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Electric arc furnace dust (EAFD) formed during steelmaking in electric arc furnace is a hazardous solid waste that is rich in zinc and iron. In our previous study, we realized the efficient extraction and separation of Zn and Fe from EAFD by co-roasting with FeSO 4 ·7H 2 O followed by water leaching processes, which achieved a high extraction rate of Zn (98.79 %) and a low extraction rate of Fe (0.11 %). However, the high temperature would lead to high energy consumption. Therefore, non-isothermal kinetic and isothermal kinetic were exploited in this study to analyze the heating and holding process for further optimizing roasting conditions. The heating process was divided into four reaction stages with different reaction models. Moreover, the holding process was also divided into two reaction stages with the Anti-Jander 3D diffusion model and Z-L-T 3D diffusion model, respectively. The major reactions in the heating and holding process were defined by thermodynamic equilibrium calculations and in situ X-ray diffraction. The rate-determining step was deduced as the desulfurization of Fe 2 (SO 4) 3 with a three-dimensional diffusion reaction model. Aiming to accelerate Fe 2 (SO 4) 3 desulfurization, the insulation conditions of this process were optimized from 675 °C for 3 h to 600 °C for 3 h, significantly reducing energy consumption. [ABSTRACT FROM AUTHOR]

• The CeO 2 -Fe 2 O 3 composite catalysts have continuously enhanced interface contact. • The electronic interaction between the dual redox sites were investigated. • The reactivities of different NH 3 and NO adsorbed species were discussed. • The reaction pathways and the roles of active Fe and Ce sites were proposed. Due to the requirements of different applications environments, higher catalytic activity or SO 2 and H 2 O tolerance, the binary or ternary metal oxide NH 3 -SCR catalysts with dual redox sites have been widely studied in recent years. The electronic interaction between the dual redox sites has a significant impact on the catalyst performance. Herein, a series of CeO 2 -Fe 2 O 3 composite catalysts with continuously enhanced interface contact as well as electronic interactions were prepared through a facile grinding method. The activity tests showed that neither the catalyst with the least interfacial contacts nor the one with the greatest interfacial contacts exhibited the highest NO x removal activity. The comprehensive characterizations demonstrated that the apparent physicochemical properties including the NH 3 adsorption ability, redox property, and so on, changed in favor of NH 3 -SCR reaction when enhancing the interface contact for the CeO 2 -Fe 2 O 3 composite catalysts. However, the reaction mechanism as well as the reactivity of main NH 3 and NO adsorbed species were also altered by the electronic interactions between Ce and Fe active species. The unsatisfactory NO x removal activity of the CeO 2 -Fe 2 O 3 catalyst with strongest electronic interactions between Ce and Fe active species was explained by the reactivity of main NH 3 and NO adsorbed species. This work can provide new ideas for improving the performance of NH 3 -SCR catalysts through changing the interface contact and electronic interaction between the dual redox sites. [ABSTRACT FROM AUTHOR]

The electric arc furnace dust (EAFD) is rich in zinc and iron, which is classified as a hazardous solid waste and generated during steelmaking in electric arc furnace. As an important secondary resource for zinc, the zinc extraction from EAFD has become crucial resource utilization direction. In this work, a novel process is proposed to extract zinc and separate iron for one-step through co-roasting EAFD with NH 4 HSO 4 , followed by water leaching. Through the co-roasting of EAFD and NH 4 HSO 4 , the zinc-containing phases in EAFD were transformed into ZnSO 4 , and the iron-containing phases were transformed into Fe 2 O 3. The separation of Zn and Fe was then performed by water leaching. The determined optimal experimental conditions were the mass ratio of NH 4 HSO 4 /EAFD of 0.75, the roasting temperature of 600 ℃, the holding time of 3 h, and the leaching time of 1 h, in which 91.14% of Zn and 3.25% of Fe were dissolved in the leaching solution. Afterwards, the reaction mechanisms of the co-roasting process of EAFD and NH 4 HSO 4 were revealed. When the temperature increased, the zinc-containing phase (NH 4) 2 Zn(SO 4) 2 and iron-containing phase NH 4 Fe(SO 4) 2 were first generated. (NH 4) 2 Zn(SO 4) 2 was then successively converted to ZnSO 4 , and NH 4 Fe(SO 4) 2 was decomposed into Fe 2 O 3 and Fe 2 (SO 4) 3. SO 3 produced by NH 4 HSO 4 decomposition in the roasting process can continue to participate in the sulfation process. Subsequently, zinc was enriched in the leaching solution, which can be considered as the raw material for Zn electrodeposition. Iron entered the leaching residue as Fe 2 O 3 , which can be used as the raw material for ironmaking. The result of leaching toxicity test showed that most of the heavy metals (i.e., Pb and Cr) were fixed in the leaching residue, which met the national standards for leaching toxicity. This study provides a theoretical reference and technical support for zinc extraction from zinc-containing solid wastes. • A novel process of the extraction of zinc and separation of iron by one-step was proposed. • The one-step separation of Zn and Fe was achieved with 91.14% of Zn and 3.25% of Fe. • The phases transition and migration mechanism of the main elements in EAFD was revealed. • The hazardous heavy metals (Pb and Cr) in EAFD were fixed in this process. [ABSTRACT FROM AUTHOR]

