CN116422286A - Method for preparing zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent by utilizing sludge ash and application of zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent - Google Patents
Method for preparing zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent by utilizing sludge ash and application of zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent Download PDFInfo
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- CN116422286A CN116422286A CN202310372308.8A CN202310372308A CN116422286A CN 116422286 A CN116422286 A CN 116422286A CN 202310372308 A CN202310372308 A CN 202310372308A CN 116422286 A CN116422286 A CN 116422286A
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- 239000010802 sludge Substances 0.000 title claims abstract description 85
- 239000003463 adsorbent Substances 0.000 title claims abstract description 43
- 238000000034 method Methods 0.000 title claims abstract description 43
- 229910000000 metal hydroxide Inorganic materials 0.000 title claims description 15
- KFZAUHNPPZCSCR-UHFFFAOYSA-N iron zinc Chemical compound [Fe].[Zn] KFZAUHNPPZCSCR-UHFFFAOYSA-N 0.000 title claims description 10
- 239000011574 phosphorus Substances 0.000 claims abstract description 58
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 58
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 54
- 238000001179 sorption measurement Methods 0.000 claims abstract description 47
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 51
- 238000003795 desorption Methods 0.000 claims description 33
- 239000007788 liquid Substances 0.000 claims description 33
- 239000007787 solid Substances 0.000 claims description 31
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 26
- 238000011282 treatment Methods 0.000 claims description 26
- 239000000706 filtrate Substances 0.000 claims description 25
- 238000002156 mixing Methods 0.000 claims description 25
- 239000002253 acid Substances 0.000 claims description 22
- 239000002893 slag Substances 0.000 claims description 17
- 239000000243 solution Substances 0.000 claims description 16
- 238000002386 leaching Methods 0.000 claims description 15
- 238000000498 ball milling Methods 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 14
- 238000001035 drying Methods 0.000 claims description 14
- 239000000047 product Substances 0.000 claims description 14
- 229910052588 hydroxylapatite Inorganic materials 0.000 claims description 12
- XYJRXVWERLGGKC-UHFFFAOYSA-D pentacalcium;hydroxide;triphosphate Chemical compound [OH-].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O XYJRXVWERLGGKC-UHFFFAOYSA-D 0.000 claims description 12
- 238000001914 filtration Methods 0.000 claims description 11
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 10
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 229910017604 nitric acid Inorganic materials 0.000 claims description 10
- 239000007864 aqueous solution Substances 0.000 claims description 9
- 238000003756 stirring Methods 0.000 claims description 9
- 239000011575 calcium Substances 0.000 claims description 7
- 239000000203 mixture Substances 0.000 claims description 7
- 230000008569 process Effects 0.000 claims description 7
- AXCZMVOFGPJBDE-UHFFFAOYSA-L calcium dihydroxide Chemical compound [OH-].[OH-].[Ca+2] AXCZMVOFGPJBDE-UHFFFAOYSA-L 0.000 claims description 5
- 239000000920 calcium hydroxide Substances 0.000 claims description 5
- 229910001861 calcium hydroxide Inorganic materials 0.000 claims description 5
- 238000004108 freeze drying Methods 0.000 claims description 5
- 238000000227 grinding Methods 0.000 claims description 5
- 238000010438 heat treatment Methods 0.000 claims description 5
- 238000003801 milling Methods 0.000 claims description 5
- 238000007873 sieving Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 150000004692 metal hydroxides Chemical class 0.000 claims description 4
- 230000007935 neutral effect Effects 0.000 claims description 4
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 230000008859 change Effects 0.000 claims description 2
- 239000002245 particle Substances 0.000 claims description 2
- 238000004140 cleaning Methods 0.000 claims 1
- 230000010355 oscillation Effects 0.000 claims 1
- 229910019142 PO4 Inorganic materials 0.000 abstract description 11
- 239000010452 phosphate Substances 0.000 abstract description 11
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 abstract description 10
- 230000007613 environmental effect Effects 0.000 abstract description 4
- MGGMTVYSPZCXTC-UHFFFAOYSA-N phosphane;trihydrate Chemical compound O.O.O.P MGGMTVYSPZCXTC-UHFFFAOYSA-N 0.000 abstract 1
- 239000000126 substance Substances 0.000 description 23
- 238000011084 recovery Methods 0.000 description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 238000004064 recycling Methods 0.000 description 7
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 6
- 239000008367 deionised water Substances 0.000 description 4
- 229910021641 deionized water Inorganic materials 0.000 description 4
- 229910001385 heavy metal Inorganic materials 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 238000005342 ion exchange Methods 0.000 description 4
- 229910052742 iron Inorganic materials 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 239000002686 phosphate fertilizer Substances 0.000 description 4
