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N-doped graphene quantum dot-decorated N-TiO2/P-doped porous hollow g-C_(3)N_(4) nanotube composite photocatalysts for antibiotic photodegradation and H2 production

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International Journal of Minerals,Metallurgy and Materials 2024年第1期31卷 165-178页

作者： Jingshu Yuan Yao zhang Xiaoyan zhang Junjie zhang shen’gen zhang Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China Xi’an Fanyi University Xi’an 710105China Shunde Graduate School of University of Science and Technology Beijing Foshan 528399China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao SAR 820000China

Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recombination rate are the two primary drawbacks of pure TiO_(2). We combined N-doped graphene quantum dots (N-GQDs), morphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) composite photocatalysts (denoted as G-TPCN). The optimal sample (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elemental doping (P and N), the improved light-harvesting resulting from the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dramatically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 times that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenomenon is attributed to the formation of Z-scheme heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Compared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4times, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 times, respectively. The optimized performance benefits from excellent photoresponsiveness and improved carrier separation and migration efficiencies. Finally, the photocatalytic mechanism of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the mechanism of multiple modification strategies to synergistically improve the photocatalytic performance of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environmental remediation and solar energy conversion.

关键词： N-doped TiO_(2) N-doped graphene quantum dots P-doped g-C_(3)N_(4) porous hollow nanotube heterojunction photocatalysis

Integrated utilization of municipal solid waste incineration fly ash and bottom ash for preparation of foam glass-ceramics

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Rare Metals 2019年第10期38卷 914-921页

作者： Bo Liu Qiang-Wei Yang shen-gen zhang Institute for Advanced Materials and Technology University of Science and Technology Beijing

For the purpose of solid waste co-disposal and heavy metal stabilization,foam glass-ceramics were produced by using municipal solid waste incineration(MWSI)bottom ash and fly ash as main raw materials,calcium carbonate(CaCO3) as foamer and sodium phosphate(Na3PO4) as foam *** influences of the raw material composition,foaming temperature and foaming time on the properties were ***,bulk density,mechanical property and leaching of heavy metals were analyzed *** product,foamed at 1150℃ for 30 min with 14% fly ash and 74% bottom ash,exhibits excellent comprehensive properties,such as high porosity(76.03%),low bulk density(0.67 g·cm-3) and high compressive strength(10.56 MPa).Moreover,the amount of leaching heavy metals,including Cr,Pb,Cu,Cd and Ni,in foam glass-ceramics is significantly lower than that of the US EPA hazardous waste *** study not only realizes the integrated utilization of bottom ash and fly ash,but also addresses a new strategy for obtaining foam glass-ceramics.

关键词： Municipal solid waste incineration ash Foamglass-ceramics Mechanical properties Stabilization

An alkaline fusion mechanism for aluminate rare earth phosphor:cation-oxoanion synergies theory

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Rare Metals 2019年第4期38卷 299-305页

作者： Yi-Fan Liu shen-gen zhang Bo Liu Han-Lin shen Institute for Advanced Materials and Technology University of Science and Technology Beijing

Waste aluminate rare earth phosphor is an important rare earth elements (REEs) secondary resource, which mainly consists of BaMgAl1()O|7:Eu2+(BAM) and CeMgAl11O19:Tb^3+(CMAT). Alkaline fusion process is widely used to recycle REEs from aluminate phosphor, but the related theory remains imperfect. In this paper, a series of alkaline fusion experiments of CMAT were performed to describe the phase change law of CMAT reactions. Based on comprehensive analysis, cation-oxoanion synergies theory (COST) was proposed to explain the aluminate phosphor structure damage. On the mirror plane of aluminate phosphor crystal structure, alkali metal cations (Na^+,K^+) would substitute rare earth ions, while free oxoanion (OH^-, CO3^2-, O2^2-) can combine with rare earth ions. These two ionic forces ensure that rare earth ions can be substituted by cations. Then, the structure is decomposed. Morphological analysis shows that observable expression of COST can be described by shrinking core model after simplification. Reaction rate constant calculated indicates that the reaction degree is nanometers per second. COST provides a more complete mechanism, and it can help improve rare earth recycling technology furtherly.