Copper-based (Cu-based) catalysts have garnered significant attention for their potential in ammonia-selective catalytic reduction (NH 3 -SCR) of nitrogen oxides (NO x). However, the widespread industrial application of Cu cation-exchanged chabazite catalysts has been hindered by poor hydrothermal stability, expensive raw materials, and complicated preparation. As a result, copper oxide-based (CuO-based) catalysts have emerged as ideal candidates due to their low cost and facile preparation. Nevertheless, the performance of NH 3 -SCR catalysts is a significantly influenced by the crystal plane effect, which has been scarcely investigated in Cu oxide-based NH 3 -SCR catalysts. In this study, CuO with exposed {001} and {111} facets were synthesized and combined with titanium dioxide (TiO 2) support to construct CuO/TiO 2 composite NH 3 -SCR catalysts. These catalysts displayed divergent NO x removal performance due to the crystal-plane effects of CuO. Specifically, the proportion of Cu+ and surface-adsorbed oxygen (O α) in CuO(111)/TiO 2 catalyst was higher than that of CuO(001)/TiO 2 catalyst, which could facilitate the NH 3 -SCR reactions. The NH 3 -TPD, NO-TPD, and DFT calculations demonstrated the better NH 3 and NO adsorption capability of CuO(111)/TiO 2 catalyst than that of CuO(001)/TiO 2 catalyst. Furthermore, the more -NH 2 and nitrate species in CuO(111)/TiO 2 catalyst resulted in better NO x removal efficiency than CuO(001)/TiO 2 catalyst. This study provides fundamental insights on the crystal-plane effect of CuO, which is critical for optimizing Cu oxide-based NH 3 -SCR catalysts. [Display omitted] • CuO with exposed {001} and {111} facets were successfully compounded with TiO 2. • The CuO(111)/TiO 2 catalyst showed the highest NO x removal rate. • The NH 3 and NO adsorption energy of the catalysts were calculated by DFT. • The CuO crystal-plane effect on gas adsorption and reaction mechanism was revealed. [ABSTRACT FROM AUTHOR]

Spent lithium-ion batteries (LIBs) are essential secondary resource, containing valuable metal elements including lithium, cobalt, nickel, manganese. Recovering valuable metals from spent LIBs is significant for achieving environmental protection and alleviating resource shortages. Herein, a sustainable and facile process for Li 2 CO 3 and Mn 2 O 3 recovery from spent LiMn 2 O 4 batteries (LMO) was proposed via sulfation roasting with waste copperas. The leaching efficiencies of Li and Mn reached approximately 100 % and 82 % under the optimal conditions, and the final recovered products were Li 2 CO 3 and Mn 2 O 3 with high purities. The sulfation reaction between LMO and copperas was the transition from solid-solid to gas-solid reaction. During the sulfation reaction, LMO spinel structure was decomposed into MnO 2 and Mn 2 O 3 crystal structures, and the anti-fluorite structure Li 2 O embedded in the spinel structure was released. The Li 2 O was easily to be sulfated, while MnO 2 was partly reduced by Fe2+ to more stable spinel structure Mn 2 O 3. Furthermore, FeSO 4 decomposed into SO 2 gas, which greatly improved the sulfation reaction through permeating into the unreacted core of LMO. As a result, the spinel structure of Mn 2 O 3 was broken, and Mn was escaped to combine with SO 4 2- to form MnSO 4. This research provided an alternative technological route for green recovery of spent LMO batteries, demonstrating high potential for broad application. [Display omitted] • An environmentally friendly approach for recycling LiMn 2 O 4 battery was proposed. • This study employed the concept of "waste + waste → resources". • Waste copperas as the only additive is used for sulfation reaction of LiMn 2 O 4. • The mechanism of the sulfation reaction of LiMn 2 O 4 was investigated. [ABSTRACT FROM AUTHOR]

