CN103990457A - Preparation method of silver/silver vanadate composite photocatalyst - Google Patents
Preparation method of silver/silver vanadate composite photocatalyst Download PDFInfo
- Publication number
- CN103990457A CN103990457A CN201410259218.9A CN201410259218A CN103990457A CN 103990457 A CN103990457 A CN 103990457A CN 201410259218 A CN201410259218 A CN 201410259218A CN 103990457 A CN103990457 A CN 103990457A
- Authority
- CN
- China
- Prior art keywords
- silver
- foil surface
- oxide
- vanadate
- solution
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 229910052709 silver Inorganic materials 0.000 title claims abstract description 52
- 239000004332 silver Substances 0.000 title claims abstract description 52
- 239000011941 photocatalyst Substances 0.000 title claims abstract description 17
- 239000002131 composite material Substances 0.000 title claims abstract description 16
- 238000002360 preparation method Methods 0.000 title claims abstract description 9
- RAVDHKVWJUPFPT-UHFFFAOYSA-N silver;oxido(dioxo)vanadium Chemical compound [Ag+].[O-][V](=O)=O RAVDHKVWJUPFPT-UHFFFAOYSA-N 0.000 title abstract 5
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical compound [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 claims abstract description 78
- NDVLTYZPCACLMA-UHFFFAOYSA-N silver oxide Chemical compound [O-2].[Ag+].[Ag+] NDVLTYZPCACLMA-UHFFFAOYSA-N 0.000 claims abstract description 36
- 229910001923 silver oxide Inorganic materials 0.000 claims abstract description 18
- 235000011114 ammonium hydroxide Nutrition 0.000 claims abstract description 13
- UNTBPXHCXVWYOI-UHFFFAOYSA-O azanium;oxido(dioxo)vanadium Chemical compound [NH4+].[O-][V](=O)=O UNTBPXHCXVWYOI-UHFFFAOYSA-O 0.000 claims abstract description 12
- 239000000843 powder Substances 0.000 claims abstract description 8
- 230000001680 brushing effect Effects 0.000 claims abstract description 7
- PLKATZNSTYDYJW-UHFFFAOYSA-N azane silver Chemical compound N.[Ag] PLKATZNSTYDYJW-UHFFFAOYSA-N 0.000 claims abstract description 6
- WQEVDHBJGNOKKO-UHFFFAOYSA-K vanadic acid Chemical compound O[V](O)(O)=O WQEVDHBJGNOKKO-UHFFFAOYSA-K 0.000 claims description 22
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 10
- 230000000694 effects Effects 0.000 claims description 6
- 229910021529 ammonia Inorganic materials 0.000 claims description 5
- 238000004090 dissolution Methods 0.000 claims description 5
- 239000011888 foil Substances 0.000 claims description 5
- 239000003054 catalyst Substances 0.000 abstract description 4
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 230000003197 catalytic effect Effects 0.000 abstract description 2
- 239000002994 raw material Substances 0.000 abstract description 2
- 238000000926 separation method Methods 0.000 abstract description 2
- 238000004065 wastewater treatment Methods 0.000 abstract description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 abstract 3
- 238000007598 dipping method Methods 0.000 abstract 2
- 230000002708 enhancing effect Effects 0.000 abstract 1
- 230000001590 oxidative effect Effects 0.000 abstract 1
- 239000002244 precipitate Substances 0.000 abstract 1
- 239000002351 wastewater Substances 0.000 description 5
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- AEEAZFQPYUMBPY-UHFFFAOYSA-N [I].[W] Chemical compound [I].[W] AEEAZFQPYUMBPY-UHFFFAOYSA-N 0.000 description 3
- 238000004042 decolorization Methods 0.000 description 3
- 238000000034 method Methods 0.000 description 3
- CQPFMGBJSMSXLP-UHFFFAOYSA-M acid orange 7 Chemical compound [Na+].OC1=CC=C2C=CC=CC2=C1N=NC1=CC=C(S([O-])(=O)=O)C=C1 CQPFMGBJSMSXLP-UHFFFAOYSA-M 0.000 description 2
- 150000001875 compounds Chemical class 0.000 description 2
- RBTBFTRPCNLSDE-UHFFFAOYSA-N 3,7-bis(dimethylamino)phenothiazin-5-ium Chemical compound C1=CC(N(C)C)=CC2=[S+]C3=CC(N(C)C)=CC=C3N=C21 RBTBFTRPCNLSDE-UHFFFAOYSA-N 0.000 description 1
- 239000003905 agrochemical Substances 0.000 description 1
- 239000008346 aqueous phase Substances 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 238000005234 chemical deposition Methods 0.000 description 1
- 238000000975 co-precipitation Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 239000000975 dye Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229960000907 methylthioninium chloride Drugs 0.000 description 1
- 239000002105 nanoparticle Substances 0.000 description 1
- 239000002957 persistent organic pollutant Substances 0.000 description 1
- 239000012071 phase Substances 0.000 description 1
- 238000005191 phase separation Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 150000003071 polychlorinated biphenyls Chemical class 0.000 description 1
