Ethylene is a compound produced naturally by fruit that can accelerate the maturity of the fruit. Controlling ethylene gas as a product of metabolism of fruit during storage will prolong the shelf life of the fruit. Controlling ethylene gas is carried out by adsorption process using carbon-impregnated cobalt oxide. In this study, carbon as a support made by pyrolysis of extraction waste of mangosteen peel at a temperature of  850°C for 15 minutes. Furthermore, the process of impregnating of cobalt oxide into the carbon pore network was carried out by using the incipient wetness impregnation method by adding a cobalt salt solution into the carbon pore network,  followed by heating at a temperature of 110oC for 8 hours and calcination at a temperature of 200oC for 6 hours. Ethylene adsorption test performed at 30°C using a static volumetric test. While Cavendish banana fruit preservation process was carried out at ambient temperature (20-32oC) by observing the changing of skin color from day to day. Adsorption test results showed that the ethylene uptake increased with the increasing of the composition of cobalt oxide on the carbon surface. The highest ethylene uptake of 6.094 mmol/(gram of adsorbent) was obtained from adsorption of ethylene using carbon-impregnated 30% cobalt oxide. Fruit preservation process indicated that the increasing of amount of adsorbent can improve the shelf life of bananas Cavendish. The highest result was obtained from the addition of 15 grams of carbon-impregnated cobalt oxide and silica gel that can extend the shelf life of bananas Cavendish for 15 days.   Keywords: adsorption; carbon;  cobalt oxide;  ethylene; impregnation Abstrak Etilen merupakan senyawa yang dihasilkan secara alami oleh buah yang dapat mempercepat kematangan pada buah. Pengontrolan gas etilen sebagai produk metabolisme buah selama penyimpanan akan memperpanjang masa simpan buah tersebut. Pengontrolan gas etilen dilakukan dengan proses adsorpsi menggunakan karbon teremban oksida cobalt. Pada penelitian ini, karbon sebagai pengemban dibuat dari pirolisis limbah kulit manggis sisa ekstraksi pada suhu 850oC selama 15 menit. Selanjutnya, proses pengembanan oksida cobalt pada permukaan karbon dibuat melalui proses impregnasi dengan incipient wetness method yang dilakukan dengan menambahkan larutan garam cobalt ke dalam jaringan pori karbon yang dilanjutkan dengan pemanasan pada suhu 110oC selama 8 jam dan kalsinasi pada suhu 200oC selama 6 jam. Uji adsorpsi etilen dilakukan pada suhu 30oC menggunakan alat uji static volumetric. Sedangkan proses pengawetan buah pisang Cavendish dilakukan pada suhu lingkungan (20 – 32oC) dengan mengamati perubahan warna kulitnya dari hari ke hari. Hasil uji adsorpsi menunjukkan bahwa semakin banyak komposisi oksida cobalt pada permukaan karbon akan meningkatkan kapasitas penjerapan terhadap etilen. Hasil tertinggi sebesar 6,094 mmol/(gram adsorben) diperoleh dari adsorpsi etilen menggunakan karbon teremban 30% oksida cobalt. Dari proses pengawetan buah menunjukkan bahwa jumlah karbon teremban oksida cobalt yang semakin meningkat dapat meningkatkan umur simpan dari buah pisang Cavendish. Hasil tertinggi diperoleh dari penambahan 15 gram karbon teremban cobalt dan silica gel dapat memperpanjang umur simpan buah pisang Cavendish selama 15 hari. Kata kunci: adsorpsi; karbon; oksida cobalt; etilen; impregnasi

Abstract.Mangosteen rind is an important source of natural antioxidants. Due to the growing interest in extracting this anti cancer substances from the mangosteen rind, the amount of this lignocellulosic residu has been generated significantly as byproduct. In this research, extraction-waste mangosteen rind (EMP) was used as alternative precusor for production of carbon-based adsorbent for ethylene removal. Steam was used as activating agent and the effect of carbonization time and temperature on the development of pore structure were examined. Pyrolysis process was carried out by heating the mangosteen rinds powder (180 μm -355 μm) from ambient temperature up to carbonization temperature of 848 K and kept for 3 hours then followed by heating up to 1123 K and kept for 15 minutes under flowing N2 and steam. This process was repeated for several pyrolysis temperature (1053 K, 1073 K, 1083 K and 1103 K) and carbonization time (0 hours, 1 hour, 2 hours, and 3,5 hours). The carbon obtained was characterized in terms of its pore structure and ethylene uptake capacity. The results show that porous carbon obtained from pyrolysis of extraction-waste mangosteen rind can be characterized as mesoporous carbon. The highest surface area of 1080 m 2 /g was obtained from pyrolysis of extraction-waste mangosteen rinds with carbonization time of 3.5 hours and pyrolysis temperature of 1123 K. Furthermore, the mesopore portion and the specific surface area increased with the increasing carbonization time. From the ethylene uptake experiment, it was noted that the ethylene adsorption capacity of EMPC is 40.12 cm 3 /g.

An experiment on Fenton degradation of sugarcane vinasse was carried out to determine its effect on the wastewater characteristics. Vinasse, a by-product of distillation in the bioethanol industry, contains high organic matter, as the value of chemical oxygen demand (COD) is >100,000 mg/L and BOD 5 is 31,250 mg/L. The Fenton reaction is one of the advanced oxidation process (AOP) methods which has been widely applied for the treatment of wastewater containing organic pollutants and contaminants. This method utilizes hydroxyl radical ( • OH) produced from the catalyzing reaction between Fe 2+ or Fe 3+ and hydrogen peroxide. The effect of pH, the ratio of [H 2 O 2 ] and [COD], and the ratio of [H 2 O 2 ] to [Fe 3+ ] were studied in this research to evaluate the Fenton reaction. Results from this experiment showed that treatment of vinasse using the Fenton reaction decreased the COD value to 48.10%, and its biodegradability enhanced almost two times at a pH value of 3.8, a ratio of [H 2 O 2 ] to [COD] of 0.62, and a ratio of [H 2 O 2 ] to [Fe 3+ ] of 50 (g/g), which demonstrated that the Fenton treatment was effective to reduce organic matter of sugarcane vinasse. Three kinetic models (first order, second order, and Behnajad-Modirshahla-Ghanbery (BMG) kinetic model) were used to evaluate the degradation of the COD value. On the basis of the value of R 2 (coefficient of determination), we suggested that BMG represented the best kinetic model. This study finds that the Fenton treatment is able to mitigate the environmental impacts of sugarcane vinasse.

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