MD657Z - Process for purification of water from fluorine ions and humic acids - Google Patents

Process for purification of water from fluorine ions and humic acids

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Publication number
MD657Z
MD657Z MDS20130034A MDS20130034A MD657Z MD 657 Z MD657 Z MD 657Z MD S20130034 A MDS20130034 A MD S20130034A MD S20130034 A MDS20130034 A MD S20130034A MD 657 Z MD657 Z MD 657Z
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Moldova
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water
humic acids
purification
aluminum
diatomite
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MDS20130034A
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Romanian (ro)
Russian (ru)
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Вячеслав ЗЕЛЕНЦОВ
Татьяна ДАЦКО
Елена ДВОРНИКОВА
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Институт Прикладной Физики Академии Наук Молдовы
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Priority to MDS20130034A priority Critical patent/MD657Z/en
Publication of MD657Y publication Critical patent/MD657Y/en
Publication of MD657Z publication Critical patent/MD657Z/en

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Abstract

The invention relates to a process for purification of water concomitantly from fluorine ions and humic acids.The process, according to the invention, includes passage of water at a flow rate of 0.3 dm3/min through a volume of 14…28 cm3 of diatomite-based sorbent modified with finely dispersed aluminum hydroxide. The modified diatomite is prepared by grinding and calcination thereof, keeping in a solution of the aluminum salt, treatment with ammonia solution, filtration, washing and drying in the air.

Description

Invenţia se referă la un procedeu de purificare a apei concomitent de ioni de fluor şi acizi humici. The invention refers to a water purification process of fluorine ions and humic acids.

Este cunoscut că pentru înlăturarea fluorului din apă prin metoda de adsorbţie în ţările dezvoltate se utilizează oxidul de aluminiu activat [1]. It is known that activated aluminum oxide is used to remove fluoride from water by the adsorption method in developed countries [1].

Dezavantajele utilizării acestuia reprezintă un şir de restricţii semnificative. În afară de problemele pur de adsorbţie, astfel cum sunt cinetica lentă şi capacitatea nu prea mare de adsorbţie, pregătirea sorbentului pentru procesul de purificare prevede un consum mare de energie şi operaţii de activare costisitoare, calcinarea la temperaturi înalte şi durata semnificativă. Afară de aceasta, utilizarea sorbentului costisitor necesită regenerarea lui, adică includerea operaţiilor suplimentare, ceea ce implică un nou consum de energie şi reagenţi. The disadvantages of its use represent a series of significant restrictions. Apart from purely adsorption problems, such as slow kinetics and not very high adsorption capacity, the preparation of the sorbent for the purification process involves high energy consumption and expensive activation operations, calcination at high temperatures and significant duration. Apart from this, the use of the expensive sorbent requires its regeneration, i.e. the inclusion of additional operations, which implies a new consumption of energy and reagents.

Este cunoscut un procedeu de defluorurare a apei cu folosirea în calitate de sorbent a unui material necostisitor, ce conţine aluminiu 27% şi reprezintă deşeuri de la procesul de prelucrare electrochimică dimensională cu utilizarea în calitate de anod a aliajului de aluminiu. Deşeurile au fost calcinate la o temperatură de 200...800ºC cu intervalul de 100ºC. Aceste produse prezintă oxihidroxizi de aluminiu [2]. A water defluoridation process is known using an inexpensive material as a sorbent, which contains 27% aluminum and represents waste from the dimensional electrochemical processing process using an aluminum alloy as an anode. The waste was calcined at a temperature of 200...800ºC with an interval of 100ºC. These products contain aluminum oxyhydroxides [2].

Dezavantajele procedeului cunoscut constau în temperaturile înalte de calcinare, compoziţia variabilă a sorbentului, complexitatea şi durata lungă de pregătire a sorbentului. The disadvantages of the known process consist in the high calcination temperatures, the variable composition of the sorbent, the complexity and the long duration of preparation of the sorbent.