- 125000005575 polycyclic aromatic hydrocarbon group Chemical group 0.000 description 1
- 238000005215 recombination Methods 0.000 description 1
- 238000010532 solid phase synthesis reaction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
Landscapes
- Catalysts (AREA)
Abstract
The invention discloses a preparation method of a silver/silver vanadate composite photocatalyst, which comprises the following steps: laying a 9-16 cm<2> silver foil on a horizontal surface, dipping a hair brush in 20-30mL of 15-30% (mass percent) H2O2 solution, brushing on the silver foil surface, and oxidizing the silver on the silver foil surface into silver oxide; dissolving 3-5g of V2O5 powder in 25-30mL of 20-25% (mass percent) of ammonia water, and keeping the ammonia water excessive to obtain an ammonium vanadate solution; dipping a hair brush into the ammonium vanadate solution, brushing on the silver foil surface of which the surface is silver oxide, dissolving the silver oxide into a silver-ammonia complex under the action of the ammonia water to finally generate a silver vanadate precipitate on the silver foil surface, thereby obtaining the silver/silver vanadate composite photocatalyst. The silver foil is the raw material and support of the catalyst, thereby avoiding the problem of separation of the powder after participating in wastewater treatment. The silver vanadate is supported on the silver surface to closely contact the silver, thereby being beneficial to transferring the photogenerated electrons and enhancing the catalytic efficiency.
Description
Technical field
The invention belongs to water treatment field, relate to the preparation method of a kind of silver/vanadic acid silver composite photo-catalyst, relate in particular to a kind of catalysis material for the treatment of organic wastewater and preparation method thereof.
Background technology
Current, follow the develop rapidly of industrial technology, the water resource that the mankind depend on for existence is all subject to pollution in various degree, and water resource pollution has become the problem demanding prompt solution that countries in the world face.The existence of the pollutant in water, particularly toxic organic pollutant, not only causes environmental pollution, ecological disruption, and serious harm human health.These organic pollutions comprise polycyclic aromatic hydrocarbon, Polychlorinated biphenyls, agricultural chemicals, environmental disturbances element, dyestuff etc.
Vanadic acid silver is that a class has visible light-responded novel photocatalyst, and its monoclinic phase energy gap is lower than 2.7eV, has higher visible light-respondedly, and stable in properties, becomes study hotspot in recent years.Vanadic acid silver has multiple preparation method, as solid-phase synthesis, coprecipitation, chemical deposition, metalorganic decomposition, hydro-thermal method, sonochemical method etc.Vanadic acid silver prepared by these methods is nano particle, although have higher specific area, easily reunites, and reduces treatment effect, and is difficult to and aqueous phase separation after processing waste water, and its practicality is reduced greatly.When catalyst and metal simple-substance compound after, can effectively transmit electronics, avoid light induced electron and hole-recombination.
Summary of the invention
The object of the invention is for overcoming the deficiencies in the prior art, the preparation method of a kind of silver/vanadic acid silver composite photo-catalyst is provided.
Object of the present invention can be achieved through the following technical solutions:
The preparation method of a kind of silver/vanadic acid silver composite photo-catalyst adopts following methods to make:
1) by a 9～16cm
2silver foil be laid in horizontal surface, with hairbrush, dip in the H that 20～30mL concentration is 15～30% (mass percentage concentration)
2o
2solution is brushed in silver foil surface, and the silver on silver foil surface is oxidized to silver oxide;
2) by 3～5g V
2o
5powder dissolution is in the ammonia spirit of 20%～25% (mass percentage concentration) in 25～30mL concentration, keeps ammoniacal liquor excessive, makes Ammonium Vanadate Solution;
3) utilize hairbrush to dip Ammonium Vanadate Solution, brushing in surface is the silver foil surface of silver oxide, and under ammoniacal liquor effect, silver oxide is dissolved as silver ammonia complex, finally generates vanadic acid silver and is deposited in silver foil surface, makes a kind of silver/vanadic acid silver composite photo-catalyst.
