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Synthesis, Characterization and Photocatalytic Performance of W6+ impregnated g-C3N4 for the Removal of Chlorophenol Derivatives in Natural Sunlight Exposure
Chemosphere ( IF 8.1 ) Pub Date : 2020-11-28 , DOI: 10.1016/j.chemosphere.2020.129135
Duna A.K. Alenazi , Sivaraman Chandrasekaran , M. Tahir Soomro , M. Aslam , A. Hameed , Shahid Ali , Ekram Y. Danish , Iqbal M.I. Ismail

The surface of the g-C3N4 was altered by impregnating W6+ ions that transformed to homogeneously coated oxide layer by a calcination process. An enhanced absorption and the suppressed de-excitation in the emission spectra, with the increasing W6+ loading, exposed the supporting role of the coated layer in extending the spectral response as well as the prolonged life span of excitons. The same was further supported by electrochemical impedance spectroscopy (EIS). The XRD and XPS analysis revealed the coated layer as highly crystalline pure phase monoclinic WO3 with the majority of impregnated tungsten ions in 6+ oxidation state respectively, whereas the FESEM and HRTEM analysis substantiated the uniformity of the coated layer with the interlayer spacing of the 0.369 nm. Additionally, the probable formation of individual WO3 nanoparticles or clusters was ruled out. The as-synthesized impregnated photocatalysts, in comparison to pure g-C3N4, were subjected to natural sunlight exposure for the photocatalytic removal of chlorophenol derivatives (2-CP, 3-CP, 4-CP, 2,3-DCP, 2,4-DCP, 2,4,6-TCP and PCP) that revealed the 5wt% coating as the optimum level for significant removal. The progress of the photocatalytic process was monitored by periodic HPLC analysis whereas ion chromatography (IC) was used for the estimation of released ions. The mineralization capability of the as-synthesized W6+ coated catalysts was measured by the time scale TOC measurements. As the formation of intermediates was indicated in HPLC analysis, selected samples were subjected to GC-MS analysis for the identification of the nature of intermediates. The variable degree of removal of chlorophenol derivatives signified the role of the position and orientation of Cl group. The kinetics of the removal process was evaluated with the calculation of rate constants. The results extracted from the analytical tools and the associated band edge potentials were correlated to speculate the probable mechanism as well as the identification of major reactive oxygen species (ROS) involved in the removal process.



中文翻译:

W 6+浸渍的gC 3 N 4的合成,表征和光催化性能在自然阳光照射下去除氯酚衍生物。

通过浸渍通过煅烧过程转化为均匀涂覆的氧化物层的W 6+离子,可以改变gC 3 N 4的表面。随着W 6+负载的增加,发射光谱中吸收的增强和抑制的去激发,暴露了涂层在延长光谱响应以及延长激子寿命方面的支持作用。电化学阻抗谱(EIS)进一步支持了这一点。XRD和XPS分析表明涂层为高度结晶的纯相单斜晶WO 3。大部分浸渍的钨离子分别处于6+氧化态,而FESEM和HRTEM分析证实了涂层的均匀性,层间间距为0.369 nm。此外,排除了可能的单个WO 3纳米颗粒或簇的形成。与纯gC 3 N 4相比,合成后的浸渍光催化剂暴露在自然阳光下以光催化去除氯酚衍生物(2-CP,3-CP,4-CP,2,3-DCP,2,4-DCP,2,4,6-TCP和PCP), 5wt%的涂层是进行有效去除的最佳水平。通过定期的HPLC分析监测光催化过程的进展,而离子色谱法(IC)用于估算释放的离子。合成后的W 6+的矿化能力通过时间标度TOC测量来测量涂覆的催化剂。由于在HPLC分析中表明了中间体的形成,因此对选定的样品进行了GC-MS分析,以鉴定中间体的性质。氯酚衍生物的不同去除程度表明Cl基团的位置和取向的作用。通过计算速率常数来评估去除过程的动力学。从分析工具中提取的结果和相关的带边缘电势相关联,以推测可能的机理以及鉴定去除过程中涉及的主要活性氧(ROS)。

更新日期:2020-12-01
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