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Microencapsulation being an emerging technique has provided effective solution to the challenges faced by pharmaceutical, cosmetic, food agriculture and textile industries to deliver ingredients in their active forms to the target sites. Chitosan is a non-toxic, biodegradable and biocompatible amino polysaccharide which makes it useful for the encapsulation of various active ingredients with positive potential applications. Chitosan coating on food products, for example, gives them protection from possible antimicrobial attacks, antioxidants and extended shelf life. Likewise, its coating on pharmaceutics has valuable applications in preservation dn targeted drug delivery. In this review, we discuss the formation of chitosan, its properties, microencapsulation process, micro-capsular morphologies, selection of core and shell materials in addition to the process of chitosan encapsulation of various active ingredients and their applications in various fields of science and technology.

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Water-stable zeolitic imidazolate frameworks (ZIF) with zinc and cobalt cations were synthesized to explore the effect of metal ions on arsenic adsorption. At room temperature (25 2 ºC) and pH 7.8, maximum adsorption capacities of arsenic (As5+) on the surface of ZIF-8 and ZIF-67 were 87.03 and 86.70 mg g-1 respectively, with encouraging results up to 95% reusability of the adsorbents. The results of this study revealed that electrostatic attraction and ion exchange were the major mechanisms responsible for better efficiencies for adsorptive removal of arsenic. The evidence for the adsorption of arsenic contaminants was confirmed by FTIR analyses. The pseudo second order and Langmuir models were best suited to explain the adsorption of arsenic species on the surface of the as-synthesized metal-organic frameworks (MOFs). Based on the results, it was possible to conclude that the metal atoms in the synthesized MOFs had a minor impact on adsorption, since these MOFs presented identical results in the removal of arsenic species. This observation can be explained by the presence of a similar organic linker (2-methyl imidazole), which points to almost the same geometry and sponginess. However, there was a slight difference in the adamsite (organo-arsenic) removal achieved by the MOFs with different metal atoms.

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