Este cunoscut, de asemenea, un procedeu de înlăturare a fluorului din apă cu aplicarea diatomitului natural, modificat cu diferiţi compuşi ce conţin metale, în particular aluminiu sau calciu, cum sunt hidroxizii de calciu şi aluminiu, fosfaţii de calciu şi aluminiu, care sunt trataţi ulterior la temperatura de 200...250ºC. Cel mai activ faţă de fluor este fosfatul de aluminiu (16,01 mM/g), după care urmează hidroxidul de aluminiu, fosfatul de calciu şi hidroxidul de calciu [3]. It is also known a process for removing fluorine from water with the application of natural diatomite, modified with different compounds containing metals, in particular aluminum or calcium, such as calcium and aluminum hydroxides, calcium and aluminum phosphates, which are treated later at a temperature of 200...250ºC. The most active towards fluoride is aluminum phosphate (16.01 mM/g), followed by aluminum hydroxide, calcium phosphate and calcium hydroxide [3].

Dezavantajul acestui procedeu constă în faptul că, de rând cu gradul suficient de defluorurare, în acest procedeu nu se cercetează problemele de înlăturare a acizilor humici. The disadvantage of this process is that, in line with the sufficient degree of defluoridation, this process does not investigate the problems of removing humic acids.

Este cunoscut un procedeu de înlăturare a acizilor humici cu aplicarea unui material natural - argilă intercalată cu hidroxizi dubli de zinc şi aluminiu, obţinuţi pe cale sintetică prin precipitare cu baze alcaline a nitraţilor de zinc şi aluminiu în raport bază alcalină : sare de metal de 0,1 : 0,05, la un pH = 7,0. Sorbentul înlătură acizii humici mai bine decât cărbunele activat. Înlăturarea acizilor humici are loc pe baza schimbului ionic [4]. A process is known for removing humic acids with the application of a natural material - clay interspersed with zinc and aluminum double hydroxides, obtained synthetically by precipitation with alkaline bases of zinc and aluminum nitrates in an alkaline base: metal salt ratio of 0 ,1 : 0.05, at a pH = 7.0. The sorbent removes humic acids better than activated carbon. The removal of humic acids takes place on the basis of ion exchange [4].

Este cunoscut, de asemenea, un procedeu de înlăturare a acizilor humici cu nisip modificat cu oxizi de fier. Adsorbţia acizilor humici de către sorbentul modificat s-a cercetat în funcţie de concentraţia lor, viteza fluxului în coloană, pH-ul soluţiei şi forţa ionică. S-a stabilit că sorbentul obţinut adsoarbe acizii humici cu o viteză de 5...7 ori mai mare decât nisipul nemodificat [5]. A process for removing humic acids with sand modified with iron oxides is also known. The adsorption of humic acids by the modified sorbent was investigated depending on their concentration, the flow rate in the column, the pH of the solution and the ionic strength. It was established that the obtained sorbent adsorbs humic acids at a rate 5...7 times higher than unmodified sand [5].

Dezavantajul acestor procedee constă în lipsa de date experimentale pentru înlăturarea ionilor de fluor. The disadvantage of these processes is the lack of experimental data for the removal of fluoride ions.

Este cunoscut procedeul de înlăturare a fluorului în prezenţa substanţelor organice, în particular, a urmelor de acizi humici, prin electrodializă cu folosirea membranelor de schimb ionic. Gradul de epurare a apei de fluor, nitraţi şi compuşii borului depinde în mare măsură de dimensiunea ionilor hidrataţi - ionii nitraţilor (cu rază mică) se înlătură prin electrodializă mai uşor decât cei de fluor, care au raza mai mare. Prezenţa urmelor de acizi humici pasivează membranele, micşorând extragerea fluorului [6]. The procedure for removing fluorine in the presence of organic substances, in particular, traces of humic acids, by electrodialysis using ion exchange membranes is known. The degree of purification of water from fluoride, nitrates and boron compounds largely depends on the size of the hydrated ions - nitrate ions (with a small radius) are removed by electrodialysis more easily than fluoride ones, which have a larger radius. The presence of traces of humic acids passivates the membranes, reducing the extraction of fluorine [6].

Dezavantajul acestui procedeu este complexitatea aparatului, legată de utilizarea membranelor, costul ridicat al apei epurate şi cel mai important - lipsa datelor ce ţin de înlăturarea acizilor humici. The disadvantage of this process is the complexity of the device, related to the use of membranes, the high cost of purified water and most importantly - the lack of data related to the removal of humic acids.

