Search Results (27)

In cases of severe injuries or burns, skin grafts (scaffolds) are often required as skin substitutes. In order not to harm the patient or the donor, biodegradable and biocompatible materials are used, which validates the search for heterografts such as poly (L-lactic acid)—PLA. However, natural polymers applied to the skin suffer great degradation in environments with large amounts of carbon and water or via binders with considerable resistivity, which implies little durability due to their low ductility. For the proposal, this work investigates PLA-based scaffolds modified with a mixture of pseudoboehmite (PB) and graphene oxide (GO), produced via the sol–gel route. The nanomaterials are incorporated into the polymer at different loadings, seeking to improve mechanical and thermal properties. Analyses via SEM, EDS, and XRD confirm the presence and distribution of these fillers. Tensile and flexural tests indicate that adding the filler can increase stress resistance, prevent deformations before failure, and increase toughness when compared to pure PLA. Full article

The objective of this study was to evaluate the applicability of zeolite Y as a catalyst for producing bisphenol F (BPF) from phenol and formaldehyde. Catalyst extrudates were prepared by extrusion after adding pseudoboehmite sol (PS) and Ludox (Lu) as alumina and silica binders, respectively. The compressive strength of the catalyst extrudates increased with the addition of Ludox. However, the formaldehyde conversion decreased as more Ludox was used as a binder, resulting in a decrease in the yield of BPF. This decrease is attributed to the reduction in the total amount of acid sites caused by the addition of Ludox. In this study, the Y_PS5_Lu5 catalyst was selected as the most suitable for BPF synthesis. In the BPF synthesis over the Y_PS5_Lu5 catalyst in a catalyst basket reactor, the optimum reaction temperature was determined to be 110 °C. The effect of stirring speed on the yield of BPF was found to be negligible in the range of 200 rpm to 350 rpm. The spent catalyst was able to recover a specific surface area and reaction activity similar to those of a fresh catalyst through regeneration in an air atmosphere at 500 °C. When the Y_PS5_Lu5 extruded catalyst was used in a continuous reaction in a fixed-bed reactor, there was no noticeable deactivation of the catalyst at low space velocities of the reactants. However, when the space velocity was increased to 18.0 h⁻¹, catalyst deactivation was clearly observed. This suggests that periodic regeneration of the catalyst is inevitable in a continuous reaction using the Y_PS5_Lu5 extruded catalyst. Full article

Eriochrome black T is considered as one of the anionic dyes with potential harmful effects on human health and the environment. Among other processes, adsorption can contribute to the removal of these dyes. In the present study, two adsorbent materials, pseudo-boehmite (γ-AlOOH) and gamma alumina (γ-Al₂O₃), were synthesized and tested in the removal of the Eriochrome black T molecule (EBT). γ-AlOOH and γ-Al₂O₃ were obtained by precipitation from NaAlO₂ solution at pH = 7, at a temperature of 80 °C, and by the thermal transformation of γ-AlOOH at 800 °C, respectively. In order to gain insights into the structural, chemical, thermal and morphological properties of these materials, numerous analytical techniques were involved, including X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), differential thermogravimetric–thermal analysis (TGA-DTA), scanning electron microscopy with energy-dispersive spectroscopy (SEM-EDS), and specific surface area measurement using the Brunauer–Emmett–Teller (BET) method. Several adsorption parameters were studied, such as the adsorbent dose, initial concentration, pH, contact time and reaction temperature. The kinetic study showed that EBT adsorption follows the pseudo-second-order model. The Langmuir isotherm model revealed a maximum EBT adsorption capacity of 344.44 mg g⁻¹ and 421.94 mg g⁻¹ for γ-AlOOH and γ-Al₂O₃, respectively. A textural and structural analysis after adsorption highlighted the effective adsorption of the dye. Full article

With the increasing concern about antimony (Sb) pollution and remediation in aquatic ecosystems, more and more feasible technologies have been developed. Adsorption has been extensively studied due to the simplicity of its operation and its minimal environmental effects, but the lack of cheap and stable adsorbents has limited its application in Sb treatment. In this study, pseudo-boehmite (PB) was successfully synthesized via aluminum isopropylate hydrolysis, and its potential for removing Sb(V) from wastewater was explored. The removal efficiency of Sb(V) was 92.50%, and the maximum adsorption capacity was 75.25 mg/g under optimal conditions (pH 5.0, 2 g·L⁻¹ PB, and 10 mg·L⁻¹ Sb(V)). In addition, better performance could be obtained at acidic conditions (pH 3.0–5.0). Surface complexation, electrostatic attraction, and hydrogen bonding were identified as potential major processes for Sb(V) elimination by PB based on experimental and characterization data. This study presents a promising approach for the efficient removal of Sb(V) from wastewater, offering a new insight into the application of aluminum-based materials for heavy metal removal. Full article

