• 펄프종이기술
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• 제41권1호
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• pp.61-66
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• 2009

Effects of aqueous ammonia soaking treatments to yellow poplar (Liriodendron tulipifera L.) were investigated to focus on chemical compositional changes and enzymatic hydrolysis characteristics changes by this treatment. Treatment temperature and time were main variables. At 3 different levels of aqueous ammonia soaking temperature and time ($145^{\circ}C$ -1 h, $90^{\circ}C$ -16 h and $45^{\circ}C$ - 6 days), lower temperature and longer soaking time led to more xylan removal based on carbohydrate compositional analysis. However, at higher temperature treatment led to more enzymatic saccharification of cellulose to glucose by commercial cellulose mixtures (Celluclast 1.5L and Novozym 342 from Novozyme, Denmark). Cellulose hydrolysis was gradually increased with increasing enzymatic hydrolysis time but xylan hydrolysis was leveled out at early stage (less than 10 h) of enzymatic hydrolysis.

• Journal of the Korean Wood Science and Technology
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• 제37권4호
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• pp.381-387
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• 2009

본 연구는 암모니아수 침지 처리가 옥수수대의 화학 조성과 효소당화 특성에 미치는 영향에 대하여 연구한 것이다. 암모니아수 침지에서 처리 온도와 시간이 본 연구에서 주요 변수였다. 무 처리 분말과 침지 처리 분말의 전체 조성 분석과 탄수화물 조성 분석 결과, 3가지 다른 수준의 암모니아수 침지 조건($140^{\circ}C$ - 1 h, $90^{\circ}C$ - 16h 및 $50^{\circ}C$ - 6일)에서 고온 단기간 처리가 더 많은 양의 자이란과 리그닌을 용출시켰다. 암모니아 침지에 의한 자일란과 리그닌 용출 제거 효과가 고온 침지 처리 된 옥수수 줄기 분말에서 상업용 셀룰라아제를 사용하는 셀룰로오스와 자이란의 효소 당화를 촉진시켰다.

• 설비공학논문집
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• 제14권10호
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• pp.817-824
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• 2002

A diffusion absorption refrigerator is a heat-generated refrigeration system. It uses a three-component working fluid consisting of the refrigerant (ammonia), the absorbent (water) and the auxiliary gas (typically hydrogen). This system has no moving parts and the associated noise and vibration. In this study, the operating characteristics of diffusion absorption refrigerator are investigated through cycle modeling and simulation. System parameters considered in this study are the charged concentration of ammonia aqueous solution, the concentration difference between absorber inlet and outlet and the system pressure determined by the amount of auxiliary gas charged. It was found that there exists a critical value of concentration difference that maximizes the refrigerating capacity. And the lower the system pressure, the higher the refrigerating capacity.

• 대한화학회지
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• 제10권2호
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• pp.54-58
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• 1966

암모니아 溶液中에서 濕式酸化에 의하여 亞鉛鑛으로부터 亞鉛 및 黃을 抽出하였다. 암모니아의 濃度는 酸化率에 미치는 影響이 至大하여 反應溫度 및 濃度가 낮을 때는 亞鉛이 黃보다 浸出率이 低下함을 알았다. 그 含有量에 대하여 最高 Zn은 55%, S는 50% 浸出이 可能하였고 이 때의 條件은 다음과 같다. 加壓壓力;$4.2kg/cm_2$, 濃度; $60^{\circ}C$ 溶媒濃度;25%$NH_3$-sa-sol, 粒度;270mesh, 時間;20hr.

• Bulletin of the Korean Chemical Society
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• 제6권6호
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• pp.329-333
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• 1985

A procedure for the preparation of peptizable pseudoboehmite has been described in detail based upon a process of neutralization of an aqueous aluminum sulfate or chloride solution with aqueous ammonia. In order to obtain peptizable pseudoboehmite products, carefully controlled conditions were required in the whole processes of neutralization, aging, washing, and drying. The optimum conditions experimentally found are the following. The aluminum salt solution is neutralized with aqueous ammonia until the final pH of the solution reaches 10.0 to 10.8 or 9.0 to 9.3 for the sulfate of chloride, respectively. The alumina gel formed is subjected to aging at $80^{\circ}C for about 3 hours and washed with water more than 5 times to reduce the residual sulfate or chloride ion in the final products to less than 4%. The pseudoboehmite gel thus obtained should be dried oven at 80 to $100^{\circ}C for a few to several hours depending on the selected temperatures.

