A Laboratory Approach to Measure Carbonate Rocks’ Adsorption Density by Surfactant and Polymer

Chemical recovery techniques have always been considered as one of the efficient secondary and tertiary recovery methods to enhance the oil recovery factor. Regarding the diversity of reservoir heterogeneity and rock properties for each field, various chemical agents were taken into consideration to provide a feasible process that has the best agreement with the reservoir characterization. The objective of this paper is to investigate the considerable influence of a set of chemical agents and temperature impact on the surfactant adsorption density of carbonate rocks. According to the results of this experiment, higher temperatures provide lower surfactant adsorption density. The lowest adsorption carbonate rocks’ adsorption density had occurred at 80°C. Furthermore, it was witnessed that hydrolyzed polyacrylamide addition to the surfactant would cause a dramatic decrease in the adsorption density in comparison with the surfactant or polymer individually.

3D Structural Optimization of Zinc Phthalocyanine-Based Sensitizers for Enhancement of Open-Circuit Voltage of Dye-Sensitized Solar Cells

We designed and synthesized two zinc phthalocyanine sensitizers (PcS27 and PcS28), substituted with branched or cyclic alkoxy chains, to investigate the structural effect of peripheral alkyl chains on the performance of dye-sensitized TiO2 solar cells. The bulky cyclic alkyl chains of PcS28 decreased the adsorption density of PcS28 on the TiO2 electrode, while the terminal branches of alkoxy chains of PcS27 did not influence the adsorption density in comparison to the previously published PcS20 with linear alkoxy chains. Under one sun conditions, PcS27 cells exhibited higher open-circuit voltage but a slightly lower energy conversion efficiency, 6.0% less than PcS20. These results suggest that the small alternation of alkoxy chains resulted in decreasing electron pushing ability of peripheral phenoxy units, giving lower short-circuit current.

Isotherm, Kinetics and Thermodynamic Study of Adsorption of Phthalocyanine and Azo Dyes by CoCl2 Doped Polyaniline

In this work, CoCl2 doped polyaniline was prepared using chemical oxidation method and used as an effective adsorbent for the removal of industrial dyes reactive blue 21 and reactive red 180. The adsorption experiments were performed with the variation of initial concentrations of dyes, pH of the solution, weight of adsorbent, temperature and agitation speed. Isotherm analysis, evaluating the correlation coefficients by ANOVA technique, kinetic study and calculation of thermodynamic parameters are carried out. Furthermore, the adsorption density of dyes onto PANI-CoCl2 adsorbent is characterized by SEM and FTIR. This study is compared with other previous works to establish that PANI-CoCl2 is an efficient adsorbent to remove dye from aqueous solution.

The Effect of Sodium Alginate on Chlorite and Serpentine in Chalcopyrite Flotation

Chlorite and serpentine are common magnesium-containing gangue minerals in copper sulfide flotation. In this study, sodium alginate, a natural hydrophilic polysaccharide, was introduced as a selective depressant for these gangue minerals. Micro-flotation tests were conducted on both single minerals and synthetic mixtures. The flotation results showed that sodium alginate could simultaneously depress the flotation of chlorite and serpentine effectively, but seldom influenced the floatability of chalcopyrite at pH 9. In the ternary mixture flotation, a concentrate with a Cu grade of 31% could be achieved at Cu recovery of 90%. The selective depression of chlorite and serpentine was also validated by the real ore flotation experiments. The selective depression mechanism was investigated through adsorption tests, zeta potential measurements, and FTIR analyses. The adsorption density results implied that sodium alginate selectively adsorbed on the surface of phyllosilicates, but no adsorption on the chalcopyrite surface was observed. The zeta potential results showed that the sodium alginate could selectively decrease the surface charge of chlorite and serpentine. The FTIR results revealed the chemical adsorption of sodium alginate on the chlorite and serpentine surface and no form of adsorption on chalcopyrite, agreeing well with the adsorption density results. On the basis of these results, a selective adsorption model of sodium alginate on the mineral surface was proposed.

Impact of Clay Minerals on the Dewatering of Coal Slurry: An Experimental and Molecular-Simulation Study

The cleaning process of coals is challenging due to the existence of clay minerals. The overall objective of this study is to investigate how the dewatering of coal slurry is impacted by the presence of clay minerals, i.e., kaolinite and montmorillonite. Filtration tests were first conducted to investigate the effect of kaolinite and montmorillonite on the dewatering efficiency of coal. Specifically, we measured the filtration velocity, moisture, average specific resistance, and porosity of filter cakes for six slurry samples, in which different amounts of kaolinite and montmorillonite were contained. Filtration tests show that a small amount of kaolinite and montmorillonite leads to a significant reduction in the filtration velocity and porosity, and a big increase in the average specific resistance and the moisture of the filter cake. We observe that most kaolinite existed in the top and middle layers of the filter cake, while most montmorillonite existed in the top layer; on the contrary, little montmorillonite is observed in the middle and bottom layers of the filter cake. Montmorillonite results in a much more deteriorative effect than kaolinite. Considering that the interactions between clay minerals and water may play a key role, we then further investigate the effect of such interactions using molecular simulations. Simulation results show that water molecules could hardly diffuse into kaolinite from the edge, while they could readily penetrate into the montmorillonite layers from the edge surface. This result can be explained by the hydrated cation in montmorillonite. The adsorption density of water on the octahedral surface of kaolinite is higher than that of water on the tetrahedral surface of kaolinite. Furthermore, the adsorption density of water on the double surfaces of kaolinite is higher than that of water on the montmorillonite surface. This research is expected to provide benefits or contributions to the dewatering of clay-rich coal tailings.