- 238000010992 reflux Methods 0.000 description 4
- 239000002699 waste material Substances 0.000 description 4
- 238000007704 wet chemistry method Methods 0.000 description 4
- 238000011010 flushing procedure Methods 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000008901 benefit Effects 0.000 description 2
- 238000010170 biological method Methods 0.000 description 2
- 239000003795 chemical substances by application Substances 0.000 description 2
- 238000002425 crystallisation Methods 0.000 description 2
- 238000000909 electrodialysis Methods 0.000 description 2
- 238000005265 energy consumption Methods 0.000 description 2
- 238000000605 extraction Methods 0.000 description 2
- 239000010440 gypsum Substances 0.000 description 2
- 229910052602 gypsum Inorganic materials 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 150000002739 metals Chemical class 0.000 description 2
- 239000002135 nanosheet Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000008929 regeneration Effects 0.000 description 2
- 238000011069 regeneration method Methods 0.000 description 2
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N Iron oxide Chemical compound [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- 241001465754 Metazoa Species 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- CKMXBZGNNVIXHC-UHFFFAOYSA-L ammonium magnesium phosphate hexahydrate Chemical compound [NH4+].O.O.O.O.O.O.[Mg+2].[O-]P([O-])([O-])=O CKMXBZGNNVIXHC-UHFFFAOYSA-L 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000001506 calcium phosphate Substances 0.000 description 1
- 229910000389 calcium phosphate Inorganic materials 0.000 description 1
- 235000011010 calcium phosphates Nutrition 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000013043 chemical agent Substances 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000012851 eutrophication Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000003337 fertilizer Substances 0.000 description 1
- 239000008394 flocculating agent Substances 0.000 description 1
- 229910052595 hematite Inorganic materials 0.000 description 1
- 239000011019 hematite Substances 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- LIKBJVNGSGBSGK-UHFFFAOYSA-N iron(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[Fe+3].[Fe+3] LIKBJVNGSGBSGK-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 230000004060 metabolic process Effects 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- -1 orthophosphate ions Chemical class 0.000 description 1
- 238000010979 pH adjustment Methods 0.000 description 1
- 229940085991 phosphate ion Drugs 0.000 description 1
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Substances OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 description 1
- 235000011007 phosphoric acid Nutrition 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- QPILZZVXGUNELN-UHFFFAOYSA-M sodium;4-amino-5-hydroxynaphthalene-2,7-disulfonate;hydron Chemical compound [Na+].OS(=O)(=O)C1=CC(O)=C2C(N)=CC(S([O-])(=O)=O)=CC2=C1 QPILZZVXGUNELN-UHFFFAOYSA-M 0.000 description 1
- 229910052567 struvite Inorganic materials 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- QORWJWZARLRLPR-UHFFFAOYSA-H tricalcium bis(phosphate) Chemical compound [Ca+2].[Ca+2].[Ca+2].[O-]P([O-])([O-])=O.[O-]P([O-])([O-])=O QORWJWZARLRLPR-UHFFFAOYSA-H 0.000 description 1
- 238000003828 vacuum filtration Methods 0.000 description 1
- 239000011592 zinc chloride Substances 0.000 description 1
- 235000005074 zinc chloride Nutrition 0.000 description 1
- JIAARYAFYJHUJI-UHFFFAOYSA-L zinc dichloride Chemical compound [Cl-].[Cl-].[Zn+2] JIAARYAFYJHUJI-UHFFFAOYSA-L 0.000 description 1
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
- B01J20/06—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising oxides or hydroxides of metals not provided for in group B01J20/04
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D15/00—Separating processes involving the treatment of liquids with solid sorbents; Apparatus therefor
- B01D15/08—Selective adsorption, e.g. chromatography
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
- B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G49/00—Compounds of iron
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2220/00—Aspects relating to sorbent materials
- B01J2220/40—Aspects relating to the composition of sorbent or filter aid materials
- B01J2220/48—Sorbents characterised by the starting material used for their preparation
- B01J2220/4875—Sorbents characterised by the starting material used for their preparation the starting material being a waste, residue or of undefined composition
- B01J2220/4887—Residues, wastes, e.g. garbage, municipal or industrial sludges, compost, animal manure; fly-ashes
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Processing Of Solid Wastes (AREA)
Abstract
The invention discloses a method for preparing zinc-iron-carrying bimetal hydroxide phosphorus adsorbent by utilizing sludge ash and application thereof. The invention takes the sludge ash as a starting point, realizes the resource utilization of the sludge ash, and solves the problem of secondary pollution caused by the sludge ash to urban environmental sanitation; the prepared phosphorus adsorbent has high adsorption capacity to phosphate, strong stability and recyclability, and can be used for treating phosphorus repeatedly.
