Water compatible functionalized chitosan-based 4-HBA mimic imprinted polymer as a potential sorbent for salicylic acid

A review on versatile applications of biomaterial/polycationic chitosan: An insight into the structure-property relationship

Chitosan is a versatile and generous biopolymer obtained by alkaline deacetylation of naturally occurring chitin, the second most abundant biopolymer after cellulose. The excellent physicochemical properties of polycationic chitosan are attributed to the presence of varied functional groups such as amino, hydroxyl, and acetamido groups enabling researchers to tailor the structure and properties of chitosan by different methods such as crosslinking, grafting, copolymerization, composites, and molecular imprinting techniques. The prepared derivatives have diverse applications in the food industry, water treatment, cosmetics, pharmaceuticals, agriculture, textiles, and biomedical applications. In this review, numerous applications of chitosan and its derivatives in various fields have been discussed in detail with an insight into their structure-property relationship. This review article concludes and explains the chitosan's biocompatibility and efficiency that has been done so far with future usage and applications as well. Moreover, the possible mechanism of chitosan's activity towards several emerging fields such as energy storage, biodegradable packaging, photocatalysis, biorefinery, and environmental bioremediation are also discussed. Overall, this comprehensive review discusses the science and complete information behind chitosan's wonder function to improve our understanding which is much needful as well as will pave the way towards a sustainable future.

Hybrid chitosan/molecularly imprinted polymer hydrogel beads doped with iron for selective ibuprofen adsorption

Pharmaceutical pollutants are a group of emerging contaminants frequently found in water streams. In this study, the composite chitosan beads with incorporated molecularly imprinted polymers (monoliths or microparticles) and iron(III) hydroxide were fabricated to remove ibuprofen from aqueous solutions. The adsorptive properties were investigated in different conditions to evaluate the influence of solution pH, adsorbent dose, ibuprofen initial concentration, adsorption time, and temperature. The highest adsorption capacity (79.41 mg g-1), about twice as large as that for the chitosan beads without polymers (39.42 mg g-1), was obtained for the ones containing monoliths imprinted with ibuprofen. The theoretical maximum adsorption capacity of 103.93 mg g-1 was obtained based on the experiments in optimal pH 5. The adsorption of ibuprofen on the hybrid hydrogel beads followed the Freundlich isotherm and pseudo-second-order kinetic models. The process was found as endothermic and thermodynamically spontaneous. The adsorbent with a molecularly imprinted polymer retained its selectivity in the presence of other molecules. The imprinted cavities, chitosan functional groups, and iron hydroxide were presumably responsible for interactions with ibuprofen molecules. Additionally, the effectiveness of the adsorbent did not change significantly in real water samples and remained at a satisfactory level for up to four desorption-adsorption cycles.

Occurrence, fate, persistence and remediation of caffeine: a review

Pharmaceutical and personal care products (PPCPs) have gained attention in recent years due to their continuous discharge in natural waters. Their persistence in the environment has impacted flora, fauna and human being worldwide. One of the most common PPCPs is caffeine (1, 3, 7-trimethylxanthine) which acts as a stimulant to the central nervous system in humans and is found in nature in about 60 plant species, especially in coffee, tea and cacao plants. Here we discuss the evidence with respect to caffeine occurrence, its persistence and remediation in light of increasing knowledge and the impact of caffeine on the environment. Daily intake of caffeine around the world is found to increase due to the frequent introduction of new caffeinated beverages as well as increased consumption of coffee, tea and carbonated soft drinks, which has led to increase in its concentration in water bodies including agricultural soil. The caffeine concentration in different water system, studied by various authors is also described. Diverse effects of the use of caffeine on several organisms including humans are also briefly presented. Therefore, urgent attention for the removal of caffeine and its derivatives is the need of the hour. Various methods described in literature for caffeine degradation/removal is also presented. Another widely used technique in environmental remediation is molecular imprinting (MIP); however, only few MIPs have been demonstrated for caffeine which is also discussed. Regular monitoring can be useful to control toxic effects of caffeine. Graphical abstract.