Pembuatan concrete zeolit-lempung serta kajian adsorpsi-desorpsinya terhadap campuran etanol/air
PUTRA, I Made Wisnu Adhi, Dr. Yateman Arryanto
2010 | Tesis | S2 Ilmu KimiaTelah dilakukan pembuatan concrete zeolit-lempung serta kajian adsorpsidesorpsinya terhadap campuran etanol/air. Concrete zeolit-lempung dibuat dengan cara mengaduk campuran 10,00 g zeolit alam, 10,00 g semen portland, 1,25 g lempung alam dan 15 mL akuabides dalam cawan porselen. Suspensi yang terbentuk ditaruh di dalam cetakan dan dibiarkan kering dalam udara terbuka selama 48 jam. Concrete zeolit-lempung hasil preparasi dikarakterisasi dengan menggunakan spektrofotometer inframerah dan difraksi sinar-X. Material testing machine digunakan untuk mengukur kuat tekan concrete zeolit-lempung sesuai dengan standar ASTM C349-08 yang ditetapkan. Karakterisasi menggunakan FTIR memberikan serapan gugus-gugus fungsional yang mengindikasikan keberadaan produk hidrasi semen portland yaitu kalsium trisulfat/monosulfat hidrat dan kalsium hidroksida serta kalsium silikat hidrat (CSH) yang dihasilkan baik melalui reaksi hidrasi semen maupun melalui hasil reaksi pozzolanik antara zeolit dan lempung dengan Ca(OH)2 hasil hidrasi semen. Gugus-gugus fungsional bahan dasar penyusun concrete zeolit-lempung juga masih terlihat. Hasil analisa FTIR ini dikonfirmasi dengan hasil pengukuran menggunakan difraksi sinar-X yang memberikan indikasi kemunculan puncak-puncak mineral ettringit (kalsium trisulfat/monosulfat hidrat), portlandit (kalsium hidroksida), tobermorit dan jennit (CSH), klinoptilolit dan modernit (zeolit alam), dan illit (lempung alam). Dari pembuatan concrete zeolit-lempung, ditemukan bahwa meningkatnya massa lempung dapat meningkatkan kuat tekan concrete dari 130,3 MPa sampai 179,9 MPa dan persentase serapan air meningkat dari 28,9% sampai 32,3%. Data adsorpsi-desorpsi menunjukkan bahwa air lebih cepat teradsorpsi ke dalam concrete zeolit-lempung dibandingkan dengan etanol, sedangkan laju desorpsi etanol pada concrete zeolit-lempung terjadi lebih cepat dibandingkan dengan laju desorpsi air. Perbedaan laju desorpsi tersebut digunakan sebagai dasar untuk memisahkan campuran etanol air melalui pervaporasi tanpa pemanasan. Uji pervaporasi campuran etanol/air dengan konsentrasi 60%, 70%, 80%, dan 90% tanpa pemanasan menggunakan concrete zeolit-lempung menghasilkan kenaikan konsentrasi etanol sebesar 82,9%, 82,5%, 87,8%, dan 93,7% secara berturut-turut.
Preparation of zeolite-clay concrete and its adsorption-desorption study with respect to the mixture of ethanol/water have been carried out. Concrete was made by mixing 10.00 g of natural zeolite, 10.00 g of portland cement, 1.25 g of natural clay and 15 mL distilled water in porcelain disk. The mixture was manually stirred until homogenous suspension obtained. The suspension formed was then placed in the mold and allowed to dry in open air for 48 hours. The concrete was characterized by infrared spectrophotometer (IR) and X-ray diffraction (XRD). Material testing machine was used to determine the compressive strength of the concrete agreeable with decided ASTM C349-08 standard. Characterization using FTIR spectrophotometer showed functional group bands indicating the presence of portland cement hydration products (calcium trisulfate/monosulfate hydrate, calcium hydroxide, and calcium silicate hydrate (CSH)), and also additional calcium silicate hydrate (CSH) produced by pozzolanic reaction between zeolite and clay with Ca(OH)2 resulted from cement hydration. Functional group bands of the concrete fillers were also observed. FTIR analysis were confirmed using X-ray diffraction analysis which indicated the present of ettringite (calcium trisulfate/monosulfate hydrate), portlandite (calcium hydroxide), tobermorite and jennite (CSH), modernite and clinoptilolite (natural zeolite), and illite (natural clay). Based on preparation of zeolite-clay concrete, it was found that the higher the mass of clay, the greater the compressive strength of concrete from 130.3 MPa to 179.9 MPa and water adsorption percentage from 28.9% to 32.3%. The adsorption-desorption data showed that the water was faster to adsorb into the concrete than ethanol, whereas the desorption rate of concrete with respect to ethanol was greater than that to water. The difference on desorption rate was then used to separate ethanol/water mixture through pervaporation without heating. Pervaporation test using the concretes resulted in the increase of ethanol feed concentration from 60%, 70%, 80%, and 90% to 82.9%, 82.5%, 87.8%, and 93.7% respectively.
Kata Kunci : Concrete, Kuat tekan, Adsorpsi, desorpsi, Campuran etanol/air, Pervaporasi, concrete, compressive strength, adsorption-desorption, ethanol/water mixture, pervaporation