关键词： Aluminate phosphor Alkaline fusion Rare earth Mechanism

Preparation of glass–ceramics from high-chlorine MSWI fly ash by one-step process

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Rare Metals 2021年第11期40卷 3316-3328页

作者： Shi-Zhen Zhao Xiao-Yan zhang Bo Liu Jun-Jie zhang Han-Lin shen shen-gen zhang Institute for Advanced Materials and Technology University of Science and Technology BeijingBeijing 100083China

Municipal solid waste incinerated(MSWI) fly ash contains heavy metals and chloride,which is urgent to be disposed via an effective ***,glass-ceramics,one of the recycling waste materials based on MSWI fly ash with high chloride content,have been developed from one-step *** fly ash and waste glass have been utilized as calcium and silicon sources,***-ceramics were successfully prepared by the one-step *** is found that the increase in MSWI fly ash promotes the fracture of glass mesh(Si-O)and the generation of non-bridging oxygen,reducing the polymerization degree of glass network structure,which leads to the decrease in glass *** difference between glass transition temperature(T_(g)) and crystallization temperature(T_(c)) was narrowed,and crystallization activation energy of basic glass was reduced,which promoted *** lower crystallization activation energy(E=217.56 kJ·mol^(-1)) and high utilization rate of 50 wt% MSWI fly ash,the optimal glass-ceramics with spherical diopside,cuspidine and glass phase,excellent hardness of 7.97 GPa and bending resistance of 114.86 MPa are *** is worth mentioning that most of the high content of chlorine in MSWI fly ash will evaporate during vitrification process;the residual chlorine as well as heavy metals can be present steadily in crystalline ***,this study not only increases the attachment value of MSWI fly ash,but also eliminates the problems caused by high chlorine and heavy metals in MSWI fly ash.

关键词： Municipal solid waste incinerated(MSWI)fly ash Glass–ceramics Crystallization behavior Microstructure Properties Chlorine

Synthesis and properties of SrFe_(12)O_(19) obtained by solid waste recycling of oily cold rolling mill sludge

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International Journal of Minerals,Metallurgy and Materials 2019年第5期26卷 642-648页

作者： Bo Liu shen-gen zhang Britt-Marie Steenari Christian Ekberg Institute for Advanced Materials and Technology University of Science and Technology Beijing Nuclear Chemistry and Industrial Material Recycling Department of Chemistry and Chemical Engineering Chalmers University of Technology

The aim of this study was to develop a new approach for the preparation of environmentally friendly, high-value products from oily cold rolling mill(CRM) sludge. Utilizing oily CRM sludge as a source of iron, strontium hexaferrite(SrFe_(12)O_(19)) powders were prepared by multi-step processes involving acid leaching, chemical conversion treatment, and synthesis by a citrate precursor. The influences of citric acid dosage and the pH of the sol system on the formation, crystallite size, and magnetic properties of the obtained SrFe_(12)O_(19) powders were investigated. High saturation magnetization(74.8 mA·m^2·g^(–1)) and intrinsic coercivities(614.46 mT) were achieved for pH 7.0 of the sol system, for which the molar ratio of citric acid dosage to the total dosage of Fe^(3+) and Sr^(2+) was 1.5. This study presents a new approach to utilizing oily CRM sludge, and even refractory iron-containing solid waste.

关键词： strontium ferrite oily cold rolling mill sludge magnetic properties citrate precursor method recycling

Recovery of waste rare earth fluorescent powders by two steps acid leaching

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Rare Metals 2013年第6期32卷 609-615页

作者： shen-gen zhang Min Yang Hu Liu De-An Pan Jian-Jun Tian Institute of Advanced Materials and Technology School of Materials Science and Engineering University of Science and Technology Beijing

The effects of the acid leaching and alkali fusion on the leaching efficiency of Y,Eu,Ce,and Tb from the waste rare earth fluorescent powders were investigated in this *** results show that hydrochloric acid is better than sulfuric acid in the first acid leaching,and NaOH is better than Na2CO3in the alkali *** the first acid leaching,the Wloss is 20.94%when the waste rare earth fluorescent powders are acid leached in H?concentration 3 mol L-1and S/L ratio 1:3 for 4 h due to red powders *** better results of the alkali fusion can be got at 800℃ for 2 h when the NaOH is *** blue powders and the green powders can be dissolved into NaAlO2and oxides such as rare earth oxide(REO).The REO can be dissolved in H?concentration 5 mol L-1,S/L1:10 for 3 h in the second acid *** leaching rates of the Y,Eu,Ce,and Tb are 99.06%,97.38%,98.22%,and 98.15%,*** leaching rate of the total rare earth is 98.60%.

