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Raw kaolinite was used as a precursor for several types of modified kaolinite. The modification processes included modification by sodium hydroxide, sodium phosphate, sodium sulfate, CTAB, and sodium acetate. The structural, morphological, and chemical properties of raw kaolinite and the modified products were evaluated using XRD, SEM, TEM, and FT-IR analyses. The modified products were used as adsorbent materials for acidic Congo red dye from aqueous solutions. The adsorption processes were evaluated as a function of reaction time, initial dye concentration, and adsorbent masses. Phosphate-modified kaolinite achieved the best removal results followed by sulfate-modified kaolinite and kaolinite sample modified by CTAB. Kinetic studies indicated that the adsorption equilibrium was obtained after 360 min for the samples, which were modified by NaOH and CTAB, whereas the modified samples that were treated by phosphate, sulfate and, acetate achieve the equilibrium after 240 min. The adsorption by all the products is of chemical nature occurs through energetically heterogeneous surfaces and fitted well with pseudo-second order kinetic model. The equilibrium studies revealed that the adsorption using kaolinite modified by sodium hydroxide, sodium phosphate, and sodium sulfate occurs in monolayer form and represented well by Langmuir model. The estimated q max values are 136.98, 149.25, and 135.13 mg/g for the three products in order. The uptake using modified kaolinite by CTAB and sodium acetate shows more fitting with Tamkin and Freundlich isotherm models rather than with Langmuir model. Kaolinite sample was modified by organic and inorganic salts to enhance its adsorption properties. Modified kaolinite samples exhibit changes in the structural and morphological features. The modified samples showed high adsorption capacity than raw kaolinite. Highlights Kaolinite was modified by several inorganic and organic salts. Effect of modification and the structural and morphological features was investigated. The adsorption behavior of the modified products for Congo red dye was addressed. The change in the adsorption behavior was studied through kinetic and isotherm studies.

Heat-assisted plasma (HAP) treatment using He gas is known to improve the adhesive-bonding and adhesive-free adhesion properties of polytetrafluoroethylene (PTFE). In this study, we investigated the effects of He and Ar gaseous species on the HAP-treated PTFE surface. Epoxy (EP) adhesive-coated stainless steel (SUS304) and isobutylene–isoprene rubber (IIR) were used as adherents for the evaluation of the adhesive-bonding and adhesive-free adhesion properties of PTFE. In the case of adhesive bonding, the PTFE/EP-adhesive/SUS304 adhesion strength of the Ar-HAP-treated PTFE was the same as that of the He-HAP-treated PTFE. In the case of adhesive-free adhesion, the PTFE/IIR adhesion strength of the Ar-HAP-treated PTFE was seven times lower than that of the He-HAP-treated PTFE. The relation among gaseous species used in HAP treatment, adhesion properties, peroxy radical density ratio, surface chemical composition, surface modification depth, surface morphology, surface hardness, and the effect of irradiation with vacuum ultraviolet (VUV) and UV photons were investigated. The different adhesive-free adhesion properties obtained by the two treatments resulted from the changes in surface chemical composition, especially the ratios of oxygen-containing functional groups and C–C crosslinks.

Titanium is widely used in medical implants despite the release of heavy metal ions over long-term use. Zirconia is very close to the color of teeth; however, its biological inertness hinders bonding with bone tissue. Alkaline treatment and coatings of calcium phosphate can be used to enhance bone regeneration adjacent to dental implants. This study examined the effects of alkaline treatment, calcium phosphate coatings, and sintering, on the physical properties of implant material. Our analysis confirmed that the calcium phosphate species were octacalcium phosphate (OCP). The sintering of calcium phosphate was shown to create B-type HAP, which is highly conducive toward the differentiation of mesenchymal stem cells (MSCs) into osteoblasts for the facilitation of bone integration. Conclusions: This study demonstrated the room-temperature fabrication of dental implants with superhydrophilic surfaces to enhance biocompatibility.

