Sorption Characteristics of Mixed Molecules of Glutaraldehyde from Water on Mesoporous Acid-Amine Modified Low-Cost Activated Carbon: Mechanism, Isotherm, and Kinetics

Mukosha Lloyd,Onyango S Maurice,Ochieng Aoyi,Taile Y Leswifi

doi:10.1155/2015/757256

Mukosha Lloyd, Onyango S Maurice + Show 2 more

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https://doi.org/10.1155/2015/757256

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Abstract

The environmental discharge of inefficiently treated waste solutions of the strong biocide glutaraldehyde (GA) from hospitals has potential toxic impact on aquatic organisms. The adsorption characteristics of mixed polarized monomeric and polymeric molecules of GA from water on mesoporous acid-amine modified low-cost activated carbon (AC) were investigated. It was found that the adsorption strongly depended on pH and surface chemistry. In acidic pH, the adsorption mechanism was elaborated to involve chemical sorption of mainly hydroxyl GA monomeric molecules on acidic surface groups, while in alkaline pH, the adsorption was elaborated to involve both chemical and physical sorption of GA polymeric forms having mixed functional groups (aldehyde, carboxyl, and hydroxyl) on acidic and amine surface groups. The optimum pH of adsorption was about 12 with significant contribution by cooperative adsorption, elucidated in terms of hydrogen bonding and aldol condensation. Freundlich and Dubinin-Radushkevich models were fitted to isotherm data. The adsorption kinetics was dependent on initial concentration and temperature and described by the Elovich model. The adsorption was endothermic, while the intraparticle diffusion model suggested significant contribution by film diffusion. The developed low-cost AC could be used to supplement the GA alkaline deactivation process for efficient removal of residual GA aquatic toxicity.

Highlights

Glutaraldehyde (GA), a five-carbon saturated dialdehyde of two terminal aldehyde groups, is a strong biocide widely used for controlling the growth of microorganisms in hospitals and industries such as paper and pulp with potential environmental release and toxic impact on aquatic organisms [1,2,3,4]
This study provided information on the adsorption characteristics of mixed molecules of glutaraldehyde (GA) on mesoporous acid-amine modified low-cost activated carbon
The information is important for assessing the potential application of activated carbon (AC) adsorption for efficient removal of GA from discharged hospital waste GA solution

Summary

Introduction

Glutaraldehyde (GA), a five-carbon saturated dialdehyde of two terminal aldehyde groups, is a strong biocide widely used for controlling the growth of microorganisms in hospitals and industries such as paper and pulp with potential environmental release and toxic impact on aquatic organisms [1,2,3,4]. Leung [4] found that GA could be stable to abiotic degradation with hydrolysis half-lives of 508, 102, and 46 days in acidic, neutral, and basic aqueous media, respectively This researcher reported a cyclic dimer of GA to be among major GA degradates in basic aqueous solution, in agreement with reported possible GA self-polymerization products in water [5]. Of serious concern to environmental pollution are large quantities of concentrated (up to 15000 mg/L) waste GA solutions from cold sterilization of heat sensitive reusable instruments in hospitals that are drained into municipal sewers without safety precautions [2, 3]

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