MoO 3 and WO 3 , as acidic promoter, were widely used in the modification of vanadium based and vanadium-free based catalysts, which could significantly ameliorate the catalytic performance of the catalysts. In this work, the effects of MoO 3 and WO 3 on the selective catalytic reduction (SCR) performance of Fe/Zr catalyst were studied, and the role of acidic promoters was clarified. The results indicated that MoO 3 and WO 3 could improve the catalytic activity of Fe/Zr catalyst in the entire reaction temperature range. Noteworthy, Fe/Zr-W catalyst exhibited the highest SCR catalytic activity, and the NO x conversion rate achieved nearly 100% at 250 °C. The characterization results suggested that the promoting effect of WO 3 on catalytic performance of Fe/Zr catalyst might be due to the improvement of redox property and surface acidity, higher Fe3+/(Fe2++Fe3+) ratio and abundant surface chemisorbed oxygen. The in-situ DRIFTS experiments indicated that both E-R and L-H mechanisms were obeyed on Fe/Zr-W catalyst, while only E-R mechanism was obeyed on Fe/Zr and Fe/Zr-Mo catalysts in the NH 3 -SCR reaction at 250 °C. This study might provide an alternative development of high-performance vanadium-free catalyst for NO x abatement. [Display omitted] • Acidic promoter of WO 3 or MoO 3 enhanced catalytic activity of Fe/Zr catalyst. • WO 3 doping increased surface acidity, Fe3+/(Fe2+ + Fe3+) ratio and surface adsorbed oxygen of Fe/Zr-W catalyst. • MoO 3 doping inhibited NO x adsorption but promoted over-oxidation of NH 3 on Fe/Zr-Mo catalyst. • Mechanism model of acidic promoter doping on Fe/Zr catalyst for NH 3 -SCR was proposed. [ABSTRACT FROM AUTHOR]

A series of MnO 2 (with different crystal types) doping CeO 2 catalysts were synthesized by combining hydrothermal method and impregnation method, and the SCR activity and N 2 O formation of the catalysts were investigated. The results showed that NO conversion rate of CeO 2 @ α-MnO 2 , CeO 2 @ β-MnO 2 and CeO 2 @ γ-MnO 2 catalysts from 75 to 250 °C was always more than 95%, which showed excellent low-temperature NH 3 -SCR activity. N 2 O amount produced by CeO 2 @ α-MnO 2 , CeO 2 @ β-MnO 2 and CeO 2 @ γ-MnO 2 catalysts during denitrification all reduced at 75–125 °C comparing with pure MnO 2 , and the N 2 O in denitration process mainly came from SCR reaction, but not from direct oxidation of NH 3. Besides, the reducibility and acidity of the complex oxides catalyst were improved, which was more beneficial to the reaction of adsorbed NH 3 with NO, thus reducing the direct oxidation of adsorbed NH 3 by O 2 and inhibiting the formation of N 2 O. What's more, the effect of Ce and different crystal types of MnO 2 also influenced N 2 O generation behavior. Moreover, the SCR reaction of CeO 2 @ α-MnO 2 and CeO 2 @ β-MnO 2 catalysts mainly followed Eley-Rideal (E-R) mechanism, while CeO 2 @ γ-MnO 2 catalyst followed Langmuir-Hinshelwood (L-H) mechanism. [Display omitted] • MnO 2 crystal types on CeO 2 @MnO 2 oxides catalysts were firstly synthesized. • Effect of different crystalline MnO 2 on CeO 2 for catalytic performance was studied. • N 2 O production in catalyst denitration reaction mainly came from SCR reaction. • Reducibility and acidity of bioxide catalysts were improved compared with MnO 2. [ABSTRACT FROM AUTHOR]

