VI SHMMT I XVIII ENTMME- 200 I -/Brasil

PROPERTIES OF SPONGILLITE AND PROSPECTIVES OF ITS USAGE

1 2 1 Angela A S. T. Delben , Petr Melnikm/, Onofre Salgado Siqueira , José Renato .Turkevicz Delben , Francisco José . 2 dos Santos 1Department of Physics, Federal University of do Sul (UFMS), Cidade Universitária s/n CEP 79070- 900, (MS), 2Departamnt of Chemistry, 1Federal University ofMato Grosso do Sul (UFMS), Cidade Universitária s/n CEP 79070-900, Campo Grande (MS), Brazil e-mail: [email protected]

ABSTRACT estimated to amount to 240 ± 40 Tmol of silicon per year [Tacke R., 1999]. The places of spongillite deposits are popularly called in Brazil "mica powder ponds" due to The present work is dedicated to lhe study of itch and irritation that may demand urgent medical principal katures of spongillite from the State of Mato attention. They are caused by microscopic spongillite Grosso do Sul (Brazil). Jt is present in the form of needles with sharp points. ln principie, in a long run it amorphous sílica, along with orthosilicic acids of might also lead to the development of chronic Jung varying composition. Main concomitant elements are condition [Rosenberg, D. M., 2000]. titanium and . Scanning electronic microscopy The practice of employing this mineral is limited. ln showed tJ1e prcsenee of hollow needles or Mato Grosso do Sul and States spongillite microcapillaries and traces of organic detrite Since tJ1c is used only as a component in bricks fabrication, in chemical composition of spongillite is that of poorly State it was used for thermal insulators and crystalliscd silica, it is recommended to be used as pigments [Petri and Fúlfaro, 1983]. So far there is no inorganic adsorhent and as a hioavailahle silicon source. other knowledge of putting it to use. However, taking Due to its composition and morphological into account that it is made of nanostructural amorphous characteristics it can he blent into one mass with glass silica (Si0 nH 0) one may envisage its use for ion waste in the fahrication of lightweight product having a 2 2 adsorption, as recently proposed [Silva Maia, F., et al., closed-cell structurc, ideal as insulating material for oil 2000]. Available general bibliography on spongillite and gas pipes. Useful materiais can he fabricated at concerns exclusi vely the sponges species producing this minimal expenses by rccycling glass waste piled up in material [Volkmer-Riheiro C. 1995, Motta J.F.M. et al., Mato Grosso do Sul and ncighbouring Brazilian States 1986] and rnineralogical characterisation of spongillite from Minas Gerais State [Araújo da Matta Machado, E. , 2000]. The present study deals with the physico­ INTRODUCTION chemical properties and morphology of spongillite from Mato Grosso do Sul State in order to ascertain the possibilities of its prospective value. Spongillitc oras it is also callcd spiculite is a produet essentially constituted hy siliceous needles that are originated from skeleton of sponges and related EXPERIMENTAL organisms and accompanied hy quartz sand and organic material. ln Brazi l it hasically occurs in peat-bog ponds in the southwcstcrn part of Minas Gerais State, southern Materiais and methods Goiás, northcastern Mato Grosso do Sul and São Paulo States [Volkmer-Rihciro C. ct al., 1995, Motta , 1986, The spongillite samples provided by the Companhia Volkmer- Ribeiro, C. et al., 1998]. Siliceous sponges de Desenvolvimento do Estado de Mato Grosso were deposit silica in necdlclikc spicules that support the taken from the pond Lagoa de Araré, Paranaiha region, organisms and provide defense against predation. They MS, where spongillite layer is about 2 m thick werc huilt up hy taking up onhosilicic acid from sea [Souza,D.D. et al., 1988]. Raw mineral was washed and water and processing it through complicated mechanically separation using different sieves hiochcmical pathways [Krocger N. ct al., I 999]. Thc performed. Density was determined at 25°C in a gross production o r biogenic silica in surface waters was pycnometer after previous evacuation of the air and

