INTERACTIONS OF PHOSPHATES AND SELECTED ORGANIC MOLECULES WITH PALYGORSKITE AND SEPIOLITE A Thesis Submitted to the College of Graduate Studies and Research in Partial FuEiillment of the Requirements for the Degree of Doctor of Philosophy in the Department of Soil Science University of Saskatchewan Hossein Shariatmadari Saskatoon, Saskatchewan, Canada Fall, 1998 O Copyright Hossein Shariatmadari, 1998. AU nghts resecved. -anbmo~pap J~Z~ILIOJms no mded ms uo~mpo~da~ ap %qg/apsgom- ap amro~el -s)mo~quo~pap ro ~aded snos asqa~a3 ap sa~do:,sap arpuarl JOJO^^ m. srsa¶- s~qljosaido:, no ianqgsrp '~aasrd'annpo~da nas JO alnqysrp %mol 'ampo~dai ap epem=) np apopen anb?qqcpa 01 30 hqgPOpW el ? ~mamrada~?snpxa ay8yop asaaq a~~snpxa non amaq ami ap_rom~E ma me,^ -non e pa~hseq ope au UNIVERSITY OF SASKATCHEWAN Coilege of Graduate Studies and Research SUMMARY OF DISSERTATION Submitted in partial fulfillment of the requkments for the DEGREE OF DOCTOR OF PHILOSOPHY by Hossein S hariatudari Department of Soil Science University of Saskatchewan . Examinuig Committee: Dr. R.J. Baker XXUdMm,Dean's Designate, Chair CoUege of Graduate Studies and Research Dr. E. de Jong Chair of Advisory Cornmittee, Deparcment of Soil Scienœ Dr, A.R. Mennut Supervisor, Department of Soil Science Dr. P.M. Huang Depamnent of Soil Science Dr. J.J. Schoenau Department of Soil Scienœ Dr. R.W. Renaut Deparmient of Geology External Examiner: Dr, L.R. Hossner Professor Depamnent of Soil and Crop Sciences Texas A and M University College Station, TX 77843 U.S.A. INTERACTIONS OF PHOSPHATES AND SELECTED ORGANIC MOLECULES WïïH PALYGORSKITE AND SEPIOLITE Palygorskite and sepiolite are silicate clay minerals that comm~nlyoccur in soils of arid and semiarid regions. Despite the significance of these minerals in soi1 agrochemisay and in a variety of industrial applications, the sorptive behavior of palygorskite and sepiolite is not fully elaborated. The objectives of this work were to: i) study the interactions of onhophosphate (Pi) and inositol hexaphosphate (IHP) with palygorskite and sepiolite in pure systems and in the presence of calcite and ii) quan* the conmburion of different sites in sorption of monovalent organic cations, crystal violet (CV)and methylene blue (MB), on palygorskite and sepiolite. The Pi sorption capacity of sepiolite and palygorskite amounted at about 0.7 and 1.5 cm01 kg13 respectively, which is higher than other crystalline silicate clays. Sepiolite has the potentid to be a canier for orthophosphate compounds. The IHP sorption capacity was 24 and 15 mol kg1 for sepiolite and palygorskite, respectively. The large surface area and Al-Mg contents, may explain the P sorptive behavior of these rninerals. The availability of sorbed P by palygorskite and sepiolite in the presence of calcite was compared with that of a montmorillonite, using a sequential exmction technique. About 90% of total Pi sorbed on a sepiolite-calcite mixture was recovered over seven extractions, while the recovery of sorbed Pi was about 20%, 129, and 2% for palygorskite-calcite, montmorillonitecalcite, and pure calcite, respectively. Application or presence of sepiolite in calcareous soils may favor the phosphate availability in these soils. The maximum sorption of MB and CV greatly exceeded the cation exchange capacity of these minerals. In sorption maxima, the neutral sites showed the highest conmbution to the sorption of organic cations as compared to the free and complexed negative sites. This part of the snidy may help the modification of clay surfaces for Merent industrial applications. PERMISSION TO USE The author has agreed that the Library, University of Saskatchewan, may make this thesis klyavailable for inspection. Moreover, the author has apedthat permission for extensive copying of this thesis for scholarly purposes may be granteci by the professor or professors who supervisai the work recorde. herein, or in their absence, by the Head of the Department or the Dean of the College in which the thesis work was done. It is understood that due recognition will be given to the author of this thesis. Copying or publication or any other use of the thesis for fmancial gain without approval by the University of Saskatchewan and the author's wrinen permission is prohibited Requests for permission to copy or make any other use of the material in this thesis in whole or in part shodd be addressed to : Head of Department Depamnent of Soi1 Science University of Saskatchewan 5 1 Campus Drive Saskatoon, Saskatchewan S7N SA8 Canada. ABSTRACT Pdygorskite and sepiolite are silicate clay minerats that commonly occur with calcite in sdsof arid rcgions. These clays have tendencies to adsort,/reIease phosphate (P) in the soil system. The sorptive characteristics of pdygorskite and