Alkaline Hydrothermal Treatment Research Articles

Alkaline hydrothermal treatment of gentamycin mycelial residues: characteristics of disintegration, solid-state fermentation, and antibiotic resistance genes reduction

Alkaline hydrothermal treatment of gentamycin mycelial residues: characteristics of disintegration, solid-state fermentation, and antibiotic resistance genes reduction

Study on the Synthesis and Photocatalytic Performance of Modified TiO2 Supported by G‐C3N4 in the Degradation of 2,4‐Dichlorophenoxyacetic Acid

AbstractThe impact of alkaline hydrothermal treatment on the structure and morphology of Degussa P25 was evaluated. The modification results in a larger surface area, which improves 2,4‐dichlorophenoxyacetic acid (2,4‐D) adsorption capacity and has a remarkable effect on the 2,4‐D photocatalytic degradation. The 30 % mod. TiO2/g‐C3N4 and 50 % mod.TiO2/g‐C3N4 composites were made by combining the treated Degussa P25 with g‐C3N4 at mass ratios of 30 % and 50 %. Using XRD, SEM, EDX, BET, UV‐vis DRS, and PL, the synthesized materials were physically characterized. When compared to their pure components, the composites show a longer “lifetime” of charge carriers and a reduced energy band gap. The 2,4‐D degradation under visible light irradiation (λ>400 nm) was used to assess their photocatalytic activity. The influence of pH and 2,4‐D initial concentration were investigated. The enhanced 2,4‐D degradation efficiency of more than 80 % is ascribed to the cooperative photocatalytic action of mod.TiO2 and g‐C3N4. Both ⋅OH, O2⋅− radicals and h+ were the ROS dominating the degradation of 2,4‐D under investigated experimental circumstances. The 2,4‐D photocatalytic degradation follows pseudo‐first order kinetics. The findings of this work indicate that Degussa P25/g‐C3N4‐based photocatalysts may be employed, depending on the pH conditions, in the wastewater treatment.

Optimization of alkaline hydrothermal treatment for humic acids production from corn straw digestate using the response surface methodology

Anaerobic digestion (AD) technology was widely used for treating waste biomass, during which a large amount of lignin-rich digestate would be produced, needing further treatment. In this study, corn straw digestate (CSD) was used as raw material for hydrothermal humic acids (HHA) producing through alkaline hydrothermal treatment (AHT). According to the response surface analysis, the optimal reaction conditions were determined to be 156°C, 2 hours, and 5% KOH (% of the dry digestate), resulting in a HHA yield of 40.3 wt%. Structural characterization analysis showed the produced HHA had abundant oxygen-containing functional groups (e.g., C-O and CO) in HHA and aromatic structures, which also showed good thermal stability. By AHT with hemicellulose and lignin, the HHA yields reached 79.2%. Hemicellulose and lignin proved to be important components for HHA formation. In addition, the protein content in the EPS extraction solution of HC was significantly reduced compared to CSD, indicating that the dewaterability of the digestate were improved after AHT. This technique provides a feasible approach for the further utilization of residual lignocellulosic materials after anaerobic digestion.

Exceptional levofloxacin adsorption/photo-regeneration cycles using nanosheets-like hollow TiO2 adsorbent: Adsorption performance and mechanism

Exploring efficient adsorbents still remains an important challenge due to the poor efficiency of the reported adsorbents for the adsorption of antibiotics. Herein, we design and prepare a novel nanosheets-like hollow TiO2 (NHT) adsorbent by using hollow TiO2 as a precursor through alkaline hydrothermal treatment. Adsorption results show that NHT exhibits a high adsorption percentage (98.05%) within 20 min and a maximum adsorption uptake of 24.51 mg/g for Levofloxacin (LVOF) pollutant (10 mg/L, 50 mL), which is 17 times higher than that (1.4 mg/g) of pristine hollow TiO2 (HT). Notably, NHT realizes >91% of the adsorption percentage for LVOF pollutant after the tenth run only through photo-regeneration without extra post-treatments, effectively overcoming the disadvantages of harsh regeneration procedures for most of the existed adsorbents. Adsorption data and the performance characterizations present deep insights into adsorption mechanism, which reveals that pore filling effect, hydrogen-bond interactions, and electrostatic attraction are the key parameters for the excellent adsorption of LVOF by NHT. Therefore, the present study can provide a promising direction for the fabrication of efficient adsorptive photocatalyst by using low-cost TiO2 as a precursor.

