Coatings
·
2019
·Vol. 9
·期 12
·867
·
IF 2.33
Diping Zeng,Zhiyi Liu,Song Bai,Jian Wang
In the present work, a coating was prepared on an Al alloy substrate by plasma electrolytic oxidation (PEO). To seal the micro defects in the oxide scale, a siloxane layer was prepared on the PEO coating by sol gel method. The polymer sealant was synthesized from Tetraethoxy silane (TEOS) and methacryloxy propyl trimethoxyl silane (MPTES). The chemical structure of the polymer was studied by Fourier transform infrared spectroscopy (FTIR). The morphologies and microstructure of the PEO coating and siloxane coating were investigated by scanning electron microscopy (SEM). The results showed that siloxane formed a continuous layer on the surface and effectively sealed the micro defects. The corrosion behavior of the coatings in three different corrosion solutions (NaCl, HCl, and NaOH) was examined by electrochemical impedance spectroscopy and potentiodynamic polarization. The corrosion resistance of the sealed coatings was superior to that of the PEO coating because it prevented the penetration of corrosive solutions. The corrosion resistance of the sealed coatings was found to decrease with increasing electrolyte concentration. The work demonstrated that siloxane sealing may greatly enhance the corrosion resistance of Al-based PEO coating in acidic, neutral, and alkaline environments.Keywords:PEO coating;silane polymer;sealing treatment;corrosion resistance
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JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY
·
2019
·Vol. 19
·期 11
·7169-7177
·
IF 1.093
Qin Zhuozhuo,Liu Wenxia,Chen Huabin,Chen Jun,Li Zhenzhen
Developing full-spectrum photocatalysts that harvests solar light from ultraviolet to near-infrared light has aroused great interest in photodegradation of organic pollutants, due to the imminent energy crisis and growing pollution issues. Herein, we report an excellent full-spectrum
photocatalyst derived from calcination of an Mg/Zn/Al/Er-hydrotalcite-like compound. The photocatalyst is a stable multi-phase oxide consisting of various syntrophic Er3+-doped metal oxides with different particle sizes and morphology. Its ultraviolet (UV) photocatalytic activity
is maximized by increasing the fraction of Zn2+ and sustaining the pure hydrotalcite-like phase with an appropriate fraction of Mg2+ in preparing the Mg/Zn/Al/Er-hydrotalcite-like precursor. The visible and NIR photocatalytic activities are triggered by an indirect excitation
involving an up-conversion process. The major active species of the photocatalyst in the photodegradation of methyl orange are superoxide anions and photogenerated holes. Nevertheless, hydroxyl radicals also play a moderate role in the photodegradation process. This work finds a new way to
prepare full-spectrum photocatalysts with tunable chemical compositions via an environmentally friendly hydrotalcite-like precursor.
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CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Xiubo Xie,Ming Chen,Peng Liu,Jiaxiang Shang,Tong Liu
The Mg-5.0 wt%Ni-2.3 wt%V nanocomposite has been produced through reducing NiCl 2 with the Mg-V nanoparticles (NPs) prepared by hydrogen plasma metal reaction (HPMR) approach. The in situ formed Ni and V particles of about 15 nm uniformly decorate on the surface of Mg NPs. The Ni NPs transform into Mg 2 Ni while the V NPs remain unchanged after first hydrogen absorption and desorption cycle at 673 K. They show synergistic catalytic effects on the hydrogen storage properties of Mg-Ni-V nanocomposite. The nanocomposite can absorb 4.6 wt% H 2 within 30 min at 473 K and desorb 5.2 wt% H 2 within 10 min at 623 K. The activation energies of hydrogenation/dehydrogenation processes are decreased to 52.8 and 85.1 kJ per mol H 2 , lower than those of the Mg-5.4 wt%Ni nanocomposite of 63.2 and 89.3 kJ per mol H 2 . The enhanced hydrogen storage performances of the Mg-Ni-V nanocomposite are mainly attributed to the synergistic catalytic effects of the Mg 2 Ni and V catalysts, and the nanosize effect of Mg NPs on the decrease of the hydrogen diffusion distance.
