Removal of anionic dyes from aqueous media by using a novel high positively charged hydrogel with high capacity

Rapid self-strengthening in double-network hydrogels triggered by bond scission

The scission of chemical bonds in materials can lead to catastrophic failure, with weak bonds typically undermining the materials' strength. Here we demonstrate how weak bonds can be leveraged to achieve self-strengthening in polymer network materials. These weak sacrificial bonds trigger mechanochemical reactions, forming new networks rapidly enough to reinforce the material during deformation and significantly improve crack resistance. This rapid strengthening exhibits strong rate dependence, dictated by the interplay between bond breaking and the kinetics of force-induced network formation. As the network formation is generally applicable to diverse monomers and crosslinkers with different kinetics, a wide range of mechanical properties can be obtained. These findings may inspire the design of tough polymer materials with on-demand, rate-dependent mechanical behaviours through mechanochemistry, broadening their applications across various fields.

Facile synthesis and optimization of Acacia senegal gum hydrogel for kinetically treated adsorptive removal of targeted industrial effluents

This context summarizes a detail on the fabrication of Acacia senegal Gum Hydrogel (ASGh) within well-engineered microemulsion, and thereafter chemical modification for environmental remediation. In brief, Divinylsulfone was used to crosslink polymeric chains and produce ASGh in ˂50 μm size within the reverse-microemulsion of Natrium-bis-(2-ethylhexyl) sulfosuccinate in gasoline. ASGh were subjected to chemical modification via versatile diethylenetriamine to produce m-[ASGh] for adsorptive removal of methyl orange (MO), eosin Y (EY) and congo red (CR) from waste-water. ASGh and m-[ASGh] were characterized through Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), and zeta potential measurements. For instance, FT-IR spectra depicted new bands upon Diethylenetriamine modification. The zeta potential measurements confirm a positively charged surface of m-[ASGh] upon Diethylenetriamine addition. Interestingly, 0.05 g m-[ASGh] demonstrated 91.0, 84.1, and 73.0 % removal efficiency towards MO, EY and CR, respectively in 2 h equilibrium time. Langmuir, Freundlich and modified-Freundlich isotherms were applied to further delineate adsorption data. Modified-Freundlich model depicted comparatively more agreeable fit, and delivered R2 value nearer to unity. Further, 143 mg·g-1, 130 mg·g-1 and, 116 mg·g-1 maximum adsorption capacity (QM) was represented by m-[ASGh] towards MO, EY and CR, respectively in 2 h. Interestingly, real water sample were tested whereby, the QM against MO, EY and CR was 146 mg·g-1, 132 mg·g-1 and, 111 mg·g-1, respectively in 2 h equilibrium time. To conclude, m-[ASGh] could be treated as decolorizing agent in real waste-water polluted through negatively charged organic pollutants, particularly MO.

Phosphate removal by a La(OH)3 loaded magnetic MAPTAC-based cationic hydrogel: Enhanced surface charge density and Donnan membrane effect

Cationic hydrogels have received great attention to control eutrophication and recycle phosphate. In this study, a type of La(OH)₃ loaded magnetic MAPTAC-based cationic hydrogel (La(OH)₃@MMCH) was developed as a potential adsorbent for enhanced phosphate removal from aqueous environment. La(OH)₃@MMCH exhibited high adsorption capacity of 105.72±5.99 mg P/g, and reached equilibrium within 2 hr. La(OH)₃@MMCH could perform effectively in a wide pH range from 3.0 to 9.0 and in the presence of coexisting ions (including SO₄^2-, Cl^-, NO₃^-, HCO₃^-, SiO₄^4- and HA). The adsorption-desorption experiment indicated that La(OH)₃@MMCH could be easily regenerated by using NaOH-NaCl as the desorption agent, and 73.3% adsorption capacity remained after five cycles. Moreover, La(OH)₃@MMCH was employed to treat surface water with phosphate concentration of 1.90  mg/L and showed great removal efficiency of 95.21%. Actually, MMCH showed high surface charge density of 34.38-59.38 meq/kg in the pH range from 3.0 to 11.0 and great swelling ratio of 3014.57% within 24 h, indicating that MMCH could produce the enhanced Donnan membrane effect to pre-permeate phosphate. Furthermore, the bifunctional structure of La(OH)₃@MMCH enabled it to capture phosphate through electrostatic attraction and ligand exchange. All the results prove that La(OH)₃@MMCH is a promising adsorbent for eutrophication control and phosphate recovery.