关键词： Waste rare earth fluorescent powders Two steps acid leaching Alkali fusion

Preparation of pure SnO_2 powders from tin slag of printed circuit boards waste

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Rare Metals 2014年第6期33卷 749-753页

作者： Bin Li shen-gen zhang Kun zhang De-An Pan Jian-Jun Tian Duan-Ting zhang Institute for Advanced Materials and Technology School of Materials Science and Engineering University of Science and Technology Beijing Beijing Nonferrous Metals and Rare Earth Research Institute

The recycling method and principle of SnO2 from the tin slag of printed circuit boards（PCB） waste were investigated. In this study, pure SnO2 powders were obtained through a multi-step process including ball-milling, roasting, dissolving, precipitating, and pickling. The total recovery rate of tin can be up to 91 %. The SnO2 powders obtained is the single phase, and the content of SnO2 is up to 99.9 %. However, the SnO2 particles are easier to agglomerate during the precipitation process. The agglomerate SnO2 particles are about 7.778 lm in mean particle size（D50）. This preparation method presents a viable alternative for the tin slag recycling. The tin is not only recycled, but also reused directly to prepare pure SnO2 powders.

关键词： SnO2 Tin slag Printed circuit boards(PCB) waste

Effects of pre-strain and baking parameters on the microstructure and bake-hardening behavior of dual-phase steel

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International Journal of Minerals,Metallurgy and Materials 2014年第8期21卷 766-771页

作者： Chun-fu Kuang shen-gen zhang Jun Li Jian Wang Hua-fei Liu School of Materials Science and Engineering University of Science and Technology Beijing Research Institute Baoshan Iron and Steel Co. Ltd.

In a typical process, C-Mn steel was annealed at 800℃ for 180 s, and then cooled rapidly to obtain the ferrite-martensite microstructure. After pre-straining, the specimens were baked and the corresponding bake-hardening （BH） values were determined as a function of pre-strain, baking temperature, and baking time. The influences ofpre-strain, baking temperature and baking time on the microstructure evolution and bake-hardening behavior of the dual-phase steel were investigated systematically. It was found that the BH value apparently increased with an increase in pre-strain in the range from 0 to 1%; however, increasing pre-strain from 1% to 8% led to a decrease in the BH value. Furthermore, an increase in baking temperature favored a gradual improvement in the BH value because of the formation of Cottrell atmosphere and the precipitation of carbides in both the ferrite and martensite phases. The BH value reached a maximum of 110 MPa at a baking temperature of 300℃. Moreover, the BH value enhanced significantly with increasing baking time from 10 to 100 min.

关键词： dual-phase steel pre-strain baking treatment microstructure hardening

Crystallization mechanism of glass-ceramics prepared from stainless steel slag

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Rare Metals 2018年第5期37卷 413-420页

作者： Wen-Di Fan Qiang-Wei Yang Bin Guo Bo Liu shen-gen zhang Institute for Advanced Materials and Technology University of Science and Technology Beijing

Glass-ceramics have been prepared by using stainless steel slag, fly ash and coal fly ash that were figobtained from industrial solid waste. The crystallization behavior and mechanical characterization of the glass-ce-ramics with different （CaO ＋ MgO）/（SiO2 ＋ Al2O3） content ratios were studied. While the basicity decreases from 1.2 to 0.9 cm^-3, the bridge oxygen content increases from 1.18 ~ 10^21 to 1.34 ~ 10^21 cm^-3. According to the deconvolution of Raman spectra, the relative abundance of the stretching of Si-Onb bond （Q^n units） can be obtained. The increase in the Q^3 units dominates the polymerization in the process of decreasing basicity. This change in bonding is demonstrated to lead to polymerization of the glass network and the increase in crystallization activation energy from 336.0 to 360.7 kJ·mol^-l. The results demonstrate that the production of the glass-ceramics from industrial steel slag, fly ash and coal fly ash is cost-effective and offers advantages over other production methods.

关键词： Glass-ceramics Stainless steel slag Augite