Alkaline Hydrothermal Treatment of Chabazite to Enhance Its Ammonium Removal and Recovery Capabilities through Recrystallization

The treatment of chabazite (CHA), a natural zeolite, with the alkaline hydrothermal method to improve its ion-exchange capacity is a widely adopted route by environmental scientists for the purpose of better ammonium (NH4+) removal from wastewater. This work addresses a noteworthy trend in environmental science, where researchers, impressed by the increased ion-exchange capacity achieved through alkaline hydrothermal treatment, often bypass the thorough material characterization of treated CHA. The prevalent misconception attributes the improved features solely to the parent zeolitic framework, neglecting the fact that corrosive treatments like this can induce significant alterations in the framework and those must be identified with correct nomenclature. In this work, alkaline-mediated hydrothermally treated CHA has been characterized through X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), solid-state magic-angle spinning nuclear magnetic resonance (MAS-NMR), high-resolution transmission electron microscopy (HRTEM), and energy-dispersive X-ray spectroscopy (EDS) and it is concluded that the treated samples have been transformed into a desilicated, aluminum (Al)-dense framework of analcime (ANA) with a low silica–alumina ratio and with a strikingly different crystal shape than that of parent CHA. This treated sample is further examined for its NH4+ removal capacity from synthetic wastewater in a fixed-bed column arrangement. It achieved a maximum NH4+ removal efficiency of 4.19 meq/g (75.6 mg/g of NH4+), twice that of the parent CHA. Moreover, the regeneration of the exhausted column yielded a regenerant solution, with 94% reclaimed NH4+ in it, which could be used independently as a nitrogenous fertilizer. In this work, the meticulous compositional study of zeolitic materials, a well-established practice in the field of material science, is advocated for adoption by environmental chemists. By embracing this approach, environmental scientists can enhance their comprehension of the intricate changes induced by corrosive treatments, thereby contributing to a more nuanced understanding of zeolitic behavior in environmental contexts.

Titanium-based substrate modified with nanoenzyme for accelerating the repair of bone defect

Titanium (Ti) and titanium alloy are the most common metal materials in clinical orthopedic surgery. However, in the initial stage of surgery and implantation, the production of excessive reactive oxygen species (ROS) can induce oxidative stress (OS) microenvironment. OS will further inhibit the growth of new bone, resulting in surgical failure. In this study, based on the fact that nanoscale manganese dioxide (MnO2) can show H2O2-like enzyme activity, a MnO2 nanocoating was prepared on mciro-nano structured surface of Ti substrate via a two-step method of alkaline thermal and hydrothermal treatment. The results of scanning electron microscopy (SEM), X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) showed that the nano-MnO2 coating was successfully fabricated on the surface of Ti substrate. The results of measurement of H2O2, dissolved O2 and intracellular ROS in vitro showed that the treated Ti substrate could efficiently eliminate H2O2 and reduce ROS. Furthermore, the modified Ti substrate could promote the early adhesion, proliferation and osteogenic differentiation of MSCs, which was demonstrated by experimental results of cell morphology, cell viability, alkaline phosphatase, collagen, and mineralization deposition. The results of quantitative real-time polymerase chain reaction (qRT-PCR) of MSCs adhered the modified Ti substrate showed that the expression of genes related to osteogenic differentiation significantly increased. More importantly, the modified Ti implant could eliminate ROS at the injury site, reduce OS and promote the regeneration of bone tissue, which was demonstrated via hematoxylin/eosin, Masson's trichrome and immunohistochemical staining. In conclusion, the modified Ti implant presented here had the effect of reducing OS and promoting osseointegration. Relevant research ideas and results provide new methods for the research and development of functional implants, which have potential application value in the field of orthopedics.

