SOME PROPERTIES AND PROBLEMS OF SMECTITE MINERALS IN JAVA SOILS - Eprints UPN "Veteran" Yogyakarta

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SOME PROPERTIES AND PROBLEMS OF SMECTITE MINERALS IN

JAVA SOILS

Article · January 2005

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SOME PROPERTIES AND PROBLEMS OF SMECTITE MINERALS

IN JAVA SOILS

M Nurcholis

Dept . of Soil Science, Universit y of Pembangunan Nasional “ Vet eran” Yogyakart a. email: nurch2003@yahoo.com

INTISARI

Keberadaan mineral smektit sangat penting dalam menentukan sifat fisik dan kimia dalam tanah atau bahan dari sumberdaya alam lainnya. Mineral smektit mempunyai kemampuan mengembang sebagai hasil dari sifat mineral ini yang dapat mengabsorbsi air dan kation-kation ke dalam ruang interlayer antar lembaran struktur kristal tetrahedral-oktahedral-tetrahedral. Sifat ini j uga dapat berpengaruh terhadap kemudahan berubah menj adi mineral lain. Kaj ian ini bertuj uan untuk memberikan informasi permasalahan yang ada dalam hubungannya dengan mineral smektit dalam tanah dan bentonit. Untuk memberikan informasi tersebut, dikumpulkan contoh tanah yang mengandung mineral smektit dari profil tanah di Semin dan Ngargosari serta bentonit Nanggulan. Fraksi lempung dipisahkan dari tanah dengan analisis mekanik, sedang mineralogi lempung dianalisis dan ditetapkan menggunakan difraksi sinar-X. Perbandingan intensitas puncak smektit antar sampel dalam satu lokasi dipergunakan untuk mengetahui perubahan yang terj adi dalam mineral smektit yang disebabkan oleh pelapukan. Hasil analisis menunj ukkan bahwa mineral smektit yang berasal dari Vertisol Semin mengandung hydroxy int erlayered smect it e (HIS) dan kaolin/ smect it e mixed layer minerals. Distribusi mineral smektit dari profil tanah di Semin menunj ukkan adanya perusakan mineral smektit di perlapisan tanah bagian atas sebagai hasil proses pelapukan. Mineral smsektit yang ditemukan di lapisan bawah profil tanah di Ngargosari sebagai penyebab terj adinya landslide. Ada kecenderungan perubahan mineral smektit menj adi pirofilit di profil tanah Nanggulan yang berkembang di atas bentonit.

INTRODUCTION

We, t he communit y of t he eart h sciences, already underst and t hat smect it e minerals are part s of import ant minerals in soils. At t ent ions have been given t o t hese minerals because t he propert ies of soils are significant ly inf luenced by t he presence of t hem. Many report s show t hat t here are much variabilit y in propert ies and behavior of t he smect it e minerals. There were report s of hydroxy int erlayer in expansible silicat es (Rich, 1968); chlorit e-like int ergrade minerals (Weed and Nelson, 1962), and many ot hers regarding t he smect it e minerals in soils. Then Nurcholis and Tokashiki (1998) report ed t he kaolin/ smect it e mixed

layer minerals in Paleudult s of Java Island.

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64 Jurnal Ilmu Tanah dan Lingkungan Vol 5(2) (2005)

are heat ed in air, t he int erlayer wat er is driven of f , t hereby causing t he collapse of t he st ruct ure around t he spont aneously in nat ure during burial met amorphism, leading t o wat er expulsions and layer collapse t hereby t ransf orming t he smect it e mineral st ruct ure t o an illit e-like st ruct ure.

According t o AIPEA (Associat ion Int enat ionale Pour I’ Et ude des Argiles), smect it e has been accept ed as t he group of name f or clay minerals wit h charge bet ween 0.2 and 0.6 per f ormula unit (Bailey, 1980). This decision was made as t here was confusion bet ween mont morillonit e and saponit e. As we already known t hat mont morillonit e is dioct ahedral t ype of expandable 2:1 t ype mineral, and saponit e is t rioct ahedral t ype one. The smect it e mineral, have abilit y t o swell as a result of t he incorporat ion of wat er molecules bet ween t -o-t sheet s, in associat ion

wit h t he int erlayer capt ions, Na+_and

Ca2+_{. At slight ly higher relat ive}

humidit y t he int erlayer cat ions became hydrat ed, causing a st epwise expansion of t he int erlayer spacing. Furt her adsorpt ion and/ or t he f illing of ext ernal micro pores. However, monovalent and bivalent exchange f orms behave rat her dif f erent ly. The

