Hydrogel Applicability for the Industrial Effluent Treatment: A Systematic Review and Bibliometric Analysis

In recent decades, hydrogels, as adsorption materials, have received important attention due to their characteristics and properties, such as mechanical strength, biocompatibility, biodegradability, swellability, and stimuli sensitivity. In the actual framework of sustainable development, it has been imperative to develop practical studies of hydrogels in the treatment of actual industrial effluents. Accordingly, the current work has, as its objective, to make evident hydrogels' applicability in the treatment of actual industrial effluents. For this purpose, a bibliometric analysis and systematic review based on the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) method were conducted. The relevant articles were selected from the Scopus and Web of Science databases. Some important findings were that: (1) China is the leading country when it comes to hydrogel application in actual industrial effluents, (2) the motor studies are focalized on the treatment of wastewater by hydrogels, (3) the fixed-bed columns are suitable unit equipment for the treatment of industrial effluents of using hydrogels, and (4) the hydrogels show excellent adsorption capacities of ion and dye contaminants present in industrial effluents. In summary, since the implementation of sustainable development in 2015, the progress of practical hydrogel applications in the treatment of industrial effluent has been receiving more attention, and the selected studies demonstrate the implementation viability of these materials.

Degradation of Hydrogels Based on Potassium and Sodium Polyacrylate by Ionic Interaction and Its Influence on Water

Hydrogels are a very useful type of polymeric material in several economic sectors, acquiring great importance due to their potential applications; however, this type of material, similarly to all polymers, is susceptible to degradation, which must be studied to improve its use. In this sense, the present work shows the degradation phenomena of commercial hydrogels based on potassium and sodium polyacrylate caused by the intrinsic content of different types of potable waters and aqueous solutions. In this way, a methodology for the analysis of this type of phenomenon is presented, facilitating the understanding of this type of degradation phenomenon. In this context, the hydrogels were characterized through swelling and FTIR to verify their performance and their structural changes. Likewise, the waters and wastewaters used for the swelling process were characterized by turbidity, pH, hardness, metals, total dissolved solids, electrical conductivity, DLS, Z-potential, and UV-vis to determine the changes generated in the types of waters caused by polymeric degradation and which are the most relevant variables in the degradation of the studied materials. The results obtained suggest a polymeric degradation reducing the swelling capacity and the useful life of the hydrogel; in addition, significant physicochemical changes such as the emergence of polymeric nanoparticles are observed in some types of analyzed waters.