ЗВІТ З НДР 29-81 ЗА 2007 – 2009 Р 81 Journal homepage: www.fia.usv.ro/fiajournal Journal of Faculty of Food Engineering, Ştefan cel Mare University of Suceava, Romania Volume XVII, Issue 1 - 2018, pag. 81 - 86 BASALT TUFA AS A BACTERICIDE FILLER FOR SOME PACKAGING MATERIALS *Igor KOBASA 1 , Mariya VOROBETS 1 , Larysa АRSENIEVA2 1Yu. Fedkovych National University of Chernivtsy, Ukraine, I.Kobasa@chnu.edu.ua 2National University of Food Technologies, Kyiv, Ukraine * Corresponding author Received 27th November 2017, accepted 19th March 2018 Abstract: A dependence of the catalytic and antibacterial activity of some basalt tufa samples on their qualitative and quantitative composition, preliminary thermal and/or chemical treatment conditions were investigated. As seen from the chemical X-ray phase and atom adsorption anal- yses, the tufa is a highly siliceous (Si/Al mass ratio is about 4.7÷5.9) zeolite-like mineral with comparatively high content of iron (68÷74 g/kg), some bioelements (Мg, Ca, К, Na) and micro- elements (Ti, Mn, Zn, Сu). The positive (≡Si+)s and negative (≡SiО -)s surface active centers were determined by IR spectroscopy. These points ensure high catalytic and bactericide activ- ity of the material. The influence of preliminary thermal and chemical treatment of basalt tufa on its bactericide activity against pathogenic Staphylococcus aureus and Escherichia coli was also investigated. Possible utilization of natural basalt tufa as an antibacterial filler for the packaging materials is discussed. Keywords: basalt tufa, catalytic and antibacterial activity, packaging materials, Staphylococcus au- reus, Escherichia coli. 1. Introduction Quality of packaging materials is an im- portant factor influencing consumer ac- ceptance, competitive potential, storage time and safe transportation of various goods. As a result, the modern packaging materials industry shows strong extension, new technologies are developing and new materials are coming to the market. Con- struction of the packaging materials con- sisting of some bioactive, bactericide agents, enzymes and genuine films is one of promising directions in this branch. Such materials can effectively preserve biologically and nutritionally valuable components and keep high overall quality of the foodstuff. The potential usability of the composites based on the natural alumosilicate basalt tufa (BT) in construction of such bacteri- cide materials is comparatively high. BT can be obtained in the form of magmatic rock (volcanic glass, basalt, slag) or as a mineral (plagioclase, pyroxene) [1]. BT tufa is one of the waste materials formed massively at modern industrial basalt pro- duction. Many efforts are being made to elaborate effective solutions for its utiliza- tion. Depending on the chemical composi- tion, BT can be used as highly effective pigments [2], sorbents for drinking water and wastewaters treatment [1], as a sub- strate for the toxic waste and exhaust gas decontamination [3] and so on. Since this mineral is easily available and ecologically safe, it can potentially be proposed as a http://www.fia.usv.ro/fiajournal Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava Volume XVII, Issue 1 – 2018 Igor KOBASA, Mariya VOROBETS, Larysa АRSENIEVA, Basalt tufa as a bactericide filler for some packaging materials, Volume XVI, Issue 4 – 2017, pag. 287 – 292 82 filler for the composite antibacterial mate- rials. It is known that the adsorption, antibacteri- al and catalytic parameters of BT can vary depending on its chemical composition, structure, porosity, dispersability and pre- liminary thermal and/or chemical treatment [1, 4]. Therefore, it is possible to govern the catalytic and antibacterial activity of BT by changes in the above characteristics that can be through thermal or chemical modification of the material. This way, ei- ther highly active catalysts and bactericide compositions or low active passive materi- als can be obtained. Both solutions seem promising in the context of construction and development the mineral fillers for modern packaging. This paper deals with the investigation of dependence of catalytic and bactericide characteristics of BT on its qualitative and quantitative composition and conditions of its thermal and chemical modification. A possibility of developing bactericide pack- aging filler using various modified and treated BT samples is also discussed. 