În calitate de cea mai apropiată soluţie serveşte procedeul de înlăturare a fluorului în prezenţa acizilor humici prin aplicarea hidroxidului de aluminiu electrogenerat, obţinut prin dizolvarea anodică a aliajului de aluminiu. Dizolvarea anodică a aluminiului s-a efectuat la intensitatea curentului electric de 1,80 A şi durata procesului de electroliză de 5,4 min. A fost cercetată înlăturarea fluorului din soluţie cu concentraţia iniţială de 2,37...19,0 mg/dm3 în prezenţa acizilor humici cu conţinutul de 7...14 mgO2/dm3. Cantitatea de aluminiu necesară pentru atingerea valorilor concentraţiei maxime admisibile (CMA) după fluor la concentraţia iniţială a acestuia de 5 mg/dm3 alcătuieşte 67,5 mg Al3+/dm3. Consumul de electricitate a fost de 580 C [7]. As the closest solution serves the process of removing fluorine in the presence of humic acids by applying electrogenerated aluminum hydroxide, obtained by the anodic dissolution of the aluminum alloy. The anodic dissolution of aluminum was carried out at the intensity of the electric current of 1.80 A and the duration of the electrolysis process of 5.4 min. The removal of fluoride from the solution with the initial concentration of 2.37...19.0 mg/dm3 in the presence of humic acids with the content of 7...14 mgO2/dm3 was investigated. The amount of aluminum required to reach the values of the maximum permissible concentration (CMA) after fluorine at its initial concentration of 5 mg/dm3 is 67.5 mg Al3+/dm3. The electricity consumption was 580 C [7].

Dezavantajele acestui procedeu sunt complexitatea aranjării aparatelor, folosirea materialului anodic costisitor din aluminiu pur ori a aliajului de aluminiu, efectuarea procesului în două etape şi consumul mare de energie. De asemenea în acest procedeu lipsesc orice date experimentale despre gradul de înlăturare a acizilor humici prezenţi în comun cu fluorul. The disadvantages of this process are the complexity of arranging the devices, the use of expensive anodic material made of pure aluminum or aluminum alloy, the performance of the process in two stages and the high energy consumption. Also, in this process, there is no experimental data on the degree of removal of humic acids present together with fluoride.

Problema tehnică pe care o rezolvă invenţia constă în majorarea eficacităţii de epurare a apei de ionii de fluor şi acizii humici prezenţi împreună, adică reducerea dozei de sorbent, a numărului de operaţii necesare pentru purificarea apei de doi componenţi, reducerea timpului şi a volumului de muncă necesar pentru purificare. The technical problem that the invention solves consists in increasing the efficiency of purifying water from fluoride ions and humic acids present together, i.e. reducing the dose of sorbent, the number of operations required for two-component water purification, reducing time and the amount of work required for purification.

Problema se soluţionează prin aceea că procedeul de purificare a apei de ioni de fluor şi acizi humici include trecerea apei cu viteza fluxului de 0,3 dm3/min printr-un volum de 14…28 cm3 de sorbent pe bază de diatomit modificat cu hidroxid de aluminiu fin dispersat, cu conţinutul acestuia recalculat la Al2O3 de 12…19% mas. Totodată diatomitul modificat se obţine prin mărunţirea şi calcinarea acestuia la temperatura de 400…450°C, menţinerea într-o soluţie a sării de aluminiu de 2M la temperatura de 50…60°C timp de 1…3 ore la agitare continuă, tratarea cu soluţie de amoniac la un pH mai mare de 9 timp de 2…5 ore, filtrarea, spălarea şi uscarea la aer. The problem is solved by the fact that the process of purifying water from fluoride ions and humic acids includes the passage of water with a flow rate of 0.3 dm3/min through a volume of 14...28 cm3 of sorbent based on diatomite modified with hydroxide finely dispersed aluminum, with its content recalculated to Al2O3 of 12...19% mass. At the same time, the modified diatomite is obtained by crushing and calcining it at a temperature of 400...450°C, keeping it in a solution of 2M aluminum salt at a temperature of 50...60°C for 1...3 hours with continuous stirring, treating with ammonia solution at a pH greater than 9 for 2...5 hours, filtering, washing and air drying.