In this work, based on a type of energy band engineering strategy as calcination, TiO 2 /ZSM-5 hybrids for photodegradation of methyl orange (MO) in water under UV light have been developed via a facile solid state diffusion method. Effects of varied calcination temperatures on TiO 2 /ZSM-5 hybrids have been systematically characterized including XRD, FT-IR, SEM, TEM, EDX mapping, BET, PL, EIS, UV–vis DRS, active species trapping experiments and Mott-Schottky curves. It was found that the calcination temperature influenced photocatalytic activity, typically on physicochemical properties of materials and adjustment for the energy gap and band position of TiO 2. The XRD analysis revealed that hybridization of ZSM-5 kept the crystal phase of TiO 2 as anatase unchanged with the high-rising calcined temperature. The optimum sample calcined at 450 °C named as Z-T (450) presented nearly 99% degradation rate for MO, owing to optimal uniform distribution, highest specific surface area and best charge separation/transfer efficiency. The FT-IR comparison result that the functional groups and peak strength of the used catalyst were alike as before, showed the stability of photocatalyst. Adoption of calcination strategy does provide not only a clean, low-cost and highly efficient path to approach the complete degradation of azo dyes, but also a chance for photocatalytic technology to fulfill the implementation in industrial applications. [Display omitted] • SSD method with calcination achieved energy band engineering of TiO 2 /ZSM-5 hybrids. • The optimal TiO 2 /ZSM-5 hybrid degraded nearly 100% of methyl orange. • The synergy between TiO 2 and ZSM-5 of different calcined temperature was contrastively studied. • The photocatalytic mechanism of TiO 2 /ZSM-5 hybrids was proposed from the perspective of energy band theory. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ca, an inexpensive alkaline earth metal, was doped into tetragonal β-In 2 S 3. • Ca doping narrowed the band gap and reduced charge transfer resistance of β-In 2 S 3. • The optimal Ca doped β-In 2 S 3 degraded 94.97% of Methyl Orange in 20 mins. • Abundant flaky structure endowed Ca doped β-In 2 S 3 with large surface area. • The photocatalytic mechanism for MO degradation over Ca doped β-In 2 S 3 was proposed. Photocatalytic technology can provide a clean, low-cost and highly efficient path to approach the degradation of azo dyes. Tetragonal β-In 2 S 3 possesses plenty of vacancies, furnishing dopants with abundant interspace, and can be used as a potential photocatalyst for dyes degradation. In this work, Ca was doped into β-In 2 S 3 via a facile one-pot hydrothermal method, which was mainly doped into the crystalline lattices of β-In 2 S 3. Ca doped β-In 2 S 3 revealed better photo-degradation of Methyl Orange (MO) than undoped β-In 2 S 3. The doped Ca ions narrowed band gap and acted as a charge transfer medium, leading to the wider light absorption range and smaller photogenerated charge transfer resistance, respectively. The optimum preparation condition of Ca doped β-In 2 S 3 was determined as holding temperature at 120 °C for 8 h, by which 94.97% of MO was degraded in 20 mins under visible light. The outstanding performance could be owed to the full-grown flaky structure with maximal specific surface area. Based on the experimental results, a possible photocatalytic mechanism for MO degradation over Ca doped β-In 2 S 3 was proposed. [ABSTRACT FROM AUTHOR]

• Fe 2 O 3 -containing solid waste was successfully utilized as NH 3 -SCR catalyst. • The deposition of CeQDs greatly enhanced redox and NH 3 adsorption of catalyst. • The optimal amount of CeQDs increased the NO conversion by more than 3.15 times. • The N 2 selectivity and SO 2 tolerance of catalyst were enhanced by CeQDs depositing. • DFT calculations describing the adsorption of O 2 and NH 3 were applied. As NO x has been turning into a crucial environmental problem, NH 3 -SCR technology with relatively simple device, reliable operation and low secondary pollution, has become a widely used commercial and mature de-nitration technology. However, some weaknesses restricted the further application of commercialized V 2 O 5 -WO 3 /TiO 2 NH 3 -SCR catalysts, while Fe 2 O 3 -based catalysts have received much attention due to their high thermal stability, passable N 2 selectivity and low cost. In this study, Fe 2 O 3 -containing solid waste derived from Zn extraction process of electric arc furnace dust was exploited as the base material for catalyst preparing. Owing to the complementary and synergistic effect of CeO 2 and Fe 2 O 3 , 0D CeO 2 quantum dots (CeQDs) with fully-exposed active sites, large specific surface area, and rapid charge transfer have been introduced and deposited onto Fe 2 O 3 -containing solid waste nanorods. The in-situ deposition of CeQDs led to the admirable enhancement in NH 3 -SCR catalytic activity, N 2 selectivity and SO 2 tolerance of the extremely low-cost Fe 2 O 3 catalyst. Comprehensive characterizations and DFT calculations describing the adsorption of O 2 and NH 3 were applied to analyze the catalyst structure and further investigate the detailed relationship between structural properties and activity as well as reaction mechanism. This work provides new insights for the high-value utilization of iron-containing solid waste and a practical reference for boosting the performance of NH 3 -SCR catalysts by introducing quantum dots. [ABSTRACT FROM AUTHOR]