Morphological evolution and biocorrosion response of a hierarchical micro- nano-structured Ti alloy: Physico-chemical characterization and electrochemical studies

In the present study, hierarchically architectured micro/nano-scale surface topography inspired from the leaves of Euphorbia myrsinites was fabricated on Ti-6Al-4V ELI alloy through laser micro-texturing (LT) followed by alkaline hydrothermal treatment (HT). The hybrid (LT + HT) surface revealed distinct multi-scaled morphological features differing from individually treated LT and HT surfaces. Alongside topographical cues, the evolved elemental and phase constitution also influenced the wettability, mechanical and corrosion properties. The (LT + HT) surface exhibited improved hydrophilicity and reduced surface stiffness of ~14.82 GPa (closely mimicking human bone-tissue), attributing to a hydrothermally-induced porous titania-layer extending up to a few microns depth. Corrosion tests in Hank's solution revealed that HT alone couldn't substantially improve the corrosion resistance as compared to polished surface (control). Integrating LT with HT not only altered the surface topography, but also introduced a relatively denser barrier-oxide layer (laser-induced oxidation) that transformed into a stable anatase-rich phase structure upon hydrothermal etching and subsequent annealing. Both LT and (LT + HT) recorded reduced corrosion current densities and suppressed corrosion rates, but (LT + HT) performed substantially better in the anodic polarization regime (till 2 V), with passivation current densities reduced by at least two orders of magnitude. AC impedance studies affirmed the role of an adsorptive nanostructured outer-layer in (LT + HT) towards accelerating the passivation kinetics, while the inner barrier layer imposed higher charge transfer resistance. Also, better biomineralization ability was observed in (LT + HT) after 30 days immersion in Hank's solution, with Ca: P (at. ratio) ~1.4, thereby indicating higher propensity of apatite nucleation.

Effects of various factors on gangue removal in alkaline hydrothermal treatment of iron ores

The upgrading technology of low-grade iron ores by alkaline treatment was investigated in this study. The basic experiments (evaluation of the effects of solvent types, treatment temperature, holding time, solvent concentration, particle size, and solid–liquid ratio) were carried out with the alkaline hydrothermal treatment in a small batch-type reactor. The gangue removal rate in the 5 M NaOH hydrothermal treatment increased with the increase in treatment temperature, and about 90% of Si, Al, and P could be removed below 250 °C. The gangue removal rate tended to increase with the increase in NaOH concentration, the decrease in particle size, and the decrease in solid–liquid ratio. The order of the removal rate was P < Al < Si. The optimum conditions for alkaline hydrothermal treatment were found to be as follows: particle size, <500 μm; solvent, NaOH; solvent concentration, >0.1 M; solid–liquid ratio, ≤1.2; heating temperature, ≥150 °C; and holding time, 30 min. According to the results of XRD and N2 adsorption measurements of the treated ores, the gangue removal from low-grade iron ores, the improvement of Fe quality (higher Fe content), and densification were possible by alkaline hydrothermal treatment.

Unlocking the potential of humic acid production through oxygen-assisted hydrothermal humification of hydrochar

The utilization of biomass as a raw material and production of hydrothermal humic acid (HHA) through hydrothermal method using hydrochar as an intermediate product is a sustainable approach for the preparation of humic acid. In this study, hydrochar was prepared through acid hydrothermal treatment of corn straw and then oxygen was introduced to alkaline hydrothermal treatment of hydrochar to improve the yield of humic acid. It was discovered that an oxygen pressure of 5 bar could significantly enhance the yield of HHA from 41.9 wt% to 49.2 wt% at a hydrothermal temperature of 180 °C, while oxygen pressures of 10 bar and 20 bar led to a decrease in HHA yield (41.5 wt% to 28.2 wt%). Oxygen addition could also reduce the energy input and the economic cost required for hydrothermal reactions. Further study revealed that the increase in HHA yield was the oxidation of aliphatic carbon in the solid residue derived from hydrochar by oxygen, which became part of the HHA and resulted in weaker fluorescence intensity of the HHA. However, excessive oxygen could increase the oxygen-containing functional groups of the HHA while also causing further cleavage of macromolecular components with high carbon numbers, generating smaller molecules that partially dissolve in the liquid phase. The HHA synthesized at an oxygen pressure of 5 bar showed good performance in promoting Chinese cabbage seedlings growth and was superior to the HHA synthesized in the absence of oxygen in terms of cadmium adsorption. This study proved an improved hydrothermal humification method and provided technical support for industrial applications.

