Effects of the Electric Double Layer Characteristic and Electroosmotic Regulation on the Tribological Performance of Water-Based Cutting Fluids.

The electroosmosis effect is a complement to the theory of the traditional capillary penetration of cutting fluid. In this study, based on the electric double layer (EDL) characteristics at friction material/solution interfaces, the influences of additives and their concentrations on capillary electroosmosis were investigated, and a water-based cutting-fluid formulation with consideration to the electroosmosis effect was developed. The lubrication performance levels of cutting fluids were investigated by a four-ball tribometer. The results show that the EDL is compressed with increasing ionic concentration, which suppresses the electroosmotic flow (EOF). The specific adsorption of OH- ions or the dissociation of surface groups is promoted as pH rises, increasing the absolute zeta potential and EOF. The polyethylene glycol (PEG) additive adsorbed to the friction material surface can keep the shear plane away from the solid surface, reducing the absolute zeta potential and EOF. The electroosmotic performance of cutting fluid can be improved by compounding additives with different electroosmotic performance functions. Furthermore, electroosmotic regulators can adjust the zeta potential by the electrostatic adsorption mechanism, affecting the penetration performance of cutting fluid in the capillary zone at the friction interface. The improvement in the tribological performance of cutting fluid developed with consideration given to the electroosmosis effect is attributed to the enhancement of the penetration ability of the cutting fluid and the formation of more abundant amounts of lubricating film at the interface.

Hierarchically porous metal hydroxide/metal-organic framework composite nanoarchitectures as broad-spectrum adsorbents for toxic chemical filtration.

We demonstrate that the hierarchically porous metal hydroxide/metal-organic framework composite nanoarchitectures exhibit broad-spectrum removal activity for three chemically distinct toxic gases, viz. acid gases, base gases, and nitrogen oxides. A facile and general in-situ hydrolysis strategy combined with gentle ambient pressure drying (APD) was utilized to integrate both Zr(OH)4 and Ti(OH)4 with the amino-functionalized MOF-808 xerogel (G808-NH2). The M(OH)4/G808-NH2 xerogel composites manifested 3D crystalline porous networks and substantially hierarchical porosity, with controllable amounts of amorphous M(OH)4 nanoparticles residing at the edge of xerogel particles. Microbreakthrough tests were performed under both dry and moist conditions to evaluate the filtration capabilities of the composites against three representative compounds: SO2, NH3, and NO2. Compared with the pristine G808-NH2 xerogel, the incorporation of M(OH)4 effectively enhanced the broad-spectrum toxic chemical mitigation ability of the material, with the highest SO2, NH3, and NO2 breakthrough uptake reaching 74.5, 55.3, and 394.0 mg/g, respectively. Post-breakthrough characterization confirmed the abundant M-OH groups with diverse binding configurations, alongside the unsaturated M (IV) centers on the surface of M(OH)4 provided extra adsorption sites for irreversible toxic chemical capture besides Van der Waals driven physisorption. The ability to achieve high-capacity adsorption and strong retention for multiple contaminants is of great significance for real-world filtration applications.

Enhanced Adsorption and Mass Transfer of Hierarchically Porous Zr-MOF Nanoarchitectures toward Toxic Chemical Removal.

Zirconium-based metal-organic frameworks (Zr-MOFs) have shown tremendous prospects as highly efficient adsorbents against toxic chemicals under ambient conditions. Here, we report for the first time the enhanced toxic chemical adsorption and mass transfer properties of hierarchically porous Zr-MOF nanoarchitectures. A general and scalable sol-gel-based strategy combined with facile ambient pressure drying (APD) was utilized to construct MOF-808, MOF-808-NH2, and UiO-66-NH2 xerogel monoliths, denoted as G808, G808-NH2, and G66-NH2, respectively. The resulting Zr-MOF xerogels demonstrated 3D porous networks assembled by nanocrystal aggregates, with substantially higher mesoporosities than the precipitate analogues. Microbreakthrough tests on powders and tube breakthrough experiments on engineered granules were conducted at different relative humidities to comprehensively evaluate the NO2 adsorption capabilities. The Zr-MOF xerogels showed considerably better NO2 removal abilities than the precipitates, whether intrinsically or under simulated respirator canister/protection filter environment conditions. Multiple physicochemical characterizations were conducted to illuminate the NO2 filtration mechanisms. Analysis on adsorption kinetics and mass transfer patterns in Zr-MOF xerogels was further performed to visualize the underlying structure-activity relationship using the gravimetric uptake and zero length column methods with cyclohexane and acetaldehyde as probes. The results revealed that the synergy of hierarchical porosities and nanosized crystals could effectively expedite the intracrystalline diffusion for the G66-NH2 xerogel as well as alleviate the surface resistance for the G808-NH2 xerogel, which led to accelerated overall adsorption uptake and thus enhanced performance toward toxic chemical removal.

[Adsorption characteristics of acetone and butanone onto honeycomb ZSM-5 molecular sieve].

Adsorption capacity of acetone and acetone-butanone mixture onto honeycomb ZSM-5 molecular sieve was measured in this paper, and the influences of relative humidity, initial adsorbate concentration and airflow velocity on the adsorption process were investigated. Besides, adsorption performance parameters were calculated by Wheeler's equation. The results showed that relative humidity had no obvious influence on the acetone adsorption performance, which suggests that this material has good hydrophobic ability; in the low concentration range, the dynamic saturated adsorption capacity of acetone increased with the increase of initial concentration, but in the occasion of high concentration of acetone gas (more than 9 mg x L(-1)), the dynamic saturated adsorption capacity maintained at a certain level and did not vary with the increase of initial concentration; the increase of air flow velocity resulted in significant increase of acetone adsorption rate constant, at the same time the critical layer thickness of the adsorbent bed also increased significantly. In the cases of acetone-butanone mixture, the adsorption capacity of butanone onto ZSM-5 was clearly higher than that of acetone.

[Evaluation of treatment technology of volatile organic compounds for fixed industrial resources].

The reduction of the emission of volatile organic compounds (VOCs) from fixed industrial resources is considered more necessary than before. The traditional treatment techniques, newly developed ones and some combinations of these treatment techniques are reviewed in this paper. The applying conditions, developing trend and existing problems of these techniques are also evaluated.

[Regulations and policies for control of volatile organic compounds and the emission standards in Taiwan].

Due to the well-developed managing system including policies, laws, regulations and emission standards, now the emission of volatile organic compounds (VOCs) is strictly controlled in Taiwai. The policy frameworks of VOCs control including both command control and economic incentives makes an excellent effect for VOCs treatment.

[Preparation of honeycombed monolithic zeolite and hydrophobic modification with SiCl4].

A kind of hydrophobic zeolitic monolith were prepared by mixing HY/ZSM-5, additives and water, followed by processes of extrusion and drying, and then hydrophobic modification with SiCl4. The structures and properties of the adsorbent were examined by nitrogen adsorption and desorption measurement, XRD, and benzene adsorption experiment. The results show that those adsorbents possess hierarchical pore structures and excellent hydrophobicity.