An integrated soda roasting–alkaline leaching–carbonization process was developed to recover platinum (Pt) and aluminum (Al) from a spent Pt/Al₂O₃ catalyst. A product with the main component of NaAlO₂ was obtained under the optimal roasting conditions of the mass ratio of Na₂CO₃ to spent catalyst 1, roasting time 2 h and roasting temperature 900 °C. The Al in the roasted residue was effectively leached in a dilute NaOH solution, while Pt was enriched in the leached residue with a Pt content that reached 29.4%, and the calculated concentration factor of Pt yielded 79.4. After carbonization was performed for the leached solution, 99.0% of the Al was recovered as the pseudo-boehmite product, which could be used as the feed for preparing the Al₂O₃ carrier. Pt and Al₂O₃ in the spent catalyst were selectively separated and enriched using the above process, which thus has good application prospects. Full article

In this present work, a new kind of sulfurized hydrodesulfurization catalyst was synthesized via the hydrothermal treatment of MoS₂, NiCO₃·2Ni(OH)₂·4H₂O, and Al₂O₃ precursors, followed by annealing under a H₂ atmosphere, which does not require a sulfurization process compared to traditional preparation methods. The influence of the annealing temperature and the type of Al₂O₃ precursor on the interactions between MoS₂ and Al₂O₃ were studied using X-ray fluorescence spectroscopy, X-ray diffraction, N₂ adsorption–desorption, Raman spectroscopy, X-ray photoelectron spectroscopy, and high-resolution transmission electron microscopy. The results indicated an increase in the number of stacked layers of the MoS₂ catalyst, accompanied by a decrease in the degree of decoration of Ni atoms onto MoS₂ nanoslabs, as a result of the strengthened MoS₂–Al₂O₃ interaction. Subsequently, the efficiency of hydrodesulfurization (HDS) was evaluated using dibenzothiophene as a representative reactant, while establishing a correlation between the structure of the catalyst and its performance. The catalysts, using pseudo-boehmite as the precursor and calcined at 500 °C, synthesized by calcining pseudo-boehmite as the precursor for Al₂O₃ at a temperature of 500 °C and possessing suitable metal–support interactions, exhibited a reduced number of MoS₂ stacking layers and lateral dimensions, along with an optimal decoration degree of Ni atoms, thereby resulting in the highest level of HDS activity. Full article

The treatment of wastewater from arsenic compounds is an important and urgent problem. Composite nanostructures consisting of boehmite and iron compounds have a high adsorption capacity towards As(V) specie. In this work, the adsorption properties of nanostructured composites prepared by the oxidation of bimetallic Al/Fe nanoparticles with different iron contents were investigated. As a result of oxidation, boehmite AlOOH nanosheets are formed, with the resultant FeAl₂ nanoparticles being distributed on the surface of boehmite nanosheets. The nanostructured composites prepared from Al/Fe nanoparticles containing 20 wt% Fe have been found to show the highest adsorption capacity towards As(V) specie, being 248 mg/g. The adsorption isotherms are most accurately described by the Freundlich model, with the arsenic adsorption process obeying pseudo second order kinetics. As a result of the study, the optimal ratio of Al and Fe in Al/Fe nanoparticles has been determined to obtain an AlOOH/FeAl₂ composite adsorbent with a developed and accessible surface and a high sorption capacity towards As(V). This allows us to consider this material as a promising adsorbent for the removal of arsenic compounds from water. Full article

This study aims to design novel amine-functionalized alumina nanofibers for the removal of lead (II) and mercury (II) ions from aqueous solutions. The $\gamma$-Al₂O₃ nanofibers were prepared by calcination of boehmite, and then functionalization with 3-(2-aminoethylamino) propyl trimethoxy silane. The characterization of the nanofibers was carried out using TEM, EDS, elemental mapping, XRD, and XPS. The effects of initial concentration, pH, contact time, and selectivity were studied. The results revealed that the nanofibers can remove 98% of Hg²⁺ ions and 90% of Pb²⁺ ions from aqueous solution at concentrations of 40 mg/L and 35 mg/L, respectively. Additionally, the optimal pH conditions for mercury and lead ion adsorption were established to be 6. It was also observed that for concentrations of 100 mg/L and 250 mg/L, the majority of ion contaminants were removed by the nanofibers within the first hour. The adsorption capacities were found to be 129 mg/g and 165 mg/g for Hg²⁺ and 72.3 mg/g and 111 mg/g for Pb²⁺ at 100 mg/L and 250 mg/L concentrations, respectively. The ion-adsorption kinetic data was best fitted to a pseudo-second-order model. High sorption capacities were also demonstrated when employed to selectively adsorb mercury (II) and lead (II) ions from aqueous solutions containing Zn²⁺, Mg²⁺, Cu⁴⁺, Sn⁴⁺, and Ni⁴⁺. Desorption tests were performed to explore the stability of the heavy metals on the nanofiber. Full article

