In the last few years, there have been significant developments in macroporous adsorption resins (MARs). These have significant commercial value and are now applied in many different fields mainly for adsorption especially in chromatographic applications.
Macroporous adsorption resins are porous cross-linked polymer beads (Wu et al., 2015).
MARs are more attractive than other commonly used adsorbents because of their favorable physical and chemical stability, large specific surface area, high adsorption capacity, simple regeneration, and long service life (Zhenbin et al., 2010).
Typical materials include Amberlite XAD7HP 20-60 mesh (Du Pont Resins). This is a macroporous cross-linked aliphatic polymer usually prepared as a spherical beads. These have particle sizes between 430 and 690 microns. The average pore size is 550 Angstroms with a water content of between 61 and 69 per cent. They can operate in the broadest pH range.
In chromatographic columns they will accept flow-rates of between 1 and 4 BV/hr (bedvolumes per hour). [This means in litres of solution per litre of resin per hour.]
These macroporous resins are used extensively in water treatment to remove a wide variety of chemicals such as pharmaceuticals or anaesthetics like procainamide and lidocaine (Marin et al., 2022).
Adsorption usually follows a Langmuir approach. The main stage of adsorption model is an intra-particle diffusion kinetic model.
Resin is usually regenerated with acetone which is preferred to 3% HCl or 10% NaOH.
References
Marin, N. M., & Stanculescu, I. (2022). Removal of procainamide and lidocaine on Amberlite XAD7HP resin and of As (V), Pb (II) and Cd (II) on the impregnated resin for water treatment. Materials Chemistry and Physics, 277, 125582 (Article).
Wu, X., Liu, Y., Liu, Y., & Di, D. (2015). Evaluation on the adsorption capability of chemically modified macroporous adsorption resin with ionic liquid. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 469, pp. 141-149 (Article).
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