Adsorption Capacities of Hygroscopic Materials Based on NaCl-TiO₂ and NaCl-SiO₂ Core/Shell Particles

Abstract

Hygroscopic materials which possess high moisture adsorption capacity were successfully upgraded by the functionalization of sodium chloride (NaCl) using two nuances of oxides. A procedure was developed to first prepare submicron-sized NaCl crystals; thereafter, these crystals were coated by choice of either titanium dioxide (TiO2) or silica (SiO2) to enhance the hygroscopic properties of NaCl and prevent its premature deliquescence. After coating, several analytical techniques were employed to evaluate the obtained composite materials. Our findings revealed that both composites NaCl-TiO2 and NaCl-SiO2 gave excellent performances by exhibiting interesting hydrophilic properties, compared to the sole NaCl. This was demonstrated by both environmental scanning electron microscope (ESEM) and water vapor adsorption experiments. In particular, NaCl-TiO2 composite showed the highest water adsorption capacity at low relative humidity and at a faster adsorption rate, induced by the high surface energy owing to the presence of TiO2. This result was also confirmed by the kinetics of adsorption, which revealed that not only does NaCl-TiO2 adsorb more water vapor than NaCl-SiO2 or sole NaCl but also the adsorption occurred at a much higher rate. While at room temperature and high relative humidity, the NaCl-SiO2 composite showed the best adsorption properties making it ideal to be used as a hygroscopic material, showing maximum adsorption performance compared to NaCl-TiO2 or sole NaCl. Therefore, NaCl-TiO2 and NaCl-SiO2 composites could be considered as promising hygroscopic materials and potential candidates to replace the existing salt seeding agents.

Shelf‐life study of a Salicornia ramosissima vegetable salt: An alternative to kitchen salt

“…They have a “J” format and are typical of crystalline materials such as sugars and salts which is the case with vegetable salt. In this case, moisture gain is very low to the point where crystals begin to dissolve in water absorbed on the crystal surface (deliquescence point) and as sodium chloride presents an RH 0 of .75, (Bermeo et al, 2020) our result can be explained by the fact that the RH 0 was lowered in this product due to the presence of amorphous ingredient. Ghorab et al (2014), studied the blend of crystalline sodium chloride with different percentages of an amorphous solid (maltodextrin) finding that individually sodium chloride presented an RH 0 of .75 but when blended with 40% of maltodextrin it would lower down to .71.…”

“…They have a "J" format and are typical of crystalline materials such as sugars and salts which is the case with vegetable salt. In this case, moisture gain is very low to the point where crystals begin to dissolve in water absorbed on the crystal surface (deliquescence point) and as sodium chloride presents an RH 0 of .75, (Bermeo et al, 2020) our result can be explained by the fact that the RH 0 was lowered in this product due to the presence of amorphous ingredient. It can also be seen that when the material is exposed to an environment of 90% RH, the moisture uptake increases with temperature, being under 50 g/100 g DM for 15 C and 25 C, but when temperature increases to 35 C and 45 C this value slightly overpasses 100 g/100 g DM.…”

Comparative quality assessment of traditional vs. improved dried Bombay duck (Harpodon nehereus) under different storage conditions: Solar chimney dryer a low‐cost improved approach for nutritional dried fish

“…Differences in moisture content exhibited in the current study might be due to dipping of fish into 5%–10% NaCl salt solution (in improved method) to avoid insect infestation in comparison to 10%–25% NaCl solution practiced in traditional method to get a higher weight benefit. The hygroscopic characteristics of NaCl salt bind with water in its structure (Bermeo et al., 2020 ), which results in a comparatively higher moisture content in the dried fish produced in that way. Irrespective of processing and packaging method, increasing moisture content was correlated with decreasing protein content during storage.…”

Enhancement in hydrolytic stability and proton conductivity of optimised chitosan/sulfonated poly(vinyl alcohol) composite membrane with inorganic fillers

“…The water uptake and swelling ratio shared a proportional relationship, where the sorption of water molecules causes dimensional expansion on the membrane, which is usually described by the term swelling ratio 87 . In the case of TiO 2 , Bermeo et al 91 reported a relative work on the adsorption capacities between SiO 2 and TiO 2 . The results demonstrate a high hygroscopic nature in TiO 2 compared with SiO 2 , where TiO 2 absorbs more water molecules.…”