Description
Technical Field
The invention belongs to the technical field of environmental protection and resource recovery, and particularly relates to a method for preparing a zinc-iron-loaded bimetal hydroxide phosphorus-philic adsorbent by utilizing sludge ash and application thereof.
Background
Phosphorus plays a vital role in the growth process of animals and plants, is essential in the cell structure and metabolism process, and widely exists in biospheres. Phosphorus in nature exists mainly in the form of phosphate ore, but the reserves of phosphate ore are certain.
The incineration is a relatively complete method for treating sludge, meets the requirements of reduction, harmlessness and recycling, can reduce the original volume by more than 80%, and after the sludge is incinerated, the nonvolatile phosphorus is enriched in the sludge ash and can be recycled as a source for producing fertilizer and other phosphate products, so that the problem of current phosphorus resource shortage can be relieved.
The prior art for extracting phosphorus from sludge ash mainly comprises a thermochemical method, an electrodialysis method, an ion exchange method, an adsorption method, a biological method and a wet chemical method, wherein the thermochemical method, the electrodialysis method, the ion exchange method, the adsorption method and the biological method have bottlenecks in industrial application, the thermochemical method has harsh reaction conditions, high energy consumption and can only realize the removal of volatile metals, and non-volatile harmful metals (such As As, ni and the like) cannot be removed. The wet chemical method has corresponding industrial application at present, and has operability and perfect theoretical basis. However, the current wet chemistry studies have the following problems: 1) The wet chemistry method is mainly researched and concentrated on sulfuric acid and hydrochloric acid extraction, sulfuric acid is easy to react with calcium in sludge ash to generate gypsum, the gypsum is attached to the surface of the sludge ash, the sulfuric acid and the sludge ash are prevented from further reaction, and the phosphorus extraction rate is reduced; 2) Wet chemistry methods not only extract phosphorus, but also with large amounts of heavy metal leaching, the low purity of phosphorus can limit the recovery and further use of phosphorus; 3) After phosphorus in sludge ash is extracted by wet chemistry, the research of subsequent residue utilization is lacking, and the method is mostly used for landfill treatment, so that a complete resource utilization way is not formed. One of the reasons for the problems is that the prior recycling process of phosphorus in the phosphorus-rich extracting solution is not perfect, wherein the struvite crystallization method and the wustite recycling method have severe requirements on operation conditions, the recycling rate of phosphorus is not high, especially the calcium phosphate crystallization method is greatly interfered by coexisting ions and the like and is not easy to form pure crystals with larger particle size aiming at sewage treatment plants which commonly use aluminum salts as flocculating agents in China, so that the phosphorus recycling rate is limited. In addition, the patent related to the preparation of the phosphate fertilizer by utilizing the phosphorus in the sludge in the prior art mainly comprises a method for preparing the phosphate fertilizer by utilizing fresh sludge to carry out phosphorus leaching, a method for preparing the phosphate fertilizer by utilizing the phosphorus in sludge ash obtained after drying and incinerating the sludge, and the like, wherein the method generally has the advantages of complex operation flow and difficult control of operation conditions; the amount of the added chemical agent is large, and the waste liquid is large, so that the problems of high energy consumption, high cost and the like are caused. Meanwhile, as the components contained in the sludge are complex and various, the risk of leaching harmful elements such as heavy metals exists in the process of preparing the phosphate fertilizer, so that the commonly adopted operation conditions are more severe, such as calcination, ion exchange and other technical means, and the production cost of the product is greatly increased.
Disclosure of Invention
Aiming at the problems, the invention aims to provide a method for preparing a zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent by utilizing sludge ash and application thereof.
