Search

H2O in flue gas causes the deactivation of V2O5/TiO2 catalysts for selective catalytic reduction (SCR) of NOx with NH3 at low temperatures. Developing water resistance requires understanding the theoretical mechanism of H2O impact on the catalysts. The aim of this work was to clarify the adsorption process of H2O and the deactivation mechanism induced by H2O through density functional theory (DFT). The process of H2O adsorption was studied based on a modeled V2O5/TiO2 catalyst surface. It was found that H2O had a strong interaction with exposed titanium atoms. Water adsorption on the catalyst surface significantly alters the electronic structure of VOx sites, transforming Lewis acid sites into Brønsted acid sites. Exposed titanium sites contribute to the decrease of Lewis acidity via adsorbed water. Ab initio thermodynamic calculations show that H2O adsorption on V2O5/TiO2 is stable at low coverage but less favorable at high coverage. Adsorption of NH3 is the most critical step for the SCR of NOx, and the adsorption of H2O can hinder this process. The H2O coverage below 15% of adsorption sites could enhance the NH3 adsorption rate and have a limited effect on the acidity, while higher coverage impeded the adsorption ability of VOx sites. This work provided electron-scale insight into the adsorption impact of H2O on the surface of V2O5/TiO2 catalysts, presented thermodynamic analysis of the adsorption of H2O and NH3, paving the way for the exploration of V2O5/TiO2 catalysts with improved water resistance. [ABSTRACT FROM AUTHOR]

Forecasting is important for social development and industrial production in today's complex and fluctuating economic environment. The nonlinearity and non-stationarity of financial time series (FTS) data make it difficult to achieve accurate prediction. This work proposes a forecasting method for the return of FTS based on the emerging field of graph signal processing (GSP). The proposed method makes forecasting decisions based on the similarity between the current tendency and historical tendencies of FTS data. First, a topological graph is created based on the underlying structural relationship of different historical FTS datasets. Subsequently, spectral clustering is used to select historical datasets that are similar to the current dataset, and then the future values are predicted by weighted averaging the selected historical samples. In addition, a momentum-driven method is introduced to improve the robustness of the forecasting results. Finally, the proposed method is extended to a collaborative forecasting framework, where auxiliary macroeconomic data is introduced to improve the forecasting accuracy. The superiority of the proposed methods is verified by a set of numerical experiments with different stock indices. [ABSTRACT FROM AUTHOR]

The reactive AlN, heavy metal ions, and salts in secondary aluminum dross make them harmful to the environment and difficult to handle, and therefore categorized as hazardous solid waste. A novel, simple, and versatile technique has been proposed here to prepare hierarchically porous ceramics using secondary aluminum dross as the sole raw material, namely, the hydrolysis‐induced simultaneous foaming and coagulation casting method. As the main component, Al and AlN could be hydrolyzed to generate aluminum hydroxide sol, which can form three‐dimensional network and lead to the outstanding compressive strength of green body (7.03 MPa). Gas release during hydrolysis, high‐temperature oxidation of AlN, and metallic Al based on Kirkendall effect could account for the final multilevel pores. The utilization of harmful components in secondary aluminum dross, supplys an alternative colloidal forming way for porous green body with complex shape when combined with other ceramic powders or inorganic solid waste. Low sintering shrinkage of 1.38%–3.60% for hierarchically porous ceramics offers this highly effective and low‐cost method to be easily promoted for industrial production. [ABSTRACT FROM AUTHOR]

This work aims to study the improvement effect of Sm on Mn-based catalysts for selective catalytic reduction (SCR) of NO with NH3. A series of SmxMn0.3−xTi catalysts (x = 0, 0.1, 0.15, 0.2, and 0.3) were prepared by co-precipitation. Activity tests indicated that the Sm0.15Mn0.15Ti catalyst showed superior performances, with a NO conversion of 100% and N2 selectivity above 87% at 180–300°C. The characterizations showed that Sm doping suppressed the crystallization of TiO2 and Mn2O3 phases and increased the specific surface area and acidity. In particular, the surface area increased from 152.2 m2·g−1 for Mn0.3Ti to 241.7 m2°g−1 for Sm0.15Mn0.15Ti. These effects contributed to the high catalytic activity. The X-ray photoelectron spectroscopy (XPS) results indicated that the relative atomic ratios of Sm3+/Sm and Oβ/O of Sm0.15Mn0.15Ti were 76.77at% and 44.11at%, respectively. The presence of Sm contributed to an increase in surface-absorbed oxygen (Oβ) and a decrease in Mn4+ surface concentration, which improved the catalytic activity. In the results of hydrogen temperature-programmed reduction (H2-TPR), the presence of Sm induced a higher reduction temperature and lower H2 consumption (0.3 mmol·g−1) for the Sm0.15Mn0.15Ti catalyst compared to the Mn0.3Ti catalyst. The decrease in Mn4+ weakened the redox property of the catalysts and increased the N2 selectivity by suppressing N2O formation from NH3 oxidation and the nonselective catalytic reduction reaction. The in situ diffuse reflectance infrared Fourier transform spectra (DRIFTs) revealed that NH3-SCR of NO over the Sm0.15Mn0.15Ti catalyst mainly followed the Eley—Rideal mechanism. Sm doping increased surface-absorbed oxygen and weakened the redox property to improve the NO conversion and N2 selectivity of the Sm0.15Mn0.15Ti catalyst. [ABSTRACT FROM AUTHOR]