2. Experimental The tufa samples obtained from Polytske-2 (Ukraine) deposit (see chemical composi- tion data in Table 1) and products of their thermotreatment at 250–1000 0C or chemi- cal treatment with H2SO4, HCl, HNO3, H3PO4 were used in this experimental se- ries. Chemical composition of the samples was determined by classical chemical methods (for Si, Al, Fe, Mg, Ca, Р and S) and AAS (for Na, К, Zn, Ni, Cu, Co) at KAC-120 M1 spectrometer in the acetylene/air flame [5]. The powder surface was analyzed with X- ray Photoelectron Spectroscopy (XPS) also referred to as Electron Spectroscopy for Chemical Analysis (ESCA) using ESCA- LA™ XI+ X-ray Photoelectron Spectrome- ter Microprobe. XPS is an elemental anal- ysis technique, which is capable of detect- ing all elements except for H and He and has a nominal detection limit of ~0.1 atom %. Spectral interferences may prohibit the detection of some elements in relatively low concentrations. Samples were meas- ured at a 90° take-off-angle yielding a sampling depth of ~10 nm. The analysis area was ~500 µm in diameter. Analyses were performed with a monochromatic Al kα x-ray source. The powder particle size analysis was performed with a Field Emis- sion Scanning Electron Microscopy (FESEM) using Hitachi SU70 Electron microscope. FESEM images depict topo- graphic features of the sample surface. FESEM imaging was performed at 2 keV. One hundred particles of each powder were measured to provide an average par- ticle size. Both powders were coated with ~100 Å of gold to facilitate analysis [6]. Surface area of the samples has been de- termined using BET method by the low- temperature argon adsorption while all IR spectra were recorded with Avatar 320 FT- 1R spectrophotometer. Antibacterial activity of the samples was investigated using the diffusion method (also known as the disks method) [7]. The bacterial colonies were cultivated from the ATCC standard strains Escherichia coli and Staphylococcus aureus, while a paper disk impregnated with antibiotic novobi- ocin was used as a control experiment. 3. Results and Discussion Following components were identified in natural tufa samples: zeolites (35–40 %), montmorillonite (30–40 %), feldspars (10– 15 %), silica materials (4–5 %) and hema- tites (3–5 %) [1]. Averaged data of the tufa composition are shown in Table 1 as mass percents of the corresponding oxides. Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava Volume XVII, Issue 1 – 2018 Igor KOBASA, Mariya VOROBETS, Larysa АRSENIEVA, Basalt tufa as a bactericide filler for some packaging materials, Volume XVI, Issue 4 – 2017, pag. 287 – 292 83 Table 1. Chemical composition of the basalt tufa from Polytske-2 deposit SiO2 ТіО2 Al2O3 Fe2O3 МnО MgO CaO Na2O K2O P2O5 SO3 67.44 1.75 12.82 10.14 0.09 5.02 0.46 0.94 1.06 0.12 0.11 The data in Table 1 prove that BT is in fact an alumosilicate having the mass ratio Si/Al=4.7÷5.9, which also contains 68÷74 g/kg of Fe. Besides that, the mineral also consists of detectable amounts of micro- elements Mn, Zn, Cu, Ni, Co ranged from 0.71 to 0.08 g/kg [1]. It was also found that many physico- chemical parameters of the tufa, which are responsible for its adsorption, catalytic and antibacterial properties, can be sufficiently altered after its thermal treatment. In this context, an influence of the treatment tem- perature of the tufa grains porosity and specific surface area was carried out for the four hours long modification at 105, 250, 400, 500, 750 and 1000 °С in air. Figure 1. Influence of the modification temperature on the BT’s specific surface area and porosity As seen from Fig. 1, the area of specific surface and porosity of the grains sized from 1 to 2 mm depend on the thermo- treatment conditions. Both dependencies look similarly – reach their maximum val- ues for 200–400 0C and then decrease for the higher modification temperatures. Such a pattern may be caused by losses of the hygroscopic and zeolite’s water that occurs at this