277 A. A. S.T. Delben, P. Melnikov, O. S. Siqueira, J. R. J. Delben, F. J. Santos

washing with helium, by using an AccuPyc 1330 V2.02 quartz phase. Thc presencc of the initial phases in the Micromeritics apparatus. Refraction index was samples of heated spongillitc indicates thc probahility of measured by immersion technique at 25°C in a reversiblc equilibrium owing to active rchydration chloroform and dimethylsulfoxide. Specitic area was during cooling and storage. determined by nitrogen absopbtion isotherms using CG2000 equipmcnt of CG Instrumentos Científicos (Brazil). X- ray diffraction patterns were registered with XEDA identification a Sicmens Kristallot1cx difractometer, CuKa radiation, The results of X ray energy dispcrsive analysis Ni filter. Phasc analysis was carried out by using a set of reported in Figure I madc possihle qualitative programs DIFRAC coupled to the difractometer. characterization of spongillite componcnts. As expected, Scanning electronic microscopy (SEM) was carried out the only intcnse peak in both graphics corresponds to the using a SM 300-TOPCON instrument. The samples Ka line of silicon. Smaller spcctrum gives evidence of were suspended in ctllanol and drops of these minor spongillite components, titanium and iron. The suspensions were deposited onto a freshly cleaved mica presence of titanium in ali prohahility is due to its layer, stuck on the stubs. The latter were dried in incorporation into sílica matrix forming solid solutions vacuum dissicator at room temperature and finally by substitution in Si0 . lron may he a concomitant sputtered in the SCD 005-BAL-TEC (445 mA, 120 sec) 2 element from the mineralogical entourage. Ni signal also with gold. X-ray Energy Dispersive Analysis (XEDA) available in the spectrum comes from detector material. was carricd out using a Princeton Gamma Tech PGT Aluminum may be present in the form of instrument providcd with a SiLi detector. The samplcs aluminosilicates like kaolinite but not detected in our were prcpared by placing some mass of spongillite onto adhesive tape of conductive carbon, stuck on thc samples because or its low content ($ 5%) and sporadic graphite carbon base. No conductive golden tilm was occurrence. 1t is mentioned however in a recent rescarch deposited. dedicated to spongillite coming from Minas Gerais State [Araújo da Matta Machado, E. 2000]

RESULTS 15000 ~ ·-1

Spongillite physical constants 10000 The following physical constants were obtained for c({) ::> raw spongillitc: o ü 1. Density (average of 5 determinations): 5000 ~ 3 2.258 ± 0,005 g/cm 0 ,0 6,0 8,0 2. Refraction index:

1.444 (in chloroform) and 1.470 (in dimethysulfoxide) 0,0 5.0 10,0 15.0 Energy I keV 3. Specific arca: lower than 1,0 m2/g Figure 1. Raw spongillite XED spectrum.

Identification hy X- ray diffractometry Spongillite micromorphology X-ray patterns of raw and heated spongillite samples are labile contirming amorphous character of the The main morphological feature of spongillite is the product and the presence of quartz (JCPDF tile 33- presence of spicules or needlelike remnants of the dead 1161) as a main crystalline phase. Secondary (in organisms having silica skelelon. ln vision tield (Figure intensities) crystalline phases detected after taking 2) spongillite. extreme care in the consideration of details were polyorthosilicic acids: tetragonal H8Si80 20 or H8(Si20s)4 and also tetragonal hydrate H 4 Si~0 1 wH 2 0 containing tetrahedra Si04 sharing faces (JCPDF files 35-0062 and 35-0060). The only difference between the heated and unheated samples were more pronounced ret1ections of

278 VI SHMMT I XVIII ENTMME- 2001 -Rio de Janeiro/Brasil

Figure 4. Electronic micrograph of ground spongillite. Figure 2. Electronic micrograph of the needles in raw They are distrihuted in an irregular way showing an average size ot· 300J.tm and sometimes broken ends. lntact fossil organisms like sponges which deposited needlelike spicules are also preserved (Figure 3).