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Inorganic Chemistry Frontiers
·
2018
·Vol. 5
·期 10
·2657-2665
·
IF 5.106
Hongwei Pang,Yihan Wu,Shuyi Huang,Congcong Ding,Shun Li,Xiangxue Wang,Shujun Yu,Zhongshan Chen,Gang Song,Xiangke Wang
In the past few decades, uranium (235, 238U(VI)) has turned into a forefront environmental issue due to its extensive use in the nuclear industry and its toxicity and radioactivity. Herein, nanoscale zero valent iron (nZVI), which was supported on Ca–Mg–Al-layered double hydroxide (Ca–Mg–Al-LDH/nZVI), was fabricated via an in situ growth route and employed for U(VI) decontamination from aqueous solutions. Spectroscopy and microscopy (SEM, TEM, FTIR, XRD, BET, and XPS) technologies were applied for the investigation of the properties of Ca–Mg–Al-LDH/nZVI and the U(VI) elimination mechanism. Ca–Mg–Al-LDH/nZVI had a remarkable BET surface (426.8 m2 g−1), abundant functional groups (i.e., Fe–O, Al–O, –OH, etc.), high efficiency (4 h to achieve equilibrium) and large adsorption capacities (Qmax = 216.1 mg g−1) for U(VI) removal. The decontamination process of U(VI) was observed to be pH-dependent and ionic strength-independent, suggesting that the adsorption was predominated by inner-sphere surface coordination. XPS spectroscopy analyses indicated that the reduction and adsorption of nZVI and the adsorption of Ca–Mg–Al-LDH dominated U(VI) elimination on Ca–Mg–Al-LDH/nZVI. The environmentally friendly synthesis method, excellent physicochemical properties and remarkable removal performance suggested that Ca–Mg–Al-LDH/nZVI was applicable as a potential adsorbent for U(VI) decontamination from wastewater in environmental pollution remediation.
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MATERIALS CHARACTERIZATION
·
2015
·
IF 1.845
Muhammad Rashad,Fusheng Pan,Wei Guo,Han Lin,Muhammad Asif,Muhammad Irfan
Powder metallurgy method was used to synthesize Mg–3Al–1Zn-(1.5Al 2 O 3 –xSiC) composites, to investigate the influence of Al 2 O 3 and SiC hybrid particles on mechanical properties of magnesium alloy. The mechanical characterization of as-extruded composites demonstrated enhanced 0.2% yield strength, and ultimate strength, and reduced fracture strain (Strain at fracture) values both in tension and compression loading. The micro hardness (Vickers hardness, Hv) of composites was increased with increasing reinforcement particle contents. The mechanical characterization of heat treated samples indicated the enhanced fracture strains and reduced microhardness, 0.2% tensile yield strength, ultimate tensile strength. The enhanced fracture strains of heat treated sample are attributed to the dissolved Mg 17 Al 12 intermetallic phases in the matrix. An attempt is made to narrate the effect of heat treatment, presence of Al 2 O 3 and SiC hybrid particles, and their increasing amount on microstructural and mechanical properties of magnesium alloy.
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CORROSION SCIENCE
·
2013
·
IF 3.615
Yingqi Chen,Guojiang Wan,Juan Wang,Sheng Zhao,Yuancong Zhao,Nan Huang
Magnesium-based materials are promising in biodegradable implants, but the proper corrosion control is a challenge. Phytic acid has potential as a coating on Mg to control the degradation rate. An alkaline pre-treatment process is implemented to form the hydroxyl group on the Mg surface and covalently immobilize phytic acid. The surface-immobilized phytic acid molecules chelate with Mg to form a dense and homogenous protective coating. The coated Mg exhibits a smaller corrosion current density and degradation rate as compared to bare Mg in the phosphate buffered saline.