The specific technical scheme is as follows:
a method for preparing a zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent by utilizing sludge ash, which comprises the following steps:
1) The pretreatment unit of the sludge ash mainly comprises ball milling treatment and primary chemical wet treatment of the sludge ash, wherein the sludge ash is ball milled by a ball mill to obtain the sludge ash with the granularity of 50-80 microns, the rotation speed of the ball mill is 1000-1200r/min, the total milling time is 10min, and the ball milling can fully reduce the granularity of the sludge ash material, so that the subsequent chemical wet treatment can be more effective; the specific method for the primary chemical wet treatment comprises the following steps: fully mixing sludge ash and dilute hydrochloric acid/nitric acid (0.2-1 mol/L) for shaking for 2-5 hours at a solid-liquid ratio of 1:5-1:20g/mL, so that more than 95% of phosphorus in the sludge ash is released into supernatant in the form of orthophosphate ions and part of metal, filtering and separating to obtain insoluble solid slag and acid extract, drying the insoluble solid slag in a blast drying oven at 65-80 ℃ for 24 hours, and extracting most of phosphate radicals from the acid extract, and containing a small amount of metal ions and other impurities; the step plays a role in extracting phosphorus in the sludge ash and removing part of impurities in the sludge ash.
2) Activating and modifying insoluble solid slag to prepare zinc-iron-carrying double metal hydroxide phosphorus adsorbent (Zn/Fe-LDHs modified sludge ash). The method mainly comprises the steps of secondary chemical wet treatment, pH adjustment, modification stirring and the like, wherein the secondary chemical wet treatment mainly lays a foundation for the subsequent reconstruction and regeneration of Zn/Fe-LDHs modified sludge ash under the conditions that insoluble solid slag and concentrated hydrochloric acid (5-8 mol/L) are placed in a magnetic stirrer and fully mixed and stirred for 2h under the conditions that the solid-liquid ratio is 1:10g/mL at 60 ℃, the secondary chemical wet treatment not only can activate sludge ash on the surface and increase the specific surface area of the sludge ash, but also can leach iron (mainly in the form of hematite) in the sludge ash, and is beneficial to improving the adsorption capacity of the modified sludge ash on orthophosphoric acid radical. Waiting for the upper liquid after the secondary chemical wet treatment to change from transparent to yellow, and adding ZnCl into the upper liquid 2 (Zn: fe molar ratio is 1:1-3:1) and evenly mixing, slowly dripping 2-5mol/L NaOH solution into the solid-liquid mixture to adjust the pH value of the solution to be stable at 11-12, heating the solid-liquid ratio to 60-80 ℃ by using a magnetic stirrer at a rotating speed of 200-500rpm for 4-6h, centrifuging to obtain Zn/Fe-LDHs modified sludge ash after the reaction is complete, and flushing the modified sludge ash to be neutral by deionized water. Freeze drying, grinding and sieving the obtained solid<200 μm) to obtain a phosphorus-philic adsorbent, namely Zn/Fe-LDHs modified sludge ash.
The application of the prepared zinc-iron-loaded double-metal hydroxide phosphorus-philic adsorbent comprises the following steps:
1) The phosphorus recovery, adsorption, desorption and purification unit comprises adsorption treatment and desorption treatment, the acid extract is introduced into a leaching device filled with the prepared phosphorus-philic adsorbent from bottom to top, and is fully and uniformly mixed for phosphorus adsorption, the liquid-solid ratio of the acid extract to the adsorbent is 0.025-0.05L/g, the adsorption temperature is 25-35 ℃, the adsorption time is 2-6h, adsorption filtrate is led out after the adsorption is completed, and the reflux of the adsorption filtrate can be used as acid leaching solution for chemical wet treatment; introducing industrial sodium hydroxide aqueous solution (0.1-1 mol/L) into the phosphorus-adsorbed phosphorus-philic adsorbent, fully mixing to desorb phosphorus, wherein the liquid-solid ratio of the sodium hydroxide aqueous solution to the phosphorus-philic adsorbent is 0.1-0.2L/g, the desorption temperature is 25-35 ℃, and the desorption time is 2-6 h; and (5) leading out desorption filtrate after the desorption is completed. The desorption filtrate is a phosphorus-rich solution for removing heavy metal impurities, the adsorption, desorption and purification unit of phosphorus in the method can be completely completed in a leaching device, and the step can be to adsorb phosphorus in the acid extracting solution on a zinc-iron-carrying double metal hydroxide phosphorus adsorbent without adsorbing impurities such as heavy metals in the acid extracting solution, so as to further purify phosphorus products.