• Photo-generated holes is key for this photocatalytic system. • Oxygen vacancies can trap the photo-generated carriers to inhibit the recombination of photo-generated electron-hole pairs. • A photocatalytic degradation mechanism of CeO 2 has been proposed. A series of CeO 2 photocatalysts were synthesized through the molten salt method. The photocatalytic activity was evaluated through the degradation of methyl orange (MO). Systematic characterizations including X-ray diffraction, Scanning electron microscopy, Fourier transformed infrared, X-ray photoelectron spectroscopy, Raman spectroscopy, electron spin-resonance spectroscopy, UV–vis diffuse reflectance spectroscopy, photoluminescence spectrometry, photocurrent response and electrochemical impedance spectroscopy were conducted to study the as-prepared CeO 2 samples. It was found that, under ultraviolet light irradiation, the apparent rate constants of CeO 2 prepared at 800 °C for degradation of MO was about 3.4 times higher than CeO 2 prepared at 500 °C. CeO 2 prepared at 800 °C held the higher oxygen vacancies concentration. According to the trapping experiments, it was demonstrated that photo-generated holes played a dominant role in this photocatalytic system. Furthermore, the possible photocatalytic mechanism which showed the roles of photo-generated holes and oxygen vacancies was proposed. [ABSTRACT FROM AUTHOR]

MnO x -CeO 2 (denoted as Mn–Ce) nanorod and MnO x -CeO 2 nanooctahedra catalysts were synthesized by the hydrothermal method and were used for selective catalytic reduction of NO with NH 3. The catalytic performance tests showed that the NO removal efficiency of CeO 2 catalysts was obviously improved after loading MnO x. The structure and properties of catalysts had been characterized by SEM、TEM、XRD、BET、XPS、H 2 -TPR、NH 3 -TPD and in situ DRIFTS. It was found that Mn–Ce catalyst were of uniform core-shell structure, higher concentrations of Mn4+ and Ce3+, better reducibility, the increase of weak acid sites. The results of in situ DRIFTS indicated that the NH 3 -SCR reaction should obey the E–R mechanism. Moreover, the promotion effect and mechanism of MnO x doped CeO 2 was demonstrated, which improved the catalytic activity of Mn–Ce catalysts. [ABSTRACT FROM AUTHOR]

Enhanced performance of Ce doping on the catalytic activity of V 2 O 5 -WO 3 /TiO 2 catalysts and its resistance properties to Na poisoning have been investigated in the research. Different Na species (NaCl and Na 2 O) were deposited on CeO 2 -V 2 O 5 -WO 3 /TiO 2 catalysts by impregnation method. The results presented that CeO 2 -V 2 O 5 -WO 3 /TiO 2 catalysts exhibited a higher NH 3 -SCR activity and better Na resistance than the V 2 O 5 -WO 3 /TiO 2 catalyst, and its poisoning resistance to Na 2 O is more superior than to NaCl, caused by more acid sites over the 10%CeO 2 -V 2 O 5 -WO 3 /TiO 2 (Ce 10 VWTi) catalyst, which indicated that the poisoning resistance of Na 2 O on Ce 10 VWTi catalysts is higher than that of NaCl. Combined with the characterization results, the dopant of Ce could enhance the surface chemisorbed oxygen on the Na poisoning V 2 O 5 -WO 3 /TiO 2 catalysts, facilitate the redox cycle, and increase the intensity of acid sites due to the newly formed Brønsted acid sites stemmed from C e 3 + − N H 4 + , thereby promoting catalytic activity and Na poisoning resistance. [ABSTRACT FROM AUTHOR]