Materialul ce conţine hidroxid de aluminiu, recalculat la Al2O3 mai puţin de 12% mas., nu asigură gradul necesar de purificare a apei, iar cu conţinutul acestuia recalculat la Al2O3 în material mai mare de 19% mas. nu duce la creşterea suficientă a indicilor de purificare şi este iraţional. The material containing aluminum hydroxide, recalculated to Al2O3 less than 12% by mass, does not provide the necessary degree of water purification, and with its content recalculated to Al2O3 in material greater than 19% by mass. it does not lead to a sufficient increase in purification indices and is irrational.

Rezultatul tehnic al invenţiei propuse constă în aceea că înlăturarea concomitentă a ionilor de fluor şi acizilor humici din apă cu sorbentul obţinut este efectivă fără utilizarea unui utilaj complex, fără un consum mărit de energie şi materiale costisitoare. Apa purificată corespunde normelor standard pentru apă potabilă după aceşti componenţi nocivi - 1,5 mg/dm3 după fluor şi 5 mgO2/dm3 după acizi humici. The technical result of the proposed invention consists in the fact that the simultaneous removal of fluoride ions and humic acids from water with the obtained sorbent is effective without the use of a complex machine, without an increased consumption of energy and expensive materials. The purified water corresponds to the standard norms for drinking water for these harmful components - 1.5 mg/dm3 for fluoride and 5 mgO2/dm3 for humic acids.

Procedeul propus permite micşorarea considerabilă a dozei de sorbent, reducerea numărului de operaţii la efectuarea epurării apei de doi componenţi nocivi, a timpului şi volumului de muncă necesar pentru epurare şi se obţine un grad înalt de purificare concomitentă de doi poluanţi. The proposed procedure allows the considerable reduction of the sorbent dose, the reduction of the number of operations when performing water purification of two harmful components, the time and the amount of work required for purification, and a high degree of simultaneous purification of two pollutants is obtained.

Modificarea superficială a diatomitului constă în următoarele: proba iniţială se supune încălzirii la temperatura de 400...450°C. Apoi se menţine într-o soluţie a sării de aluminiu de 2M la temperatura de 50…60°C timp de 1…3 ore la agitare continuă, după care faza solidă se separă de soluţie şi se tratează cu soluţie de amoniac la un pH mai mare de 9 timp de 2…5 ore. Faza solidă se separă, se spală, se menţine la aer şi se usucă la temperatura de 110°C. The superficial modification of diatomite consists of the following: the initial sample is subjected to heating at a temperature of 400...450°C. Then it is maintained in a 2M aluminum salt solution at a temperature of 50...60°C for 1...3 hours with continuous stirring, after which the solid phase is separated from the solution and treated with ammonia solution at a pH higher sea of 9 for 2...5 hours. The solid phase is separated, washed, kept in air and dried at a temperature of 110°C.

Tratarea termică a diatomitului la temperatura de 400...450°C este însoţită de carbonizarea parţială a componenţilor organici în diatomit şi de majorarea afinităţii materialului faţă de acizii humici, iar tratarea cu soluţia sării de aluminiu la încălzire la 50...60°C la agitare şi tratarea ulterioară cu soluţie de amoniac provoacă precipitarea hidroxidului de aluminiu fin dispersat pe suprafaţa şi în porii diatomitului, ceea ce duce la mărirea suprafeţei specifice şi a capacităţii de adsorbţie a materialului sintetizat faţă de fluor. Aceste operaţii asigură şi selectivitatea mărită a sorbentului concomitent faţă de ionii de fluor şi acizii humici. The thermal treatment of diatomite at a temperature of 400...450°C is accompanied by the partial carbonization of the organic components in the diatomite and the increase of the affinity of the material towards humic acids, and the treatment with the aluminum salt solution when heated to 50...60° C upon stirring and subsequent treatment with ammonia solution causes the precipitation of finely dispersed aluminum hydroxide on the surface and in the pores of the diatomite, which leads to an increase in the specific surface area and the adsorption capacity of the synthesized material for fluorine. These operations ensure the increased selectivity of the sorbent at the same time against fluoride ions and humic acids.

Mai jos sunt demonstrate exemple de realizare a procedeului propus pentru purificarea apei concomitent de fluor şi acizi humici. Below are demonstrated examples of the proposed process for simultaneously purifying water from fluorine and humic acids.

