The Effect of Biopolymer Chitosan on the Rheology and Stability of Na-Bentonite Drilling Mud

The utilization of greens resources is a grand challenge for this century. A lot of efforts are paid to substitute toxic ingredients of the conventional drilling mud system with nontoxic natural materials. In this paper, the effect of the natural polymer chitosan on the rheology and stability of sodium-bentonite drilling mud was investigated in the polymer concentration range of 0.1–3.0 wt.%. Both the shear and time dependent rheological properties of pure chitosan, pure bentonite and bentonite–chitosan dispersions were studied. Moreover, zeta potential measurements were used to evaluate the stability of bentonite-chitosan suspension. Adding chitosan improved the natural properties of drilling mud, namely: yield stress, shear thinning, and thixotropy. The viscosity of bentonite suspension increased significantly upon the addition of chitosan in the concentration range of 0.5 to 3.0 wt.% forming network structure, which can be attributed to the interactions of hydrogen bonding between -OH clusters on the bentonite surface with the NH group in the chitosan structure. On the other hand, dispersed chitosan–bentonite suspension was observed at low chitosan concentration (less than 0.5 wt.%). Increasing both bentonite and chitosan concentrations led to the flocculation of the bentonite suspension, forming a continuous gel structure that was characterized by noteworthy yield stress. The desired drilling mud rheological behavior can be obtained with less bentonite by adding chitosan polymer and the undesirable effects of high solid clay concentration can be avoided.

Technological evaluation of bentonite suspension obtained using hydromechanical method

Изучены физико-химические свойства суспензии бентонита, полученной гидромеханическим способом в сравнении с традиционным. Представлены результаты исследований по обеспечению стабильности винодельческой продукции против необратимых коллоидных помутнений при применении суспензии бентонита, приготовленной гидромеханическим способом. Установлено, что суспензия бентонита, приготовленная гидродинамическим способом при частоте вращения ротора 2980 об/мин. в течение 5 мин. и средним размером частиц от 8 до 10 мкм, позволяет значительно повысить качество обработки виноматериалов и достичь высоких показателей их стабильности, а также снизить объем образующихся осадков до 10 процентов. Результаты технологической оценки суспензии бентонита, полученной на экспериментальной установке, положены в основу определения режимных и конструктивных параметров оборудования для приготовления растворов и суспензий вспомогательных материалов в виноделии. Physicochemical properties of bentonite suspension obtained using hydromechanical method in comparison with traditional one have been studied. The results of studies on providing the wine product stability against nonreversible colloidal haze in applying bentonite suspension prepared using hydromechanical method are presented. It was found that bentonite suspension prepared using hydrodynamic method at a rotor speed of 2980 rpm during 5 minutes and an average particle size of 8 to 10 µm, can significantly improve the quality of processing base wines, achieve high stability level and reduce the amount of sediment by up to 10 percent. The results of technological evaluation of bentonite suspension obtained using experimental unit are the basis for determining the operating and design parameters of equipment for preparation of solutions and suspensions of auxiliary materials in winemaking.

Effect of Polyethylene Oxide on the Rheological Behavior of Bentonite Suspensions

The effect of Polyethylene Oxide (PEO) with a molecular weight 10000g/mol on the rheological behavior of bentonite suspension was examined in terms of viscosity, yield stress and viscoelastic modulus (G’ and G’’); characteristic of complex behaviour of montmorillonite in water. A Physica MCR301 rheometer has been used to measure the rheological properties of samples (6% bentonite) as well as bentonite-PEO mixtures at different concentrations of PEO (0.18%, 0.25%, 0.5% and 1%). The polyethylene oxide adsorbs onto clay particles, which changes their basic characteristics depending on the amount of PEO adsorbed.

Ultrasonic oscillations induced property development of water-bentonite suspension containing sulfonated wood coal

During drilling fluid preparation, ultrasonic oscillations were introduced into water-bentonite suspension incorporating sulfonated wood coal (SMC) by a specially designed device. The influences of ultrasonic oscillations on fluid loss and rheological performances of the drilling fluid as well as mechanism of ultrasonic action were investigated. The experimental results showed that the filtrate volume decreased with the increase of ultrasonic time till a certain extent and then leveled off. In the presence of ultrasound, shorter time of 15 min and mild intensity of 250 W could lead to a satisfactory result in fluid loss properties, including the reasonable filtrate volume and thin and compact filter cakes. With increasing ultrasonic intensity, the fluid loss properties changed relatively little but various rheological data of the drilling fluids always increased. Adsorption tests through total organic carbon, infrared spectrum and thermogravimetic analyses as well as clay particle size analysis confirmed that as compared with the conventional agitation, ultrasound-assisted mud preparation could not only increase adsorbed amount of SMC on bentonite but also decrease average clay particle diameter attributed to acoustic cavitation. A plausible mechanism based on sonochemical thermodynamics is proposed to explain the improvement of the colloidal structure and performances of drilling fluid.