Figure 5. Electronic micrograph of a typical rod surface. The size of tlle central cavity having form of a regular tunnel is around 111 O to 1/2 of the cylinder' s diameter or even more A section of a typical rod is reported in Figure 6. Figure 3. Electronic micrograph of a fossil sponge. After heing reduced to powder by grinding and DISCUSSION sieving the needles have an appearance of short hollow rods resemhling cera mie insulators (Figure 4 ). ln raw spongillite the inner tunnels are obstructed by small As ensues from the above characterisation, main pieces of externa! origin, such as quartz particles and features of spongillite are: l. it is composed of active organic detrite. They contain also gas but its hydrated sílica; 2 it is present in tlle form of hollow rods; composition was not determined. It may be air, carbon 3. The rods, along with the air, probably, contain gas in dioxide or methane. Anyway, after calcination there their inner recesses . These can indicate at least three would be only air prescnt. Mineral and organic particles possible fields of application. The first is the use of are easily eliminated by washing and calcination at spongillite for the adsorption of inorganic and/or organic moderate temperatures. Rods surface (Figure 5) is compounds owing to the presence of orthosilicic acids uniform hut slightly rough, t11at is implies points, with free protons and water covering the surface. hristles, ridgcs or mechanical defects. Actually, raw formulae H8Si80 20 and H4Si 80 18·H20 of the hydrates mentioned above do not mean that spongillite over tlle whole volume is characterised by this composition, since it is only an average value given by chemical analysis of a block witll no NMR

279 A. A. S.T. Delben, P. Melnikov, O. S. Siqueira, J. R. J. Delben, F. J. Santos

measurements performed. So in fact the superficial arca graphite providing carbon dioxide as a result of is much richer in hydrated sílica containing a stratum carbonate decomposition or incineration of organic capable of tixing charged particles dueto the orientation matter. Not long ago, diatomitc minerais closely related of its dipoles within double electric layer [Schukin, E.D. to spongillite were mentioned as a source of self glass et ai., 1988]. That is why spongillite may be envisaged supply making these additives unnecessary [Saakian, as a material with activated surface and therefore be E.R., 1991]. Recent research showed tllat cellular glass recommended as a potent absorbent. preparation allows the recycling of glass waste in industrial scale [Auadi, A. et ai., 1997; Eslinger, J.M. , 1980]. At present, the installations providing Bolivian oil to Brazil will have to deal with tl1e problems of pipes overheating and large amount of Jow cost insulators may be needed for thcir protection. Since the properties of raw glass (colour, transparency, composition, etc) do not interfere with cell formation and tl1ermal conductivity, good insulators can be fabricated at minimal expenses by recycling glass waste piled up in Mato Grosso do Sul and neighbouring Brazilian States. So spongillite, locally occurring natural cell-forming material may bc recommended for tlle production of tl1esc insulators. ln this way two problems - Figure 6. Electronic micrograph of rod's transversal deactivating of an irritant and preparation of a valuable section. product- will be resolved. The second recommendation concerns silicon as bioactivc trace element. It is concentrated in connectivc ACKNOWLEDGMENTS tissue and is thought to play a rôle in cross-linking tissue structures, the by helping to create tough but t1exible strength. A Jack of silicon is known to reduce normal The autllors are indebted to PROPP!UFMS and growth and repair of tl1e skin, hair and nails FUNDECT (Mato Grosso do Sul State, Brazil) for [Jugdaohsingh, R. et al., 2000]. However, direct silicon financial support. They thank also Dr. Mario Cilense for supplementation has delivered few benefits. The reason tl1e possibility of performing electron microscopy for this in most cases is that a nonbioavailable silicon studies and Dr. Amílcar Guimarães Morato for fruitful source has been used [Reffitt, D. M. and Jugdaohsingh, discussions. R., 1999]. Therefore, stabilised orthosilicic acid is the only form of supplemental silicon that has been shown bioavailablc to humans [Calomme, M. R., 1998]. That is REFERENCES exactly the composition found present on the surface of spongillite. So it may be used as a precursor for medical preparations fulfilling physiological requirements and as Araújo Da Matta Machado. E., Characterização well for beauty products. mineralógica de espongiolito da região de João The third and more promissory possibility of using Pinheiro, MO, Master Thesis, , spongillite even in its partially purified form is to take UFMG, 2000 advantage of both the composition (sílica, no matter Auadi, A., Palou, T.M., Kovar, V. Preparation of foam 1 hydrated or not) and gas closed up within the remnants glass from glass waste, ln: Proceedings of l4 h of biological structures. It is evident tllat the evolution Conference on Thermal Analysis, Belousske of this gas into a liquid medium will produce bubbles Slatini, October 1-3, Bratislava, 1997, p. 112 making the product to look "foamy", as it is customary in thc fabrication of cellular glass. This material is Calomme, M. R., Absorbtion of silicon in healthy widely used for industrial insulators protecting oil and subjects. ln: Collery et ai. editors, Metal ion in gas pipes, retinery columns and even as a high strength biology and medicine, vol.5, Paris, John Libbey, sound absorber [Godeke, H. and Fichs H.V., 1998]. The 1998, p.228 process of fabrication of cellular glass implies, as a rule, the usage of gas-forming additives, such as CaC03 or