2) Preparing a hydroxyapatite product. Adding calcium hydroxide into the desorption filtrate, keeping the molar ratio of P to Ca to be 1:2-1:4 for reaction, filtering and separating after full reaction to obtain filter residues and filtrate, and washing and drying the filter residues to obtain a hydroxyapatite product, wherein the filtering and separating adopts vacuum filtration.
The beneficial effects of the invention are mainly shown in the following steps:
1) The sludge ash is taken as a starting point, so that the resource utilization of the sludge ash is realized, and the problem of secondary pollution caused by the sludge ash to urban environmental sanitation is solved;
2) The prepared zinc-iron-carrying double-metal hydroxide phosphorus-philic adsorbent-Zn/Fe-LDHs modified sludge ash forms a special metal plate layer structure, is favorable for phosphate ion exchange, contains a large amount of hydroxyl free radicals on the surface, can provide multichannel adsorption sites for phosphate, has high adsorption capacity for phosphate, has strong stability and recycling property, and can reach the adsorption capacity of 540 mg-P kg -1 Can recycle and treat phosphorus, and the adsorption capacity can still reach the original value after 10-cycle adsorption/regeneration experiments88%；
3) The zinc-iron-carrying double-metal hydroxide phosphate adsorbent can eliminate the interference of other elements in sludge ash to obtain a high-quality hydroxyapatite product, can be used as the phosphate adsorbent for adsorbing phosphate in actual agricultural running water, river water and lake water, solves the problem of water eutrophication hazard, and achieves the aim of treating waste with waste;
4) The method of the phosphorus adsorption, the phosphorus desorption and the hydroxyapatite precipitation is adopted, the process flow is simple, the operation is convenient, at least 70 percent of phosphate in the sludge ash can be recovered to generate a high-value high-purity hydroxyapatite product, the application is wide, and the method has good market potential and obvious economic and environmental benefits; the method can achieve the recycling of the leaching agent by the wet chemical method, and reduces the use of the leaching agent and the generation of redundant waste liquid.
Drawings
FIG. 1 is a schematic illustration of a process flow of the present invention;
FIG. 2 is a schematic diagram of the structure of the modified sludge ash.
Detailed Description
The invention will be further described with reference to the drawings and examples of the specification, but the scope of the invention is not limited thereto.
Example 1
Referring to fig. 1, the iron-rich sludge ash is firstly ball-milled, the rotation speed of the ball mill is 1100r/min, the total milling time is 10min, the granularity obtained by ball milling the sludge ash is 50-80 microns, the first-stage chemical wet treatment is carried out on the sludge ash after ball milling, and the specific steps of the first-stage chemical wet treatment are as follows: mixing the sludge ash subjected to ball milling with 0.5mol/L dilute hydrochloric acid/nitric acid, wherein the solid-liquid ratio of the sludge ash to the dilute hydrochloric acid/nitric acid is 1:10g/mL, fully mixing and oscillating for 4 hours, then filtering and separating by a solid-liquid separator to obtain insoluble solid slag and acid extract, drying the insoluble solid slag in a blast drying oven at 80 ℃ for 24 hours, and then performing secondary chemical wet treatment, wherein the specific operation steps are as follows: placing the dried insoluble solid slag and 6mol/L concentrated hydrochloric acid in a magnetic stirrer, fully mixing and stirring for 2h at 60 ℃ under the condition that the solid-liquid ratio is 1:10g/mL until the upper layer liquid turns from transparent to yellow, and addingInto ZnCl 2 Uniformly mixing (Zn: fe molar ratio is 2:1), slowly dripping 5mol/LNaOH into the solid-liquid mixture to regulate the pH value of the solution to be stable at 11, heating the solid-liquid ratio between 1:10 to 80 ℃ by using a magnetic stirrer, vigorously stirring for 4 hours at 300 rpm, centrifuging to obtain Zn/Fe-LDHs modified sludge ash after the reaction is complete, flushing the modified sludge ash to be neutral by deionized water, and freeze-drying, grinding and sieving the obtained solid to obtain the catalyst<200 μm) to