The purpose of this study was to modify bentonite (B) by iron using the solid-phase ion exchange method to enhance the asphaltene adsorption. According to the scanning electron microscope (SEM) and x-ray diffraction analysis (XRD) results, after solid-state ion exchange, the structure of parent bentonite was changed slightly. An energy-dispersive x-ray analysis (EDX) showed that after ion exchange, the iron contents of bentonite increased from 0.6% to 1.6% w/w. Bentonite modification with iron increases asphaltene adsorption capacity (about 60%) compared to parent bentonite. Optimal adsorbent conditions for adsorption of asphaltene are 100 ppm concentration, 5 g/L adsorbent, and 60 min contact time. Adsorbent behavior showed that the adsorption kinetics and isotherm are in good agreement with the pseudosecond-order model and the Langmuir equation.
In recent years, due to the occurrence of water shortage and drought problems, particularly in arid and semi-arid regions of the world, new methods to reduce evaporation from the surface of dam reservoirs, lakes, and other water-free surfaces are investigated. This study aimed to use hydrophobic bentonite to reduce water evaporation from water surfaces, on a laboratory scale, and field conditions for the first time. Bentonite initially became hydrophobic by stearic acid (SA). Under such conditions, hydrophobic bentonite floats on the surface of water and forms a thin coating layer. The produced hydrophobic bentonite had a contact angle of 150°, indicating its superhydrophobicity. Evaporation reduction was measured under laboratory and field conditions and it was compared to hexadecanol as the reference material. The results demonstrated that the hydrophobic bentonite efficiency under laboratory conditions was similar to that of hexadecanol and prevented water evaporation by 36%. However, under field conditions, hydrophobic bentonite and hexadecanol efficiencies were 40% and 23% to reduce evaporation for 30 days, respectively. In terms of stability, hexadecanol needed to be re-injected after three days, while hydrophobic bentonite was stable and remained on the surface for more than 100 days under laboratory conditions and for more than 15 days under field conditions without needing re-injection. This coverage with method can be used to reduce evaporation from lakes, tanks, and reservoirs of small dams.
Evaporative loss reduction has recently received attention due to increasing water demand and decreasing water availability. For this reason, researchers are trying to produce and use high efficiency with easy and cheap materials and methods. In this; research, Leca stone has been hydrophobized by stearic acid and used to reduce water evaporation in tanks in a laboratory environment. The structural properties and hydrophobicity of the hydrophobic Leca coating were analyzed by BET (Brunauer Emmett Teller), (Fourier-transform infrared spectroscopy) FT-IR, XRD (X-ray diffraction spectroscopy) and (Thermo Gravimetric Analysis) TGA. The stability of the synthesized hydrophobic sample is more than 200 days, and its contact angle is 143 degrees. The evaporation efficiency of hydrophobic Leca and hexadecanol was investigated at 5, 25, and 40 ºC and in the presence of wind and sunlight. It prevented water evaporation by 26 and 30%, respectively, at an average relative humidity of 56%.
The hydrologic cycle is the continuous circulation of water in nature between the atmosphere, land, and oceans. The hydrological cycle has five main processes namely compaction, precipitation, infiltration, runoff, and evaporation-transpiration (Chow et al., 1988). Evaporation occurs when the sun's radiation energy heats water and activates the water molecules. Therefore, part of the molecules enters the atmosphere as vapor (Hassan et al., 2015). Furthermore, owing to the limited amount of fresh water in the world and providing it in a balanced and stable supply manner, water is stored in wet seasons in tanks to be used when needed (Yao et al., 2010). Evaporation from the surface of the reservoirs can reduce the amount of this valuable and limited source of stored water. In recent years, numerous studies have been conducted on the methods to reduce evaporation in order to minimize evaporative losses. These methods are mainly classified into two categories: chemical (Brzozowska et al., 2012) and physical (Benzaghta & Mohamad, 2009).Chemical methods are based on the use of suitable chemicals, including fatty alcohols like hexadecanol, which have the ability to form monolayers on the water surface (Han et al., 2019).Surfactants are needed to dissolve these substances in water and form monolayers. In this case, if more surfactant is added to the hexadecanol than required, it will produce micelle in the water over time and contaminate the water. In addition, surfactants are often toxic and damage organisms in the ecosystem. Furthermore, it is difficult to separate and refine the missiles in the future. Eventually, hexadecanol is degraded and destroyed by bacteria and small organisms in the water over a short period like 3 days; therefore, it is necessary to add a compensatory amount of the substances (Yao et al., 2010). Longmuir (1917) studied the effect of using molecular layer films such as hexadecanol and its dispersion on the water surface for the first time to study the evaporation reduction. The author concluded that molecular layers had an acceptable efficiency of reducing dam water evaporation despite their low durability. Kahalekar and Kumawat (2013) used chemical film layers such as cetyl alcohol on A-type pans and obtained 30% efficiency in the optimum Abstract Evaporation is the natural process of vaporization of water from reservoirs, which exacerbates water scarcity. The authors aimed to provide a hydrophobic silver-doped titanium dioxide (TiO 2 ) nanoparticles coating to reduce the amount of water evaporation behind the dams. Accordingly, the silver-doped TiO 2 nanoparticles were first hydrophobized using stearic acid (SA). The produced material's properties were identified under various analyses such as contact angle, X-ray diffraction spectroscopy (XRD), scanning electron microscopy (SEM), Brunauer Emmett Teller (BET), energy-dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FT-IR), Thermo Gravimetric Analysis (TGA), and total organic carbon (TOC). The results of the analy...
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