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Recovery Processes and Utilisation of Valuable Materials from Acid Mine Drainage
Published in Geoffrey S. Simate, Sehliselo Ndlovu, Acid Mine Drainage, 2021
The ion-exchange methodology has been found to be technologically simpler compared to other techniques and enables efficient removal of even traces of impurities from solutions. In fact, according to Hardwick and Hardwick (2016) when the concentration of impurities in a waste stream is very low, efficiency of removal by ion-exchange resins is relatively high because at that point it is film diffusion rather than particle diffusion that limits the kinetics. By its nature the undesirable ions in waste streams are replaced by the ones on ion-exchange resins, for example, that do not contribute to contamination of the environment (Dąbrowski et al., 2004). In other words, ion exchange enables replacing the undesirable ion by another one which is neutral within the environment. At the moment new types of ion exchangers with specific affinity to specific metal ions or groups of metals are available as an effort to enhance selectivity. To sum it up, the importance of ion exchange with respect to AMD treatment is characterised by two basic approaches according to Dinardo et al. (1991): (1) the selective removal of heavy metals from the AMD solution, and (2) water recovery to produce potable water, which involves the total removal of both anions and cations from AMD.
Amino Acids and Vitamin Production
Published in Debabrata Das, Soumya Pandit, Industrial Biotechnology, 2021
Two such methods that can be used for purification are chromatography and crystallization. Ion-exchange chromatography can be used for the purification and separation of amino acids such as glutamic acid from the fermentation broth based on their affinity to the ion exchanger. The adsorption of amino acids is based on the type of ion exchange resins. Ion-exchange resins are of two types: i) anion exchange resins and ii) cation exchange resins.
The Acid Mine Drainage Problem from Coal Mines
Published in Mritunjoy Sengupta, Environmental Impacts of Mining, 2021
Ion exchange involves the reversible interchange of ions between a solid medium and the aqueous solution. To be effective, the solid ion exchange medium must contain ions of its own, be insoluble in water, and have a porous structure for the free passage of the water molecules. Within the solution and the ion exchange medium, the number of charges (charge balance) must stay constant. Ion exchange materials show an affinity for multivalent ions; therefore, they tend to exchange their monovalent ions. This reaction can be reversed by increasing the concentration of monovalent ions. Thus, the ion exchange material can be regenerated once its capacity to exchange ions has been depleted.
Review of Vanadium Production Part I: Primary Resources
Published in Mineral Processing and Extractive Metallurgy Review, 2022
Feng Gao, Afolabi Uthmon Olayiwola, Biao Liu, Shaona Wang, Hao Du, Jianzhong Li, Xindong Wang, Donghui Chen, Yi Zhang
Ion exchange is a commonly used method in purifying vanadium-containing solutions. According to the types of ions exchanged between resins and liquid, ion exchange resins are classified into cationic resins, anionic resins, and chelating resins. Cation exchange resin is not suitable for adsorbing vanadium. The cation exchange resin uses acid as the eluent, under strong acid conditions, the vanadium ion will be eluted by the H+ in the solution while the resin absorbs vanadium ions, which will cause the loss of vanadium. (Zhang 2014b). Anion exchange resin is the most important adsorbent which means V4+ cannot be treated with anion resin because it does not form anions. Some chelating resins can be converted into amphoteric resins to adsorb V4+ and V5+, but they require a long conversion time. The typical anion exchange resin adsorption process of vanadium can be expressed by the following formula (Zhang 2014a).
Hydrometallurgical processes for heavy metals recovery from industrial sludges
Published in Critical Reviews in Environmental Science and Technology, 2022
Viraj Gunarathne, Anushka Upamali Rajapaksha, Meththika Vithanage, Daniel S. Alessi, Rangabhashiyam Selvasembian, Mu. Naushad, Siming You, Patryk Oleszczuk, Yong Sik Ok
Resins that contain chelating functional groups to form complexes with metal ions can be used for selective separation of targeted metal ions. Impregnated resins are developed by adsorbing solvent extraction reagents onto polymer beads (Tavlarides et al., 1987). The first hydrometallurgical application of ion exchange resins was for uranium recovery. However, their usage became widespread with the development of chelating and impregnated ion-exchange resins. The effectiveness of an ion-exchange resin is typically expressed as the equilibrium loading capacity or exchange capacity. Other characteristics of resins are functional groups, their selectivity ratio, cross-linking, porosity, and matrix geometry. Ion exchange can successfully be used for selective separation and recovery of metal ions by changing the properties of resins, specifically their functional groups. The ease of operation, no reagent losses, no disengagement of phases, economic feasibility for use in low concentrations of metal ions, and environmental safety can be considered as the advantages of using ion-exchange resins for metal recovery (Nikoloski & Ang, 2014; Tavlarides et al., 1987).
Biological reconditioning of sodium enriched zeolite by halophytes: case study of dairy farm effluent treatment
Published in International Journal of Phytoremediation, 2021
Ezra Orlofsky, Simon Chernoivanov, Asi Asiag, Ido Maor, Nimrod Levi, M. Iggy Litaor
There are abundant onsite pretreatment techniques available for agro-industrial waste concerned primarily with avoiding eutrophication and clogging of waterways (Litaor et al.2015). However, there are few options available for removal of effluent salt content that are applicable to small-scale systems. Ion exchange, and more generally adsorption, is an attractive technique since it is easy to implement in field conditions, potentially regenerable and depending on selectivity could result in high removal efficiency (Lata et al.2015). Naturally occurring minerals such as clinoptilolite zeolite have high cation exchange capacity (CEC) up to 200 cmolc/kg, due to extensive porosity coupled with electronegative charge within the crystal lattice (Bergaya et al.2013). Sodium removal from wastewater by zeolite is a promising technique yet challenges remain to improve zeolite’s cost and regenerability since no bio-regeneration process currently exists for sodium saturated zeolite (Wen et al.2018).