The invention has the beneficial effects as follows:
1, silver foil is the raw material of catalyst, is again the carrier of catalyst, and the present invention has avoided the separation problem of powder after participating in wastewater treatment.
2, vanadic acid silver is carried on silver surface, and silver-colored close contact, is conducive to the transmission of light induced electron, avoids compound, is conducive to improve catalytic efficiency.
The specific embodiment
Embodiment 1
By a 16cm
2silver foil be laid in horizontal surface, with hairbrush, dip in the H that 20mL concentration is 30% (mass percentage concentration)
2o
2solution is brushed in silver foil surface, and the silver on silver foil surface is oxidized to silver oxide; By 5g V
2o
5powder dissolution is in the ammonia spirit of 25% (mass percentage concentration) in 30mL concentration, keeps ammoniacal liquor excessive, makes Ammonium Vanadate Solution; Utilize hairbrush to dip Ammonium Vanadate Solution, brushing in surface is the silver foil surface of silver oxide, and under ammoniacal liquor effect, silver oxide is dissolved as silver ammonia complex, finally generates vanadic acid silver and is deposited in silver foil surface, makes a kind of silver/vanadic acid silver composite photo-catalyst.
The silver obtaining/vanadic acid silver composite photo-catalyst is joined and is equipped with in the beaker of Orange II waste water that 100mL concentration is 30mg/L, under 300w iodine-tungsten lamp irradiates, react 60 minutes, percent of decolourization is 94.7%.
Embodiment 2
By a 9cm
2silver foil be laid in horizontal surface, with hairbrush, dip in the H that 20mL concentration is 30% (mass percentage concentration)
2o
2solution is brushed in silver foil surface, and the silver on silver foil surface is oxidized to silver oxide; By 3g V
2o
5powder dissolution is in the ammonia spirit of 20%% (mass percentage concentration) in 25mL concentration, keeps ammoniacal liquor excessive, makes Ammonium Vanadate Solution; Utilize hairbrush to dip Ammonium Vanadate Solution, brushing in surface is the silver foil surface of silver oxide, and under ammoniacal liquor effect, silver oxide is dissolved as silver ammonia complex, finally generates vanadic acid silver and is deposited in silver foil surface, makes a kind of silver/vanadic acid silver composite photo-catalyst.
The silver obtaining/vanadic acid silver composite photo-catalyst is joined and is equipped with in the beaker of Orange II waste water that 100mL concentration is 30mg/L, under 300w iodine-tungsten lamp irradiates, react 60 minutes, percent of decolourization is 90.7%.
Embodiment 3
By a 12cm
2silver foil be laid in horizontal surface, with hairbrush, dip in the H that 30mL concentration is 15% (mass percentage concentration)
2o
2solution is brushed in silver foil surface, and the silver on silver foil surface is oxidized to silver oxide; By 5g V
2o
5powder dissolution is in the ammonia spirit of 25% (mass percentage concentration) in 30mL concentration, keeps ammoniacal liquor excessive, makes Ammonium Vanadate Solution; Utilize hairbrush to dip Ammonium Vanadate Solution, brushing in surface is the silver foil surface of silver oxide, and under ammoniacal liquor effect, silver oxide is dissolved as silver ammonia complex, finally generates vanadic acid silver and is deposited in silver foil surface, makes a kind of silver/vanadic acid silver composite photo-catalyst.
The silver obtaining/vanadic acid silver composite photo-catalyst is joined and is equipped with in the beaker of methylene blue waste water that 100mL concentration is 30mg/L, under 300w iodine-tungsten lamp irradiates, react 60 minutes, percent of decolourization is 90.2%.