In order to solve the problem of blocking the filter media when bag filters are used to deal with high-humidity dust, hydrophobic surface-modified filter media were prepared. Here we constructed a multi-layer rough structure using TiO 2 and SiO 2 , with polydimethylsiloxane (PDMS) subsequently deposited to reduce its surface energy to prepare stable and robust TiO2–SiO2@PDMS modified superhydrophobic filter media. Through modification of the filter media, its surface was changed from superhydrophilic to superhydrophobic, and the water contact angle reached 158°. For the particles with 0.3 μm, the filtration efficiency and quality factor of the modified filter media are higher than those of the unmodified filter media at a flow velocity of 0.043–0.127 m/s, which improves the filtration performance of the filter media. In addition, the modified filter media has strong durability in harsh environmental conditions (such as mechanical wear, strong acid or alkali solution), and has excellent self-cleaning performance. Therefore, such superhydrophobic filter media have great potential for the application of bag filters in various industrial production processes. Graphical abstract Highlights Superhydrophobic filter media is prepared by TiO2–SiO2@PDMS coating. The filtration efficiency and quality factor of the modified filter media are improved by 4.64% and 0.52% on average compared with the unmodified filter media. The filter media modified by TiO2–SiO2@PDMS has excellent stability and self-cleaning performance.

In this study, a surface hardening of AISI 52100 bearing steel was performed by ultrasonic nanocrystal surface modification (UNSM), and electrolytic-plasma thermo-cyclic surface modification (EPSM), and their effects on the wear resistance were investigated. To evaluate the impact of these treatments on the wear resistance, the friction tests under dry conditions were conducted using a ball-on-disk tribometer in accordance with ASTM G99. The microstructure of the samples before and after treatment was characterized by scanning electron microscopy. The micro-hardness with respect to the depth from the top surface was measured using a Vickers micro-hardness tester. Microstructural observations showed that EPSM treatment led to the formation of residual austenite in the surface layer, while UNSM treatment led to the formation of a surface severe plastic deformation layer on the surface of the samples. The increase in the micro-hardness of the treated layer was confirmed after UNSM at room temperature and after EPSM at different cycles. The highest increase in wear resistance was observed for the specimen treated by UNSM treatment at 700 °C and five cycles of EPSM treatment. In addition, the wear volume, which has correlation with the friction coefficient and hardness, was determined.

Sol–gel technology continues to interest researchers from both industries and governmental institutions in many parts of the world decades after its discovery. It offers efficient and high-purity production of nanopowders, fibres, solid structures and thin-film coatings. Possible applications of sol–gel technology can be found in a wide range of sectors, such as pharmacy, medicine, construction, aerospace, transport, food industry, optics, agriculture, semiconductor devices, catalysis and biotechnology. Also in the textile sector, sol–gel technology is expected to lead the production of fabrics with completely novel properties or the combination of various functions in one fabric. The sol–gel reaction is easy to perform and does not require special conditions and high temperatures. The reaction consists of a series of simple hydrolysis and condensation reactions. This paper presents an overview of sol–gel technology and discusses the fabric functions that can be achieved by the technology. Graphical Abstract

This study is focused on developing visible-light sensitive anatase TiO 2 photocatalysts rather than the conventional UV-sensitive photocatalysts. We have adopted a surface modification technique using sodium borohydride (NaBH 4 ) chemical treatment. Thermal treatment under remarkably, favourable ambient air conditions were employed in this work instead of the previously reported inert gas or vacuum conditions, making it noteworthy. The synthesized surface-modified anatase TiO 2 is yellow in colour and has a crystalline core and disordered shell structure. The surface-modified sample was enriched with photocatalytically active shallow-traps due to the presence of Ti 3+ ions and singly ionized oxygen vacancies (V o + ). This surface-modified TiO 2 sample showed enhanced photodegradation of organic pollutants under visible light. The photocatalytic performances of the pristine and surface-modified samples were compared with the commercially available standard photocatalyst, Degussa P25. Notably, the surface-modified sample showed the highest degradation of Rhodamine B (RhB) dye, with a rate constant of 6.11 × 10 –3 min −1 . In contrast, the corresponding values for the pristine sample and Degussa P25 catalysts were only 4.15 × 10 –3 and 1.92 × 10 –3 min −1 , respectively. Our study summarises that surface modification is an effective strategy for developing efficient visible-light-sensitive TiO 2 photocatalysts. Graphical Abstract