Ceramic corundum abrasives were prepared using pseudo-boehmite as a raw material via the sol-gel method. Additives can significantly change the microscopic morphology of abrasives and improve mechanical properties. When 2 wt% CaO-TiO₂-SiO₂ with a molar ratio of 3:4:9 was added, samples with the best morphology and mechanical properties were obtained. Single-particle compressive strength, density, Vickers hardness, and average grain size were 51.45 N, 3.94 g·cm⁻³, 16.43 GPa, and 0.98 μm, respectively. We compared the same additive system with abrasives prepared by ball milling, and found that ball milling was beneficial for obtaining denser and smaller grain size abrasives. On the other hand, abrasives obtained without ball milling had relatively higher single-particle compressive strength. Additionally, the additives are non-precious metal oxides, which can reduce the cost of the synthesis process. In addition, there has been discussion of the connection between microstructure and mechanical characteristics. Full article

It is of great importance to develop a spherical γ-alumina support with high hydrothermal stability to be used in platinum reforming catalyst processes. The porous pseudo-boehmite powder with a high surface area was first synthesized via a simple separate nucleation and aging steps method, and was then used as a precursor to produce a spherical γ-Al₂O₃ support via an oil–ammonia column method. The as-synthesized pseudo-boehmite has a substantially greater specific surface area of 336.0 m²·g⁻¹ in comparison with the commercial Sasol boehmite powder (293.0 m²·g⁻¹) from Sasol Chemicals. In addition, the as-prepared spherical γ-Al₂O₃ support derived from the as-synthesized pseudo-boehmite also possesses a higher specific surface area of 280.0 m²·g⁻¹ compared to the corresponding Sasol sample. Moreover, the as-prepared spherical γ-Al₂O₃ balls demonstrate a much higher specific surface area of 185.0 m²·g⁻¹ compared with the Sasol sample of 142.0 m²·g⁻¹ after hydrothermal tests at 600 °C, suggesting its promising application in the chemical industry. Full article

Graphene-encapsulated nickel nanoclusters are a feasible strategy to inhibit the nickel deactivation of nickel-based catalysts. In this work, graphene-encapsulated catalysts (Ni@C/HZSM-5) were prepared by a compression forming process, using pseudo-boehmite, Al₂O₃, and ZrO₂ as binders. The pseudo-boehmite was gradually transformed from amorphous to crystalline alumina at high temperatures, which destroyed the nucleation of Ni@C. In contrast, the crystal-stabilized zirconia was more favorable for the nucleation of Ni@C. The extensive dispersion of alumina on the surface of HZSM-5 covers the acid sites of HZSM-5. In contrast, when zirconia was used as the binder, the binder existed in the form of the direct aggregation of ~100 nm zirconia spheres; this distribution form reduced better the damage of the binder to the acid site of the catalyst. Furthermore, the particle size of Ni crystals in the graphene-encapsulated catalysts decreased significantly (mostly <11 nm), and no evident agglomeration of nickel particles appeared. It was found that the stabilization of the metal interface delayed, to an extent, the accumulation rate of carbon deposits and, thus, postponed the deactivation of the acid sites. After 8 h of continuous reaction, the conversion of the traditional catalyst Ni/Z5+Zr dropped significantly to 60%. In contrast, the conversion of Ni@C catalysts prepared with ZrO₂ remained above 90%. The regeneration test shows that air roasting could effectively remove carbon deposits and restore the catalyst activity. Full article

