Zeolites as Adsorbents and Photocatalysts for Removal of Dyes from the Aqueous Environment

Abstract

This study investigated the potential of zeolites (NH4BETA, NH4ZSM-5, and NaY) to remove two frequently used dyes, methylene blue (MB) and rhodamine B (RB), from an aqueous environment. The removal of dyes with zeolites was performed via two mechanisms: adsorption and photocatalysis. Removal of dyes through adsorption was achieved by studying the Freundlich adsorption isotherms, while photocatalytic removal of dyes was performed under UV irradiation. In both cases, the removal experiments were conducted for 180 min at two temperatures (283 K and 293 K), and dye concentrations were determined spectrophotometrically. Additionally, after photodegradation, mineralization was analyzed as chemical oxygen demand. A computational analysis of the structures of MB and RB was performed to gain a deeper understanding of the obtained results. The computational analysis encompassed density functional theory (DFT) calculations and analysis of two quantum-molecular descriptors addressing the local reactivity of molecules. Experimental results have indicated that the considered zeolites effectively remove both dyes through both mechanisms, especially NH4BETA and NH4ZSM-5, due to the presence of active acidic centers on the outer and inner surfaces of the zeolite. The lowest efficiency of dye removal was achieved in the presence of NaY zeolite, which has a lower SiO2/Al2O3 ratio. A more efficient reduction was completed for RB dye, which agrees with the computationally obtained information about reactivity.

Biochar-Based Photothermal Hydrogel for Efficient Solar Water Purification

“…Organic pollutants are another primary source of water contamination that will accumulate in the environment and the human body, leading to a variety of adverse effects [ 62 , 63 ]. Therefore, we prepared an organic dye (Rhodamine B, methyl orange, and methylene blue) solution to investigate the decontamination performance of the ACPH-10 membrane.…”

Insight into Adsorption Kinetics of Cs+, Rb+, Co2+, and Sr2+ on a Zeolites-Based Composite: Comprehensive Diffusional Explanation and Modelling

“…Furthermore, aluminosilicate geopolymer materials provide relatively good mechanical properties and thermal stability [33,34], but they possess a weak surface area and a low number of active surface sites in comparison with crystalline aluminosilicates such as zeolites. Some of the zeolite types have great importance in heavy metal removal [35], dye removal [36], or even in agricultural area like soil amending [37]. In pure zeolites like NaA and NaP, their frameworks contain the highest atomic Al/Si ratio and thereby possess the highest negative-charge density.…”

Hydrothermal carbonization of vegetable-tanned leather shavings (HTC-VTS) for environmental remediation: optimization of process conditions

“…Nowadays, the research of outstanding porous materials for the removal of various pollutants from liquid or gaseous effluents using adsorption technique is a matter of global concern. Some primary materials such as biomass wastes [1][2][3][4], organic polymers [5][6][7], clays [8], silica gel [9], activated alumina [10], zeolites [11][12][13], industrial and municipal wastes [14] have been studied and used as precursors for the porous materials preparation. Their high adsorption capacity, high efficiency for adsorbing substances at low concentrations, high selectivity, easy regeneration and low cost are the required criteria for the good adsorbents production.…”