H2SO4 Etching Research Articles

Comparative study on physicochemical properties of macroporous hydroxyapatite coatings on 316L stainless steel implants using sol-gel and inverse opal templating

This study focuses on enhancing metallic implant biocompatibility by fabricating a three-dimensional ordered macroporous hydroxyapatite (HAP) architecture through inverse opal technology. Utilizing colloidal crystal templates on 316L stainless steel, specifically with polystyrene and polymethyl methacrylate, successful fabrication was achieved through H2O2 plus H2SO4 etching. The calcination process at different temperatures (350, 500 and 700°C) resulted in distinct HAP structures, and the sample was calcined at 500°C (HAP500), exhibiting superior physicochemical properties, including enhanced crystallinity, surface roughness and wettability. Biological experiments demonstrated that HAP500 significantly promoted mesenchymal stem cell adhesion and proliferation compared to HAP350 and bare 316LSS, suggesting its potential as a highly effective medical device for bone implantation.

Stability and reactivity improved bimetallic 2D metal organic frameworks for electrocatalytic degradation of p-acetaminophenol

The blooming consumption and disposal of p-acetaminophenol (APAP) calls for green technology for pollution control with high efficiency. In this study, series eco-friendly bimetallic 2D Metal-Organic Frameworks (MOFs)—(NixCuy)HITP were prepared as anode materials for APAP electrocatalytic degradation. With the co-existence of bimetallic centers, about 11–18 % enhanced performance was obtained by comparing with Ni3(HITP)2 and Cu3(HITP)2, resulting in 98 % APAP removal in 40 min. For mechanism, both experiment (Ni/Cu modulation and H2SO4 etching) and density functional theory (DFT) results proved the contributions of metal sites for electron transfer acceleration, rather than as direct active sites. The accelerated electron transfer then bloomed the secondary active species generation, including active chlorine, •O2− and 1O2. Meanwhile, the superior stability and reactivity of (NixCuy)HITP encountered attractive pH tolerance and recycle possibility for practical application. The detailed APAP degradation pathways were further provided according to GC-MS results to complete whole process mechanism discussion from “reaction site” to “activated species ’’ to “ pollutant degradation pathways”.

On the synergistic effect of sulfonic functionalization and acidic adhesive conditioning to enhance the adhesion of PEEK to resin-matrix composites

ObjectiveThe objective of this study was to evaluate the combined effect of the sulfuric acid etching and an acidic adhesive conditioning on the shear bond strength of PEEK to a resin-matrix composite. Materials and methodsForty PEEK specimens were assigned randomly to 4 groups for H2SO4 etching followed by universal adhesive (pH at 2.5) conditioning for 0, 1, 3, and 5 min. Thirty PEEK specimens were divided into 3 groups for only acidic adhesive conditioning for 0, 1, 3, and 5 min. After the light-curing of the adhesive, a nanohybrid resin composite was applied onto the surfaces and then light-cured following the manufacturer`s guidelines. All specimens were stored in distilled water at 37 °C for 24 h mechanical testing. Shear bond strength tests were performed using a universal testing machine. Surfaces were analyzed by SEM, light interferometry, FTIR, and liquid contact angle measurement. Statistical analysis was performed by one-way ANOVA and Tukey’s post hoc tests (p < 0.05). ResultsNo adhesion was achieved between untreated PEEK a resin-matrix composite, regardless of the adhesive conditioning time points. Shear bond strength of H2SO4-etched PEEK to resin-matrix composite increased with time (0 mmin. 4.95 ± 2.86 MPa < 1 min: 9.35 ± 2.26 MPa < 3 min: 17.84 ± 2.82 MPa < 5 min: 21.43 ± 5.00 MPa). SEM images revealed a significant modification of PEEK surface topography after the H2SO4 etching. SignificanceThe acidic adhesive was unable to modify the untreated PEEK surface to establish an effective adhesion although a synergistic effect was noticed when the universal (acidic) adhesive was applied over a H2SO4-etched PEEK surface, thus improving the PEEK to resin-matrix composite adhesion.

