Abstract. In this study, silica thin film pH=6 (precursor TEOS:tetraethyl ortosilicate) developed from sol gel process and deposited (2 layers) directly onto alumina substrate(tubular support with 100 nm pore size) without depositing interlayer (interlayer-free).Then, the desalination process via pervaporation was applied to test the membranesperformanceusing artificial saline water and wetland saline water. Results show the decrease of water flux (1.9 to 1.43 kg m -2 h -1 ) and salt rejection(97 to 95%) when using artificial salty water (0-7.5 wt%) and the long-term stability of silica membrane was stable at 1.7 kg m -2 h -1 for over 100 hours when using wetland saline water as a feed.Keywords: silica membranes; desalination; sol gel process, water flux and salt rejection. IntroductionLiterature reported that water is the basic needs of human living.Unfortunately, there is only 3% of water available as fresh water, the remaining 97% of watercontain salt. The World Health Organization (WHO) also said that there is more than 15% of the world's population does not have access to drinking water.One way to overcome the problem of accessing the clean water is by applying the appropriate membrane technology. Water desalination is one part of the technology to adapt. In addition, desalination has an environmentally friendly, energy-efficient, low operating cost and minimal use of chemicals. So this method becomes an interesting option for further investigation.Based on solubility or salt content in water, salty water can be grouped into three types (brackish water, saline water and brine water). Fresh water, brackish water, saline (sea) water and brine water has a salinity of less than 0.5, between 0.5 -17, 35 and above 35 ppt (part per thousand), respectively. Desalination is a process for reducing minerals dissolved in seawater into fresh water with a maximum concentration of 500 ppm. Membrane technology is a part of desalination process that mostly chosen due to its high efficiency, ease of operation, energy-saving and non-chemical. This technology has been widely applied to various processes such as gas separation, pervaporation, ion exchange membranes, membrane reactors and wastewater treatment. This technology has also several advantages, such as: enable to separate within specific chemical molecules, enable to operate at low temperatures, low energy consumption andfriendly environment. In addition, separation technique using membranes can run continuously and do not require much energy and the addition of chemicals (coagulant andflocculants). Sol gel process is a simple way to separate the molecules.

Abstrak: Air limbah pabrik tahu jika dibuang langsung ke lingkungan menyebabkan pencemaran lingkungan yang akan merusak kualitas air, terutama air limbah tersebut dialirkan ke badan sungai. Oleh sebab itu, sangatlah diperlukan suatu teknologi yang efisien untuk pengolahan air limbah tahu ini. Tujuan dari penelitian ini adalah untuk mengetahui pengaruh performansi membran silika pada proses desalinasi via pervaporasi. Penelitian ini dilakukan dengan menyiapkan silika sol yang dipersiapkan dari proses sol-gel menggunakan prekursor TEOS dalam larutan etanol. Selanjutnya adalah dengan menggunakan metode “2 step acid and base catalysts” dengan menggunakan HNO3 dan NH3 sebagai katalis. Silica thin film yang dihasilkan berupa sol di-dipcoating dan kemudian dilakukan proses kalsinasi pada suhu 600oC selama 1 jam menggunakan metode RTP (Rapid Thermal Process). Jumlah lapisan/layer dari membran silika tersebut adalah berdasarkan pengulangan proses dipcoating dan kalsinasi yang mana pada penelitian ini menggunakan variasi 3 layer. Performansi membran ini dilakukan dengan proses desalinasi via pervaporasi dengan menggunakan air limbah tahu yang bertujuan untuk memperoleh air bersih. Adapun nilai water flux membrane ini berkisar antara 1,74 – 1,48 kg m-2 h-1 dengan rejection berkisar antara 93,63 – 89.27 %. Hasil ini membuktikan bahwa membrane silika bisa mengolah air limbah tahu menjadi potable water walaupun nilai water flux perlu ditingkatkan. Sebagai tambahan analisis, uji karakteristik membran seperti uji FTIR dilakukan untuk mengetahui gugus fungsi dari membran silika dan uji morfologi menggunakan SEM untuk mengetahui ketebalan lapisan membran yang dihasilkan.       Keywords: limbah tahu, water flux, rejection, membran silika dan pervaporasi.