ACTIVATION OF NATURAL ZEOLITE AS AN ADSORBENT FOR LOW TEMPERATURE DRYING SYSTEM. Drying is one process which is used in many industries, especially in food product. The process usually still has low energy efficiency and can make food deterioration because of the usage of high temperature. One alternative in drying technology is the use of zeolite as a water vapor adsorbent. This kind of drying method make it possible to operate in lower temperature, hence it will be suitable for heat sensitive product. Natural zeolit can be one promising adsorbent since it is spreadly abundant in Indonesia. Natural zeolite must be activated first before used, in order to get zeolite with high adsorption capacity. Activation process in natural zeolite will change the Si/Al ratio, polarity, and affinity of zeolite toward water vapor and also increase the porosity. Activation of natural zeolite can be done with two methods, chemical activation use NaOH and physical activation use heat. In the activation using NaOH, natural zeolite is immersed with NaOH solution 0.5-2N in 2 hour with temperature range 60-900C. The process is continued with the drying of zeolite in oven with 1100C for 4 hours. While in heat treatment, zeolit is heated into 200-5000C in furnace for 2-5 hours. SEM analysis is used to compare the change in zeolite morphology before and after each treatment, while to know the adsorption capacity of zeolite, the analyses were done in many temperature and relative humidity. Result gives the best condition in NaOH activation is NaOH 1N and temperature 700C, with water vapor loading is 0.171 gr/gr adsorbent. In heat treatment, the best condition is 3000C and 3 hours with loading 0.137 gr water vapor/gr adsorbent.  Pengeringan merupakan salah satu proses yang banyak digunakan pada produk pangan. Proses ini umumnya menyebabkan kerusakan pada bahan pangan, disamping masih rendahnya efisiensi energi. Salah satu alternatif pada proses pengeringan yaitu penggunaan zeolit sebagai adsorben uap air. Proses pengeringan dengan menggunakan zeolit sebagai adsorben ini memungkinkan operasi pengeringan dilakukan pada suhu rendah sehingga sesuai untuk bahan yang tidak tahan panas. Zeolit alam merupakan salah satu alternatif bahan adsorben. Akan tetapi zeolit ini harus diaktivasi terlebih dahulu untuk mendapatkan zeolit dengan kemampuan adsorpsi yang tinggi. Proses aktivasi pada zeolit akan merubah rasio Si/Al zeolit, polaritas serta afinitas zeolit terhadap air dan meningkatkan pori-pori zeolit Adsorpsi zeolit alam dilakukan dengan dua cara yaitu dengan NaOH dan dengan panas. Pada aktivasi dengan NaOH, zeolit dicampur dengan NaOH 0,5-2N selama 2 jam pada suhu 60-900C. Sementara pada aktivasi fisis, zeolit dipanaskan pada 200-5000C selama 2-5 jam. Untuk mengetahui perubahan struktur pori zeolit maka dilakukan analisa SEM dan untuk mengetahui kemampuan adsorpsi zeolit maka dilakukan analisa daya adsorpsi zeolit terhadap uap air pada berbagai suhu dan berbagai kelembaban relatif. Hasil menujukkan bahwa pada aktivasi dengan NaOH diperoleh kondisi aktivasi terbaik adalah NaOH 1N pada pemanasan 700C dengan daya adsorpsi 0,171 gr uap air/gr adsorben. Sementara untuk aktivasi dengan panas, kondisi aktivasi terbaik adalah pemanasan 3000C selama 3 jam dengan daya adsorpsi 0,137 gr uap air/gr adsorben.

Geopolymer as a Portland cement substitute had been synthesized from alkaline activation of co-combustion residuals of bamboo and kaolin. Types of used alkaline activators were NaOH solution, KOH solution, a mixture of NaOH solution-water glass, and a mixture of KOH solution-water glass. Geopolymer with NaOH solution as activator had a compressive strength which was higher compared to geopolymer with KOH solution as an activator. However, geopolymer with NaOH solution-water glass as activator had a compressive strength which was lower compared to geopolymer with KOH solution-water glass as activator either at room temperature curing or at a curing temperature of 60 °C. The use of water glass with NaOH or KOH solution as activator could increase the compressive strength of geopolymer and yielded geopolymer having more dense and more homogeneous microstructure seen from SEM images. XRD patterns revealed the presence of sodium aluminosilicate hydrate in geopolymer with NaOH solution and NaOH solution-water glass as activators, and potassium aluminosilicate hydrate in geopolymer with KOH solution and KOH solution-water glass as activators. Furthermore, FTIR spectra indicated asymmetrical vibration of Si(Al)-O at around 1008 cm-1 related to geopolymer product.

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Bamboo has been widely used in Indonesia for construction, handicrafts, furniture and other uses. However, the use of bamboo as a biomass for renewable energy source has not been extensively explored. This paper describes the thermal and ash characterization of three bamboo species found in Indonesia, i.e. Gigantochloa apus, Gigantochloa levis and Gigantochloa atroviolacea. Characterization of bamboo properties as a solid fuel includes proximate and ultimate analyses, calorific value measurement and thermogravimetric analysis. Ash characterization includes oxide composition analysis and phase analysis by X-Ray diffraction. The selected bamboo species have calorific value comparable with wood with low nitrogen and sulphur contents, indicating that they can be used as renewable energy sources. Bamboo ash contains high silicon so that bamboo ash has potential to be used further as building materials or engineering purposes. Ash composition analysis also indicates high alkali that can cause ash sintering and slag formation in combustion process. This implies that the combustion of bamboo requires the use of additives to reduce the risk of ash sintering and slag formation.