Claims (1)
1. a preparation method for silver/vanadic acid silver composite photo-catalyst, is characterized in that in turn including the following steps:
1) by a 9～16cm
2silver foil be laid in horizontal surface, with hairbrush, dip in the H that 20～30mL concentration is 15～30% (mass percentage concentration)
2o
2solution is brushed in silver foil surface, and the silver on silver foil surface is oxidized to silver oxide;
2) by 3～5g V
2o
5powder dissolution is in the ammonia spirit of 20%～25% (mass percentage concentration) in 25～30mL concentration, keeps ammoniacal liquor excessive, makes Ammonium Vanadate Solution;
3) utilize hairbrush to dip Ammonium Vanadate Solution, brushing in surface is the silver foil surface of silver oxide, and under ammoniacal liquor effect, silver oxide is dissolved as silver ammonia complex, finally generates vanadic acid silver and is deposited in silver foil surface, makes a kind of silver/vanadic acid silver composite photo-catalyst.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410259218.9A CN103990457B (en) | 2014-06-11 | 2014-06-11 | The preparation method of a kind of silver/silver vanadate composite photo-catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410259218.9A CN103990457B (en) | 2014-06-11 | 2014-06-11 | The preparation method of a kind of silver/silver vanadate composite photo-catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103990457A true CN103990457A (en) | 2014-08-20 |
| CN103990457B CN103990457B (en) | 2015-12-09 |
Family
ID=51304936
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201410259218.9A Active CN103990457B (en) | 2014-06-11 | 2014-06-11 | The preparation method of a kind of silver/silver vanadate composite photo-catalyst |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103990457B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103990477A (en) * | 2014-06-11 | 2014-08-20 | 常州大学 | Preparation method of silver/silver vanadate composite photocatalyst |
| CN105432663A (en) * | 2015-11-17 | 2016-03-30 | 中国科学院海洋研究所 | Ag/AgVO3 plasma composite photocatalytic fungicide as well as preparation method and application thereof |
| CN105498771A (en) * | 2015-12-01 | 2016-04-20 | 合肥学院 | Preparation method of flaky silver/silver vanadate composite photocatalyst |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4137259A (en) * | 1976-07-09 | 1979-01-30 | Stamicarbon, B.V. | Catalytic gas phase oxidation of toluene to benzaldehyde and/or benzoic acid |
| CN102500371A (en) * | 2011-10-18 | 2012-06-20 | 山东大学 | Visible light response photocatalysis material Ag@Ag3VO4 and preparation method thereof |
| CN102600869A (en) * | 2012-02-23 | 2012-07-25 | 常州水木环保科技有限公司 | Synthetic method of supported silver phosphate photocatalyst |
| CN103990477A (en) * | 2014-06-11 | 2014-08-20 | 常州大学 | Preparation method of silver/silver vanadate composite photocatalyst |
-
2014
- 2014-06-11 CN CN201410259218.9A patent/CN103990457B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4137259A (en) * | 1976-07-09 | 1979-01-30 | Stamicarbon, B.V. | Catalytic gas phase oxidation of toluene to benzaldehyde and/or benzoic acid |
| CN102500371A (en) * | 2011-10-18 | 2012-06-20 | 山东大学 | Visible light response photocatalysis material Ag@Ag3VO4 and preparation method thereof |
| CN102600869A (en) * | 2012-02-23 | 2012-07-25 | 常州水木环保科技有限公司 | Synthetic method of supported silver phosphate photocatalyst |
| CN103990477A (en) * | 2014-06-11 | 2014-08-20 | 常州大学 | Preparation method of silver/silver vanadate composite photocatalyst |
Non-Patent Citations (1)
| Title |
|---|
| S.KITTAKA等: "Interaction of Ag ion with a vanadium pentoxide hydrate-Formation of silver vanadate at low temperature", 《JOURNAL OF MATERIAL SCIENCE》 * |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103990477A (en) * | 2014-06-11 | 2014-08-20 | 常州大学 | Preparation method of silver/silver vanadate composite photocatalyst |
| CN103990477B (en) * | 2014-06-11 | 2015-12-30 | 常州大学 | The preparation method of a kind of silver orthophosphate/silver vanadate composite photo-catalyst |
| CN105432663A (en) * | 2015-11-17 | 2016-03-30 | 中国科学院海洋研究所 | Ag/AgVO3 plasma composite photocatalytic fungicide as well as preparation method and application thereof |
| CN105498771A (en) * | 2015-12-01 | 2016-04-20 | 合肥学院 | Preparation method of flaky silver/silver vanadate composite photocatalyst |
| CN105498771B (en) * | 2015-12-01 | 2018-05-25 | 合肥学院 | A kind of preparation method of silver/silver vanadate sheet composite photo-catalyst |