Red mud is a waste discharged from alumina production by Bayer process. It contains iron and titanium resources. Secondary aluminum dross (SAD) is a waste discharged from aluminum smelting and processing. It contains hazardous reactive aluminum nitride (AlN). In this work, iron and titanium in red mud were reduced by AlN in SAD by pyrometallurgy, and slag was manufactured into glass ceramics. Recovery rates of iron and titanium were 97% and 75%, when addition amount of red mud was double of SAD. The reduced iron and titanium were in form of metal iron and titanium nitride (TiN). Reduction process consisted of two steps: AlN, iron and titanium entered aluminosilicate network of melt; AlN reduced iron and titanium. Density, water absorption and microhardness of the glass ceramics were 3.10 g cm−3, 0.03% and 1195 HV. Utilizing 1 ton of SAD to replace carbon for iron reduction could reduce carbon emissions by 407 kg. In addition, co-disposing 400 kg red mud and 200 kg SAD could gain profit of 293 dollars. This work realized the total recycling of both red mud and SAD. [ABSTRACT FROM AUTHOR]

Coal fly ash (CFA) is a type of solid waste produced in the process of coal combustion, which is rich in silicon oxide, aluminum oxide and a small number of heavy metals and radioactive elements. Therefore, CFA is considered a secondary resource with high recovery value. Currently, CFA is mainly reused in the fields of building materials, mine backfilling, soil conditioners and fertilizers, among which the production of building materials is one of the most important ways to realize large-scale utilization of CFA. This paper introduces the physical and chemical properties, classification and environmental impact of CFA and summarizes the utilization status of CFA in building materials such as cement, concrete, ceramics and geopolymers, as well as the management policy of CFA. In addition, the existing problems in the utilization of CFA as a building material are analyzed, and their development prospects are discussed. [ABSTRACT FROM AUTHOR]

TiO2 is the dominant and most widely researched photocatalyst for environmental remediation, however, the drawbacks, such as only responding to UV light (<5% of sunlight), low charge separation efficiency, and difficulties in recycling, have severely hindered its practical application. Herein, we synthesized magnetically separable Fe3O4@MoS2@mesoporous TiO2 (FMmT) photocatalysts via a simple, green, and template-free solvothermal method combined with ultrasonic hydrolysis. It is found that FMmT possesses a high specific surface area (55.09 m2·g−1), enhanced visible-light responsiveness (∼521 nm), and remarkable photogenerated charge separation efficiency. In addition, the photocatalytic degradation efficiencies of FMmT for methylene blue (MB), rhodamine B (RhB), and tetracycline (TC) are 99.4%, 98.5%, and 89.3% within 300 min, respectively. The corresponding degradation rates are 4.5, 4.3, and 3.1 times higher than those of pure TiO2 separately. Owing to the high saturation magnetization (43.1 A·m2·kg−1), FMmT can achieve effective recycling with an applied magnetic field. The improved photocatalytic activity is closely related to the effective transport of photogenerated electrons by the active interlayer MoS2 and the electron—hole separation caused by the MoS2@TiO2 heterojunction. Meanwhile, the excellent light-harvesting ability and abundant reactive sites of the mesoporous TiO2 shell further boost the photocatalytic efficiency of FMmT. This work provides a new approach and some experimental basis for the design and performance improvement of magnetic photocatalysts by innovatively incorporating MoS2 as the active interlayer and integrating it with a mesoporous shell. [ABSTRACT FROM AUTHOR]

