Comprehensive monolayer two-parameter isotherm and kinetic studies of thiamine adsorption on clay minerals: Experimental and modeling approaches

One of the main reasons for shale swelling is the interaction between the montmorilonite (Mt) and water molecules. Using shale inhibitors is a principal method for preventing shale swelling when drilling shale formations with water-based drilling fluids. In the present study, for the first time, thiamine is introduced as a new shale inhibitor and as an ecofriendly substance in water-based drilling muds. The adsorption amount of the shale inhibitor onto the shale formation is an important parameter affecting the performance of the shale inhibitor. In the present study, firstly, the adsorption of thiamine onto shale formation is investigated. Batch experiments were carried out to investigate the adsorption of thiamine on sodium bentonite. The critical micelle concentration (CMC) of thiamine in the aqueous solution was obtained as 2.3 g/L Various isotherm and kinetic adsorption models have been fitted to the experimental data and the parameters of the models have been determined. Results showed that the Jovanovich isotherm adsorption model with squared correlation coefficient of R-2 = 0.96 and pseudo-second order kinetic model with contribution of intrapartide diffusion can predict the adsorption of thiamine on montmorillonite. The inhibitory properties of thiamine were investigated by various dynamic tests such as particle size measurement, consolidation test, cutting dispersion test and dynamic linear swelling test. The particle size of clay in the presence of thiamine increased from 574 to 7920 nanometer (nm) in comparison with deionized water. The consolidation test results showed that in the presence of thiamine, the compression index decreases from 02681 to 0.2172 and the swelling index decreases from 0.0954 to 0.0389. In the presence of thiamine, the reduction in the indices is higher than that in the presence of potassium chloride. The results indicated that the amount of recovered shale cuttings in the presence of thiamine with the concentration of 10 g/L is larger by 24.19% and 7.41% in comparison with that in deionized water and potassium chloride, respectively. The linear swelling of thiamine is lower than the potassium chloride and deionized water. In addition, thiamine enjoyed marked morphological characteristics, elemental analysis and specific surface area revealed via scanning electron microscopy, energy dispersive X-ray and Brunauer-Emmett-Teller method. In addition, the artificial neural network (ANN) was used to model the adsorption experimental data. The developed ANN model with R-2 = 0.97 is accurate enough to predict the kinetic adsorption behavior of thiamine onto montmorillonite. Hence, 10 g/L is the optimum and economical concentration of thiamine as the shale inhibitor. Based on the results obtained in this study, thiamine has a high potential to prevent swelling and hydration of water sensitive shale. Also, the results from this study are applicable in determining the optimum concentration of thiamine in drilling fluids and selecting the best shale inhibitor concentration in drilling operations. (C) 2020 Elsevier B.V. All rights reserved.