obtain a phosphorus-philic adsorbent, namely Zn/Fe-LDHs modified sludge ash, the structure is shown in figure 2, a plurality of multi-sided laminated plate-shaped structures are attached to the surface of the modified sludge ash, and representative LDH nano-sheets ([ Zn) 2+ (1-x) Fe 3+ x (OH) 2 ] x+ [Cl n- ] x/n ∙ mH 2O). The Zn/Fe-LDHs nano sheet layer makes the surface of the modified ceramsite become coarser, and has rich pores, and the porosity and the overlapping structure are obviously increased, which indicates that the heterogeneity is improved, so that the modified sludge ash can obtain a richer ion diffusion channel. The dynamic phosphorus adsorption capacity of the Zn/Fe-LDHs modified sludge ash can reach 540 mg-P.kg -1 . The theoretical maximum phosphorus adsorption amount is 14430 mg-P.kg -1 。
Introducing the acid extract from bottom to top into a leaching device filled with the prepared phosphorus-philic adsorbent, fully and uniformly mixing to adsorb phosphorus, wherein the liquid-solid ratio of the acid extract to the adsorbent is 0.01L/g, the adsorption temperature is 25 ℃, and the adsorption time is 6h. Leading out adsorption filtrate after the adsorption is finished, wherein the reflux of the adsorption filtrate can be used as acid leaching liquor for primary chemical wet treatment; introducing industrial grade sodium hydroxide aqueous solution (0.5 mol/L) into the phosphorus-adsorbed adsorbent, fully mixing to desorb phosphorus, wherein the liquid-solid ratio of the sodium hydroxide aqueous solution to the phosphorus-adsorbed adsorbent is 0.1L/g, the desorption temperature is 25 ℃, the desorption time is 6 hours, the desorption filtrate is led out after the desorption is completed, calcium hydroxide is added into the desorption filtrate, the molar ratio of P to Ca is kept to be 1:2 for reaction, filtering and separating to obtain filter residues and filtrate after the full reaction, and washing and drying the filter residues to obtain a hydroxyapatite product (the main component is Ca 5 (PO 4 ) 3 OH and CaPO 3 OH·2H 2 O，The purity reaches 97 percent, the recovery rate of phosphorus in the sludge ash reaches 93 percent, the recovery rate of phosphorus in the sludge ash still reaches 78 percent after repeated circulation of ten adsorption experiments, and the purity of the repeatedly obtained hydroxyapatite product still reaches 93 percent.
Example 2
Referring to fig. 1, the iron-rich sludge ash is firstly ball-milled, the rotation speed of the ball mill is 1000r/min, the total milling time is 10min, the granularity obtained by ball milling the sludge ash is 50-80 microns, the first-stage chemical wet treatment is carried out on the sludge ash after ball milling, and the specific steps of the first-stage chemical wet treatment are as follows: mixing the sludge ash subjected to ball milling with 0.2mol/L dilute hydrochloric acid/nitric acid, wherein the solid-liquid ratio of the sludge ash to the dilute hydrochloric acid/nitric acid is 1:20g/mL, fully mixing and oscillating for 2 hours, then filtering and separating by a solid-liquid separator to obtain insoluble solid slag and acid extract, drying the insoluble solid slag in a blast drying oven at 65 ℃ for 24 hours, and then performing secondary chemical wet treatment, wherein the specific operation steps are as follows: placing the dried insoluble solid slag and 5mol/L concentrated hydrochloric acid in a magnetic stirrer, fully mixing and stirring for 2h at 60 ℃ under the condition that the solid-liquid ratio is 1:10g/mL until the upper layer liquid turns from transparent to yellow, and then adding ZnCl into the upper layer liquid 2 Uniformly mixing (Zn: fe molar ratio is 1:1), slowly dripping 2mol/L NaOH into the solid-liquid mixture to regulate the pH value of the solution to be stable at 11, heating the solid-liquid ratio between 1:5 to 60 ℃ by using a magnetic stirrer, vigorously stirring for 4 hours at 300 rpm, centrifuging to obtain Zn/Fe-LDHs modified sludge ash after the reaction is complete, flushing the modified sludge ash to be neutral by deionized water, and freeze-drying, grinding and sieving the obtained solid<200 μm) to obtain a phosphorus-philic adsorbent, namely Zn/Fe-LDHs modified sludge ash. The dynamic phosphorus adsorption capacity of the Zn/Fe-LDHs modified sludge ash can reach 490 mg-P.kg-1. The theoretical maximum phosphorus adsorption amount is 11370 mg-P.kg < -1 >.