• MoO 3- x nanosheets were prepared by a novel hydrogen peroxide etching method. • The bulk MoO 3 and MoO 3- x nanosheets both improved the activity of Fe 2 O 3 catalysts. • MoO 3- x nanosheets-Fe 2 O 3 exhibited much higher N 2 selectivity than bulk MoO 3 -Fe 2 O 3. • The bulk MoO 3 and MoO 3- x nanosheets showed disparate NH 3 and NO adsorption ability. • The N 2 O formation pathways via L-H and E-R mechanism were both investigated. NH 3 -SCR technology with commercialized V 2 O 5 -WO 3 (MoO 3)/TiO 2 catalysts has become the most efficient technology for the removal of NO x from coal-fired power plants. However, the weaknesses of V 2 O 5 -WO 3 (MoO 3)/TiO 2 catalysts such as the biotoxicity of vanadium species and high cost restrict their increased applicability. Fe 2 O 3 -based NH 3 -SCR catalysts show potential in placing traditional catalysts due to their good N 2 selectivity, excellent environmentally friendly performance, high thermal stability, and low cost. In this work, low cost Fe 2 O 3 -containing solid waste was exploited as the base material for NH 3 -SCR catalyst preparing. Moreover, bulk MoO 3 and MoO 3-x nanosheets decorated Fe 2 O 3 composite NH 3 -SCR catalysts were synthesized and both revealed conspicuously improved NO x removal efficiency compared with bare-Fe 2 O 3 catalyst. However, the N 2 selectivity of these two catalysts showed significant differences. Therefore, comprehensive characterizations, NH 3 oxidation experiments, and in-situ diffusion Fourier transform infrared spectroscopy (DRIFTS) experiments were performed to determine the N 2 O formation pathways of the above two catalysts. The redox properties were highly related to the N 2 O generated from NH 3 oxidation. Moreover, the huge difference in NH 3 and NO adsorption ability led to disparate reaction mechanisms over the two catalysts. This new understanding of the N 2 O formation mechanism has the potential to guide the rational design of improved NH 3 -SCR catalysts suffering from low N 2 selectivity. [ABSTRACT FROM AUTHOR]

Doping WO 3 with proper amount could increase the concentration of Fe3+ and chemisorbed oxygen, and enhance the surface acidity and redox ability. The in-situ DRIFTS spectra demonstrated that only the E-R mechanism was followed in the NH 3 -SCR reaction on Fe/Zr catalyst, while the NH 3 -SCR on Fe/Zr-0.1W catalyst followed both Eley-Rideal and Langmuir-Hinshelwood mechanisms. [Display omitted] • WO 3 doped Fe/Zr catalysts were prepared via wet impregnation. • The introduction of WO 3 enhanced the catalytic performance of Fe/Zr catalyst. • WO 3 doping promoted the amount of surface acid sites and the adsorption of NH 3. • WO 3 doping increased the L-H reaction pathway on the surface of Fe/Zr catalyst. To clarify the effect of WO 3 doping over Fe/Zr catalyst, several Fe/Zr- x W catalysts were prepared via conventional wet impregnation method, and the selective catalytic reduction (SCR) performance was studied. The Fe/Zr-0.1 W catalyst showed the highest catalytic activity and achieved nearly 100 % in a wide operating temperature window of 300–500 °C, and the N 2 selectivity exceeded 90 % over the entire temperature range under a high hour space velocity of 90, 000 h−1. In addition, Fe/Zr-0.1 W catalyst also exhibited superior resistance to SO 2 compared to Fe/Zr catalyst without WO 3 introduction. Further characterization results indicated that the Fe/Zr-0.1 W catalyst possessed larger BET specific surface area, better dispersion of active component, higher concentration of Fe3+ and more surface chemisorbed oxygen species, which might be the predominant factors for its superior catalytic performance. More importantly, WO 3 doping improved the redox capacity and surface acidity, thus promoting the redox circle and enhancing the adsorption ability of NH 3. According to the transient in-situ DRIFTS experiment results, the doping of WO 3 increased the L-H reaction pathway on the surface of Fe/Zr catalyst during the NH 3 -SCR reaction. The present work could provide a new way for developing a high-performance non-vanadium SCR catalyst in practical application. [ABSTRACT FROM AUTHOR]

