In this study, composite hydrogels with interpenetrated polymer networks (IPNs), based on bacterial cellulose (BC) and poly(acrylic acid-co-N,N′-methylene-bis-acrylamide) (PAA), were synthesized by radical polymerization and characterized herein for the first time. Liquid fertilizer (LF) formulations, containing potassium, phosphorus, ammonium oxides and micronutrients, were encapsulated directly into the IPNs of the composite hydrogels during synthesis. Thermal analyses and scanning electron microscopy of control and composite xerogels highlighted the formation of IPNs between BC and PAA. Swelling determinations confirmed the influence of the crosslinker and of the liquid fertilizer concentration upon the density of the IPNs. Further rheology studies and release profiles indicated how the presence of BC and the increase of the crosslinking density of IPNs improved the mechanical strength and the release profile of LF for the innovative composite BC-PAA hydrogels. Results regarding the fertilizer release indicated that the presence of the BC led to a more controlled liberation of the fertilizer proving that this new formulation is potentially viable for application in agricultural practices.

Hydrogel-based wastewater treatment technologies show certain outstanding features, which include exceptional efficiency, sustainability, reusability, and the precise targeting of specific contaminants. Moreover, it becomes possible to minimize the environmental impact when using these materials. Their flexibility, low energy consumption, and adaptability to meet specific requirements for different purposes offer significant advantages over traditional methods like activated carbon filtration, membrane filtration, and chemical treatments. Recent advancements in hydrogel technology, including new production methods and hybrid materials, enhance their ability to efficiently adsorb contaminants without altering their biocompatibility and biodegradability. Therefore, innovative materials that are ideal for sustainable water purification were developed. However, these materials also suffer from several limitations, mostly regarding the scalability, long-term stability in real-world systems, and the need for precise functionalization. Therefore, overcoming these issues remains a challenge. Additionally, improving the efficiency and cost-effectiveness of regeneration methods is essential for their practical use. Finally, assessing the environmental impact of hydrogel production, use, and disposal is crucial to ensure these technologies are beneficial in the long run. This review summarizes recent advancements in developing polymer-based hydrogels for wastewater treatment by adsorption processes to help us understand the progress made during recent years. In particular, the studies presented within this work are compared from the point of view of the synthesis method, raw materials used such as synthetic/natural or hybrid networks, and the targeted class of pollutants—dyes or heavy metal ions. In several sections of this paper, discussions regarding the most important properties of the newly emerged adsorbents, e.g., kinetics, the adsorption capacity, and reusability, are also discussed.

Pesticides are widely used in agriculture to increase and protect crop production. A substantial percentage of the active substances applied is retained in the soil or flows into water courses, constituting a very relevant environmental problem. There are several methods for the removal of pesticides from soils and water; however, their efficiency is still a challenge. An alternative to current methods relies on the use of effective adsorbents in removing pesticides which are, simultaneously, capable of releasing pesticides into the soil when needed. This reduces costs related to their application and waste treatments and, thus, overall environmental costs. In this paper, we describe the synthesis and preparation of activated carbon-containing poly(β-cyclodextrin) composites. The composites were characterized by different techniques and their ability to absorb pesticides was assessed by using two active substances: cymoxanil and imidacloprid. Composites with 5 and 10 wt% of activated carbon showed very good stability, high removal efficiencies (>75%) and pesticide sorption capacity up to ca. 50 mg g⁻¹. The effect of additives (NaCl and urea) was also evaluated. The composites were able to release around 30% of the initial sorbed amount of pesticide without losing the capacity to keep the maximum removal efficiency in sorption/desorption cycles.

Molecular imprinting (MI) is the most available and known method to produce artificial recognition sites, similar to antibodies, inside or at the surface of a polymeric material. For this reason, scholars all over the world have found MI appealing, thus developing, in this past period, various types of molecularly imprinted polymers (MIPs) that can be applied to a wide range of applications, including catalysis, separation sciences and monitoring/diagnostic devices for chemicals, biochemicals and pharmaceuticals. For instance, the advantages brought by the use of MIPs in the sensing and analytics field refer to higher selectivity, sensitivity and low detection limits, but also to higher chemical and thermal stability as well as reusability. In light of recent literature findings, this review presents both modern and dedicated methods applied to produce MIP layers that can be integrated with existent detection systems. In this respect, the following MI methods to produce sensing layers are presented and discussed: surface polymerization, electropolymerization, sol–gel derived techniques, phase inversionand deposition of electroactive pastes/inks that include MIP particles.

Chitosan is used in medicine, pharmaceuticals, cosmetics, agriculture, water treatment, and food due to its superior biocompatibility and biodegradability. Nevertheless, the complex and relatively expensive extraction costs hamper its exploitation and, implicitly, the recycling of marine waste, the most abundant source of chitosan. In the spirit of developing environmental-friendly and cost-effective procedures, the present study describes one method worth consideration to deliver calcium-carbonate-enriched chitosan from shrimp shell waste, which proposes to maintain the native minerals in the structure of chitin in order to improve the thermal stability and processability of chitosan. Therefore, a synthesis protocol was developed starting from an optimized deacetylation procedure using commercial chitin. The ultimate chitosan product from shrimp shells, containing native calcium carbonate, was further compared to commercial chitosan and chitosan synthesized from commercial chitin. Finally, the collected data during the study pointed out that the prospected method succeeded in delivering calcium-carbonate-enriched chitosan with high deacetylation degree (approximately 75%), low molecular weight (Mn ≈ 10.000 g/ mol), a crystallinity above 59 calculated in the (020) plane, high thermal stability (maximum decomposition temperature over 300 °C), and constant viscosity on a wide range of share rates (quasi-Newtonian behavior), becoming a viable candidate for future chitosan-based materials that can expand the application horizon.