• 한국동물학회지
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• 제7권2호
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• pp.1-5
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• 1964

산소 용존하의 triglycine 수용액을 ${\gamma}-선으로$ 조사하여 carbonly 화합물, glycine, ammonia, ECO_2$ 및 수소를 검출하였다. 이 수용액계에서 일어나는 방사선화학반응을 초과정과 분해산물을 가지고 논의하였다. Triglycine 분자는 먼저 중간생성물을 이루게 되고 이것이 carbonyl 화합물과 acid amide 로 분해하게 된다. 이들은 일차적 또는 이차적으로 free radical 의 작용에 의하여 acetamide, glycie, glyoxylic acid, formic acid, oxalic acid, ammonia 및 ECO_2$ 로 분해하게 된다. 또한 radical-radical 결합에 의하여 생성물이 생길 미확인반응의 가능성도 있으며 타당한 물질평행은 앞으로의 연구에 기대한다.

• Korean Chemical Engineering Research
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• 제53권6호
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• pp.682-689
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• 2015

A two-step process was investigated for pretreatment and fractionation of rice straw. The two-step fractionation process involves first, soaking rice straw in aqueous ammonia (SAA) in a batch reactor to recover lignin-rich hydrolysate. This is followed by a second-step treatment in a fixed-bed flow-through column reactor to recover xylo-oligomer-rich hydrolysate. The remaining glucan-rich solid cake is then subjected to an enzymatic process. In the first variant, SAA treatment in the first step dissolves lignin at moderate temperature (60 and $80^{\circ}C$), while in the second step, hot-water treatment is used for xylan removal at higher temperatures ($150{\sim}210^{\circ}C$). Under optimal conditions ($190^{\circ}C$ reaction temperature, 30 min reaction time, 5.0 ml/min flow rate, and 2.3 MPa reaction pressure), the SAA-hot-water fractionation removed 79.2% of the lignin and 63.4% of the xylan. In the second variant, SAA was followed by treatment with dilute sulfuric acid. With this process, optimal treatment conditions for effective fractionation of xylo-oligomer were found to be $80^{\circ}C$, 12 h reaction time, solid-to-liquid ratio of 1:12 in the first step; and 5.0 ml $H_2SO_4/min$, $170^{\circ}C$, and 2.3 MPa in the second step. After this two-step fractionation process, 85.4% lignin removal and 78.9% xylan removal (26.8% xylan recovery) were achieved. Use of the optimized second variant of the two-step fractionation process (SAA and $H_2SO_4$) resulted in enhanced enzymatic digestibility of the treated solid (99% glucan digestibility) with 15 FPU (filter paper unit) of CTec2 (cellulase)/g-glucan of enzyme loading, which was higher than 92% in the two-step fractionation process (SAA and hot-water).

• Bulletin of the Korean Chemical Society
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• 제19권1호
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• pp.128-131
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• 1998

• Bulletin of the Korean Chemical Society
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• 제18권2호
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• pp.226-229
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• 1997

• 공업화학
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• 제8권1호
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• pp.23-28
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• 1997

활성탄에 의한 암모니아 구리착물의 흡착 특성에 대하여 연구하였다. 활성탄 비표면적을 BET 흡착장치에서 측정하였고, 암모니아수용액에서 암모니아 착물을 이용하여 Cu(II)이온 제거 특성과 활성탄에 의한 착물흡착에서 암모니아착물 형태에 대하여 연구하였다. 실험 결과 비표면적 크기는 mesh No.가 감소할 수록 증가하였고, 활성탄에 의한 Cu(II)이온 흡착은 pH 6 범위가 적합함을 알았다. 또한 암모니아수용액에서 암모니아 구리착물이 활성탄에 흡착되는 형태는 $[Cu(NH_3){_2}]^{2+}$와 $[Cu(NH_3){_3}]^{2+}$로 흡착됨을 알았으며, 암모니아 농도는 $2.25{\times}10^{-4}{\sim}2.25{\times}10^{-3}(mol/{\ell})$ 범위에서 검토하였다.