Decomposition of Alkylammonium Cations Intercalated in Vermiculite

DECOMPOSITION OF ALKYLAMMONIUM CATIONS INTERCALATRn IN VERKICULITE J.L. PEREZ RODRIGUEZ, E. MORILLO • MAQlIEDA AND Instituto de Recursós Naturales y Agrobiología de Sevilla. Apartado 1 41080 Sevilla (Spain). of alkylammon:ium decorr.position on rnon::morilloníte surThe~pno;r faces has been studied by several researehers. In 1964, Calvet et sho...,ed that it ...,as possible to transform alkylamrnonium eations adsorbed on montmorillonite surface temperatures considerably bel.ow the theor<: tical deeomposition te:,:peratures al' arúnes or their chlorhydrates. Abo- ve 100ºC, in presenee of cxygen, tlle cations descompose lnto NH; (wllich remains on the clay). organic residues and hydrocabns~ The observa- C-N bond. tions were interpreted as the result ol' eatalytic break of The eatalytfc el'feet was attributed to pretens of the water adsorbed the montmorillonite surface. Durand et al. (1972) have studied in an inert atmosphere the thermal transformation mon'¡..::morilloni alkylammonium catiens adsorbed on the :3urface in various conditions of hydration. ved were mainly transalkylations, fo:, whieh a C'eohanism ef sis was proposad. of The reactio11.s obser d eataly- A high degree of dissociation of the water remaining the surfaee of the clay was requíred for these processes. There are sorne differences between the thermal transfermation of alky.1: arnmonium montmorillonite i~ inert atmosphere and the corresponding transfor:r.ation in presence of oxygen. of the ~H In the lat:te:--, a fas ter increase content was observed, and trar.salkylation processes do not operate. The m of this paper to determine the decomposition of decylammo- ni:..:.:7" cations on vermiculite surface, as a resul-L of the acidity of the medil.lrn. The vermiculi -ce used was obtained froT'o the "Sant?l Ola::!.lal! Huelva, Spain, and it was saturated in decylammonium cations, to the C'.e rllod proposed by Lagaly Wei 435 (J9G9) . t depos~ ~coding in The decylammonium-verf71iculite complex was treated with solutions l~i in water and butanol, and solutions of of N'-(4chlor2metyp~n -N,N-dímethy1 methaneimidamide hydrochloride in butanol, which prodllces an acidity similar to the He1 solutions. The treatmer.ts were carried out at 60 Q C in stoppered glass tubes. The solutions were changed week1y up to lOO days of treatment; from that time on, the solutions were left in contact with the samples without furtner change until a year pased~ The X-rey diffraction pattern and the infrared spectra of a1kylammoni um-vermi culí te complex do not show changes after treatment wi th de ioní zed water or butanol. The basal spacing of decylammonium-vermiculite complex changes from 21.21 .A to 12.8 A after several treatments wi butano1. Hel solution in water or The latter diffraction increases to about ]4 A if the solutio:cs are kept in contact with the samples without any chango. In tho i nfrared spectrul1'. of the sample showi ng a 12.8 A di ffrac ti on, bands appear at l430, 3240 and 3040 cm- l corresponding to amC\onium ca- tíons present in the interlal'1ellar spaces (Ah1r'ichs et al., 1972; Stone and Wild, 1978). The ammonium ls produced by tha break of the e-N bond of alkylammonium due to their high degree of surface acidity presont as a consequence of the pH in the 801"tion used. When the solution are kept unchanged, the experil'1ental data show thc 2 release of Mg + ions frorn the vermic..:li 1:e structure due to the acidity 2 of the medium. This Mg + displaces the alkylammonium and am"\onium from inter1amellar space. The ammonium 18 exchanged completely in the sam- pIes treated with aqc:eous solution, whereas in butano1 solutibn ;t 18 partíally displaced. The 1430 cm- NH: ls displaced to 1400 1 absorpr;ion band corresponding to -1 due to release of structural , prcdu- cing a higher lamellar charge and increasing the interaction between NH~ ion and the surface. The decomposi tion of decylammonium cations on the ver?7'.lculi te sl:rfa- ces ts also prodl:ced when the decylammonium vermiculite complex i5 tr".". ted with solution of an o~ganic compound (N'-(4-chloro-2-methylphenll -N, N-di",.e thyl methanoimidamide hydroch1oride) in butano1. the e-N In this case bond breaking i8 due to the high acidity which i8 produced dissociation of the scarce water by remaining in the interlrune~olecus llar space. 436 REfERE"ICES 1972. rlCteractiolC of AHLRICHS, J.L.; FRASER, A.R. and RUSSELL, J.D. 263-273. mnmoni¡;¡ with vermiculite. Ciay Miner. ~, CALVET, et al. Pro~ns de tution, protons adsorbéc. Rull. Grpe. fr. Argi les XIV, 59-104. DURAND, D.; PELET, R. and tion on montffiorillonite Miner. 20, 21-35. ¡bres et eau J.L. 1972. A1kylammonium decomposl_ in an inert atmosphere. Cl.ays Clay LAGALY, G. and WEISS, A. 1969. Determination of the layer charge in mlca-type layer licates. Froc. Int. Clay Conf. 1969, Tokyo, Vol Israel Universities Press, Jerusalem, 234-277. STONE, M.H. and WILD, A. te and hydrobioti te. 1978. The reaction of ammonia wi th vermiculiClay Miner. ~, 437