Exemple de realizare a invenţiei Examples of realization of the invention

Exemplul 1 Example 1

Apa pentru purificare cu concentraţia iniţială a acizilor humici de 20,8 mgO2/dm3 şi a ionilor de fluor de 5,2 mg/dm3 a fost trecută printr-un volum de sorbent de 15 cm3 cu viteza fluxului de 0,3 dm3/min. Conţinutul de hidroxid de aluminiu recalculat la Al2O3 - 12% mas., suportul silicios - restul. Water for purification with an initial concentration of humic acids of 20.8 mgO2/dm3 and fluoride ions of 5.2 mg/dm3 was passed through a sorbent volume of 15 cm3 with a flow rate of 0.3 dm3/min . The content of aluminum hydroxide recalculated to Al2O3 - 12% by mass, the silicon support - the rest.

Indicii apei iniţiale şi tratate după procedeul propus Indexes of the initial and treated water according to the proposed procedure

Caracteristicile apei: Water characteristics:

Poluantul Apa iniţială Apa după purificare Concentraţia maximă admisibilă Fluorul total, mg/dm3 5,2 1,0 1,5 Acizii humici, mgO2/dm3 20,8 4,5 5,0 Pollutant Initial water Water after purification Maximum admissible concentration Total fluoride, mg/dm3 5.2 1.0 1.5 Humic acids, mgO2/dm3 20.8 4.5 5.0

Exemplul 2 Example 2

Apa pentru purificare cu concentraţia iniţială a acizilor humici de 20,8 mgO2/dm3 şi a ionilor de fluor de 5,2 mg/dm3 a fost trecută printr-un volum de sorbent de 15 cm3 cu viteza fluxului de 0,3 dm3/min. Conţinutul de hidroxid de aluminiu recalculat la Al2O3 - 19% mas., suportul silicios - restul. Water for purification with an initial concentration of humic acids of 20.8 mgO2/dm3 and fluoride ions of 5.2 mg/dm3 was passed through a sorbent volume of 15 cm3 with a flow rate of 0.3 dm3/min . The content of aluminum hydroxide recalculated to Al2O3 - 19% by mass, the silicon support - the rest.

Indicii apei iniţiale şi tratate după procedeul propus Indexes of the initial and treated water according to the proposed procedure

Caracteristicile apei: Water characteristics:

Poluantul Apa iniţială Apa după purificare Concentraţia maximă admisibilă Fluorul total, mg/dm3 5,2 0,35 1,5 Acizii humici, mgO2/dm3 20,8 3,5 5,0 Pollutant Initial water Water after purification Maximum admissible concentration Total fluoride, mg/dm3 5.2 0.35 1.5 Humic acids, mgO2/dm3 20.8 3.5 5.0

În aşa mod, la un conţinut al ionilor de fluor în apă de 5 mg/dm3 şi mai mult şi al acizilor humici de 20,8 mgO2/dm3, procedeul propus asigură un grad de purificare a apei concomitent de ioni de fluor şi acizi humici până la concentraţiile maxime admisibile ale acestor componenţi pentru apă potabilă. Procedeul permite micşorarea considerabilă a dozei de sorbent, reducerea numărului de operaţii la efectuarea epurării apei de doi componenţi nocivi, a timpului şi volumului de muncă necesar pentru epurare şi obţinerea unui grad înalt de purificare concomitentă de doi poluanţi. In this way, at a content of fluorine ions in water of 5 mg/dm3 and more and of humic acids of 20.8 mgO2/dm3, the proposed process ensures a degree of simultaneous water purification of fluorine ions and humic acids up to the maximum permissible concentrations of these components for drinking water. The process allows for the considerable reduction of the sorbent dose, the reduction of the number of operations when performing water purification of two harmful components, the time and the amount of work required for purification and obtaining a high degree of simultaneous purification of two pollutants.

