Fabrication of Robust and Effective Oil/Water Separating Superhydrophobic Textile Coatings.

A superhydrophobic (SH) surface is typically constructed by combining a low-surface-energy substance and a high-roughness microstructure. Although these surfaces have attracted considerable attention for their potential applications in oil/water separation, self-cleaning, and anti-icing devices, fabricating an environmentally friendly superhydrophobic surface that is durable, highly transparent, and mechanically robust is still challenging. Herein, we report a facile painting method to fabricate a new micro/nanostructure containing ethylenediaminetetraacetic acid/poly(dimethylsiloxane)/fluorinated SiO2 (EDTA/PDMS/F-SiO2) coatings on the surface of a textile with two different sizes of SiO2 particles, which have high transmittance (>90%) and mechanical robustness. The different-sized SiO2 particles were employed to construct the rough micro/nanostructure, fluorinated alkyl silanes were employed as low-surface-energy materials, PDMS was used for its heat-durability and wear resistance, and ETDA was used to strengthen the adhesion between the coating and textile. The obtained surfaces showed excellent water repellency, with a water contact angle (WCA) greater than 175° and a sliding angle (SA) of 4°. Furthermore, the coating retained excellent durability and remarkable superhydrophobicity for oil/water separation, abrasion resistance, ultraviolet (UV) light irradiation stability, chemical stability, self-cleaning, and antifouling under various harsh environments.

Polysaccharidic spent coffee grounds for silver nanoparticle immobilization as a green and highly efficient biocide.

Spent coffee grounds (SCGs) contain abundant polysaccharides and several components with bioactivities. Despite many bio-functionalities, their bioactivities are not always satisfactory. Modifications of SCGs may overcome this issue. This work describes the method for reusing the SCGs as biological macromolecular supports and reducing agents to prepare silver nanoparticle (AgNP)/SCGS composites (AgNPs@SCGs) by biogenic synthesis. The AgNPs anchored on the surface of SCGs were synthesized by mixing the SCGs in AgNO3 solution with various pH conditions at room temperature. Scanning electron microscopy (SEM) and X-ray diffractometer (XRD) analysis confirmed the reduction of silver ions to AgNPs, and showed that the pH 4.5 condition could generate uniform and impurity-free AgNPs on the surface of SCGs. Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), and thermal gravimetric analysis (TGA) showed that the reducing process of AgNPs was mild and could preserve the original nature of the SCGs. The AgNPs@SCGs composites exhibited an excellent antimicrobial ability against S. aureus and E. coli compared to SCGs. The transformation of the polysaccharidic SCGs to AgNPs@SCGs composites by the green and sustainable method makes them highly valuable for developing the applications on antimicrobial products.

Novel synthesis of high-surface-area ordered mesoporous TiO2 with anatase framework for photocatalytic applications.

Ordered mesoporous TiO(2) materials with an anatase frameworks have been synthesized by using a cationic surfactant cetyltrimethylammonium bromide (C(16)TMABr) as a structure-directing agent and soluble peroxytitanates as Ti precursor through a self-assembly between the positive charged surfactant S(+) and the negatively charged inorganic framework I(-) (S(+)I(-) type). The low-angle X-ray diffraction (XRD) pattern of the as-prepared mesoporous TiO(2) materials indicates a hexagonal mesostructure. XRD and transmission electron microscopy results and nitrogen adsorption-desorption isotherms measurements indicate that the calcined mesoporous TiO(2) possesses an anatase crystalline framework having a maximum pore size of 6.9 nm and a maximum Brunauer-Emmett-Teller specific surface area of 284 m(2) g(-1). This ordered mesoporous anatase TiO(2) also demonstrates a high photocatalytic activity for degradation of methylene blue under ultraviolet irradiation.

Sol-gel synthesis and morphological control of nanocrystalline TiO(2) via urea treatment.

Nanocrystalline TiO(2) rods and hollow tubes with an engraved pattern on the surface have been prepared by a novel anionic template-assisted sol-gel synthesis via urea treatment and under hydrothermal condition. X-ray diffractometry (XRD) results indicate that these nanocrystallines consist predominantly of anatase TiO(2), with minor amounts of rutile and brookite. Scanning and transmission electron microscopy (SEM and TEM) analyses reveal these rods and hollow tubes may result from the aggregates of nanorods of approximately 10 nm in diameter. The crystallographic faceting found from TEM further reveals the polymorphic nature of the nanocrystalline TiO(2) thus prepared. A "reverse micelle" formation mechanism taking into account the hydrothermal temperature, the pH effect of the sol-gel system, the isoelectric point, the formation of micelles, and the electrostatic interaction between the anionic surfactant and the growing TiO(2) particulates is proposed to illustrate the competition between the physical micelle assembly of the ionic surfactants and the chemical hydrolysis and condensation reactions of the Ti precursors.