Industrial solid waste (ISW)—cement blends have the advantages of low carbon, low energy consumption, and low pollution, but their clinker replacement level in low carbon cement is generally low. To address this challenge, this study considers the latest progress and development trends in the ISW—cement blend research, focusing on the activation of ISWs, the formation of ISW—cement blends, and their associated hydration mechanisms. After the mechanical activation of ISWs, the D50 (average size) typically drops below 10 µm, and the specific surface area increases above 350 m2/kg. Thermal activation can increase the glassy-phase content and reactivity of ISWs, where the coal gangue activation temperature is usually set at 400–1000°C. Furthermore, the roles of ISWs in the hydration of ISW—cement blends are divided into physical and chemical roles. The physical action of ISWs usually acts in the early stage of the hydration of ISW—cement blends. Subsequently, ISWs participate in the hydration reaction of ISW—cement blends to generate products, such as C—(A)—S—H gels. Moreover, alkali activation affects the hydration kinetics of ISW—cement blends and modifies the proportion of gels. Environmental impacts and costs of ISW—cement blends have also been discussed to guide stakeholders in selecting sustainable ISWs. [ABSTRACT FROM AUTHOR]

Herein, a simple, versatile, and low‐cost approach has been proposed to realize the green utilization of secondary aluminum dross, the hazardous solid waste, namely directly sintering dry‐pressed green bodies from secondary aluminum dross to fabricate porous ceramics according to high‐temperature foaming process spontaneously without adding spare foaming agents. Aluminum nitride (AlN) in secondary aluminum dross was employed to realize high‐temperature foaming due to its oxidation, which makes traditional AlN and salts removal process needless. Moreover, near‐zero shrinkage or even expansion during sintering of porous ceramics have occurred because in‐situ foaming process together with the oxidation of Al particles well offset the sintering shrinkage. After sintering at 1400°C for 2 h, porous ceramics composed of α‐Al2O3 and spinel phases with open porosity of 37.91%, sintering expansion rate of 1.13%, flexural strength of 45.67 MPa, and thermal conductivity of 0.97 W/(m·K) have been prepared. Cenospheres as pore‐forming agents have been added to further improve the porosity, and alumina‐based porous ceramics with open porosity of 28.39%–43.20% and flexural strength of 15.80–52.48 MPa have been obtained. This effective solution for recycling secondary aluminum dross could supply high‐performance porous ceramics, which is expected to be applied in the fields of light‐weight structural components and thermal insulations. [ABSTRACT FROM AUTHOR]

Municipal solid waste incineration products of bottom ash (BA), fly ash (FA), and pickling sludge (PS), causing severe environmental pollution, were transformed into glass ceramic foams with the aid of CaCO3 as a pore-foaming agent during sintering. The effect of the BA/FA mass ratio on the phase composition, pore morphology, pore size distribution, physical properties, and glass structure was investigated, with results showing that with the increase in the BA/FA ratio, the content of the glass phase, Si-O-Si, and Q3Si units decrease gradually. The glass transmission temperature of the mixture was also reduced. When combined, the glass viscosity decreases, causing bubble coalescence and uneven pore distribution. Glass ceramic foams with uniform spherical pores are fabricated. When the content of BA, FA, and PS are 35wt%, 45wt%, and 20wt%, respectively, contributing to high performance glass ceramic foams with a bulk density of 1.76 g/cm3, porosity of 56.01%, and compressive strength exceeding 16.23 MPa. This versatile and low-cost approach provides new insight into synergistically recycling solid wastes. [ABSTRACT FROM AUTHOR]

The effect of Cu, Fe, Co, Ni, Cr and Zn on Mn–Zr–Ti mixed oxides catalysts introduced by co-precipitation was investigated. The Mn–Co catalyst showed the highest NO conversion near 100% and a good N2 selectivity > 90% at 200–300 °C. Comparing with the Mn–non catalyst, the Mn–Co catalyst presented a higher reaction rate constant at 120 °C with 23.3 ml s−1 g−1. The Mn–Co catalyst possesses a high concentration of Mn4+ and surface labile oxygen, which should improve the redox property and increase catalytic activity. Additionally, the Mn–Co showed the highest ratio of Lewis acid sites. The resistance to SO2 was improved by incorporation of Co. In summary, the Mn–Zr–Ti mixed oxides catalyst have a better N2 selectivity than other Mn-based catalysts and could be improved by doping with Co. [ABSTRACT FROM AUTHOR]

