Hotspots, Frontiers, and Emerging Trends of Superabsorbent Polymer Research: A Comprehensive Review

Rational Design of a Multifunctional Hydrogel Trap for Water and Fertilizer Capture: A Review

Water scarcity and land infertility pose significant challenges to agricultural development, particularly in arid and semiarid regions. Improving soil-water-retention capacity and fertilizer utilization efficiency through the application of soil additives has become a pivotal approach in agricultural practices. Hydrogels exhibit exceptional water absorption and fertilizer retention capabilities, making them extensively utilized in the fields of agriculture, forestry, and desert control. Currently, most reviews primarily focus on the raw materials, classification, synthesis methods, and application prospects of hydrogels, with limited attention given to strategies for enhancing water-retention performance, mechanisms underlying fertilizer absorption, and environmental risks. This review covers the commonly used cross-linking methods in hydrogel synthesis and the structure-activity relationship between hydrogels and water as well as fertilizer. Additionally, a thorough analysis of the ecological benefits and risks associated with hydrogels is presented. Finally, future prospects and challenges are delineated from the perspectives of material design and engineering applications.

An approach of pectin from Citrus aurantium L. for superabsorbent resin with superior quality for hygiene products: Salt resistance, antibacterial, nonirritant and biodegradability

In this paper, a kind of superabsorbent resin (SAR) with superior quality for hygiene products was developed using Fructus Aurantii Immaturus pectin (FAIP) from Citrus aurantium L.. FAIP-g-AM/AMPS SAR was established by free radical graft co-polymerization with FAIP as skeleton structure, N, N'-Methylene-bis (acrylamide) (MBA) as the cross-linker. Meanwhile, the functional monomers of acrylamide (AM) and 2-acrylamido-2-methylpropane sulfonic acid (AMPS) were introduced. The structure and morphology of FAIP-g-AM/AMPS were characterized by FTIR, ¹³C NMR, XRD, SEM and TG-DSC analysis. The results confirmed that the AFIP-g-AM/AMPS SAR was successfully prepared, which exhibited a three-dimensional (3D) network structure and an excellent thermal stability. The absorption and retention capacity of FAIP-g-AM/AMPS was comparable to or even better than commercial diapers and sanitary napkins. Significantly, FAIP-g-AM/AMPS itself exhibited excellent antibacterial and safety. FAIP-g-AM/AMPS has an inhibition ratio of 97.1 % for Escherichia coli (E. coli) and 98.5 % for Staphylococcus aureus (S. aureus), and was non-irritating and non-allergic to the skin. In addition, FAIP-g-AM/AMPS presented amazing biodegradability and a weight loss reached 37.1 % after 30 days by soil burial test. The research provides a safe and high-performance SAR, which expected to be used in hygiene products such as baby diapers, adult incontinence pads and sanitary napkins.

Double-Network Hydrogel Films Based on Cellulose Derivatives and κ-Carrageenan with Enhanced Mechanical Strength and Superabsorbent Properties

Covalently crosslinked sodium carboxymethyl cellulose (CMC)-hydroxyethyl cellulose (HEC) hydrogel films were prepared using citric acid (CA) as the crosslinking agent. Thereafter, the physically crosslinked κ-carrageenan (κ-CG) polymer was introduced into the CMC-HEC hydrogel structure, yielding κ-CG/CMC-HEC double network (DN) hydrogels. The κ-CG physical network provided sacrificial bonding, which effectively dissipated the stretching energy, resulting in an increase in the tensile modulus, tensile strength, and fracture energy of the DN hydrogels by 459%, 305%, and 398%, respectively, compared with those of the CMC-HEC single network (SN) hydrogel. The dried hydrogels exhibited excellent water absorbency with a maximum water-absorption capacity of 66 g/g in distilled water. Compared with the dried covalent SN gel, the dried DN hydrogels exhibited enhanced absorbency under load, attributed to their improved mechanical properties. The water-absorption capacities and kinetics were dependent on the size of the dried gel and the pH of the water.

Effects of Water-Retaining Agent Dosages on Slope-Protection Plants and Soil Nutrients on Rocky Slopes

Rocky slopes lack the necessary conditions for plant growth, i.e., soil and water, making vegetation recovery difficult and necessitating artificial soil conditions for vegetation establishment. Water-retaining agents are essential functional substances for constructing artificial soil on rocky slopes. In this study, the effect of water-retaining agents on the growth of artificial vegetation and soil nutrient loss was investigated by setting different application rates of water-retaining agents (10 g/m2, 20 g/m2, 30 g/m2, 40 g/m2, and 50 g/m2). Artificially simulated rocky slope conditions were achieved using the guest soil spraying technology after hanging the net, which provided support for the application of the water-retaining agent. Results showed that the contents of extractable nitrogen (EN), extractable phosphorus (EP), and extractable potassium (EK) in the soil, the number of plant individuals per unit area, plant height, and ground diameter of the water-retaining agent treatment were significantly higher than those of the control group (set up with no water retention as the control group, hereafter “CK”). By contrast, the nutrient content in the runoff fluid was significantly lower than that of CK. The application of the water-retaining agent significantly enhanced the soil’s ability to retain water and fertilizer, thus improving the growing environment and plant growth. Under the conditions of this experiment, the application rate of a 40 g/m2 water-retaining agent is reasonable from the perspectives of economic cost, soil nutrients, and plant growth.