CN107537452A - A kind of ion exchange resin preparation method for Treating Municipal Sewage - Google Patents

A kind of ion exchange resin preparation method for Treating Municipal Sewage Download PDF

Info

Publication number
CN107537452A
CN107537452A CN201710793740.9A CN201710793740A CN107537452A CN 107537452 A CN107537452 A CN 107537452A CN 201710793740 A CN201710793740 A CN 201710793740A CN 107537452 A CN107537452 A CN 107537452A
Authority
CN
China
Prior art keywords
prefabricated material
ion exchange
exchange resin
municipal sewage
parts
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.)
Withdrawn
Application number
CN201710793740.9A
Other languages
Chinese (zh)
Inventor
姚能平
樊致娟
将大庆
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Anhui Wandong Chemical Co Ltd
Original Assignee
Anhui Wandong Chemical Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Anhui Wandong Chemical Co Ltd filed Critical Anhui Wandong Chemical Co Ltd
Priority to CN201710793740.9A priority Critical patent/CN107537452A/en
Publication of CN107537452A publication Critical patent/CN107537452A/en
Withdrawn legal-status Critical Current

Links

Landscapes

  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Water Treatment By Sorption (AREA)

Abstract

The invention discloses a kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:Macropore chloromethylated polystyrene resin is sent into the piperazine aqueous solution and is swelled, adds 2 aminoethyle alcohols, is heated up, is stirred, cooling, washing obtains the first prefabricated material;Chitosan, propionic acid are well mixed, water is added and stirs, polyethylene glycol is added, heating stirring, heating, adds locust bean gum, the first prefabricated material, calcining coconut shell flour stirring, filter, washing, be dried to obtain the second prefabricated material;In ice-water bath, thionyl chloride is added dropwise into the second prefabricated material, adjusts temperature, is incubated, cools, washs, filtering, is sent into N, is swelled in N dimethylformamides, adds trimethylamine and reacts to obtain the ion exchange resin for Treating Municipal Sewage.

