Enhanced adsorption of heavy metal ions onto simultaneous interpenetrating polymer network hydrogels synthesized by UV irradiation

SYNTHESIS AND PROPERTIES OF CROSS-LINKED HYDROGELS BASED ON CHITOSAN AND POLYACRYLAMIDE

The synthesis and physico-chemical properties of chemically cross-linked hydrogels based on polyacrylamide and chitosan, which form interpenetrating polymer networks, are considered in the work. The strategy of obtaining cross-linked networks of both polyacrylamide and polyacrylamide grafted on chitosan by radical polymerization was used. The equilibrium swelling properties, which depend on the pH value of the solution and the composition of the gels, were studied. The chemical structure of the obtained hydrogels was characterized by IR spectroscopy.

Soft Materials by Design: Unconventional Polymer Networks Give Extreme Properties

Hydrogels are polymer networks infiltrated with water. Many biological hydrogels in animal bodies such as muscles, heart valves, cartilages, and tendons possess extreme mechanical properties including being extremely tough, strong, resilient, adhesive, and fatigue-resistant. These mechanical properties are also critical for hydrogels' diverse applications ranging from drug delivery, tissue engineering, medical implants, wound dressings, and contact lenses to sensors, actuators, electronic devices, optical devices, batteries, water harvesters, and soft robots. Whereas numerous hydrogels have been developed over the last few decades, a set of general principles that can rationally guide the design of hydrogels using different materials and fabrication methods for various applications remain a central need in the field of soft materials. This review is aimed at synergistically reporting: (i) general design principles for hydrogels to achieve extreme mechanical and physical properties, (ii) implementation strategies for the design principles using unconventional polymer networks, and (iii) future directions for the orthogonal design of hydrogels to achieve multiple combined mechanical, physical, chemical, and biological properties. Because these design principles and implementation strategies are based on generic polymer networks, they are also applicable to other soft materials including elastomers and organogels. Overall, the review will not only provide comprehensive and systematic guidelines on the rational design of soft materials, but also provoke interdisciplinary discussions on a fundamental question: why does nature select soft materials with unconventional polymer networks to constitute the major parts of animal bodies?

Removal of Cu(II) from aqueous solution using synthetic poly(catechol-diethylenetriamine-p-phenylenediamine) particles

A novel poly(catechol-diethylenetriamine-pphenylenediamine)(PCEA) adsorbent was synthesized in methanol, with chelating groups supplied by catechol and diethylenetriamine, which showed a strong removal performance and efficient adsorption toward Cu(II) ions in aqueous solution. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Besides, factors such as adsorbent dosage, pH, initial ionic and metal concentrations, contact time, and temperature on the adsorption of Cu(II) were studied. The data revealed that the adsorption followed a pseudo-second order kinetic model and the adsorption rate was influenced by the intra-particle diffusion. Furthermore, the adsorption process followed the Langmuir isotherm model, and the maximum adsorption capacity (Qm) was 44.2mg/g at 298K in simulated wastewater. The value of ΔG (kJ/mol) and ΔH (kJ/mol) also demonstrated that the adsorption process was spontaneous and endothermic. Studies revealed that PCEA particles were powerful and stable for the removal of Cu(II) in water, and it could be directly applied to the Cu(II)-contaminated water.

Modified chitosan for the collection of reactive blue 4, arsenic and mercury from aqueous media

In the present investigation a series of modified chitosan as adsorbents were synthesized free radically at 70 °C using acryloylated chitosan (AC-chitosan) as macromer, 2-acrylamido-2-methyl-1-propansulfonic acid (AMPS), 2-(diethylamino) ethylmethacrylate (DAEMA) as co-monomers and N,N'-methylene bisacrylamide (N-MBA) as a crosslinker for using as adsorbents in effluent remediation. Their structures ((1)H and (13)C NMR), thermal stability (TG/DTG), surface morphology (SEM), reactive blue 4 (RB4), toxic metals such as arsenic (AsO(2-)) and mercury (Hg(2+)) uptake, swellability and reusability were evaluated. The adsorption of RB4 (701 mg/g), and the uptake of AsO(2-) (551 mg/g) and Hg(2+) (455 mg/g) showed Langmuir isotherm behavior with pseudo-first-order kinetics. The diffusion of water, RB4, AsO(2-) and Hg(2+) into the matrix followed non-Fickian mechanism. The evaluated changes in Gibbs free energy (ΔG°), entropy (ΔS°) and enthalpy (ΔH°) for adsorption indicated that the process was exothermic.