Na+_{-exchanged clay represent s a series}

of hydrat ion st at es. As an increasing in humidit y, t he molecule of wat er in t he int erlayer space also increase t hat result ing in t he basal spacing expansion of clay lat t ice. Then t he immersion of sodium smect it e may result in unlimit ed swelling t o large int erlayer spacing. In cont rast , in t he case of

Ca2+_{-exchanged clay, t here are higher}

hydrat ion energy needed f or calcium ion and t he st abilit y of t he oct ahedral

Ca(H2O)62+ solvat ion complex causes

init ial expansion t o bilayer complex and lat t er a t hree layers complex. The t hat also cont ains some colloidal silica. It is t he result of devit rif icat ion and accompanying chemical alt erat ion of glassy igneous rock mat erial, usually t uf f or volcanic ash. Commercial applicat ions of t he bent onit e are already wide use in pet roleum explorat ion and ot her drilling act ivit ies. It is needed at t ent ion in bent onit e for t he ot her purpose such as in soil remediat ion, and in t he f ert ilizat ion of soils.

St udies of t he smect it e minerals in det ail may f ind variabilit y in propert ies of t hese minerals. In t his paper, t here is lit t le inf ormat ion in regarding t he smect it e minerals in soil and underlying mat erial t hat presence in Java soils. Many problems may appear as an ef f ect of t he presence of t he smect it e minerals in soils, and even t he use of mat erial cont aining smect it e minerals. But in here, only some propert ies and problems t hat can be report ed according t o some collect ed researches in clay minerals.

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The second locat ion was Ngargosari village Samigaluh sub dist rict Kulonprogo. This village has a st eep slope surf ace, and generally t he soil surf ace is covered by dense annual t rees. Landslides of t en occur at t he st art of rainy season. St udy on t he landslide was conduct ed by Suparman (2005) t o explain how t he landslide happens. In t his st udy, soil profile was made and t he soil morphology was examined. Soil samples of each horizon and underlying mat erial were collect ed. The clay mineralogy of all samples, as a part of all analysis, was det ermined using XRD.

Third locat ion was Nanggulan Kulonprogo. Exploit at ion of bent onit e was done in t his locat ion by using t he open pit mining met hod. The overlying soil dept h is relat ively shallow, but t he soil t ext ure is clay. To ext ract t he bent onit e, it was done by excavat ing t he coverage soil and removed t o t he side place. Af t er t he mining act ivit y f inish, t here are some large holes on t he soil surf ace. Invest igat ion on t he prospect of bent onit e was conduct ed by Bunt oro et al. (2003). In t his st udy t here were bent onit e and overlying soil were sampled. For mineralogical st udy, t he clay f ract ion was collect ed as same as t he above t wo locat ions ot hers.

The XRD analysis was perf ormed on t he parallel orient ed clay

of t he Mg2+_{and K}+_{sat urat ed clay}

XRD pattern of the clay in Semin soil In t his st udy it was select ed a clay sample from Vert isol at Semin t hat showed specific minerals (Fig. 1). There were t wo peaks t hat showed by clay sample result ed in broader peak f orming shoulder over 12.61 Å unt il 14.72 Å. The t ypical smect it e minerals give a sharp peak of 12.5 Å on t he K-sat urat ed clay. As t he peak is higher t han 12.5 Å, t here are some mat erials in t he int erlayer space. There are hydroxy-Al polymers t hat commonly develop in t his space, however it is st ill weak and it needs long period t o develop chlorit e (Rich, 1968). This mineral is generally t ermed as Hydroxy-Al Int erlayered Smect it e (HIS) or Smect it e-chlorit e Int ergrade minerals. These minerals were already report ed by several researches as t he alt erat ion of mineral t hat occur in

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Figure 1. X-ray dif f ract ion pat t ern of t he parallel orient ed clay specimen of t he Vert isol f rom Semin.

The sample also showed a broad peak of 7.76 Å on t he Mg-sat urat ed clay, and it is int erpret ed as a 7 Å halloysit e. Glycerol solvat ion caused lowering and broadening t he peak, and it is int erpret ed as an irregular expansion of t he sheet layer. Some port ion of glycerol may ent er t he int erlayer space bet ween clay lat t ice of halloysit e, but it was not in t he same The K-sat urat ed clay showed a peak of 7.39 Å which sharper t han t hat result ed on t he Mg-sat urat ed clay. It indicat es t hat pot assium may reduce t he basal spacing of halloysit e. Furt her heat ing t o 550oC result ed in complet ely collapse t he peak of 7.39 Å.