A kind of nano-ZSM-5 zeolite crystal was synthesized by the hydrothermal method, and HZSM-5 zeolite powder was obtained via acid exchange. By using pseudoboehmite as a binder, a series of HZSM-5 zeolite catalysts for methanol-to-hydrocarbons (MTH) were prepared through adjusting the binder content between 20 and 50% in addition to the molding method of wet extrusion and mechanical mixing. XRD, ²⁷Al NMR, SEM-EDS, ICP, low-temperature N₂ adsorption and desorption, NH₃-TPD, Py-FTIR, FT-IR, TG and elemental analyses were used to characterize the properties of fresh catalysts and coke-deposited catalysts. Then, MTH catalytic performance was evaluated in a continuous-flow fixed-bed reactor. The characterization and evaluation results showed that the addition of dilute nitric acid during the molding process increased the amount of moderate-strength acid and formed a hierarchical pore distribution, which helped to reduce the reaction ability of cracking, aromatization and hydrogen transfer, improve the diffusion properties of the catalyst and slow down the coke deposition rate. The catalyst with a binder content of 30% made by wet extrusion with dilute nitric acid had the best performance, whose activity stability of MTH increased by 96 h, higher than other catalysts, and the coke deposition rate was slower, which was due to the most suitable distribution of acid strength and B/L ratio as well as the most obvious hierarchical pore structure. Full article

Fluid catalytic cracking (FCC) has been the primary processing technology for heavy oil. Due to the inferior properties of heavy oil, an excellent performance is demanded of FCC catalysts. In this work, based on the acid extracting method, Si-modified pseudo-boehmite units (Si-PB) are constructed in situ and introduced into the structure of kaolin to synthesize a Si-PB@kaolin composite. The synthesized Si-PB@kaolin is further characterized and used as a matrix material for the FCC catalyst. The results indicate that, compared with a conventional kaolin matrix, a Si-PB@kaolin composite could significantly improve the heavy oil catalytic cracking performance of the prepared FCC catalyst because of its excellent properties, such as a larger surface area, a higher pore volume, and a good surface acidity. For the fresh FCC catalysts, compared with the FCC catalysts using conventional kaolin (Cat-1), the gasoline yield and total liquid yield of the catalyst containing Si-PB@kaolin (Cat-2) could obviously increase by 2.06% and 1.55%, respectively, with the bottom yield decreasing by 2.64%. After vanadium and nickel contamination, compared with Cat-1, the gasoline yield and total liquid yield of Cat-2 could increase by 1.97% and 1.24%, respectively, with the bottom yield decreasing by 1.80 percentage points. Full article

Effluent reuse is a common practice for sustainable industrial water use. Salt removal is usually carried out by a combination of membrane processes with a final reverse osmosis (RO). However, the presence of silica limits the RO efficiency due to its high scaling potential and the difficulty of cleaning the fouled membranes. Silica adsorption has many advantages compared to coagulation and precipitation at high pHs: pH adjustment is not necessary, the conductivity of treated waters is not increased, and there is no sludge generation. Therefore, this study investigates the feasibility of using pseudoboehmite and its calcination product (γ-Al₂O₃) for silica adsorption from a paper mill effluent. The effect of sorbent dosage, pH, and temperature, including both equilibrium and kinetics studies, were studied. γ-Al₂O₃ was clearly more efficient than pseudoboehmite, with optimal dosages around 2.5–5 g/L vs. 7.5–15 g/L. The optimum pH is around 8.5–10, which fits well with the initial pH of the effluent. The kinetics of silica adsorption is fast, especially at high dosages and temperatures: 80–90% of the removable silica is removed in 1 h. At these conditions, silica removal is around 75–85% (<50 mg/L SiO₂ in the treated water). Full article

Rich in Fe, Ce, Mn, Si and other elements which have good catalytic activity, Bayan Obo rare-earth tailings are naturally advantaged as the carrier of denitrification catalysts. In this paper, pseudo boehmite (γ-Al₂O₃) was mixed with Bayan Obo tailings using different ball milling methods for modification to prepare NH₃-SCR catalysts. The effect of different mixing methods on the SCR denitrification activity at a low temperature was investigated and the prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), temperature programed desorption (NH₃-TPD), temperature programed reduction (H₂-TPR) and other means. The conversion rate of NOx at 250–350 °C was above 80% and the highest conversion rate of NOx of 90% was achieved at 300 °C. SEM and XRD revealed that the tailings modified by pseudo boehmite (γ-Al₂O₃) using the ordinary ball milling method have loose structure and good dispersion of active substances, and specific surface area (BET) analysis shows that the tailings have the maximum specific surface area and pore volume. However, over grinding and secondary spheronization were observed in the tailings modified by pseudo boehmite (γ-Al₂O₃) using high energy ball milling method, leading to the decrease of specific surface area and pore volume, poor dispersion of active substances, and ultimately low denitrification rate. Full article