Facile synthesis of PVDF photocatalytic membrane based on NCQDs/BiOBr/TiO2 heterojunction for effective removal of tetracycline

Porous TiO2 nanorods were synthesized by H2SO4 etching method, combined with the synthesis technology of BiOBr-TiO2 heterojunction and NCQDs to synthesis the ternary NCQDs-BiOBr-TiO2 photocatalyst. The micromorphology and structural composition of different powder catalysts and photocatalytic composite membranes were studied by means of various characterization methods. The UV–vis DRS results indicated that the formation of BiOBr-TiO2 heterojunction and the introduction of NCQDs extended the visible light absorption range of photocatalytic materials. The BSA adsorption performances of different composite membranes were investigated, and the results showed that 0.5-NCQDs-BiOBr-TiO2/PVDF composite membranes had strong antifouling properties. Moreover, it was found that the 0.5-NCQDs-BiOBr-TiO2/PVDF composite membranes exhibited high regeneration stability and easy separation recovery performance. The results showed that the TC degradation rate of 0.5-NCQDs-BiOBr-TiO2/PVDF composite membranes reached 77% within 120 min. Moreover, the pseudo first order kinetic apparent rate constant k value of the 0.5-NCQDs-BiOBr-TiO2/PVDF composite membranes was 0.01342 min−1.

Sulfuric acid etching for fabrication of porous MnO2 for high-performance supercapacitor

We developed a facile and efficient route to prepare highly porous nanostructure MnO2 by etching of proton-type layered manganese oxide (H-MnO2) with sulfuric acid (H2SO4). Results from TEM images and N2 adsorption showed that H2SO4 etching created porous MnO2 with average pore size of about 4 nm and high specific surface area (315 m2 g−1). With such porous structure, the obtained MnO2 exhibits a high specific capacitance of 253 F g−1 and enhanced rate capability (62.1% capacitance retention from 0.5 to 10 A g−1) when comparing with the H-MnO2 precursor (154 F g−1, 45.5%) and annealed H-MnO2 in the absence of H2SO4 (134 F g−1, 43.3%). The excellent capacitive properties demonstrate that creation of porous structure on H-MnO2 not only provides large ion-accessible surface area for efficient charge storage, but also to some extent promotes the kinetics of electrochemical reactions.

Enhancing Selective Photooxidation through Co–Nx-doped Carbon Materials as Singlet Oxygen Photosensitizers

Singlet oxygen (1O2) is considered one of the most effective and selective oxygen agents. However, it is always obtained with the help of heavy atoms in the photosensitizers to sensitize 3O2. Herein, metal–nitrogen (M–Nx) doped 1O2 photosensitizers were readily prepared from metal–nitrogen complex. Their relative metal centers (e.g., Co) chelated with the N/C moiety (Co–Nx/C) provide the primary active sites for 1O2 generation and selective oxidation. The structures of Co–Nx active sites are investigated by scanning and transmission electron microscopy and X-ray photoelectron, Fourier transform infrared, and X-ray absorption fine structure spectroscopy. Their functions for 1O2 generation are confirmed by electrons spin resonance, 1O2 emission, KSCN poisoning test, and H2SO4 etching test. These Co–Nx photosensitizers show excellent selective photooxidation abilities for 1,5-dihydroxynaphthalene after irradiation by a light-emitting diode lamp. After simple concentration and filtration, it is easy to obtain...

Preparation of rimose NiZnP electrode for hydrogen evolution reaction in alkaline medium by electroless and H2SO4 etching

In this paper, a rimose NiZnP electrode was prepared by electroless and H2SO4 etching. This electrode acts as an efficient and stable catalytic cathode for water splitting, affording 10 mA cm−2 at an overpotential of 50 mV. It is found that using H2SO4 as an etching reagent is favorable for the formation of Ni(OH)2, and can obtain higher eletrocatalytic activity than using NaOH. It is, moreover, verified that the kinetic parameters do not vary with etching time except for the beginning stage through the study of Tafel slopes and normalized exchange current density. At last the analysis of electrochemically surface area proves that the high catalytic activity for hydrogen evolution is owing to the high surface area.

Etching Three-Dimensional Pattern on Sapphire Substrate by Dynamic Self-Masking Alunogen Compound

Maskless H2SO4 wet-etching on sapphire substrates creates three-dimensional pyramidal pattern on sapphire surface. Alunogen self-forming mask grows in H2SO4 etching generating a dynamic self-masking action, which fabricates 3-dimensional pyramidal pattern on the etched sapphire wafers. The slope and size of the pyramids are controlled by rate ratio (k) between alunogen growth rate and c-plane etching rate. Constant k results in flat facet side-planes of sapphire pyramids and varying k in etching produce curved side-planes of the sapphire pyramid. © The Author(s) 2015. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0051506ssl] All rights reserved.