Description

A kind of ion exchange resin preparation method for Treating Municipal Sewage
Technical field
The present invention relates to ion-exchange resin technique field, more particularly to a kind of ion exchange for Treating Municipal Sewage Process for preparing resins.
Background technology
Water is Source of life, is the most valuable resource of nature.Protection, utilization and the processing of water resource are in the world today One of most popular topic.Therefore, the research work in the world about water quality and water technology have developed rapidly, from Industry Waste The significant problem that the pollution of water and sanitary wastewater and country face.China is one of country that water resource lacks in the world, water The exploitation of matter and water technology has very big development, very big contribution is made that to environmental protection, water saving shield water, using ion Exchanger resin increasingly becomes main flow for handling sewage.
In recent years, the rate of economic development in China city is relatively fast, in city produce and live caused by sewage quantity Also gradually increasing, current ion exchange resin adsorption capacity does not reach demand increasingly, in view of the above-mentioned problems, improving resin Adsorption capacity, improve municipal sewage treatment efficiency, it would be highly desirable to solve.
The content of the invention
Based on technical problem existing for background technology, the present invention proposes a kind of ion exchange for Treating Municipal Sewage Process for preparing resins, the gained ion exchange resin rate of adsorption is fast, and selectivity is high, is firmly combined between carrier, can after absorption Elution is complete, and easily desorbs, regenerates, and can realize repeatedly, recycle.
A kind of ion exchange resin preparation method for Treating Municipal Sewage proposed by the present invention, comprises the following steps:
It S1, will be swelled in the macropore chloromethylated polystyrene resin feeding piperazine aqueous solution, add 2 hydroxy ethylamine, rise Temperature, stir, cooling, washing obtains the first prefabricated material;
S2, chitosan, propionic acid be well mixed, add water and stir, added polyethylene glycol, heating stirring, heating, add Enter locust bean gum, the first prefabricated material, calcining coconut shell flour stirring, filter, washing, be dried to obtain the second prefabricated material;
S3, in ice-water bath, be added dropwise thionyl chloride into the second prefabricated material, adjust temperature, be incubated, cool, washing, mistake Filter, it is sent into DMF and is swelled, adds trimethylamine and react to obtain the amberlite for Treating Municipal Sewage Fat.
Preferably, in S1, it is in the 34-38wt% piperazine aqueous solution that macropore chloromethylated polystyrene resin is sent into concentration 3-6h is swelled, adds 2 hydroxy ethylamine, is warming up to 60-80 DEG C, stirs 10-16h, cooling, washing obtains the first prefabricated material.
Preferably, in S1, it is dense that 50-60 part macropore chloromethylated polystyrenes resin is sent into 150-180 parts by weight Spend to be swelled 3-6h in the 34-38wt% piperazine aqueous solution, add 1-2 part 2 hydroxy ethylamines, be warming up to 60-80 DEG C, stir 10- 16h, cooling, washing obtain the first prefabricated material.
Preferably, in S2, chitosan, propionic acid are well mixed, water is added and stirs, add polyethylene glycol, be warming up to 92-98 DEG C of stirring 4-6h, is warming up to 105-112 DEG C, adds locust bean gum, the first prefabricated material, calcining coconut shell flour stirring 40- 100min, mixing speed 640-700r/min, filter, washing, be dried to obtain the second prefabricated material.
Preferably, in S2,5-10 parts chitosan, 1-2 part propionic acid are well mixed by weight, 20-40 part water is added and stirs Mix uniformly, add 50-80 part polyethylene glycol, be warming up to 92-98 DEG C of stirring 4-6h, be warming up to 105-112 DEG C, add 10-16 parts Locust bean gum, the first prefabricated material of 20-40 parts, the calcining coconut shell flour stirring of 1-6 parts 40-100min, mixing speed 640-700r/ Min, filter, washing, be dried to obtain the second prefabricated material.
Preferably, in S3, in ice-water bath, thionyl chloride is added dropwise into the second prefabricated material, adjusts the temperature to 80-90 DEG C, 2-4h is incubated, is cooled, is washed, filtering, is sent into DMF and is swelled 4-8h, trimethylamine reaction 5-10h is added, obtains To the ion exchange resin for Treating Municipal Sewage.