Efficient enrichment of platinum group metals from spent automotive catalysts by alkaline hydrothermal treatment and the subsequent acid leaching method

Spent automotive catalysts (SAC) is the most important secondary resource for the recovery of platinum group metals (PGMs). This paper demonstrates that the acid-resistant and alkali-resistant cordierite carrier can be transformed into hydroxysodalite by a alkaline hydrothermal treatment (AHT), which can then be dissolved by subsequent acid leaching (AL) to enrich PGMs. Experiments were conducted to assess the influencing factors and the optimal conditions were determined as follows: holding temperature of 150 °C; NaOH to raw material mass ratio 10:10; holding time of 60 min; liquid to solid ratio of 3:1, and stirring speed of 400 rpm. The residue ratio in the AHT process was 132.57% under optimized conditions. The total residue ratio was 18.68% under fixed acid leaching experimental conditions of holding temperature of 60 °C, liquid to solid ratio of 15:1, holding time of 60 min, stirring speed of 400 rpm, and hydrochloric acid concentration of 2.5 mol·L-1. The contents of Pt, Pd, and Rh in the enriched residue reached 650.50, 2131.54, and 405.28 g·t−1, respectively, and the corresponding enrichment times were 7.13, 7.25, and 7.07. The additions of sodium formate before the AHT and aluminum powder during the AL were found to effectively inhibit PGMs leaching. The losses of Pt, Pd, and Rh throughout the entire process were only 2.77%, 1.89%, and 4.28%, respectively.

Alkaline hydrothermal activation of molybdenum tailings to prepare one-part geopolymer: Activation mechanism and strength

Molybdenum tailings (MT) are solid waste from molybdenum ore beneficiation, which can cause environmental pollution when stored in tailings ponds for a long time. The use of alkaline hydrothermal activation to improve the low reactivity of MT as an active precursor to one-part geopolymers is a novel way to resource MT. This paper evaluates the feasibility of alkaline hydrothermal activation of MT and investigates the mechanical properties of the activated MT base polymer prepared by a one-part method. The results showed that alkaline hydrothermal activation greatly promoted the dissolution of silicon in MT, weakened the crystal properties of quartz phase in MT and destroyed the original structure of MT. The amorphous sodium aluminosilicate on the surface of activated MT dissolves in water and provides an alkaline environment for the geological polymerization reaction. Combined with the analytical results of XRD and FTIR, the alkaline hydrothermal activation of MT was controlled by the optimal sodium hydroxide solution concentration, activation temperature and activation time of 5 M NaOH, 200 °C and 4 h, respectively. Based on this, the one-part geopolymer was prepared directly by adding water to activated MT 5-4-200 and slag, and the compressive strength can be improved. SEM and EDS results show that alkaline hydrothermal activation treatment renders inert MT reactive and the reaction product of activated MT and slag forming a one-part geopolymer is an amorphous C(N)A-S-H gel.

Experimental and Theoretical Insight of Perfluorooctanoic Acid Destruction by Alkaline Hydrothermal Treatment Enhanced with Zero-Valent Iron in Biochar

Experimental and Theoretical Insight of Perfluorooctanoic Acid Destruction by Alkaline Hydrothermal Treatment Enhanced with Zero-Valent Iron in Biochar

Co3O4/hydrogen titanate composite nanomaterials with enhanced enzyme-like activity for antibacterial application

Co3O4/hydrogen titanate (HTO) nanocomposites were prepared though a facile dissolution-reprecipitation method and post alkaline hydrothermal treatment. Compared with pure Co3O4, as-designed Co3O4/HTO catalyst with optimum Ti/Co ratio showed highly enhanced peroxidase-like activity that can catalyze H2O2 to produce more reactive oxygen species. The enhanced enzyme-like catalytic performance was contributed to the HTO sheets that prevent the agglomeration of Co3O4 nanoparticles during the preparation, and thus expose more catalytic active sites. As a result, the bacteriostatic efficiencies of the catalyst against E. coli with the presence of 1 mM H2O2 is about 2 times higher than that without H2O2 addition, exhibiting an excellent bacteriostatic activity.

