Preparation, characterization and utilization of TiO2-SiO2 as photocatalyst for methyl violet (MV) decolorization has been conducted. In this research, preparation of TiO2-SiO2 was developed based on natural renewable silica source; rice husk ash (RHA) via a sol-gel technique. The composite was formed by the dispersing of titanium isopropoxide as titania precursor into the gel of silica followed by aging, drying and calcination. The TiO2-SiO2 sample was characterized by powder X-ray diffraction (XRD), diffuse reflectance-UV Visible spectrophotometric analysis (DRUV-Vis), gas sorption analyzer and Scanning electron micrograph (SEM) before its utilization as photocatalyst in methyl violet photooxidation. As comparison to the physicochemical character study, the synthesis of TiO2-SiO2 by using tetraethyl ortosilicate (TEOS) was performed as a confirmation. Result showed that prepared TiO2-SiO2 has the character similar to TiO2-SiO2 as synthesized by TEOS precursor. The formation of crystalline titania in anatase and rutile phase was identified with increasing surface porosity data and the value of band gap energy which sufficiently contribute to a photocatalytic mechanism. The character data are in line with the kinetic data of methyl violet decolorization. From the compared photooxidation, photolysis, photocatalysis and adsorption process, it can be concluded that TiO2-SiO2 acts efficiently as a photocatalyst.

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Southeast Asia is the region most heavily planted with oil palm tree in the world. As the third-ranking country producing palm oil, a large quantity of oil palm tree waste is generated in Thailand. Thailand's palm oil production achieves roughly 11-13 million tons or a matter of 1.2% of world production [1]. These biomass wastes may come from plantations (oil palm trunks and fronds) or palm oil mills (empty fruit bunches, mesocarp fiber, and palm kernel shells) [2]. Wastes such as trunks of the plant, fronds, and both male and female flower are direct agricultural wastes along pruning and harvesting seasons. Among the parts of the oil palm tree, male flowers are not currently used productively once they have matured. In the life-cycle of the palm tree, the male flower, which grows separately in a spike, fertilizes the female flowers. The oil palm is a monoecious plant with

Molybdenum oxide (20 wt. %) supported on nano hydroxyapatite mixed was prepared by impregnation method and calcinated at 400 o , 500 o , 600 o and 700 o C in static air atmosphere. The catalysts were characterized by thermogravimetry (TG), differential thermal analysis (DTA), X-ray diffraction (XRD), Transmission Electron Microscope (TEM) and nitrogen sorption measurements. The gas-phase oxidation of methanol to formaldehyde was carried out in a conventional fixed flow bed reactor. The obtained results clearly revealed that the formation of CaMoO 4 spinel nano particles was active and selective catalyst towards the formation of formaldehyde. The maximum yield of formaldehyde was 97% on the catalyst calcined at 400 o C. Moreover, the yield of formaldehyde was found unaffected by increasing the calcination temperature up to 700 o C. Keywords: MoO 3 ; nano hydroxyapatite support; structure; surface area; oxidation; methanol. IntroductionHydroxyapatite (HAP) has attracted the attention of researchers to biomaterials field in recent years [1]. HAP is a highly non-stoichiometric calcium phosphate compound with a Ca/P molar ratio ranging from 1.5 to 1.67. Moreover, HAP also is known [2] to have the character of both acidic and a basic catalyst when its Ca/P ratio is between 1.5 and 1.67. On the other hand, formaldehyde is obtained from oxidative dehydrogenation of methanol by two commercial processes: (i) On iron-molybdate based catalysts and (ii) On silver based catalysts. In both processes, a conversion of about 99 % and 92 % selectivity respectively are obtained the temperature of reaction is about 400 o C in the first and 650 o C in the second process. The silver process has high operating costs due to steam consumption. Moreover, the selective oxidation of methanol to formaldehyde takes place on MoO 3 mixed oxide catalysts [3,4]. However, the catalytic gas oxidation of methanol to formaldehyde over MoO 3 supported on nano hydroxyapatite to our knowledge has not yet been reported. Therefore, the main objective of the present work is synthesis of formaldehyde by oxidative dehydrogenation of methanol over MoO 3 (20 wt %) supported on n-HAP as a competitive catalyst with previous applied industrial catalysts.

RINGKASANHidrosol adalah produk samping distilasi minyak atsiri. Dalam dunia industri, keberadaan hidrosol tidaklah diperhatikan untuk rendemen minyaknya. Hidrosol merupakan cairan emulsi dari minyak yang terikat oleh molekul air. Dalam penelitian ini, hidrosol dipisahkan dengan tujuan untuk mendapatkan minyak yang dapat meningkatkan rendemen minyak atsiri.Pemisahan hidrosol dilakukan dengan metode elektrolisis. Dengan adanya elektron yang mengalir dari anoda, diharapkan agar tegangan antarmuka dari minyak dan air dalam hidrosol dapat terpisahkan. Metode elektrolisis dilakukan kimia minyak hasil elektrolisis. Minyak hasil distilasi diuji dengan GC-MS untuk dijadikan sebagai pembanding/standar. Elektrolisis hidrosol dilakukan dengan 3 (tiga) variabel, yakni jenis elektroda, waktu elektrolisis, dan besar tegangan. Optimasi dilakukan dari perlakuan eletrolisis hidrosol yang optimal. Minyak hasil elektrolisis diuji kembali dengan GC-MS dan dibandingkan dengan standar untuk melihat kualitasnya.Hasil elektrolisis menyatakan bahwa jenis elektroda yang paling baik adalah seng. Waktu elektrolisis optimal dengan menggunakan seng terjadi pada waktu 60 menit dengan besar tegangan 20V. Minyak hasil elektrolisis dengan elektroda seng hasil optimasi memberikan kualitas minyak yang lebih baik dari minyak hasil distilasinya. Hal ini dinyatakan secara kuat dari kadar patchouli alcohol dalam minyak hasil elektrolisis yaitu 36,40%, sedangkan dalam minyak hasil distilasi yakni 33,46%. Kadar patchouli alcohol mengalami kenaikan hingga 0,08%.