280 VI SHMMT I XVIII ENTMME- 2001 -Rio de Janeiro/Brasil

Eslinger, J.M., Verre cellulaire a base de verre de adjacências com indicação de preservação de recuperatinn: fahricatinn et proprietés chimiques, habitat, Biociências, 3, no 2 ( 1995) Theses, Université Luis Pasteur, Strasbourg, Volkmer-Ribeiro, C, Mona J .F., Callegaro, L.M. ln: 1980 Sponge Sciences Multidisciplinary Godeke H, Fkhs, H. V., Sintered open-pore glass as a Perspectives, Y.Watanabe, N. Fusetani (Eds.), high strength sound absorber, Glastechnische Springer Verlag, Tokyo, 1998, p 272 Berkhtc - Glass S<:ience and Technology, 71 , 282 (1998) Jugdaohsingh, R. , Oligomcric but not monomeric sílica prcvents aluminium absorption in humans, Am. J. Clin. Nutr., 71 , 944 (2000) Kroegcr, N. Deutzman, R., Samper, M., Polycationic peptides from diatom biosilica thar direct sílica nanosphere lromation, S<:ience, 286, 1129 (1999) Motta, J. F. M., Cabral, M., Jr. , Alves Campanha, V., Anais do XXXIV Congresso Brasileiro de geologia, Goiánia, Goiás, 5, 2329 (1986) Rosenberg, D.M., Silka exposure and silicosis, Amer. Ccram.Soc. Buli., 79, 60 (2000) Petri, S and Fúlfaro, V .J. , Geologia do Brasil, Editora da Universidade de São Paulo, SP, 631 p. Riffitt, D. M., Jugdaohsingh, R., Silicic acid: its gastrointestinal uptake and urinary excretion in man, J. Inorg. Biochem., 76, 141 (1999) Saakian, E.R., Cellular glasses from diatomites, Steklo i Ceramka, 3, 3 ( 1991) Schukin, E.D., Pertsov, A.V., Amelina, E.A., Química coloidal, Mir, Moscou, 1988, 383 p. Silva Maia, F., Alves Teixeira, M., Rodrigues Coimbra, P., dos Santos, F. J., Melnikov, P., Salgado Si queira, 0., S ynthesis and characterisation of materiais obtained from spongolite, X Brazilian Meeting on Inorganic Chemistry, 28 September 2000, Florianopolis, S.C., Brazil Souza, D.D.D., Jordão, M.A. P., Dias, E.G.C., Neves, M.R., Estudos preliminares de beneticiemento de cspongilito da Lagoa de Araré, MS. Encontro Nacional do Talco, 4 e Simposio de Carga$ Minerais, 2, 1988, Ponta Grossa, Anais. Sindicato da Indústria de Extração de Minerais não Metálicos de Ponta Grossa, 1988, .257 Tackc, R., Milestones in lhe biochemistry of silicon: from basic research to biotechnological applications, Angcw. Chem. Int. Ed.38, no. 20, 3015 (1999) Volkmer-Ribciro, C, Esponjas formadoras de espongiolitos em lagoas de triângulo mineiro e

281