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Free-volume hole size evaluated by positron annihilation lifetime spectroscopy in the amorphous part of poly ( ethylene a b s t r a c tChitosan is a linear copolymer composed of (1 / 4)elinked 2-acetamido-2-deoxy-b-D-glucan (GlcNAc) and 2-amino-2-deoxy-b-D-glucan (GlcN) units in varying proportions, having a high molecular weight and strong intra-and intermolecular hydrogen bondings. Sonication has become an alternative for degrading chitosan into low-molecular-weight chitosan (LMWC), chitosan oligomers and glucosamine. In this study, chitosan was treated with sonication at 40 C and 60 C for 30 min and 120 min with various acetic acid concentrations (0.2% v/ve1% v/v); the very-low-concentration acid solution functioned both as a solvent and catalyst. After sonication, the samples were tested for changes in molecular weight, water soluble proportion of chitosan (chitosan oligomers and glucosamine), degree of deacetylation, degree of crystallinity, and morphology. The soluble and insoluble product yields at low concentration (0.5% v/v) at 40 and 60 C were 33.66e39.37 % and 32.43e34.26%, respectively. The main product was 5-hydroxy methyl furfural with composition 92.16e99.43%. At high concentrations (1% v/v), the soluble product and insoluble yields were 43.72e49.74% and 43.1e50.26%, respectively. The main product was glucosamine with composition 77.75e93.16% of glucosamine. There were changes in the morphology and crystallinity of the degraded chitosan, but no change in the chemical structure. The crystallinity had a tendency to increase. The degree of deacetylation tended to decrease due to the glucosamine breakage.

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Coffee pulp waste composition consist of cellulose, hemicellulose, lignin, pectin and caffeine, tannin, and polyphenol as inhibitor substance. The high cellulose compound in coffee pulp can be used for alternative raw materials in the manufacture of biogas. This study aims to define the composition of the mixture of microorganisms of Pseudomonas putida, Trichoderma harzianum, and Aspergillus niger that are best to use in coffee pulp pretreatment to degrade inhibitor substance. The best result of pretreatment will be applied to biogas production. The first step is to do a pretreatment of the coffee pulp with variable Pseudomonas putida : Trichoderma harzianum : Aspergillus niger with a ratio of 1:1:1, 1:2:1, 1:1:2, 1:2:2, 2:1:1, 2:1:2, 2:1:1 (v:v:v), then variables that are most excellent in degrading inhibitor substance are selected. The second step, is doing anaerobic fermentation for 20 days at mesophilic temperature (30-40°C) on a reactor working volume of 4.5 L. In the making of biogas, a varied starter as much as 10% of the total are put into the reactor in the form of a mixture of cow dung : rumen fluid with a ratio of 1:0, 0:1, 1:1, 1:2, 2:1 (w/v). The parameters measured include the decreasing of the inhibitor substance, Chemical Oxygen Demand (COD), biogas (CH4 and CO2) and calorific value of combustion (Heating value). This study results a composition of ingredients within the pretreatment process which includes a mixture of microorganisms with a ratio of Pseudomonas putida : Trichoderma harzianum : Aspergillus niger is 1:2:1 (v:v:v). For biogas, a mixture of cow dung and rumen fluid can produce higher methane gas is the ratio of cow dung : rumen fluid is 1:2 (w/v) with the concentration of methane (CH4) formed at 1.825%. At the concentration of methane is 1.825%, the heating value obtained is 76.032 kcal/kg with volume biogas 0.0032 m3/ kg converted of COD.

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