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JOURNAL OF ALLOYS AND COMPOUNDS
·
2017
·
IF 3.133
Liuting Shi,Jia Hu,XuDong Lin,Liang Fang,Fang Wu,Jiao Xie,FanMing Meng
Composite coatings consisting of polyphenylene sulfide (PPS), polytetrafluoroethylene (PTFE) and 40 nm silicon dioxide (SiO 2 ) nanoparticles (PPS-PTFE/SiO 2 ) with SiO 2 in the range of 0–4 g/l were successfully prepared on AZ31 Mg alloys by a simple spray process. The morphology, composition, water contact angle (WCA), wear behavior and corrosion properties of the composite coatings were measured by using SEM, FT-IR, OCA20, sandpaper abrasion and electrochemical workstation, respectively. Effects of SiO 2 content on the wear behavior and corrosion properties of the coatings were studied. It is found that micro-sized protrusions distribute on the surface of the coatings, and a fibrous-network structure of PTFE arranges on the protrusions. WCAs of the PPS-PTFE/SiO 2 (0–4 g/l) coating are in the range of (152°–145.5°) ± 0.3° and the sliding angles (SAs) are less than 5°. The WCAs of the un-abraded and 10 m-abraded-on-sandpaper PPS-PTFE/SiO 2 (4 g/l) coating are 145.5°±0.3° and 142.5°±0.3°, respectively, implying the PPS-PTFE/SiO 2 coating is a robust superhydrophobic one with good wear resistance. Due to the superhydrophobic characteristics, the PPS-PTFE-based coatings show superior corrosion resistance in 3.5 wt% NaCl solution to pristine AZ31 Mg alloys. Owing to the excellent superhydrophobicity, wear resistance and corrosion resistance properties, the robust PPS-PTFE/SiO 2 coating is regarded to possess great potential to be applied in automobiles and navigation industries in future.
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INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2017
·
IF 2.843
Peng Chen,Siyang Tang,Hairong Yue,Changjun Liu,Chun Li,Bin Liang
A new method coupling CO2 mineralization and solvent extraction was proposed and investigated to precipitate magnesium from high Mg/Li ratio brine. Organic amine was employed to extract HCl formed during the CO2 mineralization process and to realize continuous conversion of MgCl2 to precipitated MgCO3, thereby removing the magnesium contained in the brine. The effects of brine concentration, extractant, diluents, extractant concentration, phase ratio, and reaction temperature were systematically investigated. A blend of trioctylamine and isoamyl alcohol was used as the extractant and diluent, and the reaction parameters were optimized. The mechanism was proposed, and a stripping process was designed. Under the optimal conditions, the conversion of magnesium was as high as 67.41%, and the Mg/Li ratio of the raffinate decreased from 20 to 5.4.
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PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
·
2024
·
IF 6.9
Pengfei Yang,Jianhong Bi,Hua Zhang,Zhenyu Wu
Herein, we explored the efficacy of ethylenediaminetetraacetic acid (EDTA) intercalation modified layered double hydroxides (LDHs) composites for removing the anionic dye methyl orange (MO) from aqueous solutions. EDTA intercalated layered hydroxides (EDTA-Mg/Fe LDHs) with a 4:1 Mg/Fe molar ratio have been successfully prepared and thoroughly characterized using SEM-EDS, FTIR, XRD, XPS, UV-Vis and Zeta potential analysis. Batch adsorption experiments were conducted to evaluate the adsorption performance of the innovative adsorbent on MO. The results indicated successful EDTA loading into Mg/Fe LDHs, exhibiting excellent adsorption performance for MO. At pH 6.0, with a 0.03 g adsorbent dose, MO removal exceeded 91.10 % within 90 min, following a pseudo second order kinetic model. The maximum adsorption capacity reached 1207.43 mg/g, fitting well with the Redlich Peterson model. Thermodynamic parameters suggested a spontaneous and favorable adsorption process. Furthermore, we assessed the desorption and regeneration effectiveness of EDTA-Mg/Fe LDHs, emphasizing the importance of developing cost-effective and environmentally friendly adsorbents with practical applications and scientific significance.
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Journal of Environmental Chemical Engineering
·
2025
·
IF 7.2
Linlin Hao,Jingshuang Yan,Jiaoying Guo,Nannan Wang,Ming Zeng
Swine wastewater is a type of highly turbid wastewater with extremly high concentration of COD, NH 4 + , and total phosphorus. To address the drawbacks of commercial coagulants in the pretreatment of swine wastewater, such as loose flocs, slow settling rates, and the inability to remove NH 4 + , a novel Mg-Fe-Al hybrid magnetic coagulant (Mg/Fe/Al-MC) is prepared by using the high-pressure acid leaching (HPAL) technology based on iron tailings waste. Compared to atmospheric acid leaching (AAL), HPAL significantly increased the iron leaching rate from 22 % to 61 %. The specific surface area was increased from 5.1 to 9.2 m 2 /g. The study revealed the synergistic crystallization-coagulation-adsorption mechanism for the purification of swine wastewater. When the dosage of Mg/Fe/Al-MC was 2.5 g/L and pH was 9.0, the removal efficiency of NH 4 + reached 60 % by forming magnesium ammonium phosphate (MAP). Zeta potential results indicated that the coagulation mechanism of Mg/Fe/Al-MC is primarily based on electrostatic neutralization. After maturing Mg/Fe/Al-MC for 60 h, the content of essential polymeric Fe-Al hydroxide complexes [Fe(III)+Al(III)](b) reached 22.7 %. The insoluble porous particles exhibited a significant adsorption capacity, suggesting its important role in pollutant removal. Under the action of an external magnetic field, the settling velocity of Mg/Fe/Al-MC was significantly faster than that of polyaluminum chloride (PAC), with a much higher clear water yield of 75.5 %. This study provides new pathway for the enhanced pretreatment of swine wastewater.
