Adsorption of three pharmaceuticals on two magnetic ion-exchange resins

The presence of pharmaceuticals in aquatic environments poses potential risks to the ecology and human health. This study investigated the removal of three widely detected and abundant pharmaceuticals, namely, ibuprofen（IBU）, diclofenac（DC）, and sulfadiazine（SDZ）, by two magnetic ion-exchange resins. The adsorption kinetics of the three adsorbates onto both resins was relatively fast and followed pseudo-second-order kinetics. Despite the different pore structures of the two resins, similar adsorption patterns of DC and SDZ were observed, implying the existence of an ion-exchange mechanism. IBU demonstrated a combination of interactions during the adsorption process. These interactions were dependent on the specific surface area and functional groups of the resin. The adsorption isotherm fittings verified the differences in the behavior of the three pharmaceuticals on the two magnetic ion-exchange resins. The presence of Cl-and SO2-4suppressed the adsorption amount, but with different inhibition levels for different adsorbates. This work facilitates the understanding of the adsorption behavior and mechanism of pharmaceuticals on magnetic ion-exchange resins.The results will expand the application of magnetic ion-exchange resins to the removal of pharmaceuticals in waters.

Effect of zeta potentials on bovine serum albumin adsorption on crown composite resin surfaces <i>in vitro</i>

We previously studied the mechanism underlying the adsorption of oral bacteria on the surfaces of dental prosthetic materials such as ceramics and resins in vitro. The aim of the present study was to examine bovine serum albumin (BSA) adsorption on crown composite resin surfaces by means of zeta potential. We measured the zeta potentials of resins alone, BSA alone, and resins after BSA adsorption. Eight resins were pulverized into powders (300 - 1000 nm). All experiments were conducted in 10 mM sodium chloride solution (pH 6.5). BSA was dissolved in 10 mM NaCl with a concentration of 2.0 × 10-5 mol/l. An adsorption assay was performed for one hour at 37°C under continuous rotation (6 rpm). The zeta potentials of both resins and BSA were negative, with BSA itself less negative than the resins themselves as an absolute value (p < 0.0001). The zeta potentials of seven resin surfaces after BSA adsorption were significantly less negative than were those of the resins without BSA adsorption (p < 0.0001). Eight resins were divided into two classes based on the size of the surface potential difference between each resin and the BSA. The difference in surface potential between the resins and the BSA were small, leading to the theory that particles with identical charges repulse each other, and the amounts of adsorbed BSA on these resins might be less. On the other, when the differences between the other resins and BSA are large, so that the repulsive force between two nonidentical particles becomes zero and an attractive force might be generated, then more BSA might be adsorbed on those resins. Therefore, the zeta potentials were affected by BSA adsorption and became less negative. These results suggested that electrostatic interactions play an important role in the adsorption of BSA on resin surfaces.

A novel aminated polymeric adsorbent for removing refractory dissolved organic matter from landfill leachate treatment plant

Refractory dissolved organic matter （DOM） from landfill leachate treatment plant was with high dissolved organic carbon （DOC） content. An aminated polymeric adsorbent NDA-8 with tertiary amino groups and sufficient mesopore was synthesized, which exhibited high adsorption capacity to the DOM （raw water after coagulation）. Resin NDA-8 performed better in the uptake of the DOM than resin DAX-8 and A100. Electrostatic attraction was considered as the decisive interaction between the adsorbent and adsorbate. Special attention was paid to the correlation between porous structure and adsorption capacity. The mesopore of NDA-8 played a crucial role during uptake of the DOM. In general, resin in chloride form performed a higher removal rate of DOC. According to the colunm adsorption test, total adsorption capacity of NDA-8 was calculated to 52.28 mg DOC/mL wet resin. 0.2 mol/L sodium hydroxide solution could regenerate the adsorbent efficiently.