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The purpose of the present study is to investigate the extraction of lithium from southern Tunisian brines. Density and concentration of Lithium in those brines were reported. Also, pondered rates of Lithium and the major elements in brines were investigated. Obtained results indicate that Lithium exist in those brines as traces. The optimization of certain parameters is required in this study. To extract Lithium from natural brines two steps were investigated. Firstly, we have used Ammonium Oxalate ((NH4)2(C2O4)⋅2H2O) to precipitate only Magnesium ion: in this procedure, three parameters were investigated (Mg/Oxalate, T (°C) and tstirring). The maximum values were found to be Mg/Ox = 0.66, T = Treflux = 100°C and tstirring ≥ 30 min. Secondly, we have used Aluminum Chloride (AlCl3⋅6H2O) in order to adsorbing lithium ions by Aluminum hydroxide. In this procedure, four parameters were investigated (pH, Al/Li, tstirring and T (°C)). Maximum values of these parameters are 7.2, 4.7, 3 h and 25°C respectively. Finally, to separate Lithium from Aluminum solution, we have used an exchange ion resin. This solution including two ions under cationic form (Al3+ and Li+). Al3+ was complexed into [Al(C2O4)3]3– using Ammonium Oxalate ions () and removed from solution using an anion exchange resin (Amberlite IRA-402). Thus, a theoretical study was carried out to determine the appropriate pH for separation. After Aluminum ions complexation by ammonium oxalate, Ox/Al molar ratio and pH was studied. Optimal values of these parameters are 3 and 4 respectively and the recovery of Li+ is set to be 98.5%. [ABSTRACT FROM AUTHOR]

It is widely accepted that the zeta potential in natural sandstones is negative in the brine pH and compositions found in the subsurface. The zeta potential is a measure of the electrical potential at a mineral surface. We report new measurements of the zeta potential using a saline natural brine rich in divalent ions. The sandstone samples were quartz dominated but some also contained dolomite, siderite, and clay minerals. The quartz‐dominated sandstones showed behavior consistent with earlier studies, but the dolomite‐ and siderite‐bearing samples returned positive zeta potentials. We suggest that this is caused by a positive zeta potential on dolomite and siderite mineral surfaces, adsorption of divalent ions onto quartz mineral surfaces, and/or ion exchange with clay minerals. The results have broad implications for the zeta potential of natural sandstones, because the magnitude and polarity of the zeta potential impact geophysical monitoring and the transport of the charged contaminants. Plain Language Summary: Sandstone is one of the most common porous rocks that form subsurface reservoirs. When the sandstone mineral surfaces are in contact with water, they become electrically charged. The magnitude and polarity of the electrical charge can be characterized by a property called the "zeta potential" which can be measured in the laboratory. Here, we show that the zeta potential of sandstone saturated with saline natural brine can be positive, rather than negative as is usually assumed. We highlight the importance of using realistic rock and water compositions in the experimental measurement of zeta potential. The zeta potential is important because it controls how electrically charged contaminants pass through sandstone aquifers, and how aquifers can be monitored remotely using geophysical methods. Assuming the zeta potential is negative when it is positive will cause serious errors in data interpretation and model predictions. Key Points: Zeta potential measured on intact sandstones saturated with natural saline brineResults differ from previously observed trends, including the first reported positive values of zeta potential in natural sandstonePositive zeta potential is attributed to adsorption of divalent ions onto mineral surfaces, ion exchange, and mineral dissolution [ABSTRACT FROM AUTHOR]

Chemical fertilizers, such as potassium chloride, ammonium nitrate and other chemical products like sodium hydroxide and soda ash are produced from electrolyte solutions or brines with a high content of soluble salts. Some of these products are manufactured by fractional crystallization, when several salts are separated as solid phases with high purity (>90%). Due to the large global demand for potassium fertilizers, a good knowledge about the compositions of salts and brines is helpful to design an effective process. A thermodynamic model based on Pitzer and Harvie's model was used to predict the composition of crystallized salts after water removal by forced evaporation and cooling from multicomponent solutions or brines. Initially, the salts’ solubilities in binary systems (NaCl–H2O, KCl–H2O and MgCl2–H2O) and ternary system (KCl–MgCl2–H2O) were calculated at 20 °C and compared with literature data. Next, the model was compared to our experimental data on the quinary system NaCl–KCl–MgCl2–CaCl2–H2O system at 20 °C. The Pitzer and Harvie's model represented well both the binary and ternary systems. Besides, for the quinary system the fit was good for brine densities up to 1350 kg/m3. The models were used to estimate the chemical composition of the solutions and salts produced by fractional crystallization and in association with material balance to respond to issues related to the production rates in a solar pond containing several salts dissolved, for instance, NaCl, KCl, MgCl2 and CaCl2.