temperature [8]. Adsorption capaci- ty of the tufa also increases for the temper- atures 105–400 0С followed by the de- crease for the higher temperature values. Pores, surface holes and channels can be seen in the electron microscope images taken with zoom x10000 (see Fig. 2). Po- rosity of the grains is rising for tempera- tures 250–400 0C and then drops at further increase of temperature. This effect is caused by sintering of the powdery parti- cles ended by melting of the mineral at 1050 0C. Mechanic strength of a material is one of important parameters outlining its possible utilization as a catalyst or bactericide agent. This parameter is linearly growing with the thermal modification temperature. А В С D Fig. 2. Electronic microscope images of the BT disperse particles during the thermomodification process: А – natural source material; B–D – after thermomodification at 250 0С, 400 0С and 1000 0С respectively. No evidence of the new phases formation was found in the X-ray structure analysis data embracing the range 105–1000 0C. Therefore, a rise in the mechanical strength can be caused by a deeper structuring of the granules because of the constitution water losses. An acidic modification of the tufa samples was performed using the 3 mole/l solutions Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava Volume XVII, Issue 1 – 2018 Igor KOBASA, Mariya VOROBETS, Larysa АRSENIEVA, Basalt tufa as a bactericide filler for some packaging materials, Volume XVI, Issue 4 – 2017, pag. 287 – 292 84 of H2SO4, HCl, HNO3 and H3PO4 during 3 hours at the room temperature for the ratio solid phase/solution 1:1.5. Following con- clusions can be drawn from analysis of the acidic modification results shown in Table 2.  The acids can be placed in the sequence НСl > H2SO4 > Н3РО4 > HNO3 accord- ing to their activity in elution of calci- um;  Similar sequence based on the magnesi- um elution efficiency would be H2SO4 > НС1 > Н3РО4 > HNO3;  Total amount of eluted aluminum and iron in the form of their oxides M2O3 de- creases in the row H2SO4 > НС1 > Н3РО4 > HNO3 [9]. As seen from Table 2, H2SO4 and HCl are the most effective acidic modifiers of the BT materials. Table 2. Concentrations of Са 2+ , Mg 2+ and (Al 3+ + Fe 3+ ) found in the acidic extracts (C) and their elu- tion degrees (α) Modifying acid Са 2+ Mg 2+ Al 3+ + Fe 3+ as Me2О3 С (g/l) α, % С (g/l) α, % С (g/l) α, % H2SO4 0.3360 68.08 0.1345 0.97 4.9280 14.30 HCl 0.5605 93.57 0.0895 1.97 4.3900 12.74 Н3РО4 0.4485 90.88 0.0560 1.23 4.5280 13.14 HNO3 0.0745 15.09 0.0220 0.49 2.4680 7.16 The acidic-soluble phases are being eluted from the surface of BT in course of its acidic modification, which results changes in the chemical composition, increase of the tufa’s defect ratio, specific surface area and concentration of the active centers. IR- spectroscopy data prove that the Bronsted- type (≡Si–OH) and Lewis-type (≡Si....O(H+)Н)- surface singular points act like catalytic and antibacterial centers of BT [1]. These conclusions were alternatively veri- fied by chemical analysis, which evidenced rise in SiO2 content after acidic modifica- tion of the tufa samples. A comparative study of catalytic activity (CA) of the source and modified tufa was realized using a model reaction of hydro- gen peroxide decomposition. An experi- mental mixture contained Н2О2 – NaOH – Н2О (рН=10) and BT powder (weight ratio was 1:20) at 20 0С. Permanganate titration was used to determine concentration of peroxide. As a result, CA of the thermally modified BT was found 1.6–3 times higher than that for the natural untreated material. Catalytic activity of tufa depends on the thermotreatment temperature and increases for the sequence: untreated tufa < modifi- cation at 250 0C < 400 0С < 1000 0С. This result proves that chemical composition of the tufa surface that changes in course of the modification is the crucial factor gov- erning its catalytic activity. As mentioned above, adsorption and cata- lytic activity of natural alumosilicates can sufficiently influence their adsorption and catalytic properties. This kind of treatment causes changes in qualitative and quantita- tive composition of the material and gener- ates new