sepiolite are also used in a number of indusaial applications. This study will primarily help sustainable crop production in and and semiarid regions. It may also lead to a more efficient industrial application of these cIay rninerals. The objectives of this thesis were to: i) establish the sorption isothams and kinetics of onhophosphate (Pi) and inositol hexaphosphate (HP) on palygonkite and sepiolite ,ii) determine the chernical extractability of sorbed phosphate on palygorskite and sepiolite in the presence of calcite, and iîi) quantify the contribution of different sites in sorption of monovalent organic cations, crystal violet (CV)and methylene blue (MB), on palygorskite and sepiolite. The P sorption experiment was canied out by application of P in the range of 0.0 to 2.0 mM for Pi and from 0.0 to 10.0 mM for iHP compounds. The Pi sorption capacity of sepiolite and palygorskite amounted at about 0.7 and 1.5 cm01 kg respectively ,which is higher than other crystalhe silicate clays. The JHP sorption capacity was 24 and 15 cmol kg-' for sepiolite and palygorskite, respectiveiy. The large surface area and AI-Mg contents, may explain the P sorptive behavior of these mineds. The sorption kinetics of Pi and IHP on palygonkite and sepiolite were modeled using a modified Freundlich equation. The data indicated the occurrence of a fast and a slow sorption process. The availability of sorbeci P by palygorskite, sepiolite and a monnnorillonite, in the presence of calcite was investigated, using a sequentiai extraction technique. About 9û% of total Pi sorbed on a sepiolite-calcite mixture was recovered over seven extractions, while the recovery of sorbed Pi was about 2546, 204, and 5% for a palygorskite-calcite, montmorillonite-calcite and pure calcite, respective1y. Sorption of organic cations, MB and CV, on palygdte and sepiolite were ah exainined. The niaximurn sorption of MB and CV greatly exceeded the cation exchange capacity of these minerais. This shows that, besides the free negative sorption sites, the sites satisfied with sorption of single cations and neuaal sorption sites on the clay surfaces contribute to the sorption of organic cations. This part of the study may help the modification of clay surfaces in diffmnt indusnial applications. ACKNOWLEDGMENTS 1would Wre to express rny sincere appreciation to Dr. A.R Mamut. my supexvisor. for his kind assistance, constant encouragement, support and valuable suggestions throughout the course of this smdy. 1 wish to extend my gratitude to other members of the advisory cornmittee: Drs. E. de Jong, P.M. Huang, R.W. Renaut @ept of Geological Sciences), and JJ. Schoenau for their valuable suggestions and criticisms. I am very grateful to Dr. D.W. Anderson for his patience, suppofi and encouragement throughout my saidies in the Deparmient of Soil Science. Many thanks am due to the following individuals: Drs. M. Abekoe, M. Batista, J.J. Dynes, RJ. Heck, H. Khademi-Moghari, G.S.R. KrishnaMurti, A. Naidja, E. Padmanabhan and C. Shang, for their valuable discussions and scientific comments. The following technical staff are thanked for their assistance and bdness; Mr. G.L. Hudy, Mr. B.G. Goetz, Mrs. J.O. Moir, Mr. G.R. Parry, Mrs. E.J Farkas, Mrs. T. Curry, Mrs. K.M. Humer, Mr. Y. Yano (Elecwn Microscope Lab. Dept. of Biology). 1would also Iike to acknowledge the Financial support received during the PhD. program: The Iranian Ministry of Culture and Higher Education, The Naturai Sciences and Engineering Research Council of Canada, and The Department of Soil Science, Univ. of Saskatchewan. Finally, spacial thanks are due to my parents and family for the special support and understanding they provided me throughout this program and heart-felt thanla to my wife. Nastaran, and my sons, Ali and Audell-Rezah, for their patience, suppon, sacrifices, and love. CHAPTER 3 CHARACTERIZATION AND PURIFICATION OF PALYGORSKITE AND SEPIOLITE ................................................ -32 3.1. Introduction ............................................................................ 32 3.2. Materials and methais .......................................................... 32 331 . Phy sicd and chernicd characteristics ............................. ......... -33 3.2.2. Mindogical characteristics ................................................ -33 3.2.3. Purification .................................................................. -34 3.2.3.1. Palygorskite .........................................................-35 3.2.3.2. Sepiolite ................................ .. .............................. -36 3.2.3.3. Homoionizarion and clay separation ............................... 36 3.3. Results and discussion .......................................................... 37 3.3.1. Palygorskite