Surface-modified proton conducting perovskite hollow fibre membranes by Pd-coating for enhanced hydrogen permeation

BaCe0.95Tb0.05O3−α (BCTb) proton conducting perovskite hollow fibre membranes were fabricated by the combined phase-inversion and sintering technique. Surface modification was performed by H2SO4 etching and/or by Pd-coating on the hollow fibre surfaces to improve the hydrogen permeation. Hydrogen permeation fluxes through the resultant hollow fibre membranes were measured between 650 and 1000 °C, using 50–50% H2–He feed on the shell side and N2 as the sweep gas in the fibre lumen. The results indicate that coating porous Pd layers on the hollow fibre membrane surfaces could promote remarkably the hydrogen flux, i.e. from 0.046 mL cm−2 min−1 at 900 °C in the original hollow fibre, to 0.272 mL cm−2 min−1 in the Pd-coated membrane, whereas the H2SO4 etching modification would deteriorate the hydrogen permeation due to the contamination of sulphur-containing compounds. The surface exchange kinetics plays an important role in the hydrogen permeation through the BCTb perovskite membranes, which can be improved by coating porous Pd layers on either or both surfaces of the hollow fibre perovskite membranes.

Improvement in the Etching Performance of the Acrylonitrile–Butadiene–Styrene Resin by MnO2–H3PO4–H2SO4 Colloid

The present study aimed to evaluate the surface etching of the acrylonitrile-butadiene-styrene (ABS) resin in the MnO2-H3PO4-H2SO4 colloid. To enhance the soluble Mn(IV) ion concentration and improve the etching performance of ABS resin, H3PO4 was added as a complexing agent into the MnO2-H2SO4 etching system. The effects of the H2SO4 concentration and etching time on the surface topography, surface roughness, adhesion strength, and the surface chemistry of the ABS substrates were investigated. The optimal oxidation potentials of MnO2 in the colloids decreased from 1.426 to 1.369 V with the addition of H3PO4. Though the etching conditions changed from 70 °C for 20 min to 60 °C for 10 min, the adhesion strength between the ABS substrates and electroless copper film increased from 1.19 to 1.33 KN/m after etching treatment. This could be attributed to the significant increase of the soluble Mn(IV) ion concentration in the MnO2-H3PO4-H2SO4 colloid. The surface chemistry results demonstrated that the oxidation reaction of -C═C- bonds in the polybutadiene phase was accelerated in the etching process by the addition of H3PO4, and the abundant -COOH and -OH groups were formed rapidly on the ABS surface with the etching treatment. These results were in agreement with the results of surface scanning electron microscopic observations and adhesion strength measurement. The results suggested that the MnO2-H3PO4-H2SO4 colloid was an effective surface etching system for the ABS surface roughness.

Effect of barium-containing glass filler reinforcement on shear bond strength of poly(ether ether ketone) to resin cement

The purpose of this study was to evaluate how barium-containing glass filler (BGF) reinforcement and pretreatment methods affect shear bond strength (SBS) of poly(ether ether ketone) (PEEK) to resin cement. PEEK composites with various amounts of BGF (10, 20, 30 and 40 wt%) were prepared as PEEK-BGF10, PEEK-BGF20, PEEK-BGF30 and PEEK-BGF40. Afterward, PEEK and PEEK-BGF40 specimens were treated with hydrofluoric acid, sulfuric acid (H2SO4), silica coating and polishing, respectively. Acrylic hollow cylinders were luted with Dentex dual-curing resin cement to the specimens. Finally, SBS measurements were conducted with a universal testing machine. The introduction of BGFs greatly enhanced SBS of PEEK to resin cement. After simply polishing with 150 grit silicon carbide papers (G150), PEEK-BGF40 exhibited the SBS value up to 19.73 ± 4.30 MPa, similar to the PEEK treated with H2SO4 etching. Scanning electron microscopy and x-ray photoelectron spectroscopy were used to investigate the surface morphological and chemical changes in PEEK and PEEK-BGF composites before and after surface treatment. The results indicate that the introduction of BGF particles plays a key role in improving the adhesion between PEEK and resin cement. This study provides a new method to enhance the adhesion to PEEK without breaking its surface structure, which encourage further research in PEEK composite application in dentistry.