1. Stewart T. Removal of fluoride from drinking water: Analysis of alumina based sorption. Institute of Biogeochemistry and Pollutant Dynamics, Department Environmental Sciences, ETH, Zurich, 2009, p. 2-24 1. Stewart T. Removal of fluoride from drinking water: Analysis of alumina based sorption. Institute of Biogeochemistry and Pollutant Dynamics, Department Environmental Sciences, ETH, Zurich, 2009, p. 2-24

2. Zelentsov V., Datsko T., Dvornikova E. Fluorine adsorption by aluminum oxihydrates subjected to thermal treatment. Surface Engineering and Applied Electrochemistry, 2008, v. 44, No. 1, p. 64-68 2. Zelentsov V., Datsko T., Dvornikova E. Fluorine adsorption by aluminum oxyhydrates subjected to thermal treatment. Surface Engineering and Applied Electrochemistry, 2008, v. 44, No. 1, p. 64-68

3. Zelenţov V., Daţko T., Dvornikova E. Studiul aplicabilităţii diatomitului modificat pentru înlăturarea ionilor de fluor din apele naturale. Simpozion Internaţional "Mediul şi Industria", România, Bucureşti, 2005, v. 1, p. 213-218 3. Zelenţov V., Daţko T., Dvornikova E. Study of the applicability of modified diatomite for the removal of fluoride ions from natural waters. International Symposium "Environment and Industry", Romania, Bucharest, 2005, v. 1, p. 213-218

4. Santosa S., Sudiono S., Shiddiq Z. Effective humic acid removal using Zn/Al layered double hydroxide anionic clay. Journal Ion Exchange, 2007, v. 18, No. 4, p. 322-326 4. Santosa S., Sudiono S., Shiddiq Z. Effective humic acid removal using Zn/Al layered double hydroxide anionic clay. Journal Ion Exchange, 2007, v. 18, No. 4, p. 322-326

5. Kim Hyon-Chong, Park Seong-Jik, Lee Chang-Gu, Han Yong-Un, Park Jeong-Ann, Kim Song-Bae. Humic acid removal from water by iron-coated sand: A column experiment. Environmental Engineering Research, 2009, v. 14, No. 1, p. 41-47 5. Kim Hyon-Chong, Park Seong-Jik, Lee Chang-Gu, Han Yong-Un, Park Jeong-Ann, Kim Song-Bae. Humic acid removal from water by iron-coated sand: A column experiment. Environmental Engineering Research, 2009, v. 14, No. 1, p. 41-47

6. Banasiak L., Schafer A. Removal of boron, fluoride and nitrate by electrodialysis in the presence of organic matter. Journal of Membrane Science, 2009, 334(1), p. 101-109 6. Banasiak L., Schafer A. Removal of boron, fluoride and nitrate by electrodialysis in the presence of organic matter. Journal of Membrane Science, 2009, 334(1), pp. 101-109

7. Матвеевич В. Сорбция фторид-ионов электрогенерированным гидроксидом алюминия в присутствии гуминовых кислот. Электронная обработка материалов, Институт прикладной физики АН Молдовы, 1999, № 2, с. 22-26 7. Матвеевич В. Sorption of fluoride ions generated by aluminum hydroxide in the presence of humic acids. Electronic processing of materials, Institute of applied physics of Moldovan Academy of Sciences, 1999, № 2, p. 22-26

Claims (1)

Procedeu de purificare a apei de ioni de fluor şi acizi humici, care include trecerea apei cu viteza fluxului de 0,3 dm3/min printr-un volum de 14…28 cm3 de sorbent pe bază de diatomit modificat cu hidroxid de aluminiu fin dispersat, cu conţinutul acestuia recalculat la Al2O3 de 12…19% mas., totodată diatomitul modificat se obţine prin mărunţirea şi calcinarea acestuia la temperatura de 400…450°C, menţinerea într-o soluţie a sării de aluminiu de 2M la temperatura de 50…60°C timp de 1…3 ore la agitare continuă, tratarea cu soluţie de amoniac la un pH mai mare de 9 timp de 2…5 ore, filtrarea, spălarea şi uscarea la aer.Water purification process of fluoride ions and humic acids, which includes the passage of water at a flow rate of 0.3 dm3/min through a volume of 14...28 cm3 of diatomite-based sorbent modified with finely dispersed aluminum hydroxide, with its content recalculated to Al2O3 of 12...19% by mass, at the same time the modified diatomite is obtained by crushing and calcining it at a temperature of 400...450°C, keeping it in a solution of 2M aluminum salt at a temperature of 50...60 °C for 1...3 hours with continuous stirring, treatment with ammonia solution at a pH higher than 9 for 2...5 hours, filtering, washing and drying in air.
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