Zirconia is a promising material for dental implants; however, an appropriate surface modification procedure has not yet been identified. Atomic layer deposition (ALD) is a nanotechnology that deposits thin films of metal oxides or metals on materials. The aim of this study was to deposit thin films of titanium dioxide (TiO2), aluminum oxide (Al2O3), silicon dioxide (SiO2), and zinc oxide (ZnO) on zirconia disks (ZR-Ti, ZR-Al, ZR-Si, and ZR-Zn, respectively) using ALD and evaluate the cell proliferation abilities of mouse fibroblasts (L929) and mouse osteoblastic cells (MC3T3-E1) on each sample. Zirconia disks (ZR; diameter 10 mm) were fabricated using a computer-aided design/computer-aided manufacturing system. Following the ALD of TiO2, Al2O3, SiO2, or ZnO thin film, the thin-film thickness, elemental distribution, contact angle, adhesion strength, and elemental elution were determined. The L929 and MC3T3-E1 cell proliferation and morphologies on each sample were observed on days 1, 3, and 5 (L929) and days 1, 4, and 7 (MC3T3-E1). The ZR-Ti, ZR-Al, ZR-Si, and ZR-Zn thin-film thicknesses were 41.97, 42.36, 62.50, and 61.11 nm, respectively, and their average adhesion strengths were 163.5, 140.9, 157.3, and 161.6 mN, respectively. The contact angle on ZR-Si was significantly lower than that on all the other specimens. The eluted Zr, Ti, and Al amounts were below the detection limits, whereas the total Si and Zn elution amounts over two weeks were 0.019 and 0.695 ppm, respectively. For both L929 and MC3T3-E1, the cell numbers increased over time on ZR, ZR-Ti, ZR-Al, and ZR-Si. Particularly, cell proliferation in ZR-Ti exceeded that in the other samples. These results suggest that ALD application to zirconia, particularly for TiO2 deposition, could be a new surface modification procedure for zirconia dental implants.

Due to immense population growth and economic development, the use of crude oil for various energy applications has escalated in the past few decades. This has led to the large-scale exploitation of oil reserves which has further resulted in the accidental release of large amounts of oil into our oceans. In recent years, significant emphasis has been placed on processes involving oil sorption by various natural and synthetic sorbents. Several sorbent materials based on synthetic polymers such as polypropylene, polyurethane, polystyrene, etc., possessing three-dimensional porous structure, large surface area, high mechanical strength, and exhibiting good oil recoverability and reusability, have been employed for oil-water separation processes. Conversely, many of these materials in their native or pristine form are amphipathic, which prevents their large-scale use in oil spill clean-up. This has led to researchers exploring surface modifications of commercially available sorbent polymeric materials to enhance their oleophilicity and hydrophobicity. This review article summarizes and discusses recent advances in the strategies for the fabrication of newer surface-modified synthetic polymeric materials and natural bio-based sorbents, and further highlights their effectiveness in dealing with the oil/water separation challenges.

In this study, we developed a one-step method for fabricating hydrophobic surfaces on copper (Cu) substrates. Cuprous oxide (Cu2O) with low free energy was successfully formed after low-fluence laser direct irradiation. The formation of Cu2O enhanced the hydrophobicity of the Cu substrate surface, and the contact angle linearly increased with the proportion of Cu2O. The Cu2O fabricated by low-fluence laser treatment showed the same crystal plane orientation as the pristine Cu substrate, implying an epitaxial growth of Cu2O on a Cu substrate.