Preparation of Al-Containing ZSM-58 Zeolite Membranes Using Rapid Thermal Processing for CO2/CH4 Mixture Separation

The synthesis of DDR-type zeolite membranes faces the problem of cracks that occur on the zeolite membrane due to differences in the thermal expansion coefficient between zeolite and the porous substrate during the detemplating process. In this study, Al-containing ZSM-58 zeolite membranes with DDR topology were prepared by rapid thermal processing (RTP), with the aim of developing a reproducible method for preparing DDR zeolite membrane without cracks. Moreover, we verified the influence of RTP before performing conventional thermal calcination (CTC) on ZSM-58 membranes with various silica-to-aluminum (Si/Al) molar ratios. Using the developed method, an Al-containing ZSM-58 membrane without cracks was obtained, along with complete template removal by RTP, and it had higher CO2/CH4 selectivity. An all-silica ZSM-58 membrane without cracks was obtained by only using the ozone detemplating method. ZSM-58 crystals and membranes with various Si/Al molar ratios were analyzed by using Fourier-transform infrared (FTIR) spectroscopy to confirm the effects of RTP treatment. Al-containing ZSM-58 zeolites had higher silanol concentrations than all-silica zeolites, confirming many silanol condensations by RTP. The condensation of silanol forms results in the formation of siloxane bonds and stronger resistance to thermal stress; therefore, RTP caused crack suppression in Al-containing ZSM-58 membranes. The results demonstrate that Al-containing ZSM-58 zeolite membranes with high CO2 permeance and CO2/CH4 selectivity and minimal cracking can be produced by using RTP.

EVALUASI KINERJA MEMBRAN SILIKA PEKTIN UNTUK DESALINASI AIR PAYAU TERHADAP SUHU KALSINASI MEMBRAN

Krisis air bersih khususnya di Kalimantan Selatan pada musim kemarau sering terjadi karena adanya intrusi air laut yang mengakibatkan air menjadi payau. Konsentrasi garam tinggi yang tidak sesuai baku mutu air bersih mengharuskan perlu adanya pengolahan. Oleh karena itu, proses desalinasi melalui pervaporasi menjadi pilihan untuk memisahkan kadar garam yang terlarut dalam air. Proses desalinasi dilakukan menggunakan membran silika yang dimodifikasi dengan menambahkan karbon dari pektin pisang untuk memperkuat struktur pori dan meningkatkan hidrostabilitas membran. Penelitian ini bertujuan untuk mengetahui kinerja membran silika-pektin pisang dengan metode pervaporasi (PV) menggunakan umpan air payau (NaCl 0,3 wt%) pada suhu ruang (~25°C). Bahan utama pada pembuatan membran ini adalah tetraethyl orthosilicate (TEOS). Membran silika-pektin pisang dengan konsentrasi 1% dikalsinasi pada suhu 300°C dan suhu 400°C melalui teknik RTP (Rapid Thermal Processing). Nilai fluks membran pada suhu kalsinasi 300°C sebesar 4,5 kg.m-2.jam-1 dengan nilai rejeksi garamnya sebesar 99,64 %. Sedangkan pada membran dengan suhu kalsinasi 400°C menghasilkan nilai fluks sebesar 13,2 kg.m-2.jam-1 dengan nilai rejeksi garam sebesar 99,78%. Kinerja kedua membran menunjukkan hasil yang sangat baik pada suhu kalsinasi 400°C dikarenakan adanya pengaruh penyisipan karbon dalam matriks silika sehingga pori yang terbentuk lebih kuat. Kata kunci: air payau, desalinasi air payau, membran silika-pektin, pektin pisang, pervaporasi. South Kalimantan during the dry season has been clean water scarcity, due to the sea water intrusion which formed brackish water. High salt concentration in brackish water is does not meet with clean water quality standards that necessary to processing before used. Therefore, the desalination process via pervaporation has chosen to separate the dissolved salt ions in water. The desalination process was carried out using a modified silica membrane by carbon templated from banana pectin to strengthen the pore structure and increase membrane hydro-stability. This work aims to determine the performance of banana silica-pectin membrane by pervaporation (PV) method, using brackish water (NaCl 0,3 wt%) at room temperature (~25°C). The main ingredient to make this membrane is tetraethyl orthosilicate (TEOS). Banana silica-pectin membrane with a concentration of 1% was calcined at 300 ° C and 400°C via RTP (Rapid Thermal Processing) technique. The water flux of membrane calcined at 300°C is 4,5 kg.m-2.h-1 with the salt rejection of 99,64%. Whereas the membrane in calcined temperature of 400°C produced a water flux of 13,2 kg.m-2.h-1 with a salt rejection of 99,78%. An excellent performance of both membranes showed at calcination temperature of 400°C due to the influence of carbon template in the silica matrices that makes the pores more robust. Keywords: banana pectin, brackish water, brackish water desalination, pervaporation, silica-pectin membrane.