Also Published As
| Publication number | Publication date |
|---|---|
| CN103990457B (en) | 2015-12-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Wang et al. | Inorganic metal‐oxide photocatalyst for H2O2 production | |
| Liu et al. | In-situ fabrication of 3D hierarchical flower-like β-Bi2O3@ CoO Z-scheme heterojunction for visible-driven simultaneous degradation of multi-pollutants | |
| Huang et al. | BiVO4 microplates with oxygen vacancies decorated with metallic Cu and Bi nanoparticles for CO2 photoreduction | |
| CN103433060B (en) | Core-shell TiO2/ZnIn2S4 composite photocatalyst and preparation method and application thereof | |
| Huo et al. | Porous graphitic carbon nitride nanomaterials for water treatment | |
| Liu et al. | Synergistic effect of single-atom Cu and hierarchical polyhedron-like Ta3N5/CdIn2S4 S-scheme heterojunction for boosting photocatalytic NH3 synthesis | |
| Wang et al. | Construction of tubular g-C3N4/TiO2 S-scheme photocatalyst for high-efficiency degradation of organic pollutants under visible light | |
| CN103055855B (en) | Preparation method of Ag/TiO2 nanotube array and application of photocatalytically degrading sugar preparing wastewater | |
| Chai et al. | Photoinduced g–C3N4–promoted Mn2+/Mn3+/Mn4+ redox cycles for activation of peroxymonosulfate | |
| Tang et al. | A novel S-scheme heterojunction in spent battery-derived ZnFe2O4/g-C3N4 photocatalyst for enhancing peroxymonosulfate activation and visible light degradation of organic pollutant | |
| Gao et al. | Construction of α-Fe2O3 and Fe/Co-N4 structures with faceted TiO2 nanocrystals for highly efficient degradation of sulfathiazole in water | |
| Yang et al. | Lanthanide-based dual modulation in hematite nanospindles for enhancing the photocatalytic performance | |
| Chen et al. | Efficient degradation of ciprofloxacin by Cu2O/g-C3N4 heterostructures with different morphologies driven under the visible light | |
| Wang et al. | Energy-efficient mineralization of perfluorooctanoic acid: Biomass energy driven solar photo-electro-fenton catalysis and mechanism study | |
| Xu et al. | Nitrogen-doping coupled with cerium oxide loading co-modified graphitic carbon nitride for highly enhanced photocatalytic degradation of tetracycline under visible light | |
| Chen et al. | Efficient Degradation of Methylene Blue over Two‐Dimensional Au/TiO2 Nanosheet Films with Overlapped Light Harvesting Nanostructures | |
| CN103990457B (en) | The preparation method of a kind of silver/silver vanadate composite photo-catalyst | |
| He et al. | A highly efficient NiFe-layer double hydroxide/TiO2 heterojunction photoanode-based high-performance bifunctional photocatalytic fuel cell | |
| Huang et al. | Peroxymonosulfate-assisted BiVO4/exfoliated g-C3N4 heterojunction for high-performance photodegradation of tetracycline induced by visible light | |
| Zhang et al. | In2O3 Nanoparticle/Bi4O5Br2 Nanosheet S-Scheme Heterojunctions with Interfacial Oxygen Vacancies for Photocatalytic Degradation of Tetracycline | |
| CN104475089B (en) | Universal light source response modifying titanium dioxide solid acid catalyst and preparation method | |
| CN103990477A (en) | Preparation method of silver/silver vanadate composite photocatalyst | |
| CN102580727B (en) | Preparation method of active carbon loaded titanium dioxide silver-doped photochemical catalyst | |
| CN105771988A (en) | Method for preparing high-catalytic-activity hierarchical structure silver molybdate | |
| Guan et al. | Improvement of Photocatalytic Performance for the g‐C3N4/MoS2 Composite Used for Hypophosphite Oxidation |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20201120 Address after: No. 159, Chengjiang Middle Road, Jiangyin City, Wuxi City, Jiangsu Province Patentee after: Jiangyin Intellectual Property Operation Co.,Ltd. Address before: Gehu Lake Road Wujin District 213164 Jiangsu city of Changzhou province No. 1 Patentee before: CHANGZHOU University |
|
| TR01 | Transfer of patent right | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20240813 Address after: 402660 plot c07-02 / 01, East Industrial Park, Tongnan District, Chongqing Patentee after: CHONGQING YUANDA CATALYST COMPREHENSIVE UTILIZATION Co.,Ltd. Country or region after: China Address before: No. 159, Chengjiang Middle Road, Jiangyin City, Wuxi City, Jiangsu Province Patentee before: Jiangyin Intellectual Property Operation Co.,Ltd. Country or region before: China |