Surface Properties and Biocompatibility of Acid-etched Titanium

The purpose of this study was to evaluate the effects of acid-etched titanium on the biological responses of osteoblast-like MC3T3-E1 cells. Four types of treatments (polishing, sandblasting, concentrated H2SO4 etching, and concentrated H2SO4 etching with vacuum firing) were carried out on the surfaces of commercially pure titanium (cpTi) disks. MC3T3-E1 cells were then cultured on the treated cpTi surfaces. Through surface roughness measurement and SEM analysis, it was found that the acid-etched surfaces showed higher roughness values than the sandblasted ones. Scanning electron microscope analysis showed that the cells on the disks treated with acid-etching and acid-etching with vacuum firing spread as well as the sandblasted ones. There were no significant differences in cell proliferation and collagen production on cpTi among the four different surface treatments. Based on the results of this study, it was concluded that etching with concentrated sulfuric acid was a simple and effective way to roughen the surface of titanium without compromising its biocompatibility.

Surface modifications of Cu(In,Ga)S2 thin film solar cell absorbers by KCN and H2O2∕H2SO4 treatments

KCN etching of the CuxS surface layer formed during the production process of Cu(In,Ga)S2 thin film solar cell absorbers as well as subsequent H2O2∕H2SO4 etching of the Cu(In,Ga)S2 surface have been investigated using x-ray photoelectron spectroscopy, x-ray excited Auger electron spectroscopy, and x-ray emission spectroscopy. We find that the KCN etching removes the CuxS layer—being identified as Cu2S—and that there is K deposited during this step, which is removed by the subsequent H2O2∕H2SO4 oxidation treatment. When a CdS buffer layer is deposited on the absorber directly after KCN etching, a K compound (KCO3) is observed at the CdS surface.

Effect of Concentrated Sulfuric Acid-Etching on Apatite-Forming Ability of Alkaline-Treated Titanium

Concentrated H2SO4 acid was applied to pretreatment for the alkaline treatment of commercially pure titanium, and the effect of acid-etching on apatite-forming ability of alkaline-treated titanium in a simulated body fluid (SBF) was investigated. Characterization analysis revealed that the concentrated H2SO4 etching formed much amount of sodium titanate, resulting a large amount of formation of apatite in SBF. It is confirmed that the etching in concentrated H2SO4 enhance apatite-forming ability of alkaline-treated titanium.

The Development of a Highly Selective KI/I2/H2O/H2SO4 Etchant for the Selective Etching of Al0.3Ga0.7As over GaAs

The selective etching of n-Al0.3Ga0.7As with respect to p+-GaAs is useful for the fabrication of AlGaAs/GaAs heterojunction bipolar transistors (HBTs). The KI/I2/H2O/H2SO4 etching solution was found to be superior to the KI/I2/H2O solution in terms of selectivity. The selectivity could be furthered improved by aging the etching solution for 3 days and by lowering the temperature from room temperature to the ice point. The best selectivity achieved was 330 with etch rates of 0.165 µ m/min and 0.0005 µ m/min for Al0.3Ga0.7As and GaAs respectively for a stabilized KI/I2/H2O/H2SO4 at an etching temperature of 3° C.

OMVPE regrowth of CH3I-vapor-etched GaAs

In experiments on the interrupted growth of GaAs by organometallic vapor phase epitaxy (OMVPE), we have compared the properties of two types of epilayers: those grown on CH3I-vapor-etched first epilayers and those grown on first epilayers that were either untreated or etched with H2SO4. The OMVPE growth and CH3I etching were performed in two different reactors, and each sample was briefly exposed to air immediately before being placed in the OMVPE reactor for growth of the second epilayer. For CH3I etch temperatures below 500° C, the two types of second epilayers are comparable in surface morphology, as characterized by Nomarski interference microscopy, and in optical quality, as characterized by low-temperature photoluminescence measurements. Electrical characterization by C-V depth profiling shows that electron accumulation at the regrowth interface is increased very little by CH3I etching. Such etching prior to regrowth eliminates most of the electron accumulation resulting from H2SO4 etching of the first epilayer.