Selective removal of the heavy metal ions from waters and industrial wastewaters by ion-exchange method.

Guidelines for Canadian Drinking Water Quality

https://www.u-cursos.cl/usuario/7c1c0bd54f14c0722cefc0fa25ea186d/mi_blog/r/Lectura_clase_ingenieria_ambiental.pdf

Arsenic contamination, consequences and remediation techniques: a review

Selectivity of ion exchange membranes: A review

We present a sugar-templated polydimethylsiloxane (PDMS) sponge for the selective absorption of oil from water. The process for fabricating the PDMS sponge does not require any intricate synthesis processes or equipment and it is not environmentally hazardous, thus promoting potential in environmental applications. The proposed PDMS sponge can be elastically deformed into any shape, and it can be compressed repeatedly in air or liquids without collapsing. Therefore, absorbed oils and organic solvents can be readily removed and reused by simply squeezing the PDMS sponge, enabling excellent recyclability. Furthermore, through appropriately combining various sugar particles, the absorption capacity of the PDMS sponge is favorably optimized.

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A polydimethylsiloxane (PDMS) sponge for the selective absorption of oil from water.

This article describes the physicochemical treatment processes typically used to remove the more common inorganic contaminants from water and wastewater. These are precipitation, coprecipitation, adsorption, ion exchange, membrane separations by reverse osmosis and electrodialysis, and combinations of these processes. The general criteria for process selection are discussed, and the processes and their typical applications are described.

Water treatment processes. III. Removing dissolved inorganic contaminants from water

Sufficient experimental data are presented here to verify the chromate ion‐exchange mechanism proposed earlier by Sengupta and Clifford (1986a). Most of the experiments were tailored to prove the validity of the mechanism, and also to highlight the unusual effects associated with it. One significant finding of this study is that, in spite of very gradual breakthrough during fixed‐bed column runs, chromate (VI) concentration at the exit of the column remains almost independent of the influent Cr(VI) concentration for a long time after the start of the run. Mass‐transfer limited kinetics are not responsible for this conspicuous column characteristic. Such an anomalous behavior is explained with the proposed ion‐exchange mechanism, which suggests dimerization of HCrO4- into Cr2O72- inside the commercial organic‐base anionexchange resins. A more theoretically sound attempt can now be developed for designing fixed bed chromate‐exchange processes at acidic pH in the presence of other competing ions.

More on Mechanism and Some Important Properties of Chromate Ion Exchange

Chromate ion-exchange process at alkaline pH

Monovalent/divalent selectivity and the charge separation concept

Field studies were conducted in Lemont, IL to evaluate specific adsorbents and reverse osmosis (RO) membranes for removing radium from ground water. A radium-selective complexer and barium-sulfate-loaded alumina appeared to have the best potential for low-cost adsorption of radium from raw water or ion-exchange brines, provided that the problem of the ultimate disposal of spent media can be solved. A new, low-pressure (70-psig) RO module achieved radium and total dissolved solids (TDS) rejections of 91 and 87%, respectively. Central treatment with standard or low-pressure RO modules would be effective for radium removal but would be expensive and unnecessary if TDS reduction is not also required. Point-of-use treatment using RO is effective for removing radium and may be cost-effective for very small communities.

https://www.jstor.org/stable/info/41292225

Suresh Subramonian

Papers

Water treatment processes. III. Removing dissolved inorganic contaminants from water

More on Mechanism and Some Important Properties of Chromate Ion Exchange

Chromate ion-exchange process at alkaline pH

Monovalent/divalent selectivity and the charge separation concept

Evaluating Various Adsorbents and Membranes for Removing Radium From Groundwater