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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.
Dairy By-Products as Source of High Added Value Compounds
Published in Francisco J. Barba, Elena Roselló-Soto, Mladen Brnčić, Jose M. Lorenzo, Green Extraction and Valorization of By-Products from Food Processing, 2019
Noemí Echegaray, Juan A. Centeno, Javier Carballo
The ion-exchange processes for purifying proteins are based on the ability of some resins to retain the proteins at a certain pH value and leave them free, thus being able to be eluted, at a different pH value. Ion-exchange resins are polymers that are able to exchange specific ions within the polymer with ions contained in a solution that passes through the resin. In short, it is about changing the surface charge attraction between the desired protein molecules and the ion-exchange resin to retain and isolate such proteins. Although it is possible to use membrane filtration for the fractionation of proteins with similar molecular weight (Zydney 1998), none of these techniques has been effectively implemented at a commercial scale. In relation to the classical membrane techniques, the ion-exchange processes allow selective retention and purification of the different whey proteins and separation of proteins that have little or no differences in molecular mass and size. This is an important aspect because purified individual milk proteins show better functionality than in their native protein mixtures (Imafidon et al. 1997).
Groundwater Remediation
Published in Kathleen Sellers, Fundamentals of Hazardous Waste Site Remediation, 2018
An ion-exchange resin may be characterized by its capacity, i.e., the number of functional groups per gram of resin (generally, capacity ranges from 1 to 10 milliequivalents per gram, or meq/g). It may also be classified by its acid or base strength.
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).
Optimization of fermentation conditions, purification and rheological properties of poly (γ-glutamic acid) produced by Bacillus subtilis 1006-3
Published in Preparative Biochemistry & Biotechnology, 2022
Ruoshi Zhang, Shihao Zhang, Guangyang Jiang, Longzhan Gan, Zhe Xu, Yongqiang Tian
The dialysate obtained was purified by anion exchange chromatography. The sample was subjected to a GE health care chromatography column with Q Sepharose Fast Flow exchanger. Before loading the sample, the column was equilibrated with buffer A (30 mM sodium acetate, pH 3.0). The column charged with dialysate was then again washed with buffer A. Elution was performed using a linear gradient with 0–100% buffer B (1 M NaCl, pH 7.0). It is reported that the characteristic absorption peak of PGA in the UV spectrum appears near 210 nm.[25] Therefore, the content of PGA was determined by monitoring the UV absorption at 215 nm in the purification process. Regeneration of ion exchange resins was carried out using 0.1 M NaOH.