Wood-based panels containing urea-formaldehyde resin result in the long-term release of formaldehyde and threaten human health.In this study,inorganic aluminosilicate coatings prepared by combining metakaolin,silica f...Wood-based panels containing urea-formaldehyde resin result in the long-term release of formaldehyde and threaten human health.In this study,inorganic aluminosilicate coatings prepared by combining metakaolin,silica fume,NaOH,and H_(2)O were applied to the surfaces of wood-based panels to obstruct formaldehyde release.The Si/Al,Na/Al,and H_(2)O/Na_(2)O molar ratios of the coatings were regulated to investigate their effects on the structure and formaldehyde-resistant barrier properties of coatings.Results showed that the cracks in the coatings gradually disappeared and the formaldehyde resistance rates of the barrier increased as the Si/Al molar ratio was increased from 1.6 to 2.2.This value also increased as the Na/Al molar ratio was increased from 0.9 to 1.2 because of the improvement of the degree of polymerization.As the H_(2)O/Na_(2)O molar ratio was increased from 12 to 15,the thickness of the dry film decreased gradually and led to the reduction in the formaldehyde resistance rate.When the Si/Al,Na/Al,and H_(2)O/Na_(2)O molar ratios were 2.2,1.2,and 12,respectively,the inorganic aluminosilicate coating showed good performance as a formaldehyde-resistant barrier and its formaldehyde resistance rate could reach up to 83.2%.展开更多
Brownmillerite-type oxides Ba_2In_(2-x-y)Mn_xAl_yO_(5+x)(0 ≤ x ≤ 0.6, 0 ≤ y ≤ 0.5) were prepared at 1300°C through solid-state reaction. X-ray diffraction(XRD) analysis showed that the structure symm...Brownmillerite-type oxides Ba_2In_(2-x-y)Mn_xAl_yO_(5+x)(0 ≤ x ≤ 0.6, 0 ≤ y ≤ 0.5) were prepared at 1300°C through solid-state reaction. X-ray diffraction(XRD) analysis showed that the structure symmetry evolved from orthorhombic to cubic with increasing Mn and Al contents. When y was greater than 0.3, peaks associated with small amounts of BaAl_2O_4 and Ba_2InAlO_5 impurities were observed in the XRD patterns. When substituted with a small amount of Mn(x ≤ 0.3), the Ba_2In_(2-x-y)Mn_xAl_yO_(5+x) samples exhibited an intense turquoise color. The color changed to green and dark-green with increasing Mn concentration. UV–vis absorbance spectra revealed that the color changed only slightly upon Al doping. The valence state of Mn ions in Ba_2In_(2-x-y)Mn_xAl_yO_(5+x) was confirmed to be +5 on the basis of X-ray photoelectron spectroscopic analysis. According to this analysis, the intense turquoise color of the Ba_2In_(2-x-y)Mn_xAl_yO_(5+x) samples is rooted in the existence of Mn^(5+); thus, the introduction of Al does not affect the optical properties of the compounds.展开更多
In this paper, V2O5 sol was firstly prepared using vanadyl sulfate as a vanadium source by modified sol-gel method at room temperature. Then flower-like V2O5 powders were prepared by coagulating as-prepared sol with a...In this paper, V2O5 sol was firstly prepared using vanadyl sulfate as a vanadium source by modified sol-gel method at room temperature. Then flower-like V2O5 powders were prepared by coagulating as-prepared sol with anhydrous ethanol and subsequent annealing crystallization. The X-ray diffraction analysis indicated that V2O5 powders exhibited orthorhombic crystal structure after annealing at 450 ℃. The experimental data obtained from both field emission scanning electron microscopy and high-resolution transmission electron microscopy identified that V2O5 powders were approximately flower-like in shape and about 5 μm in size. Besides, the Brunauer-Emmett-Teller specific surface area of flowerlike V2O5 powders was 24.25 m^2/g. According to Uv-Vis spectroscopy, the degradation rate of toluidine blue O(TBO) on as-prepared flower-like V2O5 powders during 10 h of visible light irradiation with an intensity of 15.4 mW/m^2 was 88%,which was faster than those over P25(46%) as a comparison. In addition, the mineralization process of TBO was investigated, which primarily consisted of demethylation and ring-opening oxidation processes, and confirmed by liquid chromatograph-mass spectrometry. The precipitation-oxidation-peptization, coagulation, and crystallization processes were proposed as the formation mechanism for the preparation of flower-like V2O5.展开更多
基金financially supported by the National Key Research and Development Program of China(Nos.2016 YFC0700607,2017YFB0304305,and 2016YFC0700901)the Fundamental Research Funds for the Central Universities of China(No.FRF-TP-20-006A3).