Synthesis, Characterization of NaA Zeolite from Blast Furnace Slag (BFS) via Alkaline Fusion and Hydrothermal Treatment

Synthesis, Characterization of NaA Zeolite from Blast Furnace Slag (BFS) via Alkaline Fusion and Hydrothermal Treatment

Novel Strategy for Surface Modification of Titanium Implants towards the Improvement of Osseointegration Property and Antibiotic Local Delivery

The topography and chemical composition modification of titanium (Ti) implants play a decisive role in improving biocompatibility and bioactivity, accelerating osseointegration, and, thus, determining clinical success. In spite of the development of surface modification strategies, bacterial contamination is a common cause of failure. The use of systemic antibiotic therapy does not guarantee action at the contaminated site. In this work, we proposed a surface treatment for Ti implants that aim to improve their osseointegration and reduce bacterial colonization in surgery sites due to the local release of antibiotic. The Ti discs were hydrothermally treated with 3M NaOH solution to form a nanostructured layer of titanate on the Ti surface. Metronidazole was impregnated on these nanostructured surfaces to enable its local release. The samples were coated with poly(vinyl alcohol)-PVA films with different thickness to evaluate a possible control of drug release. Gamma irradiation was used to crosslink the polymer chains to achieve hydrogel layer formation and to sterilize the samples. The samples were characterized by XRD, SEM, FTIR, contact angle measurements, "in vitro" bioactivity, and drug release analysis. The alkaline hydrothermal treatment successfully produced intertwined, web-like nanostructures on the Ti surface, providing wettability and bioactivity to the Ti samples (Ti + TTNT samples). Metronidazole was successfully loaded and released from the Ti + TTNT samples coated or not with PVA. Although the polymeric film acted as a physical barrier to drug delivery, all groups reached the minimum inhibitory concentration for anaerobic bacteria. Thus, the surface modification method presented is a potential approach to improve the osseointegration of Ti implants and to associate local drug delivery with dental implants, preventing early infections and bone failure.

KOH-Based Hydrothermal Synthesis of Iron-Rich Titanate Nanosheets Assembled into 3D Hierarchical Architectures from Natural Ilmenite Mineral Sands

The synthesis of titanate nanostructures from low-cost mineral precursors is a topic of continuous interest, considering not only their fundamental aspects but also the benefits of incorporating such nanomaterials in a wide variety of applications. In this work, iron-rich titanate nanosheets were synthesized from Ecuadorian ilmenite sands (ilmenite–hematite solid solution-IHSS) through an alkaline hydrothermal treatment (AHT) using potassium hydroxide (KOH). The effect of the duration of the KOH-AHT was assessed at 180 °C for 24, 48, 72, and 96 h. The morphology evolution over time and the plausible formation mechanisms of titanate nanostructures were discussed. The most significant morphological transformation was observed after 72 h. At this time interval, the titanate nanostructures were assembled into well-defined 3D hierarchical architectures such as book-block-like arrangements with open channels. Based on X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM-EDS) analyses, it was determined that these nanostructures correspond to iron-rich layered titanates (Fe/Ti mass ratio of 7.1). Moreover, it was evidenced that the conversion of the precursor into layered nanostructures was not complete, since for all the tested reaction times the presence of remaining IHSS was identified. Our experiments demonstrated that the Ecuadorian ilmenite sands are relatively stable in KOH medium.

Preparation and characterization of Ce-MOF/g-C3N4 composites and evaluation of their photocatalytic performance

In this study, unique hybrid structures were constructed between a Ce-based metal-organic framework (Ce-MOF) and graphitic carbon nitride (g-C3N4) materials. In addition, the g-C3N4 materials used for these heterostructures were prepared by five different methods, namely the conventional pyrolysis method, chemical exfoliation by a strong acid, activation by an alkaline hydrothermal treatment, melamine-cyanuric acid supramolecular assembly with a mechanochemical method, and by the solvothermally pre-treated method. The structural and morphological properties of the resulting g-C3N4 sheets and their composites were characterized using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrometry (FTIR), thermogravimetric analysis-derivative thermogravimetry (TGA-DTG), diffuse reflectance UV–vis spectroscopy (UV–vis DRS) and N2 sorption-desorption isotherms (BET). Finally, the photocatalytic performance of the composites was determined by following the photocatalytic degradation of methylene blue (MB) in an aqueous solution under UV–visible light irradiation. It was found that the photocatalytic efficiency of the Ce-MOF/g-C3N4‒TS composite was significantly higher than that of their counterparts (Ce-MOF or g-C3N4‒TS) for the photocatalytic degradation of MB. When employing the composite, UV light-induced degradation of MB yielded an efficiency of 96.5% after 120 min for a dye solution containing 10 mg/L MB. This corresponds to a 5-fold or 2-fold improvement of the rate constant (k) when compared to the Ce-MOF or g-C3N4, respectively.

