In this work, textile wastewater is explored for resource recovery in a hybrid loose nanofiltration (NF)-bipolar membrane electrodialysis (BMED) process for fractionation of dyes and salt, in view of dye purification and water and salt reuse. A loose nanofiltration membrane, i.e., Sepro NF 6 (Ultura), found to have a low salt rejection (0.27% in 120 g· L −1 NaCl solution) and high rejection for direct dyes and reactive dyes (≥99.93%), was used for fractionation of dye/salt mixtures through diafiltration. In diafiltration, the addition of pure water with a volume factor of 5.0 can effectively remove the NaCl salt by using Sepro NF 6 with an invariable dye concentration, in view of the recovery of high purity dyes. The overall salt rejections in diafiltration for the dye/salt mixtures with 40, 50 and 60 g·L −1 NaCl are 2.2%, 1.8% and 1.1%, respectively, enabling a further treatment by BMED. Subsequently, application of BMED for reuse of salt-containing NF permeate demonstrates that desalinated water with ∼100 ppm of NaCl can be obtained, and base/acid can be produced from the salts without any membrane fouling by dyes. Therefore, the hybrid loose NF-BMED process allows for resource (i.e., dye, salt and pure water) extraction from textile wastewater, which closes the salt and water cycle, in view of process intensification.

Amphiphilic Janus particles with catalyst selectively loaded on either the hydrophobic or hydrophilic region are promising candidates for efficient and phase-selective interfacial catalysis. Here, we report the synthesis and characterization of Janus silica particles with a hydrophilic silica domain and a silane-modified hydrophobic domain produced via a wax masking technique. Palladium nanoparticles were regioselectively deposited on the hydrophobic side and the phase selectivity of the catalytic Janus particles was established through kinetic studies of benzyl alcohol hydrodeoxygenation (HDO). These studies indicated that the hydrophobic moiety provided nearly 100x the catalytic activity as the hydrophilic side for benzyl alcohol HDO. The reactivity was linked to the anisotropic catalyst design through microscopy of the particles. The catalysts were used to achieve phase-specific compartmentalized hydrogenation and selective in-situ catalytic degradation of a model oily pollutant in a complex oil/water mixture.

Micro/nanoswimmers convert diverse energy sources into directional movement, demonstrating significant promise for biomedical and environmental applications, many of which involve complex, tortuous, or crowded environments. Here, we investigated the transport behavior of self-propelled catalytic Janus particles in a complex interconnected porous void space, where the rate-determining step involves the escape from a cavity and translocation through holes to adjacent cavities. Surprisingly, self-propelled nanoswimmers escaped from cavities more than 20× faster than passive (Brownian) particles, despite the fact that the mobility of nanoswimmers was less than 2× greater than that of passive particles in unconfined bulk liquid. Combining experimental measurements, Monte Carlo simulations, and theoretical calculations, we found that the escape of nanoswimmers was enhanced by nuanced secondary effects of self-propulsion which were amplified in confined environments. In particular, active escape was facilitated by anomalously rapid confined short-time mobility, highly efficient surface-mediated searching for holes, and the effective abolition of entropic and/or electrostatic barriers at the exit hole regions by propulsion forces. The latter mechanism converted the escape process from barrier-limited to search-limited. These findings provide general and important insights into micro/nanoswimmer mobility in complex environments.

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Much research has been done using polymer and silica particles as support materials for catalytically active noble metal nanoparticles, but these materials have limited stability in organic solvents or under extreme reaction conditions such as high pH. Here we present a robust and versatile composite polymer-diamond support for ultrasmall noble metal nanoparticles combining chemical and mechanical stability of diamond with the chemical versatility of a polymer. By exploiting the rich surface chemistry of nanodiamond and incorporating a reactive thiol−ene polymer, a thinly coated polymer-diamond composite was formed. Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and thermogravimetric analysis (TGA) confirmed the presence of the polymer. High resolution scanning transmission electron microscopy (S/TEM) analysis showed that in situ growth of gold, platinum and palladium nanoparticles produced high density coverage at the polymer-diamond support surface. Energy dispersive spectroscopy mapping and S/TEM imaging indicated spatial alignment of nanoparticles with chemical groups present in the polymer used for particle tethering. The polymer-diamond supported nanoparticles catalyze the NaBH 4 reduction of paranitrophenol to para-aminophenol and possess better stability than silica supports which dissolve at high pH resulting in nanoparticle aggregation. With the high robustness of the diamond and the ability to tailor the monomer combinations, this polymer-diamond support system may be expanded to a wide range of nanoparticle compositions suitable for various reaction conditions.