文摘Wood-based panels containing urea-formaldehyde resin result in the long-term release of formaldehyde and threaten human health.In this study,inorganic aluminosilicate coatings prepared by combining metakaolin,silica fume,NaOH,and H_(2)O were applied to the surfaces of wood-based panels to obstruct formaldehyde release.The Si/Al,Na/Al,and H_(2)O/Na_(2)O molar ratios of the coatings were regulated to investigate their effects on the structure and formaldehyde-resistant barrier properties of coatings.Results showed that the cracks in the coatings gradually disappeared and the formaldehyde resistance rates of the barrier increased as the Si/Al molar ratio was increased from 1.6 to 2.2.This value also increased as the Na/Al molar ratio was increased from 0.9 to 1.2 because of the improvement of the degree of polymerization.As the H_(2)O/Na_(2)O molar ratio was increased from 12 to 15,the thickness of the dry film decreased gradually and led to the reduction in the formaldehyde resistance rate.When the Si/Al,Na/Al,and H_(2)O/Na_(2)O molar ratios were 2.2,1.2,and 12,respectively,the inorganic aluminosilicate coating showed good performance as a formaldehyde-resistant barrier and its formaldehyde resistance rate could reach up to 83.2%.
基金financially supported by the National Natural Science Foundation of China (No.51402016)the Fundamental Research Funds for the Central Universities (No.FRF-TP-15-008A2)
文摘Brownmillerite-type oxides Ba_2In_(2-x-y)Mn_xAl_yO_(5+x)(0 ≤ x ≤ 0.6, 0 ≤ y ≤ 0.5) were prepared at 1300°C through solid-state reaction. X-ray diffraction(XRD) analysis showed that the structure symmetry evolved from orthorhombic to cubic with increasing Mn and Al contents. When y was greater than 0.3, peaks associated with small amounts of BaAl_2O_4 and Ba_2InAlO_5 impurities were observed in the XRD patterns. When substituted with a small amount of Mn(x ≤ 0.3), the Ba_2In_(2-x-y)Mn_xAl_yO_(5+x) samples exhibited an intense turquoise color. The color changed to green and dark-green with increasing Mn concentration. UV–vis absorbance spectra revealed that the color changed only slightly upon Al doping. The valence state of Mn ions in Ba_2In_(2-x-y)Mn_xAl_yO_(5+x) was confirmed to be +5 on the basis of X-ray photoelectron spectroscopic analysis. According to this analysis, the intense turquoise color of the Ba_2In_(2-x-y)Mn_xAl_yO_(5+x) samples is rooted in the existence of Mn^(5+); thus, the introduction of Al does not affect the optical properties of the compounds.
基金supported by the China National Key Research & Development Plan (Grant Nos.2016YFC0700901,2016YFC0700607) and project (BZZ14J001)
文摘In this paper, V2O5 sol was firstly prepared using vanadyl sulfate as a vanadium source by modified sol-gel method at room temperature. Then flower-like V2O5 powders were prepared by coagulating as-prepared sol with anhydrous ethanol and subsequent annealing crystallization. The X-ray diffraction analysis indicated that V2O5 powders exhibited orthorhombic crystal structure after annealing at 450 ℃. The experimental data obtained from both field emission scanning electron microscopy and high-resolution transmission electron microscopy identified that V2O5 powders were approximately flower-like in shape and about 5 μm in size. Besides, the Brunauer-Emmett-Teller specific surface area of flowerlike V2O5 powders was 24.25 m^2/g. According to Uv-Vis spectroscopy, the degradation rate of toluidine blue O(TBO) on as-prepared flower-like V2O5 powders during 10 h of visible light irradiation with an intensity of 15.4 mW/m^2 was 88%,which was faster than those over P25(46%) as a comparison. In addition, the mineralization process of TBO was investigated, which primarily consisted of demethylation and ring-opening oxidation processes, and confirmed by liquid chromatograph-mass spectrometry. The precipitation-oxidation-peptization, coagulation, and crystallization processes were proposed as the formation mechanism for the preparation of flower-like V2O5.