Silica-based adsorbent was prepared by radiation-induced grafting of dimethylaminoethyl methacrylate (DMAEMA) onto the silanized silica followed by a protonation process. The FTIR spectra and XPS analysis proved thatDMAEMAwas grafted successfully onto the silica surface. The resultant adsorbent manifested a high ion exchange capacity (IEC) of ca. 1.30 mmol/g and the Cr (Ⅳ) adsorption behavior of the adsorbent was further investigated, revealing the recovery of Cr (Ⅳ) increased with the adsorbent feed and the equilibrium adsorption could be achieved within 40 min. The adsorption capacity, strongly depended on the pH of the solution, reached a maximum Cr(Ⅵ) uptake (ca. 68 mg/g) as the pH was in the range of 2.5-5.0. Furthermore, even in strong acidic (4.0 mol/L HNO3) or alkaline media (pH 11.0), the adsorbent had a sound Cr(Ⅵ) uptake capacity (ca. 22 and 30 mg/g, respectively), and the adsorption followed Langmuir mode. The results indicated that this adsorbent, prepared via a convenient approach, is applicable for removing heavy-metal-ion pollutants (e.g. Cr(Ⅵ)) from waste waters.

Most of the hydrogels deswell more remarkably in Fcontaining solutions than in other monovalent anion containing solutions. However, significant deswelling followed by abnormal reswelling of polymer gel in KF solutions with increasing F concentration was observed in a series of polymer gels consisted of phenyl rings, for instance, poly(styrene sulfonic acid) (PSSA), hydroxypropyl methylcellulose phthalate (HPMCP) and poly (4-vinyl phenol) (P4VPh) gel. Driving force of this phenomenon was studied to reveal the specific interactions involved in the aqueous systems of aromatic polymers. Elemental analysis and XPS results suggest that F is embedded to the gel by the physical adsorption of KF, as well as the interactions between phenyl ring and F. Further theoretical calculations revealed that the interaction may be (phenyl)CH F (H2O)n interaction, which is stronger than (phenyl) CH (H2O)n hydrogen bond. This kind of interaction decreases with the increasing water number and it is invalid when the surrounding water number ismore than 5 for the phenol-F (H2O)n system. Therefore, we conclude that F could bind to phenyl ring via such (phenyl) CH F (H2O)n interaction in solutions with low hydrophilicity. The strong polarization effect of F and (phenyl)CH…F(H2O)n interaction are two important driving forces for the reswelling of gels.

A novel ETFE-based amphoteric ion exchange membrane (AIEM) was prepared through a two-step radiation-induced grafting technique. ETFE film was first grafted with styrene (St) (denoted as ETFEg-PS), followed with a sulfonation treatment to obtain a cation exchange membrane (ETFE-g-PSSA). The ETFE-g-PSSA membrane was subsequently grafted with dimethylaminoethyl methacrylate (DMAEMA) and then protonated, resulting in an AIEM with both anionic and cationic groups. The grafting yields (GY) in the above two steps increased with absorbed dose and leveled off at about 30 kGy and 20 kGy, respectively. Micro-FTIR and XPS analyses testified that the AIEM had been prepared as designed. The obtained AIEM exhibited high ion exchange capacity (IEC) and conductivity, as well as significantly reduced permeability of vanadium ions. Vanadium redox flow battery (VRFB) assembled with the AIEM maintained an open circuit voltage (OCV) higher than 1.3V after placed for 300 h, and exhibited higher columbic efficiency and energy efficiency than that with Nafion 117 membrane.

The carboxymethylated chitosan (CMCts) hydrogels were synthesized by c-ray radiation-induced crosslinking at paste-like state with the concentration of CMCts from 12% to 22%. The gel fraction firstly increased with adsorbed dose and leveled off at ca. 20 kGy. The diffusion behavior of water in CMCts gels was Fickian diffusion, and the swelling of CMCts gels was affected by pH and ionic strength. Preliminary crosslinking mechanism of CMCts with c-ray irradiation was discussed based on the FTIR and sol-gel analysis. The adsorption kinetics study showed that the adsorption of Fe(Ⅲ) ions onto CMCts gels was very fast (ca. 20 min) due to the coordination of Fe(Ⅲ) ions with amino, hydroxyl and carboxyl groups of CMCts molecules. pH 4.7 was the optimum for the adsorption of Fe(Ⅲ) ions onto CMCts gels. The maximum uptake of Fe(Ⅲ) ions, based on Langmuir equation, was determined to be 18.5 mg/g gel.