Sorption of Lithium on Bentonite, Kaolin and Zeolite

Li sorption was studied on natural bentonite, kaolin and zeolite in batch experiments at variable Li and Na concentrations (0, 1.5, 15, 150, 750 mM LiCl and 0.01, 0.1, 1, 3, 5 M NaCl). The solid-to-solution ratio was 1:4 and pH ranged from 2 to 10. Maximum Li sorption was determined at 0.01 M NaCl and 750 mM LiCl concentration in solution. It was 3800 ± 380 ppm, 1300 ± 130 ppm and 3900 ± 390 ppm on bentonite, kaolin and zeolite, respectively, which is in the average to upper range typical for clay minerals. Under these conditions, kaolin was saturated with Li, whereas Li in bentonite and zeolite occupied only about 55%–79% and 9%–26% of the typical cation exchange capacity (CEC) of smectites and zeolites, respectively. This is explained by differences in the way Li is bound in the materials studied. Li sorption on bentonite was independent of pH due to strong pH buffering. Above pH 5, kaolin was transformed to gibbsite, which completely changed its Li sorption capabilities. Extremely low as well as extremely high pH destabilized the crystal lattice of zeolite. All in all it was shown that, under the studied conditions, Li sorption on the studied materials occurs in detectable quantities. So, clay minerals and zeolites can act as a sink for Li if Li concentrations in solution are sufficiently high

Hydrothermalism in the Tyrrhenian Sea: inorganic and microbial sulfur cycling as revealed by geochemical and multiple sulfur isotope data

The Palinuro volcanic complex and the Panarea hydrothermal field, both located in the Tyrrhenian Sea (Italy), are associated with island arc magmatism and characterized by polymetallic sulfide mineralization. Dissolved sulfide concentrations, pH, and Eh measured in porewaters at both sites reveal a variable hydrothermal influence on porewater chemistry. Multiple sulfur isotopic measurements for disseminated sulfides (CRS: chromium reducible sulfur) extracted from sediments at Palinuro yielded a broad range in δ34S range between −29.8 and + 10.2‰ and Δ33S values between + 0.015 and + 0.134‰. In contrast, sediments at Panarea exhibit a much smaller range in δ34SCRS with less negative values between −11.3 and −1.8‰. The sulfur isotope signatures are interpreted to reflect a mixture between hydrothermal and biogenic sulfide, with a more substantial biogenic contribution at Panarea. Multiple sulfur isotope measurements were performed on sulfides and elemental sulfur from drill core material from the Palinuro massive sulfide complex. δ34S and Δ33S values for pyrite between −32.8 and −1.1‰ and between −0.012 to + 0.042‰, respectively, as well as for elemental sulfur with δ34S and Δ33S values between −26.7 and −2.1‰ and between + 0.035 and + 0.109‰, respectively, point to a microbial origin for much of the sulfide and elemental sulfur studied. Moreover, data suggest a coupling of bacterial sulfate reduction, sulfide oxidation and sulfur disproportionation. In addition, δ34S values for barite between + 25.0 and + 63.6‰ are also in agreement with high microbial turnover of sulfate at Palinuro. Although a magmatic SO2 contribution towards the formation of the Palinuro massive sulfide complex is very likely, the activity of different sulfur utilizing microorganisms played a fundamental role during its formation. Thus, porewater and multiple sulfur isotope data reveal differences in the hydrothermal activity at Palinuro and Panarea drill sites and underline the importance of microbial communities for the origin of massive sulfide mineralizations in the hydrothermal subsurface

Study on the effect of cetyltrimethylammonium bromide on gas-liquid flow characteristics at low gas flow rates and gas pressure

Cenomanian gas deposits account for about 80% of natural gas production in Russia. Today, mature Cenomanian gas fields are depleted by more than 75% on average, the reservoir pressure in the productive formation zone has decreased by almost 90% compared to the initial pressure and in some places reaches 1.0-1.5 MPa. Reduction of pressure in the pay zone leads to active intrusion of water from the aquifer. The liquid is loading the well, and gas production decreases. The technology of gas well operation with foaming agent is widespread in the world, which is characterized by a high level of efficiency, including economic. The use of technology leads to a solution to the liquid loading and requires a preliminary selection of the optimal concentration of surfactants. The optimal concentration should ensure the creation of a relatively stable foam and provide a minimum pressure gradient in the production tubing. The article presents the results of studies of CTAB foaming agent influence on the process of liquid removal and pressure gradient in production tubing. Sequential studies to determine CMC, foamability, foam stability, and pressure gradient under foam flow were conducted on small-scale and large-scale facilities. These results can be reliable when using CTAB foaming agent, foaming agents based on it, or other cationic foaming agents in Cenomanian gas wells under the condition of reservoir water inflow. Besides, the effect of pressure on the optimal concentration of the foaming agent was also studied in this work