Cellulose has experienced a renaissance as a precursor for carbon fibers (CFs). However, cellulose possesses intrinsic challenges as precursor substrate such as typically low carbon yield. This study examines the interplay of strategies to increase the carbonization yield of (ligno-) cellulosic fibers manufactured via a coagulation process. Using Design of Experiments, this article assesses the individual and combined effects of diammonium hydrogen phosphate (DAP), lignin, and CO2 activation on the carbonization yield and properties of cellulose-based carbon fibers. Synergistic effects are identified using the response surface methodology. This paper evidences that DAP and lignin could affect cellulose pyrolysis positively in terms of carbonization yield. Nevertheless, DAP and lignin do not have an additive effect on increasing the yield. In fact, combined DAP and lignin can affect negatively the carbonization yield within a certain composition range. Further, the thermogravimetric CO2 adsorption of the respective CFs was measured, showing relatively high values (ca. 2 mmol/g) at unsaturated pressure conditions. The CFs were microporous materials with potential applications in gas separation membranes and CO2 storage systems.

Isroaniso matrix precursor synthesized from commercially available petroleum pitch was stabilized in air. The influence of oxygen mass gain during stabilization on the yield of matrix precursor was studied. Additionally, the influence of pressure on the yield of the stabilized matrix precursor in a real system was studied. The fourier transform infrared spectrometry (FTIR), thermogravimetric analysis (TGA), yield, yield rate, and yield impact were used to check the effect of stabilization and pressure on the yield of the matrix precursor and the end properties of the composite thereafter. The results showed that the yield increased with stabilization duration up to 20 h whereas it decreased for stabilization duration beyond 20 h. Further results showed that the stabilized matrix precursor for a duration of 5 h could withstand almost two-fold greater hot-pressing pressure without resulting in exudation as compared to that of a 1 h stabilized matrix precursor. The enhanced hot-pressing pressure significantly improved the yield of the matrix precursor. As a consequence, the densification and mechanical properties were increased significantly. Further, the matrix precursor stabilized for a duration of 20 h or more failed to provide proper and uniform binding of the reinforcement.

본 연구에서는 초임계 CO2 추출법을 이용하여 공정변수가 대두유의 수율에 미치는 영향과 초고압 처리가 초임계 추출에 미치는 영향에 대하여 분석하였다. RSM 실험법을 통한 최적화 실험에서 468.18 bar, 80.23oC, 46.82 g/min의 조건에서 최대값 25.88%를 나타내었다. 초임계 추출법의 최적추출조건에서 초고압 전처리 후 추출 수율은 17.15-23.66%로 전처리 전보다 감소하는 경향을 나타내었다. 462.13MPa, 1분의 추출조건에서 정상점은 최대값으로 24.91%가 예측되었다. 초고압 전처리 후 초임계 추출에서 수율이 증가하지 않은 이유는 초고압 전처리시 입자의 뭉침현상이 일어나 평균입자크기가 증가하여 나타난 현상으로 추론하였다. 결과적으로 초고압 전처리는 초임계 추출 수율 증가에 영향을 미치지 못하는 것을 알 수 있었다. 초임계 CO2 추출법을 이용하여 대두유를 추출할 경우 추출 압력, 유량이 높을수록 추출온도가 낮을수록 더 많은 양의 대두유를 추출할 수 있다.

This study evaluated the effect of organic fertilizer on the yield of sesame and the movement of nitrogen and carbon in soil under mulching cultivation. The seven fertilizer treatments investigated are as follows: 1) 8-4-9 kg N-P2O5-K2O 10a-1-control, 2) 80% of control treatment N from mixed expeller cake (MEC)-MEC 80%, 3) 100% of control treatment N from MEC-MEC 100%, 4) 80% of control treatment N from mixed organic fertilizer (MOF)MOF 80%, 5) 100% of control treatment N from MOF-MOF 100%, 6) 80% of control treatment N from latex coated urea complex fertilizer (LCU)-LCU 80%, and 7) no nitrogen. The soil mineral N available in the applied organic MEC and MOF fertilizers was less than the available N in the applied urea fertilizer during the early growth stage of sesame but the amount was observed to increase with time. The concentration of nitrate-N in leached solution 35 days after application was highest at 75 mg l-1 in the control, followed in descending order by MEC 100%, MOF 100%, LCU 80%, MOF 80% and MEC 80%. The concentration of nitrate-N in the leachate in all treatments was observed to rapidly decrease 45 days after fertilizer application and recorded at less than 20 mg l-1 65 days after application. The concentration of dissolved organic carbon in the leached solution and organic carbon in the soil of the organic fertilizer plots was higher than in the urea- and LCU-fertilized plots during the whole growing period. The yields of sesame applied with MEC and MOF organic fertilizers were 2 to 7% higher than those fertilized with urea. The amount of retained mineral N or organic carbon in the soil is higher in the LCU and organic fertilizer plots than in the urea-fertilized treatments, which resulted in the reduction of nitrate leaching, increasing N efficiency and sesame yield.