The results of experimental investigation in water purification from pharmaceuticals by the example of diclofenac by means of activated carbon adsorption and using nanofilter membranes are presented. High efficiency of application of these processes in water purification is shown

Vergun, А. P.

Vlasov, А. V.

Electronic archive of Tomsk Polytechnic University

IntroductionOne of the new areas of ecological chemistry is connectedwith the appearance of pharmaceutical active compounds inaqueous medium. Investigations in this problem were carriedout in many countries – in Austria, Brazil, Canada, Croatia,Great Britain, Germany, Greece, Italy, Spain, Switzerland,the Netherlands and the USA. They showed that more than80 different compounds, pharmaceuticals and a number ofmetabolites are present in aqueous medium. Some pharmaceuticals of different categories were found in sewage water atconcentration to several ml/g and also in some surface watersituated downstream from sewage water reprocessing stations.The investigations show that some pharmaceuticals are notcompletely removed at sewage disposal plants. In some casesthey were found in drinking water samples at the level of minimally detectable concentration [1–8].The given paper includes the results of investigationsin water purification from pharmaceuticals, particularly(specifically) from widespread analgesic–diclofenac.The experiments were carried out in the laboratories ofthe university in Karlsruhe (Germany) – water purification from diclofenac by means of activated carbon adsorption and using of nanofilter membranes. Purification bythe mentioned methods was carried out both with humicsubstances (HS) in aqueous medium and without them.Materials and methodsThe experiments were carried out using diclofenacsodium (C14H10Cl2NNaO2). For carrying out the experiments with humic substances water with their high content from Holo lake (Black forest, Germany) was used.Water was of brownish color with dissolved organic carbon concentration in a sample equals 25 mg/l. For determining diclofenac concentration the spectrophotometer Cary 50 with measurement wavelength 275 nmwas used. Analyzing samples 1sm quartz cell was used.For determining organic substances concentrationthe analyzer Sievers 820 of total organic carbon was used.Diclofenac concentration in the presence of impurities(in this case – humic substances) was determined by means of highperformance liquid chromatography at chromatograph Agilent 1100. Carrying out measurements UVdetector and two columns N24 Purospher RP18 withparameters (length, inner diameter) 125×4 mm and N25Purospher RP18 250×4 was used. Diclofenac was foundat wavelength 230 nm within time intervals – 19,5 and12,5 min in the first and the second columns respectively. Phosphate buffer with concentration 9,8 мМ KH2PO4and 8,8 мМ H3PO4, pH 3,1; flow rate 1 ml/l, introducedsample volume 10 microliter were used for all columns.Membranes NF90 and NF200 of FilmTec company [9],applying in roll nanofiltration elements manufacturingwere used for carrying out nanofiltration, table 1.Table 1. Main characteristics of membranes NF90 and NF200Activated carbon Norit SA UF produced by Noritcompany [10] was used for carrying out adsorption, table 2. The mentioned sorbent has high clinical characteristics because of hyperfine structure of its particles.Norit SA UF has high adsorptive capacitance for anumber of compounds; it is especially widely applied indrinking water purification. Dimineralized water wasused when preparing all solutions. pH magnitude in studied solutions was maintained equal to 7±0,2.Table 2. Sorbent Norit SA UF specificationsExperimental investigations on adsorption activatedcarbons diclofenac and humic substancesSeries of experiments was carried out to study diclofenac sorption on activated carbon. Calibration curves for diclofenac have been plotted at spectrophotometer and chroProducer NoritName Norit SA USpecific surface area, m2/g 1200Particles mean diameter, micrometers 7Particle size >180 mkm, max. % of total mass 0,1>400 mkm 0,0Packed density, kg/m3 160Humidity, max., % 5Characteristics NF 90 NF200Selectivity, % – – NaCl 85...95 – MgSO4 >97 97CaCl2 – 35...50Atrazine – 95Type of a membrane Polyamide thinfilm compositeMaximal working temperature, °C 45Maximal working pressure, bar 41 Maximal pressure drop, bar 1,0 pH range, continuous exposure 3...10pH range, shorttime purification(30 min)1...12Maximal feeding flow, m3/h 15,9 Bulletin of the Томsк Pоlytеchnic University. 2007. V. 310. № 1124UDC 628.16APPLICATION OF SORPTION AND MEMBRANE METHODS IN THE PROCESS OF WATER PURIFICATION FROM DICLOFENACА.V. Vlasov, А.P. VergunTomsk Polytechnic UniversityEmail: chair23@phtd.tpu.edu.ruThe results of experimental investigation in water purification from pharmaceuticals by the example of diclofenac by means of activated carbonadsorption and using nanofilter membranes are presented. High efficiency of application of these processes in water purification is shown.matographer beforehand. Maximal degree of absorption ofdiclofenac by activated carbon (AC), rate of sorption weredetermined. Then HS were added into initial solutions andthe experiments were carried out in their presence. Influence of HS on sorption in various conditions was studied.Freundlich model was applied for sorption isotherms plotting. As a result, sorption curve which shows that maximalcharge of AC is obtained at high concentration of diclofenac was plotted and it amounted a specific value of the order of 0,25...0,28 (diclofenac/sorbent).Humic substanceshaving appreciably larger size of molecules were absorbedin significantly less degree than diclofenac. Therefore theirpresence did not influence significantly maximal charge ofAC, their absorption was minimal.Fig. 1. Experimental isotherm of diclofenac adsorption withNorit SA UF activated carbonFig. 