Analysis of the Behavior of As and Pb during the Pretreatments Applied to a Jarosite Residue for the Recovery of Gold and Silver

The recovery of valuable metals from jarosites is a topic of great relevance regarding the implementation of the circular economy; however, these materials also contain metals such as arsenic and lead, which are harmful to health and the environment. Considering these factors, it is important to monitor these metals at each stage of treatment used to recover the valuable metals. In the present work, the behavior of As and Pb was assessed during the pretreatment conducted on a jarositic residue using direct zinc leaching (DLR), as well as leaching in cyanide and cyanide media with glycine. It was found that when no DLR pretreatment was performed, As and Pb naturally dissolved in the cyanide-leaching medium at concentrations of 34.08 mg/L and 99.12 mg/L, respectively. When an alkaline treatment was conducted on the residue (DLR-AH), it was found that there was no presence of As and Pb in the cyanidation solution, while in the case of the cyanide solution with glycine, we observed 83.35 mg/L of As and 213.63 mg/L of Pb. During the oxidizing alkaline hydrothermal treatment (DLR-AHO), 27.5 mg/L of As and 106.78 mg/L of Pb were detected in the cyanide solution. In the cyanide solution with glycine, there was less dissolution of As and Pb (11.68 and 66.75 mg/L), respectively. Finally, when desulfurization of the DLR was conducted prior to the DLR-AHO treatment, the dissolution of As and Pb increased due to the elemental sulfur covering the arsenopyrite and galena particles, so that, when removed, these were more susceptible to pretreatment and cyanidation.

Extraction of Novel Effective Nanocomposite Photocatalyst from Corn Stalk for Water Photo Splitting under Visible Light Radiation

Novel (Ca, Mg)CO3&SiO2 NPs-decorated multilayer graphene sheets could be successfully prepared from corn stalk pith using a simple alkaline hydrothermal treatment process followed by calcination in an inert atmosphere. The produced nanocomposite was characterized by SEM, EDX, TEM, FTIR, and XRD analytical techniques, which confirm the formation of multilayer graphene sheets decorated by inorganic nanoparticles. The nanocomposite shows efficient activity as a photocatalyst for water-splitting reactions under visible light. The influence of preparation parameter variations, including the alkaline solution concentration, hydrothermal temperature, reaction time, and calcination temperature, on the hydrogen evolution rate was investigated by preparing many samples at different conditions. The experimental work indicated that treatment of the corn stalk pith hydrothermally by 1.0 M KOH solution at 170 °C for 3 h and calcinating the obtained solid at 600 °C results in the maximum hydrogen production rate. A value of 43.35 mmol H2/gcat.min has been obtained associated with the energy-to-hydrogen conversion efficiency of 9%. Overall, this study opens a new avenue for extracting valuable nanocatalysts from biomass wastes to be exploited in hot applications such as hydrogen generation from water photo-splitting under visible light radiation.

Endowing osseointegration ability to bioinert alumina by carbonate apatite coating

The main reason for revision arthroplasty with an alumina-based prosthesis is aseptic loosening of the prosthesis. To prevent loosening of the prosthesis, endowing bioinert alumina with osteogenic ability is deemed an effective approach. Hence, we developed an alumina substrate with carbonate apatite and evaluated its effectiveness for early binding to the bone. Alumina substrates were coated with carbonate apatite using the following procedures: (1) etching the alumina substrate by alkaline hydrothermal treatment; (2) calcium carbonate coating of the etched alumina substrate; and (3) composition conversion of calcium carbonate coating into carbonate apatite by phosphatization. The tensile bond strength of carbonate apatite coating to alumina substrate was 17.6 MPa, which satisfied the criteria defined by the International Organization for Standardization. Contrary to the results of etched alumina substrates, the carbonate apatite-coated alumina substrates promoted the proliferation and osteogenic differentiation of mesenchymal stem cells and induced mineralization. Furthermore, the carbonate apatite-coated alumina substrates strongly adhered to the rabbit tibia 4 weeks after implantation compared to the etched alumina substrates. The contact area and adhesion strength of carbonate apatite-coated alumina substrates to bone were approximately 19- and 6-fold higher than those of etched alumina substrates, respectively. Thus, carbonate apatite coating may contribute to preventing the loosening of alumina prostheses.