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Facile Preparation, Characterization and Application of Chitosan-Coated Natural Diatomaceous Earth for the Removal of Arsenic V from Drinking Water
Citation:
Koumai, O., G. Sorial, AND E. Sahle-Demessie. Facile Preparation, Characterization and Application of Chitosan-Coated Natural Diatomaceous Earth for the Removal of Arsenic V from Drinking Water. American Chemical Society meeting, Chicago, IL, August 20 - 25, 2022.
Impact/Purpose:
Water contamination with organic and inorganic polutant has been a challenge to many comminities. Heavy metal pollution is a serious environmental problem in many parts of the world, especially in developing countries. Among different treatment technologies, biosorption seems a promising alternative method. Chitosan-based biosorbents are potential and effective for heavy metal removal from aqueous solution. The preparation and characterization of the natural polymer chitosan, modified chitosan and chitosan composites, and their application for the removal or recovery of toxic heavy metals, precious metals and radionuclides from wastewater were introduced. Chitosan structures and their properties, chitosan modifications (physical conditioning and chemical modification), blends and composites as well as the metal sorption by chitosan-based biosorbents were briefly presented. The metal sorption capacities, influence of intrinsic nature of metal ions, pH and contact time, desorbing agents, isotherm and kinetics models, biosorption mechanisms were discussed. Diatomaceous earth coated chitosan can have a wider application for removing emerging contaminatns of water.
Description:
It is becoming a necessity to provide resource constrained small public water utilities with diverse, cost-effective, low-technology and sustainable alternatives for removing arsenic and other contaminant clusters in order to provide safe drinking water.Chitosan-coated Diatomaceous Earth (CCDE), was prepared by coating natural diatomaceous earth with chitosan. The chitosan to DE percent mass ratios were varied between 0 and 50%, and the effect of chitosan content on the effectiveness of the resulting hybrid biosorbent was evaluated. The CCDE was characterized by assessing its microstructure, surface functional groups, specific surface area, morphology, elemental composition, surface of zero charge, acidity/ alkalinity and thermal stability.Batch bottle point isotherm equilibrium experiments were conducted to study the uptake of As(V) by CCDE from a solution of disodium hydrogen arsenate heptahydrate (Na2HAsO4, 7H2O) in MilliQ water adjusted to a desired pH. The effects of the synthetic water’s initial pH were also evaluated. As(V) in samples was measured as total As by inductively-coupled plasma atomic emission spectroscopy.The experimental results indicated that the amount of As(V) adsorbed increased with chitosan content of CCDE while the treated water filterability reduces. The CCDE with 30% chitosan content (CCDE30) is optimal for removing As(V) from drinking water. As(V) uptake decreased with increasing pH, and the optimal range between 5 and 6. The Isotherm data fit both Langmuir and Freundlich models.The isotherm data indicated that CCDE30 could be a viable alternative adsorbent for As(V) for small system applications because of its effectiveness, ease of preparation, affordability, and technology sustainability. In a comparative study, CCDE30 is as effective as Bayer’s Bayoxide E33® for As removal at observed occurrence levels through major parts of the U.S.A. CCDE30 showed 3 to 4 times lesser capacity than E33®, but equivalent if expressed in mg/g of Chitosan. The CCDE30 presents the added benefit for multiple regenerations.