[Display omitted] • ZrO 2 /SO 4 2− enhanced catalytic activity and resistance to PbO over CeO 2 /ZrO 2 catalyst. • ZrO 2 /SO 4 2− doping increased surface acidity, Ce3+/(Ce3+ + Ce4+) ratio and surface adsorbed oxygen. • Surface acid sites and active sites of CeO 2 /ZrO 2 -S catalyst were protected by ZrO 2 /SO 4 2− from PbO damage. • Mechanism model of PbO poisoning over CeO 2 /ZrO 2 and CeO 2 /ZrO 2 -S catalysts was proposed. The serious deactivation of denitration catalysts caused by heavy metals still a thorny issue in the practical application of selective catalytic reduction of NO x with NH 3. Herein, we proposed a novel anti-poisoning strategy by designing SO 4 2−/ZrO 2 superacid supported CeO 2 /ZrO 2 catalyst, and the effect of SO 4 2−/ZrO 2 supported CeO 2 /ZrO 2 for PbO-resistance NO x catalytic reduction was investigated. It was worthy to note that the introduction of solid superacid SO 4 2−/ZrO 2 significantly enhanced catalytic performance over the entire temperature range, with an exceptionally high NO x removal efficiency over 98 % during 250–500 °C. When 2 wt% PbO was deposited on the fresh catalyst, the catalytic activity of CeO 2 /ZrO 2 catalyst decreased obviously, while CeO 2 /ZrO 2 -S catalyst can still maintain a higher NO x conversion over 90 % from 275 to 500 °C. The characterization results confirmed that the introduction of solid superacid SO 4 2−/ZrO 2 enhanced the surface acidity and promoted the transformation from Ce4+ to Ce3+. The results of in situ DRIFTS implied that the Eley-Rideal (E-R) mechanism was obeyed over CeO 2 /ZrO 2 catalyst, and both Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms were followed over CeO 2 /ZrO 2 -S catalyst in the SCR process. With regard to poisoned catalysts, the NH 3 adsorption was inhibited to some extent, while the reaction mechanism wasn't changed by PbO poisoning. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel indirect carbonation process by using solid waste as reagent was proposed. • Nickel was co-extracted in this process, enhancing the economy. • Process intensification mechanism by Na 2 SO 4 was presented. • The maximum CO 2 storage capacity reached 291 kg·t−1 laterite ore. CO 2 mineral sequestration is one of the most promising strategies for combating global warming, which is composed of direct and indirect pathways. However, the high cost and heat consumption for recycling reagents used in the indirect carbonation process is the biggest obstacle for its widespread applications. In this study, a novel process by using a solid waste, copperas, as reagent to extract magnesium and nickel from laterite ore was proposed for simultaneous CO 2 mineralization and recovery of nickel. In this process, the copperas was decomposed into SO 2 , which sulfated the laterite ore by in situ gas–solid reaction. The addition of Na 2 SO 4 facilitated the formation of low melting point substances, converting the gas–solid reactions into a multiphase gas–liquid-solid reaction, thus the extraction was enhanced. Meanwhile, the heat of sulfation of laterite ore can compensate the heat of copperas decomposition, reducing the overall energy consumption. The maximum extraction efficiency of 94 % for Mg and 87 % for Ni was achieved at Na 2 SO 4 dosage larger than 10 wt%. The carbonation of MgSO 4 -riched leachate experiments revealed the optimal CO 2 storage capacity was approximately 291 kg·t−1 laterite ore. Compared with the conventional acid-based Mg extracted process for CO 2 mineralization, the cheap copperas avoided the recycle of reagent and obtained weak acidic leachate, reducing the amount of alkali used in the subsequent carbonation process. [ABSTRACT FROM AUTHOR]

• Precipitant style served a vital role on catalyst phase transition and structure features. • Surface acidity induced by precipitants acted as the main motivation for activity. • E-R and L-H paths co-existed on both catalysts while the former contributed more. • Possible structure-activity model of different precipitants on catalyst was proposed. Herein, the structure-activity strategy comparison of two different precipitants on MnO x catalyst for low-temperature NH 3 -SCR was investigated in detail. XRD results confirmed that ammonium carbonate (denoted as AC) could transfer manganese precursor from MnCO 3 to Mn 2 O 3 phase with temperature from 80 to 450 °C, while ammonium hydroxide (denoted as AH) facilitated the phase transition of MnO x from Mn 3 O 4 to the final Mn 5 O 8 phase. Further morphology defined that Mn-AC catalyst possessed a peculiar spherical feature while Mn-AH catalyst presented an accumulation of abundant nano-particles. The activity results suggested that Mn-AC catalyst possessed higher activity compared with Mn-AH catalyst at lower temperature, with over 60% conversion achieved from 100 to 225 °C and the maximum NO conversion reached circa (denoted as ca.) 85% at 175 °C. In addition, Mn-AC catalyst possessed stronger surface acidity and redox properties than Mn-AH catalyst, which served as an important motivation for the difference in activity. More manganese ions with higher valence and surface oxygen favored the superior redox circle of Mn-AC catalyst. Transient reaction revealed that the catalysts followed both Eley–Rideal (E-R) and Langmuir–Hinshelwood (L-H) pathways while the L-H pathway was harder to occur than the former due to the intense NO x transformation over catalysts. On account of these analyses, the possible structure-activity strategy comparison model of (NH 4) 2 CO 3 and NH 4 OH precipitants on MnO x catalyst was proposed. The anions of precipitant played a leading role in the formation of the catalytic phase and surface morphology, in which AC induced active Mn precursor to transfer from MnCO 3 to spherical Mn 2 O 3 while AH developed the initial Mn 3 O 4 to final Mn 5 O 8 phase. The transition behavior of active precursors under different precipitants was the root cause of the internal motivation of catalytic properties. [Display omitted] [ABSTRACT FROM AUTHOR]

