Abstract Detail

Abstract

Developing efficient and cost-effective methods to remove azo dyes from industrial effluents is crucial for environmental health. Various methods have been explored, whereas adsorption is widely used for azo-dye removal due to its low cost, high efficiency, and absence of secondary pollution. It has been found that nano-ZnO is one of the most relevant metal oxide adsorbents; However, the effectiveness of the adsorption is sensitive to the specific surface area and the ZnO morphology. Therefor efforts have been made to synthesize nano-ZnO through a cost-effective route and that have a great surface area, opt morphology and high thermostability. In this study, a nano-zinc oxide silica (ZnO/SiO₂) hybrid aerogels and xerogels was synthesized via a sol-gel process through the simultaneous co-gelation of zinc and silica precursors in a non-aqueous medium. Characterization by SEM, XRD, BET, and TGA confirmed the formation of a mesoporous wurtzite ZnO structure well dispersed within the open 3D silica framework. The calcined ZnO/SiO₂ aerogels and xerogels were evaluated as adsorbents for removing the ionic dye Congo Red (CR) from aqueous solutions. The impact of adsorbent dosage, initial CR concentration, and contact time on adsorption efficiency was systematically investigated. Efforts have also been made to compare the adsorption efficiency of the as-prepared aerogels and xerogels with that of their calcined counterparts. Results indicated that adsorption followed the Freundlich isotherm at higher CR concentrations and the Langmuir isotherm at lower concentrations. Thermodynamic analysis revealed the process to be spontaneous, while adsorption kinetics conformed to a pseudo-second-order model. Additionally, the composite demonstrated excellent reusability, maintaining effectiveness over five adsorption cycles. These findings highlight the potential of nano-ZnO silica aerogels and xerogels, as competent adsorbents for water remediation. The high absorbance ability of the calcined materials is attributed to the meso-porosity of the zinc oxide crystals in comparison to zinc nitrate hydroxide crystals. 

Biography

Alaa Jasim Mohammed (BSc biology science) completed her M.Sc. in ecology from University Putra Malaysia, Faculty of Science, Biology Department, in 2021. Currently she is an assistant lecturer in the Environmental Health Department, Energy and Environmental College, Al-Karikh University for Science, Iraq; also, she is a Ph.D. student at University Putra Malaysia, Faculty of Science, Biology Department. She has published more than 15 research articles in journals and international conferences.