiO₂. The samples were characterized by FT-IR, XRD, SEM, EDX, and DRS. To investigate the photocatalytic activity of the samples, the photodegradation of methyl orange was carried out under visible light irradiation with pure TiO₂, SbVO₄, and SbVO₄-TiO₂ nanocomposite. The SbV-T photocatalyst exhibited higher visible light driven photocatalytic efficiency to degrade MO dye. Furthermore the effect of SbVO4 and cationic vacancies in the photocatalytic activity of the SbV-T sample are described.

Abstract: Water pollution is increasing at an ever increasing pace and the whole world is in the cancerous grip of this pollution. Various industries are discharging their untreated effluents into the nearby water resources; thus, adding to the existing water pollution to a great extent. Hence, there is a pressing demand to develop an alternate technology for wastewater treatment and in this context; photocatalysis has emerged as an Advanced Oxidation Process with green chemical approach for such a treatment. This chapter deals with photocatalytic degradation of different kinds of organic pollutants; mainly surfactants, pesticides, dyes, phenols, chloro compounds, nitrogen containing compounds etc. Mechanisms of their degradation have also been discussed with hydroxyl and allied radicals as the main active oxidizing species.