Preferably, in S3, in ice-water bath, 3-5 part protochlorides are added dropwise by weight into the second prefabricated material of 60-80 parts Sulfone, 80-90 DEG C is adjusted the temperature to, be incubated 2-4h, cooled, washed, filtering, is sent into 150-240 part DMFs 4-8h is swelled, 4-10 parts trimethylamine reaction 5-10h is added, obtains the ion exchange resin for Treating Municipal Sewage.
The present invention has bigger serface and high porosity, the Sewage Environment of complexity can be dealt with, suitable for sewage disposal.This Invention is dissolved chitosan in propionic acid, the three-dimensional net structure formed with polyethylene glycol due to hydrogen bond action, not only lubricity It is good, and preparation process it is green, it is pollution-free, without discharge, can effectively promote between locust bean gum and the first prefabricated material, calcining coconut shell flour Scattered, mutual combination degree is high, and soft plasticity is good, and water-retaining property is strong, and shrinkage factor is small, and specific surface area is high, and absorption is lived Property it is high, make that gained resin specific surface area is high, and uniform pore diameter is suitable, significantly improves exchange capacity, to heavy metal ions in sewage Adsorption activity it is high, it is environment-friendly.
The gained ion exchange resin rate of adsorption of the invention is fast, and selectivity is high, is firmly combined between carrier, can after absorption Elution is complete, and easily desorbs, regenerates, and can realize repeatedly, recycle;Performance survey is carried out to gained ion exchange resin It is fixed:Its full exchange capacity is 3.05-3.14mmol/g, and adsorption capacity reduced by only 1.22-1.85% after regenerating ten times, after processing Water can reach drinking water standard (GB5749-2011).
Embodiment
Below, technical scheme is described in detail by specific embodiment.
Embodiment 1
A kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:
It S1, will be swelled in the macropore chloromethylated polystyrene resin feeding piperazine aqueous solution, add 2 hydroxy ethylamine, rise Temperature, stir, cooling, washing obtains the first prefabricated material;
S2, chitosan, propionic acid be well mixed, add water and stir, added polyethylene glycol, heating stirring, heating, add Enter locust bean gum, the first prefabricated material, calcining coconut shell flour stirring, filter, washing, be dried to obtain the second prefabricated material;
S3, in ice-water bath, be added dropwise thionyl chloride into the second prefabricated material, adjust temperature, be incubated, cool, washing, mistake Filter, it is sent into DMF and is swelled, adds trimethylamine and react to obtain the amberlite for Treating Municipal Sewage Fat.
Embodiment 2
A kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:
S1,50 parts of macropore chloromethylated polystyrene resins are sent into 180 parts of concentration by weight is 34wt% piperazine water 6h is swelled in solution, adds 1 part of 2 hydroxy ethylamine, is warming up to 80 DEG C, stirs 10h, cooling, washing obtains the first prefabricated material;
S2,10 parts of chitosans, 1 part of propionic acid are well mixed by weight, add 40 parts of water and stir, added 50 parts and gather Ethylene glycol, 98 DEG C of stirring 4h are warming up to, are warming up to 112 DEG C, add 10 parts of locust bean gums, 40 part of first prefabricated material, 1 part of calcining coconut palm Shell powder stirs 100min, mixing speed 640r/min, filters, and washing, is dried to obtain the second prefabricated material;
S3, in ice-water bath, by weight into 80 part of second prefabricated material be added dropwise 3 parts of thionyl chlorides, adjust the temperature to 90 DEG C, 2h is incubated, is cooled, is washed, filtering, is sent into 240 parts of DMFs and is swelled 4h, adds 10 parts of trimethylamine reactions 5h, obtain the ion exchange resin for Treating Municipal Sewage.
Embodiment 3
A kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:
S1,60 parts of macropore chloromethylated polystyrene resins are sent into 150 parts of concentration by weight is 38wt% piperazine water 3h is swelled in solution, adds 2 parts of 2 hydroxy ethylamines, is warming up to 60 DEG C, stirs 16h, cooling, washing obtains the first prefabricated material;