Mixed oxide catalysts yMn-Zr-Ti (y/10/10 with y = 1, 3, 5, 7 and 9) for the selective catalytic reduction (SCR) of NOx with NH3 in the presence of oxygen were synthesized by co-precipitation. The catalyst 5Mn-Zr-Ti exhibited a catalytic activity higher than 87% above 160 °C and N2 selectivity above 92% at 100-300 °C. The SCR performance was quite stable at 180 and 200 °C for 15 h. Mn species are shown to improve the catalytic activity by providing more surface labile oxygen, while a synergistic effect among Mn, Zr and Ti species suppressed the generation of N2O. According to in situ DRIFT analysis, NOx was primarily reduced by the reaction of bidentate nitrate and monodentate nitrito species with adsorbed NH3. Subsequently, a comprehensive reaction mechanism was proposed. Accordingly, the formation of NH species was inhibited, and hence, the N2O formation by the reaction of NH and bidentate nitrate was suppressed. Furthermore, the investigation of the deactivation mechanism by SO2 indicated that both the deposition of ammonium sulfates and the sulfation of Mn active sites resulted in the deactivation of the catalyst 5Mn-Zr-Ti. The deposition of ammonium sulfates at 180 °C was more pronounced than that at 220 °C. [ABSTRACT FROM AUTHOR]

Emerging contaminants are considered as some substances of actual or potential threat to human health or environment, which include endocrine disruptors, pharmaceutical, personal care products, nanoparticles, antibiotic resistance genes and chemicals used in packaging products, etc. The disposal and treatment of emerging contaminants has become a key problem in the field of water pollution control. The purpose of this review is to summarize published researches on emerging pollutants treatment in 2015. [ABSTRACT FROM AUTHOR]

Emerging contaminants are considered as some substances of actual or potential threat to human health or environment, which include endocrine disruptors, pharmaceutical, personal care products, nanoparticles, antibiotic resistance genes and chemicals used in packaging products, etc. The disposal and treatment of emerging contaminants has become a key problem in the field of water pollution control. The purpose of this review is to summarize published researches on emerging pollutants treatment in 2014. [ABSTRACT FROM AUTHOR]

A facile high-energy ball-milling method is developed to synthesize MoS2–graphite (MoS2–C) nanocomposites, which can be used for scalable industrial mass production. As an anode material for a lithium-ion battery, the obtained MoS2–C composite with 30% C shows a discharge capacity as high as 736 mA h g−1 in the first cycle and retains the capacity of up to 720 mA h g−1 after 200 cycles at a current density of 100 mA g−1. Even at a large rate of 2000 mA g−1, the reversible capacity is still 428 mA h g−1. Moreover, a high Coulombic efficiency is attained. After carefully comparing it with a MoS2–C composite with 20% C, raw MoS2 and pure ball-milled MoS2, we ascribe the remarkably improved performance of the MoS2–C composite with 30% C to the synergistic effect of carbon coating and nano-crystallization derived by ball milling. [ABSTRACT FROM AUTHOR]

This paper presents a classic process-structure-properties approach for optimizing the magnetic properties of electrical steels. Cold-rolled non-oriented electrical steel (Fe; 0.001 wt% C; 0.2 wt.% Mn; 1.3 wt% Si) was subjected to extremely short 3-30 seconds annealing cycles in a range from 880 °C to 980 °C with a heating rate varying from 15 °C to 300 °C/sec. The resulting microstructure was studied by means of optical microscopy and X-ray orientation distribution function analysis. Recrystallized grains were refined with increased heating rate, caused by the nucleation rate increase, which is faster than the growth rate due to rapid heating. The optimal grain size of 60 to 80 mm in terms of magnetic properties was obtained by increasing the annealing temperature range to 920 °C to 940 °C with a higher heating rate of 300 °C/sec and an annealing time of 6 to 9 seconds. With the heating rate increase, the characteristic {111} recrystallization fiber of cold-rolled steel was depressed, but the beneficial {110}〈001〉 Goss texture component was significantly strengthened. The recrystallized grain size and texture were enhanced by rapid annealing, and, as a result, the magnetic properties of non-oriented electrical steel improved. [ABSTRACT FROM AUTHOR]

