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Wetland saline water has great potential to overcome water scarcity due to high salinity of intruded seawater. This work determines performance of silica membranes using organo catalyst applied for wetland saline water desalination via pervaporation and investigates the effect of calcination temperatures. These membranes were prepared from precursor tetraethyl orthosilicate (TEOS) for 3 h through sol-gel process refluxed at 0°C (membrane A) and 50°C (membrane B). The sols were dipcoated onto alumina (Al2O3) support for 4 layers followed by calcination for 1 h. Performance of membranes were evaluated by feeding wetland saline water through desalination at room temperature. Results show the water flux for membrane A were 0.27 & 0.15 kg.m-2.h-1 and salt rejection were 97.5 & 99 % as a function of calcination temperature (200 & 250°C), respectively. Furthermore, water flux of membranes B were 0.90 & 0.93 kg.m-2.h-1 and excellent salt rejection (>99.9 %) for both calcination temperatures. The highest water flux and salt rejection were found for membranes B. For both using citric acid under refluxed and calcination process, it gives more vibration of Si-C formation and membrane pores. This membrane is the very first and mesoporous organo silica membranes which is successfully fabricated from organo catalyst.

Silica material has limited hydrostability when it is produced as a thin film. In order to mitigate this restriction a modification strategy is needed. This article provides details of mesoporous hybrid organo-silica thin films that were successfully fabricated from a combination of a dual silicate precursor of tetraethyl orthosilicate/triethoxy vinyl silane, using organic catalysts. The research investigated the effect of calcination temperatures (350°C and 600°C) on the materials, and compared the application of single (citric acid) and dual catalysts (citric acid and ammonia) during fabrication of the thin film.

Silica network was tailored configuring siloxane (Si-O-Si) and silanol (Si-OH) groups which are essential to produce porous-structured materials. As silanols are hydrophilic, react with water to form fouling. This research address to actualize strategy for synthesizing highly functionalized silica carbon (Si-C) using hybrid organic-inorganic structures as the primary method for improving hydro-stability by employing precursor TEOS and organic catalyst through a sol-gel process. Catalysis employs citric acid or citric acid-ammonia whereas carbon templated into silica network. The synthesis scheme involves: a) sol-gel process at 0°C and b) calcination. Silica sol dried into xerogels were prepared and calcined at 200°C and 250°C. Characterization of xerogels showed the infrared band areas of the organic groups to evaluate the thermal stability. For xerogel employed single (pH 5.5) and dual (pH 7.65) catalyst, infrared spectra showed mostly look similar Si-C area at similar wavelength. Silica xerogel is more effectively prepared from TEOS with one-step single acid catalyst including calcination.

The physicochemical properties of organo-silica xerogels derived from organo catalyst were pervasively investigated, including the effect of one-step catalyst (citric acid) and two-step catalyst (acid-base), and also to observe the effect of sol pH of organo-silica xerogel toward the structure and deconvolution characteristic. The organo-silica xerogels were characterized by FTIR, TGA and nitrogen sorption to obtain the physicochemical properties. The silica sol–gel method was applied to processed materials by employing TEOS (tetraethyl orthosilicate) as the main precursor. The final molar ratio of organo-silica was 1:38:x:y:5 (TEOS:ethanol: citric acid: NH3:H2O) where x is citric acid concentration (0.1–10 × 10−2 M) and y is ammonia concentration (0 to 3 × 10−3 M). FTIR spectra shows that the one-step catalyst xerogel using citric acid was handing over the higher Si-O-Si concentration as well as Si-C bonding than the dual catalyst xerogels with the presence of a base catalyst. The results exhibited that the highest relative area ratio of silanol/siloxane were 0.2972 and 0.1262 for organo catalyst loading at pH 6 and 6.5 of organo-silica sols, respectively. On the other hand, the organo-silica matrices in this work showed high surface area 546 m2 g−1 pH 6.5 (0.07 × 10−2 N citric acid) with pore size ~2.9 nm. It is concluded that the xerogels have mesoporous structures, which are effective for further application to separate NaCl in water desalination.