S2,5 parts of chitosans, 2 parts of propionic acid are well mixed by weight, add 20 parts of water and stir, added 80 parts and gather Ethylene glycol, 92 DEG C of stirring 6h are warming up to, are warming up to 105 DEG C, add 16 parts of locust bean gums, 20 part of first prefabricated material, 6 parts of calcining coconut palms Shell powder stirs 40min, mixing speed 700r/min, filters, and washing, is dried to obtain the second prefabricated material;
S3, in ice-water bath, by weight into 60 part of second prefabricated material be added dropwise 5 parts of thionyl chlorides, adjust the temperature to 80 DEG C, 4h is incubated, is cooled, is washed, filtering, is sent into 150 parts of DMFs and is swelled 8h, adds 4 parts of trimethylamine reactions 10h, obtain the ion exchange resin for Treating Municipal Sewage.
Embodiment 4
A kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:
S1,52 parts of macropore chloromethylated polystyrene resins are sent into 170 parts of concentration by weight is 35wt% piperazine water 5h is swelled in solution, adds 1.2 parts of 2 hydroxy ethylamines, is warming up to 75 DEG C, stirs 12h, cooling, washing obtains the first prefabricated material;
S2,8 parts of chitosans, 1.2 parts of propionic acid are well mixed by weight, add 35 parts of water and stir, add 60 parts Polyethylene glycol, be warming up to 96 DEG C of stirring 4.5h, be warming up to 110 DEG C, add 12 parts of locust bean gums, 35 part of first prefabricated material, 2 parts forge Coconut shell flour stirring 80min, mixing speed 660r/min are burnt, filters, washing, is dried to obtain the second prefabricated material;
S3, in ice-water bath, by weight into 75 part of second prefabricated material be added dropwise 3.5 parts of thionyl chlorides, adjust the temperature to 88 DEG C, 2.5h is incubated, is cooled, is washed, filtering, is sent into 220 parts of DMFs and is swelled 5h, adds 8 parts of trimethylamines 6h is reacted, obtains the ion exchange resin for Treating Municipal Sewage.
Embodiment 5
A kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:
S1,58 parts of macropore chloromethylated polystyrene resins are sent into 160 parts of concentration by weight is 37wt% piperazine water 4h is swelled in solution, adds 1.8 parts of 2 hydroxy ethylamines, is warming up to 65 DEG C, stirs 14h, cooling, washing obtains the first prefabricated material;
S2,6 parts of chitosans, 1.8 parts of propionic acid are well mixed by weight, add 25 parts of water and stir, add 70 parts Polyethylene glycol, be warming up to 94 DEG C of stirring 5.5h, be warming up to 106 DEG C, add 14 parts of locust bean gums, 25 part of first prefabricated material, 4 parts forge Coconut shell flour stirring 60min, mixing speed 680r/min are burnt, filters, washing, is dried to obtain the second prefabricated material;
S3, in ice-water bath, by weight into 65 part of second prefabricated material be added dropwise 4.5 parts of thionyl chlorides, adjust the temperature to 82 DEG C, 3.5h is incubated, is cooled, is washed, filtering, is sent into 160 parts of DMFs and is swelled 7h, adds 6 parts of trimethylamines 8h is reacted, obtains the ion exchange resin for Treating Municipal Sewage.
Embodiment 6
A kind of ion exchange resin preparation method for Treating Municipal Sewage, comprise the following steps:
S1,55 parts of macropore chloromethylated polystyrene resins are sent into 165 parts of concentration by weight is 36wt% piperazine water 4.5h is swelled in solution, adds 1.5 parts of 2 hydroxy ethylamines, is warming up to 70 DEG C, stirs 13h, cooling, it is prefabricated that washing obtains first Material;
S2,7 parts of chitosans, 1.5 parts of propionic acid are well mixed by weight, add 30 parts of water and stir, add 65 parts Polyethylene glycol, 95 DEG C of stirring 5h are warming up to, are warming up to 108 DEG C, add 13 parts of locust bean gums, 30 part of first prefabricated material, 3 parts of calcinings Coconut shell flour stirs 70min, mixing speed 670r/min, filters, and washing, is dried to obtain the second prefabricated material;
S3, in ice-water bath, by weight into 70 part of second prefabricated material be added dropwise 4 parts of thionyl chlorides, adjust the temperature to 85 DEG C, 3h is incubated, is cooled, is washed, filtering, is sent into 200 parts of DMFs and is swelled 6h, adds 7 parts of trimethylamine reactions 7h, obtain the ion exchange resin for Treating Municipal Sewage.
The foregoing is only a preferred embodiment of the present invention, but protection scope of the present invention be not limited thereto, Any one skilled in the art the invention discloses technical scope in, technique according to the invention scheme and its Inventive concept is subject to equivalent substitution or change, should all be included within the scope of the present invention.

