Adsorption is the most widely used technique for advanced wastewater treatment. The preparation and application of natural renewable and environmentally friendly materials makes this process easier and more profitable. Chitosan is often used as an effective biomaterial in the adsorption world because of its numerous functional applications. Chitosan is one of the most suitable and functionally flexible adsorbents because it contains hydroxyl (-OH) and amine (-NH₂) groups. The adsorption capacity and selectivity of chitosan can be further improved by introducing additional functions into its basic structure. Owing to its unique surface properties and adsorption ability of chitosan, the development and application of chitosan nanomaterials has gained significant attention. Here, recent research on chitosan nanoparticles is critically reviewed by comparing various methods for their synthesis with particular emphasis on the role of experimental conditions, limitations, and applications in water and wastewater treatment. The recovery of pollutants using magnetic nanoparticles is an important treatment process that has contributed to additional development and sustainable growth. The application of such nanoparticles in the recovery metals, which demonstrates a “close loop technology” in the current scenarios, is also presented in this review.

Owing to environmental pollution and increasingly strict regulations, heavy metals have attracted the attention of many researchers in various disciplines. Alginate and chitosan derivatives have gained popularity as biosorbents for water treatment. An increase in the number of publications on modified biosorbents for the biosorption of toxic compounds reveals widespread interest in examining the requirements and positive contribution of each modification type. This paper reviews the advantages and disadvantages of using alginate and chitosan for adsorption. Well-known modifications based on chitosan and alginate, namely, grafting, functionalization, copolymerization and cross-linking, as well as applications in the field of adsorption processes, especially amino acid functionalization, are reviewed. The selection criteria for the best biosorbents and their effectiveness and proposed mechanism of adsorption are discussed critically. In the conclusion, the question of why these adsorbents need modification before use is addressed.

Designing a sustainable and economical distillation system is a big global challenge in the industrial chemical field. To address this issue, one of most promising solutions is the so-called dividing wall columns addressed in this work, which not only can cut energy cost but also use limited installation space. An improved shortcut design approach is developed in this work to provide accurate models for each section of dividing wall columns; meanwhile Underwood’s and Gilliland’s equations are employed to determine minimum reflux ratio and total number of stages in different column sections in terms of corresponding design specifications and operating conditions. This proposed approach has been applied to separations of mixtures of hydrocarbons and alcohol with different values on the ease of separation index. To test its effectiveness, the preliminary design parameters obtained through the improved proposed shortcut method are further validated by a rigorous simulation in Aspen HYSYS. Furthermore, the results indicate that this method could provide much more accuracy of average interconnecting stream composition of the prefractionator and main column than those of other methods. In practice, this method has been applied to a case of liquefied petroleum gas (LPG) separation with three targeted products in an industrial liquefied petroleum gas plant. The applications and efficiency of the shortcut method in this study lay a theoretical foundation for designing the separation of ideal mixtures involving dividing wall columns.