There were several broad peaks bet ween 7.39 Å and 14.72 Å shown on t he K-sat urat ed clay. This appearance may provide st rong support f or t he presence of kaolin/ smect it e mixed layer mineral. This t ype of t he mineral was also report ed by Nurcholis and Tokashiki (1998) on t he Paleudult at Bogor, West Java.

Distribution of the smectite minerals in the soil profile

Furt her analysis of t he result of t he XRD dat a of all layers in soil prof ile are shown as int ensit y of peak of t he smect it e minerals (Figure 2). The int ensit y of t he peak of t he smect it e minerals was measured as a high of t he 15-16Å peaks of t he Mg-sat urat ed clay specimen. This met hod was already

used by Harris et al_{. (1989) t o st udy}

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Format ions in Gunungpanggung Gunungkidul Yogyakart a Special Region. It was suggest ed t hat t here was an alt erat ion of t he st ruct ure of t he mineral lat t ice result ed in broken of t he mineral cryst al. This process might be result ed by t he int ensively weat hering in t he upper part s of t he soil prof ile.

Landslide in Ngargosari Village

Problem t hat may occur in relat ion wit h smect it e mineral is landslide. As an example, a soil in Ngargosari Kulonprogo dist rict develops overlying clay mat erial t hat rich wit h smect it e mineral.

Prast ist ho and Paripurno (2002) report ed t hat t he underlying clay mat erial was as one of several causes t he occurrence of landslide in t his area. There was an ext remely dif f erence in t he porosit y bet ween soil and underlying mat erial. Permeabilit y of t he soil was also relat ively high so t hat wat er from rainf all was inf ilt rat ed t o t he soil body. As t he slope of t he surface soil was relat ively st eep causing wat er f low in t he soil is lat erally dist ribut ed and running along t he int erf ace bet ween soil body and underlying clay mat erial. This condit ion may cause t he surf ace of t he clay mat erial t o be slippery. Then t he weight force of t he upper soil mass t hat is sat urat ed wit h wat er increases, causing t he at t ract ion f orces among soil part icle can not hold t he soil body

140 120 100 80 60 40 20

0

0 1 2 3 4 5 6

Itensity

De

p

th

(

c

m

)

Figure 2. Relat ive int ensit y of t he peak of smect it e mineral under Mg

sat urat ion clay at Semin soil

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over t he slippery surf ace and it moves downward along t he slope direct ion as landslide.

Addit ions t here are many annual t rees growing over t he surf ace soil t hat add t he weight of soil. Landslides in t his locat ion generally occur at t he early of t he rainy season. It can be t hought t hat t here is a process of swelling of mat erials, especially t he smect it e mineral, when t he st art ing point of t he rainy season. The process of t he swelling clay part icles result s in pressures among t hem in many direct ions. As a result t here is decreasing in at t ract ion among soil part icles.

Bentonite and Overlying Soil at Nanggulan

Act ually bent onit e has a higher economic value if it meet s requirement in engineering purpose, especially in drilling proj ect . For t his purpose, bent onit e t hat is usually used is Na-bent onit e. Bent onit e t hat develop in Tanj ungharj o village Nanggulan sub dist rict is dominat ed by Ca-smecit e

(Bunt oro et al_{., 2003). Act ivat ion}

using NaOH did not increasing t he qualit y of t he bent onit e. St udying t he soil in Nanggulan t hat developed over bent onit e (Fig. 4) showed t hat t he dominant mineral in clay part icle of t he soil also smect it e.

Figure 4. t he sket ch of t he soil profile and underlying bent onit e

There was an int erest ing on t he clay mineral in t he soil, t hat small peak of 9 A was also present . The peak of 9 A is probably pyrophylit e or t alc. According t o AIPEA, bot h minerals are included in t he 2:1 t ype minerals t hat have not negat ive charge. Act ually, pyrophyllit e and t alc are included in t he group of pyrophylit e-t alc, but t hey are separat ed int o sub group, but st ill in dual names (Bailey, 1980). The pyrophilit e is a rare mineral and it is f ormed in some environment s which are charact erized by high magnesium (Wilson, 1987). Format ion of pyrophilit e requires environment t hat has silica-alumina rat io of more t han 4

and high cont ent of Ca and Mg and high t emperat ure (Grim, 1968). The presence of t his mineral in t he nat ural environment , especially in t he soil wit h lower t emperat ure, needs more at t ent ion t o explain t he f ormat ion process of mineral. As for t he

abundant of SiO2 and Ca and Mg cat ions

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Furt her st udies are needed t o explain what kind process t hat result ed in t his mineral and t o det ermine t he name of t he mineral, i.e. pyrophyllit e or t alc. Transf ormat ion of smect it e t o illit e in t he laborat ory experiment was

successf ully done by Drief et al.

