Adsorption behavior of benzenesulfonic acid by novel weakly basic anion exchange resins

Preparation of resin-based composites containing Ce and cationic polymers with abundant promotional affinity sites for phosphate capture

A new type of composite, D301-Ce+, for efficient and selective phosphate removal.

Co-monomer polymer anion exchange resin for removing Cr(VI) contaminants: Adsorption kinetics, mechanism and performance

Modified anion exchange resin (EDE-D301) was synthesized by mixing monomers: epichlorohydrin (ECH), dimethylamine (DMA), ethylenediamine (EDA) with the weakly alkaline anion exchange resin D301 through in-situ polymerization method. Adsorption performance of EDE-D301 for removing Cr(VI) contaminants was investigated in batch and column systems. Physicochemical properties of the anion exchange resins were characterized to determine the adsorption mechanism and regeneration ability. Characteristic results revealed that EDE-D301 showed enhanced surface area, positive charge and contents of N and Cl elements, indicating that the modifying reagents of monomers were successfully polymerized in the resin. The experimental adsorption data fitted well to the pseudo-second-order kinetic model and the Langmuir isotherm model. The fixed-bed experiments showed that the exhaustion time increased with increasing the bed depth, and decreased with increasing the flowrate and influent concentration. Adsorption capacity for Cr(VI) onto EDE-D301 was determined at a maximum level of 298 mg·g^-1, and remained at 93% after four consecutive cycles. FTIR and XPS analysis indicated that the ion exchange and complexation were responsible for the Cr(VI) adsorption.

Effect of Functional Group Density of Anion Exchange Resins on Removal of p-Toluene Sulfonic Acid from Aqueous Solution

Adsorption using anion exchange resins is an efficient method for the removal of aromatic sulfonic acids (ASAs) from industrial wastewater. In this study, a series of weak-base anion exchangers (SD1–SD5) were synthesized to investigate the effect of functional group density of resins on the adsorption of ASAs from wastewater containing competitive inorganic anions. p-Toluene sulfonic acid (PTSA) was selected as a target pollutant, and Na2SO4 was chosen as the competitive inorganic salt because of its widespread existence in industrial wastewater. Adsorption performances of these resins were evaluated and compared in terms of selectivity, kinetics, isotherms, regeneration, and dynamic adsorption behavior. Importantly, the PTSA uptake increased with the raising content of functional groups on resins in the absence of Na2SO4; however, in the presence of a high level of Na2SO4 (for example, ≥1%), a decrease in the functional group density could improve the adsorption capacity of resins for PTSA. Moreover, desorption and fixed bed column experiments were conducted in all resins, thereby confirming the effect of functional group density of resins on the PTSA adsorption in actual application. In brief, this research will provide a better understanding for the design and preparation of anion exchangers for the effective removal of ASA from wastewater.

Removal of 2-naphthalenesulfonic acid using novel dual functional weakly basic anion exchange resins from aqueous solution

Two novel weakly basic anion exchange resins BNH and BN2 bearing two different functional groups was fabricated via the two-step amination of chloromethylated polystyrene-divinylbenzene beads with dibutylamine and dimethylamine. The adsorption properties of BNH and BN2 for the 2-naphthalenesulfonic acid (NSA) removal from wastewater were compared with two synthesized monofunctional anion exchange resins BN0 and BN6 (derived from dimethylamine and dibutylamine, respectively). The experimental data revealed that the adsorption process on the four resins fitted well with the pseudo-second-order kinetics equation and the equilibrium isotherms were in good agreement with the Langmuir model. Thermodynamic analyses illustrated that 2-naphthalenesulfonic acid adsorption onto resins was an endothermic and spontaneous process. Importantly, BN2 still displayed relatively high adsorption capacity in the existence of Na2SO4, indicative of an excellent selectivity for 2-naphthalenesulfonic acid over sulfate than other resins. The obtained results elucidate that BN2 could have potential industrial application in effluent disposal fields because of its superior selectivity, acceptable kinetics, and desorption capability.

Adsorption of Ethylenediaminetetraacetic Acid on a Gel-Type Ion-Exchange Resin for Purification of Liquid Waste Containing Cs Ions

Because of its excellent chelating property, ethylenediaminetetraacetic acid (EDTA) is used as a complex agent, not only for heavy metals, but also for radioactive isotopes during the decontamination of nuclear facilities. The removal of EDTA was investigated by adsorption with commercially available, gel-type, anion-exchange resins (AERs), which are based on cross-linked polystyrene with positive tertiary amine groups. Because of the positive charge on AERs, they could adsorb EDTA effectively even in a solution mixed with ions of cesium (Cs) via electrostatic attraction. Because EDTA adsorption by cation-exchange resins (CERs) was not possible, it was concluded that the negative charges on CERs do not contribute to the interaction with EDTA. The maximum adsorption capacity (q_max) of AER (2 g/L) for EDTA removal, calculated by the Langmuir isotherm model was 0.47 mmol/g for initial EDTA concentrations in the range of 0.01–1 mM in the EDTA/Cs mixed solution. The Langmuir isotherm model was found to be suitable for EDTA adsorption on AERs, indicative of monolayer adsorption. The results clearly suggested that the AERs could efficiently remove EDTA, regardless of the presence of nuclides, such as Cs ions in the aqueous solution.

Research on adsorption of Cr(Ⅵ) by Poly-epichlorohydrin-dimethylamine (EPIDMA) modified weakly basic anion exchange resin D301

A novel composite, EPIDMA/D301, with high adsorption capacity and particular affinity toward Cr(Ⅵ) was well prepared utilizing cationic polyelectrolyte poly-epichlorohydrin-dimethylamine (EPIDMA) impregnated in the networking pores of the styrene macroporous weak basic anion exchange resin D301. The physicochemical characteristics of EPIDMA/D301 were characterized by the Brunauer-Emmett-Teller (BET), zeta potential, FTIR, SEM-Mapping and XPS. The adsorption properties were researched via the influence of the concentration of EPIDMA, adsorbent dose, pH, the initial concentration of Cr(Ⅵ) solution, contact time and temperature. Results presented that the weakly basic anion exchange resin supported cationic polymer showed the excellent potential of removing Cr(VI) ions primarily due to the nonspecific Cr(VI) adsorption resulted from the polymeric host D301, the electrostatic attraction of amino groups fixed on the D301 matrix and the embedded EPIDMA with Cr(VI) ions and the ion exchange by the displacement of Cl^- mainly derived from EPIDMA with Cr(VI) ions. The kinetic data were best fitted by the pseudo-second-order kinetic model. The batch equilibrium data followed Langmuir isotherm model well with the maximum adsorption capacity of 194 mg g^-1 at 25 °C, which demonstrated that the styrene anion exchange resin modified with EPIDMA might be an efficient approach to eliminate potentially toxic metals.