Claims (7)

1. a kind of ion exchange resin preparation method for Treating Municipal Sewage, it is characterised in that comprise the following steps:
It S1, will be swelled in the macropore chloromethylated polystyrene resin feeding piperazine aqueous solution, add 2 hydroxy ethylamine, heating, stir Mix, cool, washing obtains the first prefabricated material;
S2, chitosan, propionic acid be well mixed, add water and stir, added polyethylene glycol, heating stirring, heating, add thorn Locust bean gum, the first prefabricated material, calcining coconut shell flour stirring, filter, washing, are dried to obtain the second prefabricated material;
S3, in ice-water bath, be added dropwise thionyl chloride into the second prefabricated material, adjust temperature, be incubated, cool, wash, filtering, send Enter in DMF and be swelled, add trimethylamine and react to obtain the ion exchange resin for Treating Municipal Sewage.
2. it is used for the ion exchange resin preparation method of Treating Municipal Sewage according to claim 1, it is characterised in that S1 In, it is that 3-6h is swelled in the 34-38wt% piperazine aqueous solution that macropore chloromethylated polystyrene resin is sent into concentration, adds 2- hydroxyls Base ethamine, 60-80 DEG C is warming up to, stirs 10-16h, cooling, washing obtains the first prefabricated material.
3. the ion exchange resin preparation method according to claim 1 or claim 2 for Treating Municipal Sewage, it is characterised in that It is 34-38wt% piperazines by weight by 50-60 part macropore chloromethylated polystyrenes resin feeding 150-180 parts concentration in S1 3-6h is swelled in the piperazine aqueous solution, adds 1-2 part 2 hydroxy ethylamines, is warming up to 60-80 DEG C, stirs 10-16h, cooling, washing obtains First prefabricated material.
4. it is used for the ion exchange resin preparation method of Treating Municipal Sewage, its feature according to claim any one of 1-3 It is, in S2, chitosan, propionic acid is well mixed, adds water and stir, add polyethylene glycol, be warming up to 92-98 DEG C of stirring 4-6h, 105-112 DEG C is warming up to, adds locust bean gum, the first prefabricated material, calcining coconut shell flour stirring 40-100min, mixing speed For 640-700r/min, filter, washing, be dried to obtain the second prefabricated material.
5. it is used for the ion exchange resin preparation method of Treating Municipal Sewage, its feature according to claim any one of 1-4 It is, in S2, is by weight well mixed 5-10 parts chitosan, 1-2 part propionic acid, adds 20-40 part water and stir, add 50-80 part polyethylene glycol, 92-98 DEG C of stirring 4-6h is warming up to, 105-112 DEG C is warming up to, adds 10-16 parts locust bean gum, 20- 40 part of first prefabricated material, 1-6 parts calcining coconut shell flour stirring 40-100min, mixing speed 640-700r/min, are filtered, washing, It is dried to obtain the second prefabricated material.
6. it is used for the ion exchange resin preparation method of Treating Municipal Sewage, its feature according to claim any one of 1-5 It is, in S3, in ice-water bath, thionyl chloride is added dropwise into the second prefabricated material, adjust the temperature to 80-90 DEG C, is incubated 2-4h, drop Temperature, wash, filtering, be sent into DMF and be swelled 4-8h, add trimethylamine reaction 5-10h, obtain being used to handle The ion exchange resin of municipal sewage.
7. it is used for the ion exchange resin preparation method of Treating Municipal Sewage, its feature according to claim any one of 1-6 It is, in S3, in ice-water bath, 3-5 part thionyl chlorides is added dropwise by weight into the second prefabricated material of 60-80 parts, adjust temperature To 80-90 DEG C, 2-4h is incubated, is cooled, is washed, filtering, is sent into 150-240 part DMFs and is swelled 4-8h, add Enter 4-10 parts trimethylamine reaction 5-10h, obtain the ion exchange resin for Treating Municipal Sewage.
CN201710793740.9A 2017-09-06 2017-09-06 A kind of ion exchange resin preparation method for Treating Municipal Sewage Withdrawn CN107537452A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN201710793740.9A CN107537452A (en) 2017-09-06 2017-09-06 A kind of ion exchange resin preparation method for Treating Municipal Sewage

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN201710793740.9A CN107537452A (en) 2017-09-06 2017-09-06 A kind of ion exchange resin preparation method for Treating Municipal Sewage

Publications (1)

Publication Number Publication Date
CN107537452A true CN107537452A (en) 2018-01-05

Family

ID=60959179

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201710793740.9A Withdrawn CN107537452A (en) 2017-09-06 2017-09-06 A kind of ion exchange resin preparation method for Treating Municipal Sewage

Country Status (1)

Country Link
CN (1) CN107537452A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111269340A (en) * 2020-03-31 2020-06-12 台州学院 Chelate resin with 1-methanesulfonyl piperazine as ligand and preparation method and application thereof