Introducing the acid extract from bottom to top into a leaching device filled with the prepared phosphorus-philic adsorbent, fully and uniformly mixing to adsorb phosphorus, wherein the liquid-solid ratio of the acid extract to the adsorbent is 0.025L/g, the adsorption temperature is 25 ℃, and the adsorption time is 2 hours. Leading out adsorption filtrate after the adsorption is finished, wherein the reflux of the adsorption filtrate can be used as acid leaching liquor for primary chemical wet treatment; introducing industrial-grade sodium hydroxide aqueous solution (0.1 mol/L) into the phosphorus-adsorbed adsorbent, fully mixing the phosphorus-adsorbed phosphorus adsorbent, carrying out desorption on phosphorus, wherein the liquid-solid ratio of the sodium hydroxide aqueous solution to the phosphorus-adsorbed phosphorus adsorbent is 0.1L/g, the desorption temperature is 25 ℃, the desorption time is 2h, and after the desorption is completed, leading out desorption filtrate, adding calcium hydroxide into the desorption filtrate, and keeping P: the Ca molar ratio is 1:2, the reaction is carried out fully, filter residue and filtrate are obtained through filtration and separation, the filter residue is washed and dried to obtain the hydroxyapatite product (purity reaches 90%), the recovery rate of phosphorus in sludge ash reaches 85%, the repeated cycle is carried out for ten times, and the recovery rate of phosphorus in sludge ash can still be 73%. The purity of the repeatedly obtained hydroxyapatite product can still reach 88 percent.
Example 3
Referring to fig. 1, the iron-rich sludge ash is firstly ball-milled, the rotation speed of the ball mill is 1200r/min, the common milling time is 10min, the granularity obtained by ball milling the sludge ash is 50-80 microns, the first-stage chemical wet treatment is carried out on the sludge ash after ball milling, and the specific steps of the first-stage chemical wet treatment are as follows: mixing the sludge ash subjected to ball milling with 1mol/L dilute hydrochloric acid/nitric acid, wherein the solid-liquid ratio of the sludge ash to the dilute hydrochloric acid/nitric acid is 1:5g/mL, fully mixing and oscillating for 5 hours, filtering and separating by a solid-liquid separator to obtain insoluble solid slag and acid extract, drying the insoluble solid slag in a blast drying oven at 80 ℃ for 24 hours, and performing secondary chemical wet treatment, wherein the specific operation steps are as follows: placing dried insoluble solid slag and 8mol/L concentrated hydrochloric acid in a magnetic stirrer, fully mixing and stirring for 2 hours at 60 ℃ under the condition that the solid-liquid ratio is 1:10g/mL, until the upper layer liquid turns yellow from transparent, then adding ZnCl2 (Zn: fe molar ratio is 3:1) into the upper layer liquid for uniform mixing, slowly dripping 5mol/L NaOH into the solid-liquid mixture, regulating the pH value of the solution to be stable at 11, heating the solid-liquid ratio between 2:5 to 80 ℃ by using the magnetic stirrer, vigorously stirring for 6 hours at a rotating speed of 500rpm, washing the modified sludge ash with deionized water, and freeze-drying, grinding and sieving the obtained solid to obtain the phosphorus-philic adsorbent, wherein the dynamic phosphorus adsorption quantity of the Zn/Fe-LDHs modified sludge ash can reach 510 mg-P.kg-1. The theoretical maximum phosphorus adsorption amount is 12430 mg-P.kg-1.
Introducing the acid extract from bottom to top into a leaching device filled with the prepared phosphorus-philic adsorbent, fully and uniformly mixing to adsorb phosphorus, wherein the liquid-solid ratio of the acid extract to the adsorbent is 0.05L/g, the adsorption temperature is 35 ℃, and the adsorption time is 6h. Leading out adsorption filtrate after the adsorption is finished, wherein the reflux of the adsorption filtrate can be used as acid leaching liquor for primary chemical wet treatment; introducing an industrial-grade sodium hydroxide aqueous solution (1 mol/L) into the phosphorus-adsorbed adsorbent, fully mixing the phosphorus-adsorbed adsorbent, carrying out desorption, wherein the liquid-solid ratio of the sodium hydroxide aqueous solution to the phosphorus-adsorbed adsorbent is 0.2L/g, the desorption temperature is 35 ℃, the desorption time is 6h, leading out a desorption filtrate after the desorption is completed, adding calcium hydroxide into the desorption filtrate, keeping the molar ratio of P to Ca to be 1:4, carrying out reaction, filtering and separating after the full reaction, obtaining filter residues and filtrate, washing and drying the filter residues, thereby obtaining a hydroxyapatite product, the purity reaches 91%, the recovery rate of phosphorus in sludge ash reaches 94%, the recovery rate of phosphorus in sludge ash still reaches 90%, and the purity of the hydroxyapatite product still can reach 88% after repeated acquisition.