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NANOTECHNOLOGY
·
2024
·
IF 2.9
Mewin Vincent,Venkata Sai Avvaru,Maciej Haranczyk,Vinodkumar Etacheri
Although Mg-Li dual metal-ion batteries are proposed as a superior system that unite safety of Mg-batteries and performance of Li-ion based systems, its practical implantation is limited due to the lack of reliable high performance cathodes. Herein, we report a high-performance Mg-Li dual metal-ion battery system based on highly pseudocapacitive hierarchical TiO2-B nanosheet assembled spheres (NS) cathode. This 2D cathode displayed exceptional pseudocapacitance (a maximum of 93%) specific capacity (303 mAh/g at 25 mA/g), rate performance (210 mAh/g at 1A/g), consistent cycling (retain ~100% capacity for 3000 cycles at 1A/g), coulombic efficiency (nearly 100%) and fast-charging (~12.1 min). These properties are remarkably dominant to the existing Mg-Li dual metal-ion battery cathodes. Spectroscopic and microscopic mechanistic studies confirmed negligible structural changes during charge-discharge cycles of the TiO2-B nanosheet assembled spheres electrodes. Exceptional electrochemical properties of the 2D electrode is ascribed to remarkable pseudocapacitive Mg-Li dual metal-ion diffusion via the numerous nanointerfaces of TiO2-B caused by its hierarchical microstrucrure. Large surface area, nanosheet morphology, mesoporous structure and ultrathin nature also acted as secondary factors facilitating improved electrode-electrolyte contact. Demonstrated approach of pseudocapacitive type Mg-Li dual metal-ion intercalation through hierarchical nanointerfaces may be further utilized for the designing of numerous top-notch electrode materials for futuristic Mg-Li dual metal-ion batteries
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APPLIED ORGANOMETALLIC CHEMISTRY
·
2024
·Vol. 39
·期 1
·e7942
·
IF 3.7
Di Su,Wen Xu,Dongbin Yang,Jiandu Lei,Jing Liu,Chunping Chen,Dermot O'Hare
As a renewable new material with high void ratio, large adsorption surface area, and high adsorption rate, biomass carbon (BC) is a promising adsorbent, which has received wide attention for the degradation of dyes. However, physical adsorption cannot completely remove dyes, and there is also the risk of secondary pollution. ZnAl-layered double hydroxide (ZnAl-LDH) is a semiconductor photocatalyst with abundant active sites and excellent degradation efficiency. In this paper, we have designed a ZnAl-layered double oxide@biomass carbon (ZnAl-LDO@BC) formed by in situ grown LDH on the waste poplar wood as a synergistic adsorption and photocatalytic system. BC as a support could enhance the dispersity of layered double oxide (LDO), whereas LDO could provide photodegradation function to BC. Our studies indicate that the prepared ZnAl-LDO@BC presents lower bandgap energy, higher surface area, and lower complexation efficiency of holes and electrons than delignified biomass (DB). As a result, ZnAl-LDO@BC increased the removal rate of malachite green (MG) to 85.8%, which is 3.5 times higher than DB. The maximum removal rate was close to 98%, and the removal capacity was 1954 mg g −1 under an initial concentration of 200 mg L −1 of MG dye, and the possible mechanism of MG degradation was also investigated. In this study, the conversion of agroforestry wastes into high-value materials applied to dye degradation provides a new pathway for the production of stable, sustainable, and superior photocatalytic material.
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