The main focus of this article was to investigate the potential of natural zeolite adsorbent for the removal of CO 2 and H 2 S in biogas produced from palm oil mill effluent (POME) in fixed-bed column adsorption. The effects of the flowrates and dosage of the adsorbent on the CO 2 adsorption were also studied. The surface area of the adsorbent was determined using the Brunauer, Emmett, and Teller (BET) model, while the pore size distribution was calculated according to the Barrett, Joyner, and Halenda (BJH) model. The morphology of the adsorbent was determined by field emission scanning electron microscopy and energy dispersive x-ray (FESEM-EDX) analysis. Before and after purification, the biogas was analyzed by gas chromatography with a thermal conductivity detector and polydimethylsiloxane as a column. Biogas from the POME, via the anaerobic digestion process, produced 89% CH 4 and 11% CO 2 . The surface and structure of the clinoptilolite zeolites was modified by a strong acid (1M HCl), strong base (1M NaOH), and calcination at 450C, and the surface area of the natural zeolites was reduced up to 16%. The working capability of CO 2 adsorption by the modified zeolites decreased with increasing flow rates (100, 200, and 300 mL/min) of the biogas, with levels of CO 2 at 106,906, 112,237, and 115,256 mg/L. The removal of the CO 2 in the biogas by using adsorbent dosages of 1.5, 2.0, and 2.5 g was 97,878, 97,404 and 93,855 mg/L, respectively. The optimum purification of the biogas occurred under the flow rate of 100 mL/min and adsorbent dosage of 2.5 g. The high working capability of the modified zeolites for the removal of CO 2 in the biogas was a key factor, and the most important characteristic for the adsorbent. The results indicate that clinoptilolite zeolites are promising adsorbent materials for both the purification and upgrading of biogas.

The production of natural hydroxyapatite (HAp) specifically from cortical bovine bones and natural calcite was studied in this paper. Bovine hydroxyapatite (BHA) was produced from bovine bone in bulk form by de-fatting continued with calcination at 900°C. Natural calcite hydroxyapatite (CHA) was produced by hydrothermal method. It was confirmed from XRD, FTIR, and SEM results that HA have been successfully produced from natural sources like bulk bovine bone and natural calcite. The results also show that the crystallinity of BHA is higher than CHA, matching with the hardness test results of sintered BHA and CHA.

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We have studied utilization of essential clove oil, extracted from clove buds by hydrodistillation, as preservative in edible packaging technology. Preservative of essential clove oil was applied on chopped papaya fruits by using two methods, namely spray and brush. The effects of concentration of clove oil from 0.05 to 0.20% on the preservation of papaya fruits (Carica papaya L.) at room temperature (25 °C) were also evaluated. Physicochemical and in vitro microbiological activities on the papaya fruits that were stored at 25 o C and 85-90% relative humidity were investigated in details. The results indicate that the clove oil at concentration ≥0.10% suppressed the decay time, 10% weight loss, 0.03 g citric acid/100 g in acidity titration test, and 20% pH value from those of control sample of papaya fruits kept in a storage. The population of fungi and bacteria were efficiently reduced by 90% when the clove oil at concentration ≥0.10% was applied as preservative on papaya fruits. This finding suggested that the extracted essential clove oil acted as effective antifungal and antibacterial agents. Preservative by essential clove oil improved the quality of fruits to extend the product shelf life and to reduce the risk of microbial growth on fruits surface. AbstrakPeningkatan Kualitas Carica papaya L. dengan Minyak Cengkeh sebagai Pengawet dalam Teknologi Lapisan yang Dapat Dimakan. Peneliti telah mempelajari pemanfaatan minyak atsiri cengkeh, yang merupakan ekstrak dari tunas cengkeh dari proses hidrodistilasi, sebagai pengawet dalam teknologi kemasan yang dapat dimakan. Pengawet atsiri cengkeh diberikan pada buah pepaya cincang dengan menggunakan dua metode, yaitu menggunakan alat penyemprot dan kuas. Efek dari konsentrasi minyak cengkeh 0,05-0,20% pada penyimpanan buah pepaya (Carica papaya L.) pada suhu kamar (25 °C) juga dievaluasi. Kegiatan fisiokimia dan mikrobiologi in vitro pada buah pepaya yang disimpan pada 25 °C dan kelembaban relatif 85-90% diselidiki secara rinci. Hasil menunjukkan bahwa minyak cengkeh pada konsentrasi ≥0,10% menekan waktu peluruhan, penurunan berat badan 10%, 0,03 g asam sitrat/100 g dalam tes keasaman titrasi, dan 20% nilai pH dari sampel kontrol buah pepaya di dalam tempat penyimpanan. Populasi jamur dan bakteri yang turun 90% ketika minyak cengkeh lebih dari 0,10% digunakan sebagai pengawet pada buah pepaya. Temuan ini menunjukkan bahwa ekstrak minyak atsiri cengkeh merupakan agen anti-jamur dan anti-bakteri yang efektif. Pengawetan dengan minyak atsiri cengkeh meningkatkan kualitas buah-buahan, memperpanjang umur simpan produk, dan mengurangi risiko pertumbuhan mikroba pada permukaan buah.