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Effect of Chemical Structure on Polymer Properties
Published in Anil Kumar, Rakesh K. Gupta, Fundamentals of Polymer Engineering, 2018
The preparation of chelating resins is still an area of active research, so it cannot be discussed in detail in the limited scope of this chapter. However, let us consider one example to illustrate the technique in which a hydroxamic acid group has been introduced into the polymer matrix. In the terpolymerization of styrene, divinyl benzene, and acrylic acid, the final polymer is a network resin with carboxylic acid groups on the chain (represented by [P]–COOH) [16]. This polymer is subjected to the following modifications:
Recovery Processes and Utilisation of Valuable Materials from Acid Mine Drainage
Published in Geoffrey S. Simate, Sehliselo Ndlovu, Acid Mine Drainage, 2021
According to Hubicki and Kołodyńska (2012) ion exchange is the exchange of ions between the substrate and surrounding medium. In addition, Patil et al. (2016) regard ion exchange as a physical treatment technique in which ions dissolved in a liquid or gas interchange with ions on a solid medium. Patil et al. (2016) state further that the ions on the solid medium are associated with functional groups that are attached to the solid medium, which is immersed in the liquid or gas. Typically, ions in dilute concentrations replace ions of like charge that are of lower valence state, but ions in high concentration replace all other ions of like charges (Patil et al., 2016). EPA (2014) define ion exchange as the reversible exchange of contaminant ions with more desirable ions of a similar charge adsorbed onto solid surfaces known as ion-exchange resins. Despite the myriad of definitions for the ion-exchange process, it is also noted that positively charged molecules bind to cation-exchange resins while negatively charged molecules bind to anion-exchange resins (Thermo Scientific, 2007). However, it must be noted that Dinardo et al. (1991) classify ion-exchange resins (i.e., insoluble matrixes or support structures that act as a medium for ion exchange) as anionic, cationic, and chelating. Anionic and cationic resins are used extensively in water purification processes. More specifically, anionic resins are significant in extracting amphoteric elements such as arsenic and metals that form sulphate complexes such as uranium (Dinardo et al., 1991). Cationic resins can have either sulphonic or carboxylic functionality and are essentially non-selective and thus can extract most polyvalent cations including magnesium, iron, calcium, and many others (Dinardo et al., 1991). Chelating resins are relatively new and have high selectivity for some specific metals.
Groundwater Remediation
Published in Kathleen Sellers, Fundamentals of Hazardous Waste Site Remediation, 2018
Chelating resins are similar to weak-acid resins; the functional group is iminodiacetate. These resins are particularly effective for mercury, copper, and lead. Due to their relatively slow kinetics, use of chelating resins requires a large resin volume and low flow rate (thus a long retention time). Chelating resins are relatively expensive compared to other resins.
Current developments in chemistry, coordination, structure and biological aspects of 1-(acyl/aroyl)-3- (substituted)thioureas: advances Continue …
Published in Journal of Sulfur Chemistry, 2019
Aamer Saeed, Muhammad Naeem Mustafa, Muhammad Zain-ul-Abideen, Ghulam Shabir, Mauricio F. Erben, Ulrich Flörke
Metals like Cu, Ni and Pd are used as catalyst in the industrial process due to which industrial waste contains an excessive amount of metals that increase the water pollution. Excessive metal ingestion might cause various diseases such as cancer and neurological disorders [84,85]. Conventional methods like ion exchange, electrolytic process and adsorption have been used to remove metals from aqueous solutions [86]. Adsorption is a most feasible method for this purpose because of high efficiency and low cost. Chelating resins are used as adsorbent material preferably because it grips metal ion through O, S, N and P atoms present in its functional groups. Huang et al. synthesized a reusable chelating resin 31 featuring thiourea and acyl groups for the adsorption of Cu ions [87,88]. The influence of pH, temperature and contact time on adsorption performance of resin was also determined. The most appropriate pH value for optimal adsorption of Cu by resin 31 was chosen to be 5.0 and its value was 0.917 mmol g−1 (Figure 12(a)). This may be ascribed to the fact that at lower pH values, the adsorption capacity of resin was markedly influenced by the protonation of amino groups while at pH = 6, Cu might present as Cu(OH)+ or Cu2(OH)22+ so the best pH value was 5.0 [89] (Figure 11).
Investigation of removal of Ag(I) from aqueous solution by a novel chelating resin containing acyl and thiourea groups
Published in Journal of Dispersion Science and Technology, 2019
Xiaoping Huang, Xiaoyu Cao, Weihong Wang, Hong Zhong, Zhan-Fang Cao
The chelating resins often used in adsorption process which have good adsorption abilities for metal ions due to its functional groups containing N, O and S coordination atoms. Much attention has been drawn to introduce some particular functional groups into resin bed, such as amino, thio, carbonyl and so on.[10–12] These functional groups can modify the chemical character of the resin surface, thereby improving its adsorption behaviors. According to the hard-soft base theory, silver ions can form a stable ligand structure with N and S atoms.[13] It can be inferred a chelating resin with more N and S atoms might have better adsorption abilities toward silver ions. Therefore, many works were focused on introducing thiourea group into chelating resins.[14–16] However, the present synthesis methods of thiourea resin usually have a long reaction time with strict reaction condition and the content of N and S atoms are typical rather low.
Removal of Th(IV) ion from wastewater using a proper Schiff base impregnated onto Amberlite XAD-4
Published in Particulate Science and Technology, 2020
The solid phase extraction technique is now routinely used in various research and application areas due to its characteristics and advantages over the classical solvent extraction or other pre-concentration techniques. Chelating resin sorption method is one of the most effective multi-element pre-concentration methods. The chelating resins include good selectivity, pre-concentration factor, binding energy, and mechanical stability, easy regeneration for multiple sorption-desorption cycles and good reproducibility in the sorption characteristics.