CO 2 mineral sequestration is a promising method for abating global warming. Mineral carbonation with titanium-bearing blast furnace slag (TBFS) can offer a sustainable option for simultaneous CO 2 emission reduction and comprehensive utilization of solid waste. In this study, a novel process combining CO 2 mineral sequestration and rutile beneficiation was proposed by using TBFS and copperas as feedstocks. TBFS and copperas were roasted at 550–750 °C to convert the calcium and magnesium into the corresponding sulfates, while titanium in the TBFS was beneficiated to rutile. The roasted slag was then subjected to carbonation followed by recovery of rutile and hematite through flotation and magnetic separation, respectively. The effects of process parameters were studied systematically. It was found that addition of Na 2 SO 4 significantly enhanced the conversion efficiency of Ti (from 53% to 98%). The mechanism revealed that the addition of Na 2 SO 4 promoted the formation of molten Na 3 Fe(SO 4) 3 , and gas-liquid-solid reactions proceeded much faster and efficiently. The carbonation of sulfated TBFS results indicated that the optimal CO 2 storage capacity can reach 187 kg t−1 TBFS. In this process, two solid wastes were utilized for CO 2 mineralization, realizing the multiple benefits of CO 2 emission reduction, solid waste disposal as well as valuable byproducts recovery. [Display omitted] • A novel process for co-disposal of Ti-bearing blast furnace slag and copperas was proposed. • Rutile beneficiation and CO 2 mineralization were realized simultaneously in the route. • The addition of Na 2 SO 4 significantly enhanced the conversion efficiency of Ti. • The maximum CO 2 storage capacity reached 187 kg t−1 TBFS. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel conversion of TBFS into high value-added materials was proposed. • FAU and MFI type zeolites were synthesized from the pretreated TBFS. • The state of Ti species in the synthesized zeolites were also thoroughly investigated. In this work, the synthesis of FAU and MFI type Ti-containing zeolites from Ti-bearing blast furnace slag was first achieved via a facile hydrothermal method. The synthesized zeolites were identified to be Ti-NaX and Ti-NaZSM-5 zeolites, with excellent specific surface area of 663.2 and 325.2 m2/g, respectively. Ti species in the Ti-NaX zeolite contained the framework Ti species and amorphous extraframework Ti species, while the Ti species in Ti-NaZSM-5 zeolite were in the form of the two species of above and another anatase TiO 2. To investigate the potential application of the synthesized zeolites in photocatalysis field, an exploratory study was carried out by degradation of methyl orange under UV irradiation. As demonstrated, the Ti-NaZSM-5 zeolite showed higher photocatalytic performance and was more suitable to be the support of the TiO 2 photocatalyst than the Ti-NaX zeolite. Innovative conversion of TBFS into Ti-containing zeolite materials does provide not only a novel and low-cost approach to waste management, but also a promising material candidate for catalytic oxidation and environmental purification. [ABSTRACT FROM AUTHOR]

Abstract: Phenolic compounds are widely distributed in the natural environment, typically existing as a mixture at the nanomole or micromole per liter level. Among the phenolic compounds, 4-nonylphenol, 4-t-octylphenol, bisphenol A and 2,4-dichlorophenol attract the most concern due to their abundance and risks in the natural environment. The former three are known as endocrine disruptors causing feminization in various organisms, whereas the latter requires further clarification for its estrogenic effect. This study aims to evaluate the combination effects of these chemicals with estrogen receptor binding as an endpoint. An ELISA based receptor binding assay was employed to avoid radioactive pollution in the traditional assay. The results showed that all these chemicals could bind with estrogen receptor with a relative binding affinity of bisphenol A>4-t-octylphenol>4-nonylphenol>2,4-dichlorophenol. The four chemicals were further mixed in two ways, at an equipotent ratio and at an equal environmental level ratio, and their combination effects on receptor binding were evaluated with both the toxicity units method and concentration addition model. The resulting effects of both mixtures showed an antagonistic mode, which was assumed to be a general mode of action with estrogen receptor binding assay due to competitive ligand binding on receptors. [Copyright &y& Elsevier]