Removal of dyes using polymers of intrinsic microporosity (PIMs): a recent approach

Removal of dyes from various industrial effluents is a great challenge, and cost-effective methods and materials with high dye removal efficacy are in high demand. Adsorption, nanofiltration and photocatalytic degradation are three major techniques that have been investigated for dye removal. PIMs are promising materials for use in these three methods based on their attributes, such as microporosity, solution processibility, high chemical stability and tunability through facile synthesis and easy postmodification. Although the number of reports on dye removal employing PIMs are limited, some of the materials have been shown to exhibit good dye separation properties, which are comparable to those of the state-of-the-art material activated carbon. In this highlight, we make an account of progress in PIMs and PIM-based composite materials in different dye removal processes over the last decade. Furthermore, we discuss the existing challenges of PIM-based materials and aim to analyze the key parameters for improving their dye removal properties.

Novel Porous Organic Polymer Catalyst with Phosphate and Sulfonic Acid Sites for Facile Esterification of Levulinic Acid

Biomass-derived value-added materials such as levulinic acid (LA) are favorable natural resources for producing ester-based biolubricants owing to their biodegradability, nontoxicity, and excellent metal-adhering properties. However, highly active catalysts must be developed to carry out efficient esterification of LA with aliphatic alcohols, especially long-chain aliphatic alcohols. In this study, we developed a novel porous covalent organic polymer catalyst (BPOP-SO3H) with dual acid sites, phosphate and sulfonic acid sites, for the esterification of LA. The prepared BPOP-SO3H catalyst was verified using various surface analysis techniques. BPOP-SO3H exhibited 98% LA conversion with n-butanol and 99% selectivity for butyl levulinate ester within 30 min, which is superior to that of most reported catalysts. BPOP-SO3H also showed high LA conversion and ester selectivity when other aliphatic alcohols were used. Moreover, BPOP-SO3H showed good recyclability for five consecutive cycles. We believe that incorporating a high density of acid sites into a porous polymer with a large surface area and hierarchical pores is a promising approach for developing heterogeneous acid catalysts for the production of alkyl levulinate esters from LA.

Salt-templated synthesis of 3D porous foam-like C3N4 towards high-performance photodegradation of tetracyclines

3D porous foam-like C₃N₄ is prepared by a salt-templated method, and it shows 64 times higher efficiency than bulk C₃N₄ in degrading tetracyclines.