(2002). They immersed t he clay cont aining smect it e mineral in t he sea

wat er t hat enriched wit h KOH at 50o_C

and basic pH f or 30 days.

Closing Remarks

There is st ill lit t le inf ormat ion, regarding t he smect it e minerals in Java soils, t hat has been report ed in t his paper. The smect it e minerals may give advant ages in specific uses if we underst and t he propert ies of t hem. swelling propert ies may cause problems in our live. Ones again, more underst anding in t he propert ies of t he smect it e minerals are needed.

REFERENCES

Bailey, S.W. 1980. Summary of recommendat ion of AIPEA nomenclat ure commit t ee on clay minerals. American Mineralogist . 65:1-7.

Bunt oro, A., M Nurcholis, and D.R. Rat naningsih. 2003. Penelit ian pemanf aat an deposit bent onit e Kulonprogo sebagai bahan dasar Lumpur yang diperlukan pada proses pemboran minyak dan gas bumi. Kerj asama PSTM LPPM UPNVY-Bappeda Kab Kulonprogo. Unpublished.

Dahlgreen, R.A., J.P. Dragon, and F.C. Ugolini. 1997. Weat hering of Mt . St . Helens Tephra under a

Cryic-Udic climat ic regime. Soil Sci. Soc. Am. J. 61:1519-1525.

Drief , A., F. Mart inez-Ruiz, F. Niet c, and Velilla Sanchez. 2002. Transmission elect ron microscopy evidence f or experiment al illit izat ion of smect it e in K-enriched seawat er solut ion at

50o_{C and basic pH. Clays and Clay}

Minerals. 50: 746-756.

Grim, R.E. 1968. Clay mineralogy. 2nd

edit ion. McGraw-Hill. New York. Harris, W.G., K.A. Hollien,

V.W.Carlisle. 1989. Pedon dist ribut ion in coast al plain Paleudult . Soil Sci. Soc. Am. J. 47:158-163.

Nurcholis, M. 1998. “ Unique” mixed layer and Mn-oxide minerals and exchangeable Al of Acidic soils in Java Island. Ph.D. dissert at ion. Kagoshima Universit y. Japan. Unpublished.

Nurcholis, M. and B. Prast ist ho. 2000. Pewat akan t anah yang berkembang di ant ara perlapisan f ormasi Semilir dan Wonosari di daerah Gunung Panggung Gunungkidul. Hasil penelit ian UPNVY. LPPM. Yogyakart a 11:1-13.

Nurcholis, M and Y. Tokashiki. 1998.

Charact erizat ion of kaolin/ smect it e mixed layer

mineral in Paleudult of Java Island. Clay Science. 10: 291-302. Post , J.L., B.L. Cupp, and F.T. Madsen. 1997. Beidellit e and associat ed clays f rom De Lamar mine and Florida mount ain area, Idaho. Clays and Clay Minerals. 45: 240-250.

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Rich, C.I. 1968. Hydroxy int erlayer in expansible layer silicat e. Clays and Clay Minerals. 16:15-30. Suparman. 2005. Kaj ian f isik t anah

berpot ensi longsor di desa Ngargosari kecamat an Samigaluh Kabupat en Kulonprogo. Skripsi S-1. unpublished.

Weed, S.B. and L.A. Nelson. 1962. Occurrence of chlorit e-like int ergrade clay minerals in Coast al Plain, Piedmont , and

Mount ain Soils of Norh Caroline. Soil Sci. Soc. Proc. 26:393-398. Wibowo, D.A. 2000. Pewat akan kimia,

f isika dan mineralogy dua pedon yang berdekat an di daerah Semin Gunungkidul. Skripsi S-1. Unpublished.

Wilson M.J. 1987. A handbook of det erminat ive met hods in clay mineralogy. Chapman and Hall. New York.