surface active centres [10]. De- tailed results of the catalytic activity values are shown in Fig. 3 for various modifica- tion conditions and concentrations of H2O2. It has been found that CA of the chemical- ly modified samples increases for 1.2–4.5 times if the pH of the medium is alkaline comparing to the activity values of untreat- ed tufa. Besides, the type of the modifying agent also influences the tufa activity and the following sequence can be built ac- cording to increase of the agents’ efficien- Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava Volume XVII, Issue 1 – 2018 Igor KOBASA, Mariya VOROBETS, Larysa АRSENIEVA, Basalt tufa as a bactericide filler for some packaging materials, Volume XVI, Issue 4 – 2017, pag. 287 – 292 85 cy: untreated tufe < modified by NaOH < HNO3 < H3PO4 < H2SO4 < HCl. Next stage of the investigation was aimed onto determination of antibacterial activity of various tufa samples. It was found that antibacterial activity of both thermally and chemically modified examples against Escherichia coli is higher than that against Staphylococcus aureus (see Table 3). Further elaboration of practical aspects re- lated to possible utilization of these mate- rials as antibacterial components leads to the concept of the tufa-containing packag- ing materials that should be developed, constructed and then compared with other packaging materials exhibiting or not ex- hibiting some antibacterial properties. Figure 3. Catalytic activity of the chemically modified tufa samples in the system Н2О2 – NaOH – Н2О С0(Н2О2) = 0.05 (a); 0.1 (b); 0.2 (c); 0.4 (d); 0.8 (e); 1.6 (f) М/l: 1 – untreated BT; 2–6 – after modification with HNO3, HCl, H2SO4, H3PO4, NaOH correspondingly. Table 3. Antibacterial activity of thermally and chemically modified tufa samples against Escherichia coli and Staphylococcus aureus In this context, the tufa-containing samples of packaging paper with 10 wt % of the basalt tufa modified at 250 0C were made and then used for the ISO 27447:2009(E) antibacterial activity tests [6]. Rather high antibacterial activity of both samples has been detected since even 4 hours long test ensured elimination of 95.7 and 92.3 % of Escherichia coli and Staphylococcus aure- us respectively while complete disinfection was registered after 8 hours long treatment No antibacterial activity has been detected in the similar experiments carried out with no tufa containing paper packaging. This gives us ground to envisage good prospects for construction and further development Sample Number of Escherichia coli (Staphylococcus aureus) after treatment with tufa and % of remaining mi- crobes Initial after 4 h % after 8 h % BT after thermotreatment at 250 ºС 7.8·104 (6.7·104) 2.8·103 (1.6·103) 96 (98) 0 0 100 (100) BT after chemical treatment with solution of HCl 7.3·105 (9.7·105) 2.2·104 (1.4·104) 97 (99) 0 0 100 (100) Food and Environment Safety - Journal of Faculty of Food Engineering, Ştefan cel Mare University - Suceava Volume XVII, Issue 1 – 2018 Igor KOBASA, Mariya VOROBETS, Larysa АRSENIEVA, Basalt tufa as a bactericide filler for some packaging materials, Volume XVI, Issue 4 – 2017, pag. 287 – 292 86 of the non-toxic tufa-containing food packaging materials. 4. Conclusion High antibacterial activity against the standard strains of Escherichia coli and Staphylococcus aureus has been estab- lished for the composite materials contain- ing some thermal or chemically modified basalt tufa. This activity remains at suffi- cient level for the paper packaging materi- als containing such composites. Therefore, they can be considered as antibacterial fill- ers for the foodstuff packaging manufac- turing. 5. References [1]. KOBASA, I.M., TSYMBALYUK, V.V., Basalt tufa: composition, properties and ways of utilization. Chernivtsi, Publishing House of Chernivtsi National University, 200 p. (2015) (In Ukrainian). [2]. MIKULA, J., HEBDOWSKA-KRUPA, M., KOBASA, I., GLANOWSKI, P., Tuf jako wypelniacz mineralny, zwalaszcza antykorozyjny, sposob jego otrzymywania i sposob wytwarzania z nim powlok lakierniczych. Poland patent applica- tion Pl 218359 B1. 28.11.2014 WUP 11/14. [3]. 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