The rapid heating effects on the microstructure, texture and magnetic properties of 3% Si non-oriented electrical steel has been investigated through optical microscopy, X-ray diffraction and Epstein frame. The results show that recrystallized grains were refined with increased heating rate, caused by the nucleation rate increase, which is faster than the growth rate due to rapid hearting. With the heating rate increase, the characteristic {111} recrystallization fibre of cold-rolled steel was depressed, but the beneficial 〈001〉//RD and 〈001〉//ND fibres were significantly strengthened. Although the grain-size decreases with heating rate increasing, the optimal magnetic properties can also be obtained through the recrystallized grain-size and texture optimization by rapid heating. In this research, we find the magnetic properties optimization can be obtained when annealed with 100°C/s heating rate: the core loss ( P) decrease 13% and the magnetic induction ( B) increase 3%. [ABSTRACT FROM AUTHOR]

Iron powder magnetic cores are used as soft magnetic rotors, in micro special motors such as BS brake motors, refrigerator compressor motors and brushless servo motors. Heat treatment of iron powder played an important role in the magnetic properties and loss of the motor cores. After the annealing process, the cracks and the pores on the surface of the powder decreased which in turn decreased the micro-hardness. The Vickers-hardness of the powder decreased from 50-42, while the resistance of the cores increased by 87% after annealing at 400°C for 30 min. The amplitude permeability and magnetic loss of the cores reached the maximum and minimum values, respectively. The magnetic loss of the cores was separated into hysteresis loss and eddy current loss by Stoppels Method which were decreased by the annealing process. [ABSTRACT FROM AUTHOR]

Bonded Terfenol-D composites, with high electrical resistivity and low eddy current loss, can be used in an alternating magnetic field with high frequency. However, the nonmagnetic binder impairs the magnetostriction of the composites. To achieve high magnetostriction and low eddy current loss, the mixture of the alloy powder and binder was compressed at low pressure in an oriented magnetic field. After this, the aligned samples were recompressed by cold isostatic pressing (CIP). Besides, the effect of particle size on the magnetostriction of the bonded Terfenol-D composites was also studied. The results showed that the bonded Terfenol-D composites had excellent magnetostriction when the particle size was 50-80 μm. The oriented magnetic field and CIP could improve the magnetostriction of the bonded composites, which reaches 1020×10. The bonded Terfenol-D composites had good compact structure and high density (7.24 g/cm). The magnetic loss of the bonded Terfenol-D composites was 192 mW/cm at a frequency of 100 kHz in a magnetic field of 960 A/m, which was about one third of that of casting Terfenol-D alloys. [ABSTRACT FROM AUTHOR]

Spherical or nearly regular hexagonal Nd powders with the size of 20–150 nm, Fe powders with the size of 20–150 nm and Mo powders with the size of 80–100 nm were prepared by Argon and Hydrogen arc plasma. The nanostructural NdFe10.5Mo1.5 compound with ThMn12-type structure have been formed after having been mechanically alloyed for 6–12 hours and crystallized at 700–850 °C under high purified Argon atmosphere. After having been nitrided at 400–500 °C for 2 hours, NdFe10.5Mo1.5N x nanopowders with ThMn12-type structure can be obtained, which have excellent permanent magnetic properties such as iH c within range of 360.4–716.2 kA/m (4528–8997 Oe), Br within range of 0.6363–0.9831 T (6363–9831 Gs), ( BH)max within range of 42.87–166.2 kJ/m3 (5.386–20.88 MGOe). [ABSTRACT FROM AUTHOR]

7XXX series aluminum alloys (Al 7XXX alloys) are widely used in bearing components, such as aircraft frame, spars and stringers, for their high specific strength, high specific stiffness, high toughness, excellent processing, and welding performance. Therefore, Al 7XXX alloys are the most important structural materials in aviation. In this present review, the development tendency and the main applications of Al 7XXX alloys for aircraft structures are introduced, and the existing problems are simply discussed. Also, the heat treatment processes for improving the properties are compared and analyzed. It is the most important measures that optimizing alloy composition and improving heat treatment process are to enhance the comprehensive properties of Al 7XXX alloys. Among the method, solid solution, quenching, and aging of Al 7XXX alloys are the most significant. We introduce the effects of the three methods on the properties, and forecast the development direction of the properties, compositions, and heat treatments and the solution to the corrosion prediction problem for the next generation of Al 7XXX alloys for aircraft structures. The next generation of Al 7XXX alloys should be higher strength, higher toughness, higher damage tolerance, higher hardenability, and better corrosion resistance. It is urgent requirements to develop or invent new heat treatment regime. We should construct a novel corrosion prediction model for Al 7XXX alloys via confirming the surface corrosion environments and selecting the accurate and reliable electrochemical measurements. [ABSTRACT FROM AUTHOR]