For the first time it is proposed to produce lithium hydroxide monohydrate as a primary derivative product from hydromineral raw materials. This technology is based on the primary lithium concentrate obtained by enriching the lithium-bearing brines and concentrating by the combined method. The produced concentrate is a pregnant lithium chloride solution which is subjected to the electrochemical conversion: LiCl ⋅ LiOH. The lithium hydroxide monohydrate crystals are extracted from the lithium hydroxide solution and, after washing, they correspond to the LGO-1 brand. [ABSTRACT FROM AUTHOR]

Though great progress on the adsorbents of heavy metal ions has been made in recent years, it is still challenging to develop economic, high-efficient and eco-friendly adsorbents. Herein, a series of MgO/palygorskite (MgO/Pal) composites with robust adsorption performance toward Zn(II) and Cd(II) were successfully prepared by a facile and industrially feasible precipitation-calcinations process using environmentally benign natural palygorskite (Pal) and Mg(II)-rich brine as the raw materials. The XRD, TG and SEM analyses confirm that MgO species was formed and uniformly distributed on the surface of Pal nanorods. The resultant MgO/Pal adsorbent exhibited high adsorption capacities of 841 and 669 mg/g for Zn(II) and Cd(II) ions, respectively. About 98.79% of Zn(II) and 98.69% of Cd(II) were removed from 200 mg/L of the initial solution by only using 1 g/L of the adsorbent. The spent MgO/Pal adsorbent can be regenerated by a simple one-step calcinations process, and the regenerated adsorbent can remove 99.5% of cationic dyes from 100 mg/L of the initial dye solution. The adsorption process obeys Langmuir isotherm model and pseudo-second-order kinetic model, which suggest the monolayer adsorption of Zn(II) and Cd(II) onto the composite. The chemo-adsorption process including phase transformation and precipitation is mainly responsible for the enhanced adsorption capacities. In a word, the composites are made from naturally available matters, which can serve as promising adsorbents for high-efficient removal of toxic metal ions from polluted water. [ABSTRACT FROM AUTHOR]

This paper refers a method for the preparation of magnesium chloride hexahydrate (bischofite) from Sebkha el Melah of Zarzis Tunisian natural brine. It is a five-stage process essentially based on crystallization by isothermal evaporation and chemical precipitation. The two first steps were dedicated to the crystallization of sodium chloride and potassiummagnesium double salts, respectively. Then, the resulting liquor was desulfated using calcium chloride solution. After that another isothermal evaporation stage was implemented in order to eliminate potassium ions in the form of carnallite, KCl.MgCl2.6H2O. At the end of this step, the recovered solution primarily composed of magnesium and chloride ions was treated by dioxan in order to precipitate magnesium chloride as MgCl2.6H2O.C4H8O2. This compound dried at constant temperature of 100°C gave good quality magnesium chloride hexahydrate. Besides this salt, the various by-products obtained from the different treatment stages are also useful.

Abstract: A salinity gradient solar pond (SGSP) is a simple and effective way of capturing and storing solar energy. The Qinghai-Tibet Plateau has very good solar energy resources and very rich salt lake brine resources. It lacks energy for its mineral processes and is therefore an ideal location for the development and operation of solar ponds. In China, solar ponds have been widely applied for aquaculture, in the production of Glauber’s salt and in the production of lithium carbonate from salt lake. As part of an experimental study, a SGSP using the natural brine of Zabuye salt lake in the Tibet plateau has been constructed. The pond has an area of 2500m2 and is 1.9m deep. The solar pond started operation in spring when the ambient temperature was very low and has operated steadily for 105days, with the LCZ temperature varying between 20 and 40°C. During the experimental study, the lower convective zone (LCZ) of the pond reached a maximum temperature of 39.1°C. The results show that solar ponds can be operated successfully at the Qinghai-Tibet plateau and can be applied to the production of minerals. [Copyright &y& Elsevier]

One concern for geologic CO 2 sequestration is the potential leakage of CO 2 or CO 2 -saturated brine containing trace metals into overlying aquifers, which poses the risk of adversely affecting underground sources of drinking water. In this work, rock and brine samples collected in the Illinois Basin – Decatur Project (IBDP), a large-scale geological CO 2 sequestration demonstration project in Decatur, Illinois, USA, as well as synthetic brine samples were used to understand the mobilization of trace metals as a result of CO 2 –rock–brine interactions under IBDP-specific conditions (50 °C and 20.6 MPa). Rock sample characterization indicated that, at the IBDP site, trace metal concentrations were greatest in cap rock samples from the Eau Claire Formation, compared with those from formations above and below this Formation. The natural brine samples collected from the Mt. Simon Sandstone reservoir were highly reducing and saline, with trace metal concentrations up to 680 times greater than the U.S. Environmental Protection Agency-prescribed drinking water standards. Batch leaching experiments indicated that both trace metal mobilization from rock and immobilization from the brine occurred when high-pressure CO 2 was introduced into the rock-brine system. The amounts of metals mobilized from the rock generally accounted for <5% of the total metals in the rock, but for some metals, including Ni, Pb, and Tl, up to 63% of the metals in the rock were mobilized to the brine. Leaching of trace metals into synthetic brines was different from that into the natural brine. The results of this study provided current information on the trace element sources and will help in risk simulations and experimental design to further evaluate potential impact of leakage on groundwater quality, which is important for future GCS projects to consider for monitoring and containment assurance purposes. [ABSTRACT FROM AUTHOR]