2. Dependence of diclofenac content in solution on adsorption time with Norit SA UF activated carbonApplication of nanofilter membranes for water purification from diclofenac Studying of filtration processes with membranes using was the second area of investigations in diclofenacabsorption from solutions. Flatchannel experimentalsetup (fig. 3) was used for carrying out the experiments infiltration. Membranes which find an application in rollmodule was used in this setup which itself is an analog ofroll module for carrying out experimental investigations.The flatchannel experimental setup operates in thefollowing way. Tank – 1 is filled up with initial solution,arriving at a pump – 3 for generating increased pressure.By means of valves – 2 values of pressure and flow supplied to membrane module – 6, registered on manometer – 5 and rotameter – 4 is controlled. In the membranemodule a portion of flow goes through the membraneand the rest portion of flow returns into the tank and cycle repeats. The tank is provided with a thermostatingdevice – 7 for supporting temperature conditions.Data of changing of diclofenac concentration andmembranes selectivity within the time of experiment arepresented in table 3.Table 3. Concentration of diclofenac, dissolved organic carbon and membrane selectivity during the process offiltrationDuring the whole experiment diclofenac concentration in permeats flow membrane selectivity increases anddecreases stepbystep. It is especially appreciable on themembrane NF200. Identical tendency is observed withHS in the initial solution. Concentration in permeatsstarts stabilizing at experimental time equal to 17 hours.This fact can be explained by diclofenac adsorption on amembrane during the first hours of the experiment. Afterthat membrane saturation to the maximal value constantin time occurs. To trace the same tendency on the membrane NF90 is not possible because of sufficiently lowdiclofenac concentration in permeats flow. The pattern ofchange of membrane selectivity with HS is rather difficult. During the first 17 hours selectivity decreases step –by – step and to 66 hours it sharply increases.Experimental data of flow changing within experimental time with HS and without it are presented in table 4.Great difference in permeats flow of the membraneNF200 in two experiments should be noted. It is connected with the fact that membranes were taken fromdifferent sets and producer admits such variant in the absence of some kind of changes in other characteristics.Presence of HS in the experiment results in significant change of flow decrease rate. Influence of HS on agiven parameter is explained by membrane contamination [11, 12]. Thus, we may reach a conclusion that HSpresence in solution results in decrease of permeats flow.Time,hDiclofenac concentration(withoutHS), mg/lSelectivitywith respectto diclofenac (withoutHS), %Concentration,mg/lSelectivity withrespect toDiclofenacwith HSDissolvedorganiccarbondiclofenac (withHS), %HS, %NF900,5 <0,02 >99,61 – – – –1 <0,02 >99,61 <0,02 0,66 >99,61 72,272 <0,02 >99,61 <0,02 0,43 >99,61 82,9417 0,023 99,49 <0,02 0,26 >99,61 89,3166 – – <0,02 0,08 99,62 97,11NF2000,5 0,071 98,43 0,09 0,34 98,03 85,371 0,082 98,19 0,11 0,29 97,63 87,672 0,085 98,14 0,13 0,71 97,06 72,3217 0,143 96,90 0,19 0,62 95,91 74,6966 – – 0,16 0,18 96,57 93,3701020304050607080901000 10 20 30 40 50 60 70 80 90 100 110 120 130Adsorbtion time, minResidual concentration of diclofenac, % AC 100 mg/lAC 50 mg/lAC 20 mg/l00,050,10,150,20,250,30 10 20 30 40 50Concentration of diclofenac, mg/lSpecific load of AC,  diclofenac/sorbentChemistry125Table 4. Change of permeatа flow without humic substancesand with themObtained experimental data are the basis for development of technology of water purification from diclofenacboth by sorption and membrane methods. The results ofinvestigations may be also applied to waste solutions purification and to valued component release from them.Conclusion1. Series of experiments in adsorption of pharmaceutical by the example of diclofenac and its nanofiltration on membranes of NF90 and NF200 batches(USA) is carried out. It is shown that sorbent loadfactor on basis of activated carbon at high concentration of diclofenac achieves 0,25...0,28 (diclofenac weight/sorbent weight). Humic substances resultsin adsorption efficiency decrease, but degree of purification from diclofenac remains sufficiently high.2. In membrane purification conditions the selectivityin respect of diclofenac remained on sufficientlyhigh level during the whole time of the experiments(more than 99% on the membrane of NF90 batchand more than 95% on NF200 one). HS influencewas in stepbystep decrease of permeats flow.Authors thank the stuff of Karlsruhe University (Germany), professor Fritz Frimmel, Florence Saravia for project management. Andalso EnglerBunte Institute for technical support and RussianGerman college for financial support. Time, hFlow of permeats, ml/minPermeability,l/(h.m2.bar)Change of permeability, %Without humic substancesNF90 NF200 NF90 NF200 NF90 NF2000,5 6,77 6,85 8,46 8,56 100,00 100,001 6,76 6,84 8,45 8,55 99,81 99,882 6,69 6,84 8,37 8,55 98,85 99,8117 6,65 6,82 8,32 8,52 98,29 99,53With humic substances0,5 6,58 3,17 8,22 3,97 100,00 100,001 6,56 3,16 8,20 3,95 99,69 99,722 6,56 3,16 8,20 3,95 99,76 99,6817 6,23 3,06 7,78 3,83 94,65 96,4766 5,95 2,99 7,44 3,74 90,50 94,29Bulletin of the Томsк Pоlytеchnic University. 2007. V. 310. № 1126Fig. 3. Diagram of flatchannel experimental setup: 1) tank with initial solution; 2) valve; 3) pump; 4) rotameter; 5) manometer;6) membrane module; 7) thermostat12345672 222?? ?????? ????to drainto drainREFERENCES1. Heberer T. Occurrence, fate and removal of pharmaceutical residuesin the aquatic environment: a review of recent research data // Toxicology Letters. – 2002. – V. 131. – P. 5–17.2. Saravia F., Frimmel F.H. 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Application of sorption and membrane methods in the process of water purification from diclofenac

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