This paper proposes a new method for producing nano-SrFe12O19 powder by the citrate precursor route using solid waste as a source of iron. This solid iron-containing waste, which exists in the form of an oily sludge, is produced by a cold rolling mill. This sludge was first subjected to a process, including sulfuric acid leaching, oxidation, precipitation, and nitric acid leaching, to obtain an iron nitrate (Fe(NO3)3) solution. Next, the Fe(NO3)3 solution was mixed with a strontium nitrate (Sr(NO3)2) solution obtained by subjecting strontium carbonate to nitric acid leaching. Subsequently, citric acid, as chelating agent, and ammonia water, as precipitating agent, were added to the mixed solution to form a gel. The gel was dried and spontaneously combusted, then annealed at different temperatures for 2 h in flowing air. The effects of the Fe3+/Sr2+ molar ratio and annealing temperature on the formation, morphology, and magnetic properties of SrFe12O19 were investigated. The results showed that single-phase SrFe12O19 powder was obtained by decreasing the Fe3+/Sr2+ molar ratio from the stoichiometric value of 12 to 11.6 and increasing the annealing temperature to 1000 °C for 2 h. Adjustment of the Fe/Sr molar ratio to 12 and the annealing temperature to 900 °C enabled the magnetic properties to be optimized, including saturation magnetization (Ms) 80.2 emu/g, remanence magnetization (Mr) 39.8 emu/g, and coercive force (Hc) 6318 Oe. [ABSTRACT FROM AUTHOR]

Reclamation of spent catalysts for the efficient recovery of palladium (Pd) is gaining growing attention due to its scarcity and high supply risk. Currently Pd extraction from spent catalysts through an efficient, economical, and green method has remained a challenge. In this study, Fe3+ is utilized for leaching through oxidation of Pd in a mild condition. Before leaching, distillation was proposed to remove and recover the organics from spent catalysts. The effects of HCl concentration, Fe3+ concentration, NaCl concentration, leaching time, and temperature on the leaching efficiency of Pd were investigated to determine the optimum leaching conditions. The results show that Pd extraction and dissolution of Al2O3 increase with higher HCl concentration. The effect of NaCl on Pd leaching efficiency is significant at low acid concentration (2.0 mol/L HCl). The leaching efficiency was 99.5% for Pd under the following conditions: 2.0 mol/L HCl, 4.0 mol/L NaCl, and 0.67 mol/L Fe3+ at 80 °C for 90 min. The leaching kinetics fits best to the shrinking-core model of surface chemical reaction. The activation energy for the leaching of Pd was 47.6 kJ/mol. PdCl42− was selectively adsorbed by anion exchange resin. The filtrate containing adequate H+, Cl-, and Fe3+ was reused as leaching agent. Pd leaching efficiency was over 96% after five cycle times. This study provides an efficient process for recovery of Pd from spent catalysts. [ABSTRACT FROM AUTHOR]

The global yield of platinum (Pt) recovery from spent catalysts is about 30%. Pt recovery from spent catalysts is one of the most significant methods to reduce its supply risk and meet future demand. The current hydro-leaching processes always involve extremely high acidity (c(H+) > 6.0 mol/L), causing serious environmental issues and consuming large amounts of reagents. This paper studied the recovery of Pt from spent petroleum catalysts in a mild leaching solution (c(H+) = 1.0−2.0 mol/L). The HCl and NaCl were used as leaching agents, while H2O2 was used for oxidation of Pt. The leaching factors, including solid/liquid ratio (S/L), acidity, leaching temperature, and H2O2 usage, were studied. The leaching efficiency of Pt was 95.7% under the conditions of S/L of 1:5 g/mL, HCl of 1.0 mol/L, NaCl of 5.0 mol/L, 10% H2O2/spent catalysts of 0.6 mL/g, and temperature of 90 °C for 2 h. The leaching kinetic of platinum fits best to the Avrami equation. The apparent activation energy for leaching platinum was 114.9 kJ/mol. Furthermore, the effects of the operating variables were assessed and optimized by employing a response surface methodology based on Box-Behnken Design. The result shows that HCl concentration had the greatest impact on the leaching efficiency as compared to the H2O2 concentration and S/L ratio. Pt leaching efficiency was increased to 98.1% at the optimized conditions of HCl of 1.45 mol/L, NaCl of 4.55 mol/L, 10% H2O2/spent catalysts of 0.66 mL/g, and S/L of 1:4.85. The purity of Pt is over 90% by the reduction of iron powder. [ABSTRACT FROM AUTHOR]