Removal of Congo Red dye from aqueous solution using Amberlite IRA-400 in batch and fixed bed reactors (original) (raw)
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Influence of Mg doping on ZnO NPs for enhanced adsorption activity of Congo Red dye
Applied Surface Science, 2019
A facile microwave-assisted combustion method was adopted to synthesize pure ZnO and Mgdoped ZnO nanoparticles (NPs), and characterization of the NPs and the sorption behavior with Congo Red (CR) Azo dye was extensively investigated. The structure, morphology and chemical assay of the synthesized NPs were studied with respect to the pure and 2% Mg-doped ZnO samples. The X-ray diffraction pattern confirmed the presence of crystalline, cubic phase with fluorite structure of both the NPs. The morphological differences between the pure and Mgdoped ZnO NPs were evaluated by FE-SEM, which revealed that the NPs were in the nanoscale regime with irregular crystalline morphology having a grain size of ~18-45 nm. N 2 adsorption/desorption isotherms measured at-196°C suggested a Type II structure with limited hysteresis loops, likely due to some interparticle porosity. The BET SSA ZnO NPs obtained was found to be 32 m 2 g-1 , indicating about its potential in sorption processes. Batch adsorption study for the removal of CR carried out showed that, the Mg-doped NPs showed higher loading efficiency (125 mg.g-1) than the ZnO NPs (25 mg.g-1) counterpart. This was corroborated by the isotherm results in which the CR dye sorption followed a Freundlich Isotherm model for both undoped ZnO and Mg-doped ZnO NPs. The sorption of CR dye followed a pseudo-second order kinetics. The negative ΔG o (-31.91 and-109.41 KJmol-1) showed the feasibility of the adsorption process. The ΔH o was determined as +13.74 KJ/mol and 50.7 KJ/mol for ZnO NPs and Mg doped-ZnO NPs respectively, confirming the endothermic nature of the adsorption for removing CR dye from the solution.
Zeitschrift für Physikalische Chemie, 2020
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Zinc peroxide nanomaterial as an adsorbent for removal of Congo red dye from waste water
Ecotoxicology and Environmental Safety, 2017
In the past decade, various natural byproducts, advanced metal oxide composites and photocatalysts have been reported for removal of dyes from water. Although these materials are useful for select applications, they have some limitations such as use at fixed temperature, ultra violet (UV) light and the need for sophisticated experimental set up. These materials can remove dyes up to a certain extent but require long time. To overcome these limitations, a promising adsorbent zinc peroxide (ZnO 2) nanomaterial has been developed for the removal of Congo red (CR) dye from contaminated water. ZnO 2 is highly efficient even in the absence of sunlight to remove CR from contaminated water upto the permissible limits set by the World Health Organization (WHO) and the United States-Environmental Protection Agency (US-EPA). The adsorbent has a specific property to adjust the pH of the test solution within 6.5-7.5 range irrespective of acidic or basic nature of water. The adsorption capacity of the material for CR dye was 208 mg g À 1 within 10 min at 2-10 pH range. The proposed material could be useful for the industries involved in water purification. The removal of CR has been confirmed by spectroscopic and microscopic techniques. The adsorption data followed a second order kinetics and Freundlich isotherm.
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Polish Journal of Environmental Studies
Dyes are synthetic organic compounds that are increasingly being produced and used extensively in the paper, leather, textile, plastic, cosmetic, and other industries. Approximately 70,000 ton of dyestuffs are discharged into waste streams each year by the textile industry [1]. The presence of even very low concentrations of dyes in water reduces light penetration through the water surface, precluding photosynthesis of the aqueous flora. Additionally, many dyes or their metabolites have toxic as well as carcinogenic, mutagenic, and teratogenic effects on aquatic life and humans. Hence, the removal of dyes from aquatic wastewater has became environmentally important. Various methods including photocatalysis [2], chemical oxidation [3], coagulation [4], electrochemical [5], and adsorption [6] techniques have been applied for the removal of dyes from aqueous solutions. Among these methods, adsorption has been found to be superior
Materials
Zinc sulfide (ZnS) nanoparticles were fabricated using the chemical precipitation method. The X-ray diffraction (XRD), Raman spectroscopy, and scanning electron microscopy (SEM) techniques were used to investigate the structural parameters of the formed ZnS. The hexagonal crystal structure of the Zn and ZnS phases was formed. The average crystallite size of the ZnS phase is 10.3 nm, which is much smaller than that of the Zn phase (54.5 nm). Several frequencies and phonon modes were detected in the Raman scattering spectrum belonging to the ZnS nanoparticles. The synthesized ZnS nanoparticles were used as catalysts to eliminate the Congo red (CR) dye, with different concentrations, from synthetic wastewater. The impact of the CR dye concentration and shaking period on the adsorption of CR was thoroughly investigated, and various adsorption kinetic models were tested. After 3 h of shaking, the adsorption efficiency reached 26.01% for 40 mg/L CR dye and 27.84% for 20 mg/L CR dye. The a...