Claims (8)
1. A method for preparing a zinc-iron-carrying double-metal hydroxide phosphorus-philic adsorbent by utilizing sludge ash is characterized by comprising the following steps:
1) Ball milling is carried out on sludge ash, then the sludge ash after ball milling is fully mixed with dilute hydrochloric acid/nitric acid for oscillation, insoluble solid slag and acid extract are obtained by filtration, and the insoluble solid slag is dried;
2) Placing the insoluble solid residue dried sample obtained in the step 1) and concentrated hydrochloric acid into a magnetic stirrer, fully mixing and stirring, waiting for the upper liquid to change from transparent to yellow, and adding ZnCl into the mixture 2 Uniformly mixing, dropwise adding NaOH solution into the solid-liquid mixture to regulate the pH value of the solution to be stable at 11-12 so that the solid-liquid ratio is 1:5-2:5, heating and stirring by a magnetic stirrer, centrifuging after the reaction is completed, washing to be neutral, freeze-drying, grinding and sieving to obtain the zinc-iron-carrying double-metal hydroxide phosphorus-carrying adsorbent.
2. The method according to claim 1, wherein the specific operation of the ball milling treatment in step 1) is that the rotational speed of the ball mill is 1000-1200r/min and the co-milling time is 10min, and the obtained sludge ash has a particle size of 50-80 microns.
3. The method according to claim 1, wherein the concentration of the dilute hydrochloric acid/nitric acid is 0.2-1mol/L, the solid-to-liquid ratio of the sludge ash in the dilute hydrochloric acid/nitric acid is 1g:5-20mL, the shaking time is 2-5 hours, and the insoluble solid slag is dried in a blast drying oven at 65-80 ℃.
4. The method as claimed in claim 1, wherein the concentration of the concentrated hydrochloric acid in the step 2) is 5-8 mol/L, the solid-liquid ratio of the insoluble solid slag dry sample and the concentrated hydrochloric acid is 1g:10mL, and the mixture is fully mixed and stirred for 2 hours at 60 ℃, and ZnCl is added 2 The molar ratio of Zn to Fe is 1:1-3:1.
5. The method according to claim 1, wherein the concentration of the NaOH solution in the step 2) is 2-5mol/L, and the magnetic stirrer is heated to 60-80℃and vigorously stirred at 200-500rpm for 4-6 hours after the NaOH solution is added dropwise.
6. Use of a zinc-iron-loaded double metal hydroxide phosphorus adsorbent prepared by the method of any one of claims 1-5, characterized by comprising the steps of:
1) Introducing the acid extract into a leaching device filled with zinc-iron-loaded double metal hydroxide phosphorus adsorbent from bottom to top, fully and uniformly mixing, then carrying out phosphorus adsorption, after the adsorption is completed, leading out adsorption filtrate, introducing the adsorbent after the adsorption of phosphorus into sodium hydroxide aqueous solution, fully mixing, carrying out desorption of phosphorus, and after the desorption is completed, leading out desorption filtrate;
2) And adding calcium hydroxide into the desorption filtrate, keeping the mole ratio of phosphorus to calcium to be 1:2-1:4, reacting, filtering and separating after full reaction to obtain filter residues and filtrate, and cleaning and drying the filter residues to obtain the hydroxyapatite product.
7. The process according to claim 6, wherein the ratio of the acid extract to the adsorbent in step 1) is 0.025 to 0.05L/g, the adsorption temperature is 25 to 35℃and the adsorption time is 2 to 6 hours.
8. The process according to claim 6, wherein the aqueous sodium hydroxide solution in step 1) has a concentration of 0.1 to 1mol/L, a liquid-solid ratio of 0.1 to 0.2L/g of aqueous sodium hydroxide solution to adsorbent, a desorption temperature of 25 to 35℃and a desorption time of 2 to 6 hours.
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