The viscosity of organic liquid suspensions of trimethyldococylammonium-montmorillonite complexes

An organophilic bentonite was prepared by means of a reaction of natural Na-montmorillonite with trimethyldococylammonium which has an especially long n-alkyl chain. The addition of trimethyldococylammonium to montmorillonite was in the range 0.25-3.0 times the cation exchange capacity (CEC) of the clay (i.e. 0.23-2.82 mmol/g clay). The particle morphology in organic liquid suspensions of organoclay complexes was studied by measuring the viscosity based on Eyring's rate process and Robinson's relative sediment volume. In toluene, montmorillonite with 1.17 mmol/g clay trimethyldococylammonium (1.25 times the CEC) had the largest specific gel volume, relative sediment volume, and K-factor. The results of the stoichiometry for trimethyldococylammonium-montmorillonite show that practically all of the quaternary ammonium was adsorbed to montmorillonite. Maximum half widths of 001 reflections from X-ray diffraction patterns were obtained in the range 0.74-1.17 mmol/g clay, indicating a disordered arrangement of the organic cation molecules intercalated between the layers. Appreciable shifts to lower-frequency regions in the Fourier transform infrared absorption spectra as a result of CH-stretching vibrations were observed with increasing amounts of the organic cation. When increasing the amount of organic cation added to the clay from 0.94 to 1.41 mmol/g clay, a large shift occurred to the lower-frequency side, approaching the frequency of the organic cation alone. This indicates that the interaction between adjacent hydrocarbon chains becomes progressively stronger, due to van der Waals attraction, with increases in the amount of organic cation. Interactions of the alkyl chains in trimethyldococylammonium-montmorillonite complexes with irregularly distributed and randomly arranged alkyl chains between the silicate layers were weak, and, as a result, solvation with external organic liquids occurred and gel formation developed through macroscopic swelling of the organoclay

Evaluation of Chemical-Resistant Bentonite for Landfill Barrier Application

耐化学性ベントナイトである多膨潤性ベントナイト(mutiswellablebentonite:MSB)の, 廃棄物処分場バリア材への適用性を実験的に検討した。MSBは塩化カルシウムや塩酸の溶液に対しても高い膨潤性を示し, 透水係数も天然ベントナイトより1オーダー以上低い値が得られたことから, 廃棄物処分場のライナーやカバーなどのバリア材に有効に適用しうることが示唆された。Chemical compatibility of a newly developted material -multiswellable bentonite- is evaluated for the purpose of landfill barrier application. A series of liquid limit, free swell, and hydraulic conductivity tests were performed. The materials used in this study are natural bentonite and multiswellable bentonite. The permeants are distilled water, and CaCl2 and/or HCl solutions. Electrical conductivity and pH values of the effluents obtained from the hydraulic conductivity tests were measured to ensure the total chemical breakthrough. Multiswellable bentonite was found to perform better than natural bentonite does when in contact with CaCl2 and/or HCl solutions. Values of free swell and liquid limit of both bentonites decreased with the increase in concentration of CaCl2. Most specimens of multiswellable bentonite had the hydraulic conductivity one or more orders of magnitude lower than that of natural bentonite when in contact with the same concentration of CaCl2 solutions. The hydraulic conductivity values of both bentonites are higher than the requirement by the US EPA for MSW landfill clay liner (k < 10-7 cm/s) when permeated with calcium chloride solution greater than 0.3 M.耐化学性ベントナイトである多膨潤性ベントナイト(mutiswellablebentonite:MSB)の,廃棄物処分場バリア材への適用性を実験的に検討した。MSBは塩化カルシウムや塩酸の溶液に対しても高い膨潤性を示し,透水係数も天然ベントナイトより1オーダー以上低い値が得られたことから,廃棄物処分場のライナーやカバーなどのバリア材に有効に適用しうることが示唆された。Chemical compatibility of a newly developted material -multiswellable bentonite- is evaluated for the purpose of landfill barrier application. A series of liquid limit, free swell, and hydraulic conductivity tests were performed. The materials used in this study are natural bentonite and multiswellable bentonite. The permeants are distilled water, and CaCl2 and/or HCl solutions. Electrical conductivity and pH values of the effluents obtained from the hydraulic conductivity tests were measured to ensure the total chemical breakthrough. Multiswellable bentonite was found to perform better than natural bentonite does when in contact with CaCl2 and/or HCl solutions. Values of free swell and liquid limit of both bentonites decreased with the increase in concentration of CaCl2. Most specimens of multiswellable bentonite had the hydraulic conductivity one or more orders of magnitude lower than that of natural bentonite when in contact with the same concentration of CaCl2 solutions. The hydraulic conductivity values of both bentonites are higher than the requirement by the US EPA for MSW landfill clay liner (k < 10-7 cm/s) when permeated with calcium chloride solution greater than 0.3 M