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102189008A (en) * 2011-04-11 2011-09-21 常州大学 Novel strongly and weakly alkaline anion exchange resin and preparation method thereof
CN102212155A (en) * 2011-04-29 2011-10-12 南开大学 High-temperature-resistant guanidine-based strong-basic anion exchange resin for strong base and synthesis method thereof
CN106745633A (en) * 2016-12-27 2017-05-31 郑州源冉生物技术有限公司 A kind of heavy metal-polluted water treatment agent and preparation method thereof

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102189008A (en) * 2011-04-11 2011-09-21 常州大学 Novel strongly and weakly alkaline anion exchange resin and preparation method thereof
CN102212155A (en) * 2011-04-29 2011-10-12 南开大学 High-temperature-resistant guanidine-based strong-basic anion exchange resin for strong base and synthesis method thereof
CN106745633A (en) * 2016-12-27 2017-05-31 郑州源冉生物技术有限公司 A kind of heavy metal-polluted water treatment agent and preparation method thereof

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN111269340A (en) * 2020-03-31 2020-06-12 台州学院 Chelate resin with 1-methanesulfonyl piperazine as ligand and preparation method and application thereof
CN111269340B (en) * 2020-03-31 2020-12-29 台州学院 Chelate resin with 1-methanesulfonyl piperazine as ligand and preparation method and application thereof

Similar Documents

Publication Publication Date Title
CN105413645B (en) A kind of preparation method of calcium base modified epoxy cellulose sorbing material
CN101569852B (en) Method for modifying natural zeolite powder
CN105923738B (en) A method of persulfate or hydrogen persulfate salt treatment organic wastewater are activated using metal organic framework efficient catalytic
CN103432987B (en) Preparation method of modified kieselguhr water purifying agent
CN107754765A (en) A kind of La doped metal-organic framework materials and its preparation method and application
CN105771876B (en) The preparation method of modified eggshell magnetic adsorbent and the method for removing heavy metal in water removal
CN109336225A (en) The mosaic electrode and preparation method thereof removed for nitrate nitrogen in sewage treatment plant tail water
CN106809921A (en) A kind of preparation method of kaolinite soil matrix three dimensional particles electrode
CN107537452A (en) A kind of ion exchange resin preparation method for Treating Municipal Sewage
CN108855084A (en) A method of high porosity ozone oxidation nbsCOD catalyst is prepared using Fenton iron cement
CN110156013A (en) A kind of activated carbon surface pore forming method
CN106964333A (en) The method that rare earth loaded catalyst for handling sewage and its preparation method and application and catalytic ozonation handle sewage
CN108421526A (en) A kind of two step of hydro-thermal/acidleach prepares method and the application of flyash defluorinating agent
CN107759825A (en) A kind of sewage disposal high adsorption ion exchange resin preparation method
CN107385241A (en) A kind of Efficient utilization method of scheelite soda boiling slag
CN103272654A (en) High specific surface area magnetic anion exchange resin, and preparation method and application of resin
CN102527155A (en) Structural filter element for removing acraldehyde from drinking water and preparation method of structural filter element
CN108043366A (en) The nanocomposite of calcium ions and magnesium ions in a kind of absorption water
CN109550486A (en) A kind of preparation method of silica gel base weight metal absorbent
CN107522199A (en) A kind of preparation technology of activated carbon
CN106140116A (en) A kind of for processing the adsorbent of nickel ion in waste water
CN106669616A (en) Heavy metal adsorption material prepared from corn cob and preparation method thereof
CN103691393B (en) Remove waterborne radioactivity from the beginning 137inorganic compounding adsorbent of Cs and preparation method thereof
CN106282573A (en) A kind of method reclaiming metals resources from hazardous solid waste
CN106975451A (en) A kind of preparation method of quick adsorption Powdered Activated Carbon

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination
WW01 Invention patent application withdrawn after publication

Application publication date: 20180105

WW01 Invention patent application withdrawn after publication