Design and preparation of reticular superabsorbent hydrogel material with nutrient slow-release and high shear strength for ecological remediation of abandoned mines with steep slopes

• Published in: International journal of biological macromolecules 2024-06, Vol.270 (Pt 1), p.132303-132303, Article 132303
• Main Authors: Wang, Shuo, Li, Sinuo, Rene, Eldon R., Lun, Xiaoxiu, Ma, Weifang
• Format: Article
• Language: English
• Subjects: absorbents; absorption; acrylic acid; adsorption; cohesion; ecological restoration; electrostatic interactions; Fertilizer retention; fly ash; hydrogels; hydrophilicity; Lolium; Mine restoration; osmotic pressure; polymers; porous media; remediation; resorption; Shear strength; skeleton; Steep slopes; Superabsorbent polymer; surface area; Water absorption and retention; water binding capacity; water uptake
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2024.132303

In order to solve ecological remediation issues for abandoned mines with steep slopes, a kind of hydrogels with high cohesion and water-retaining were designed by inorganic mineral skeleton combining with polymeric organic network cavities. This eco-friendly hydrogel (MFA/HA-g-p(AA-co-AM)) was prepared with acrylic acid (AA)-acrylamide (AM) as network, which was grafted with humic acids (HA) as network binding point reinforcement skeleton and polar functional group donors, KOH-modified fly ash (MFA) as internal supporter. The maximum water absorption capacities were 1960 g/g for distilled water, which followed the pseudo-second-order model. This super water absorption was attributed to the first stage of 62 % fast absorption due to the high specific surface area, pore volume and low osmotic pressure, moreover, the multiple hydrophilic functional groups and network structure swell contributed to 36 % of the second stage slow adsorption. In addition, the pore filling of water in mesoporous channels contributed the additional 2 % water retention on the third stage. The high saline-alkali resistance correlated with the electrostatic attraction with MFA and multiple interactions with oxygen-containing functional groups in organic components. MFA and HA also enhanced the shear strength and fertility retention properties. After 5 cycles of natural dehydration and reabsorption process, these excellent characteristics of reusability and water absorption capacity kept above 97 %. The application of 0.6 wt% MFA/HA-g-p(AA-co-AM) at 15° slope could improve the growth of ryegrass by approximately 45 %. This study provides an efficient and economic superabsorbent material for ecological restoration of abandoned mines with steep slopes. [Display omitted] •Hydrogel synthesized with inorganic mineral skeleton, organic networks and internal supporter.•The saturated water absorption capacity of MFA/HA-g-p(AA-co-AM) hydrogel was 1960 g/g.•Inorganic mineral MFA enhanced shear strength with 22.5 Kpa cohesion and salt resistance.•HA as internal supporting contributed to the medium and slow speed of water adsorption.•MFA/HA-g-p(AA-co-AM) enhanced plant growth and water holding capacities of soil.