Chlorfenapyr containing anions uptake from industrial wastewater by ethylene glycol functionalized benzyl dimethyl tetradecyl ammonium bromide membrane

Construction of a multi-layer protection of CS polymer brush grafted DA@CNTs coating on PVDF membrane for effective removal of dye effluent

In the process of removing dye wastewater, the membrane surface is susceptible to contamination, resulting in reduced performance and limited dye separation efficiency. A single hydrophilic modification layer is not enough to achieve effective separation of different types of dyes. The present research designed a "double layer protection" method in order to overcome the above deficiencies. A solution of dopamine (DA) coated carbon nanotubes (CNTs-COOH) was covered on the surface of the polyvinylidene fluoride (PVDF) membrane by deposition, followed by grafting a layer of chitosan (CS) polymer brushes on its surface. The spatial double layer structure provides an excellent barrier effect and effectively reduces the contamination of dyes. When filtering different types of dyes, effective filtration of anionic and cationic dyes through the electrostatic effect of the first layer, the adsorption of CNTs in the second layer and the hydration layer of both layers. All membranes have excellent rejection properties. More importantly, the membranes also had good chemical and mechanical stability and their serviceability was not degraded. Therefore, the prepared PVDF-based multi-layer composite membranes behave a potential application prospect in the wastewater purification field.

Preparation and performance of chlorfenapyr microcapsules with a degradable polylactide-based polyurethane wall material

To improve the utilization rate of chlorfenapyr and make the wall material of chlorfenapyr microcapsules easily degradable, polylactide diol, toluene diisocyanate and 1,4-butanediol were used to prepare a chlorfenapyr microcapsule suspension by interfacial polymerization. The product was characterized by the methods of optical microscopy, scanning electron microscopy and Fourier-transform infrared spectroscopy. The results indicated that the microcapsule particles were spherical, with an encapsulation efficiency of 84.20%. The diluted product had good wetting and spreading abilities on cabbage leaves. Compared with other commercial formulations, the slow-release effect of the microcapsule suspension was more obvious and the release mechanisms conform to Fickian diffusion, with the release rate controllable by adjusting the external pH conditions. Furthermore, the wall material of the microcapsules showed good degradation performance in a phosphate-buffered solution. Microencapsulation by this method significantly increased the validity period of chlorfenapyr and the wall material was also degraded easily.

Microscopic mechanism about the selective adsorption of Cr(VI) from salt solution on nitrogen-doped carbon aerogel microsphere pyrolysis products

A series of nitrogen-doped carbon aerogels (NCAs) were obtained through phase reaction polymerization and different carbonization temperatures to enhance adsorption efficacy of hexavalent chromium (Cr[VI]) from wastewater significantly. Factors that influence adsorption properties of carbon aerogel microspheres toward Cr(VI), such as pH, adsorbent content, initial Cr(VI) concentrations, and coexisting anion, were investigated. Three isotherm (Langmuir, Freundlich, and Sips) and three kinetic (pseudofirst-order, pseudosecond-order, and Elovich) models were used to interpret the adsorption process. The adsorption capacity of Cr(VI) reached 180.62 mg·g^-1, which was superior to that of most aerogel adsorbents. In addition to the adsorption effect, the XPS results also showed that N-containing groups on the NCA surface reduce the adsorbed Cr(VI) to the less toxic Cr(III). The prepared sorbent demonstrates a negligible loss in adsorption capacity after 6 cycles. NCAs show acceptable application prospects in selective removal of Cr(VI) ions.