Characterization of the Dynamic Properties of Natural Rubbers Coagulated Using Different Methods

Tianming Gao,Ruihong Xie,Linghong Zhang,Puwang Li,Hongxing Gui,Maofang Huang,Kyungho Chung(정경호) 한국고분자학회 2016 폴리머 Vol.40 No.3

천연고무 라텍스를 아세트산을 사용한 응고(A-NR), 자연 응고(N-NR) 및 미생물을 사용한 응고(M-NR) 등 다른 방법들로 응고하였고, 이들의 가교도, 가교특성, 동적특성 및 열축적 특성 등을 조사하였다. 결과에 따르면 MNR의 경우 가장 높은 가교도와 가장 빠른 경화속도를 나타냈으며, A-NR은 정 반대인 가장 낮은 가교도와 가장 느린 경화속도를 나타내었다. 이들 고무의 동적특성은 rubber process analyzer(RPA), dynamic mechanical analyzer(DMA) 및 압축 열축적 분석방법 등을 이용하여 측정하였다. 동적특성은 고무의 가교도와 매우 밀접한 관계가 있었음을 알 수 있었고, 손실계수는 M-NR이 가장 낮았으며 A-NR의 경우는 가장 높은 값을 나타내었다. Natural rubber (NR) was coagulated using different methods, i.e., acid coagulation with acetic acid (A-NR), natural coagulation (N-NR), and microorganism coagulation (M-NR). The crosslink density, vulcanization properties, dynamic properties, and heat build-up were investigated. The results showed that M-NR had the highest crosslink density and fastest cure rate, and A-NR had the lowest crosslink density and slowest cure rate. The dynamic properties were measured using a rubber process analyzer, dynamic thermomechanical analysis and compression heat build-up tester; the results showed that the dynamic properties had a close relationship with the crosslink density. The loss factor was lowest for M-NR and highest for A-NR.

Production of Polyhydroxyalkanoates (PHA) by Haloferax mediterranei from Food Waste Derived Nutrients for Biodegradable Plastic Applications

( Ke Wang ),( Ruihong Zhang ) 한국미생물생명공학회(구 한국산업미생물학회) 2021 Journal of microbiology and biotechnology Vol.31 No.2

Polyhydroxyalkanoates (PHA) are a family of microbial polyesters that are used as biodegradable plastics in replacement of conventional plastics for various applications. However, the high production cost is the barrier for PHA market expansion. This study aimed to utilize food waste as low-cost feedstock to produce poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by Haloferax mediterranei. The effects of acetate (Ac), propionate (Pr), butyrate (Bu), and the short-chain carboxylates derived from food waste were examined on the microbial growth and PHBV production. Results showed that a mixture of carboxylates provided a 55% higher PHBV yield than glucose. The food-waste-derived nutrients achieved the yields of 0.41 to 0.54 g PHBV/g Ac from initial loadings of 450 mg/l to 1,800 mg/l Ac of total carboxylates. And the consumption of individual carboxylate varied between different compositions of the carbon source. The present study demonstrates the potential of using food waste as feedstock to produce PHBV by Haloferax mediterranei, which can provide economic benefits to the current PHA industry. Meanwhile, it will also help promote organic waste reduction in landfills and waste management in general.

牛糞 堆肥化時 空氣注入率이 산소 및 황화합물 가스 排出에 미치는 影響

강항원(Hang-Won Kang),Ruihong Zhang,이인구(In-Koo Rhee) 한국토양비료학회 2000 한국토양비료학회지 Vol.33 No.6

밀폐형 Bench - scale reactor 에서의 우분 퇴비화시 Aeration 이 생물학적 활성에 미치는 영향

이인구,강항원,박향미,고지연,Zhang, Ruihong,박경배 한국환경농학회 1998 한국환경농학회지 Vol.17 No.3

밀폐형 bench-scale reactor(242ℓ)에 thermocouples, oxygen sensor 및 datalogger 등을 연결하여 우분과 볏짚 혼합물의 퇴비화 촉진 및 양질의 퇴비생산을 위한 기초자료를 얻고자 공기주입량(0.09, 0.18, 0.90, 1.79ℓmin^(-1)㎏ dry solids^(-1))에 따른 생물학적 활성 변수들의 일시적이고 공간적인 변화를 모니터링한 결과는 다음과 같았다. 공기주입량이 높을수록 퇴비화 초기 및 뒤집기 이후 단계 모두 부숙온도의 증가 및 감속속도가 빨랐고 퇴적물과 배출공기의 온도차이는 적었으며, 모든 처리에서 퇴적물의 경우 50∼53℃에서 약 5시간 동안, 배출공기는 45℃에서 약 5∼15시간 동안 온도정지기를 보인 후 다시 증가하는 경향을 보였다. 최대온도는 퇴비화 초기단계에서는 공기주입량이 많을수록 감소하였지만 뒤집기 이후 단계에서는 1.79ℓmin^(-1)㎏^(-1)처리를 제외하고는 그 반대 경향이었으며, 퇴적물의 최고온도 도달시간은 초기 및 뒤집기 이후 단계 모두 공기주입량이 적을수록 늦었다. 45℃이상의 고온 유지시간은 공기주입량이 증가할수록 급격히 감소하였고, 퇴비화 초기단계에 있어서 0.09 및 0.18ℓmin^(-1)㎏^(-1) 처리는 45∼54.9℃의 유지시간이 가장 길었다. 배출공기의 최저 산소농도 및 최대 산소비율은 공기주입량이 많을수록 높아지는 경향이었으나 그 수준에 도달하는 시간은 일정한 경향이 없었다. This experiment used the enclosed bench-scale reactors of 242 liters was conducted to obtain basic data on temporal and spatial variations in temperature, oxygen and moisture content, which were important factors of biological activities, during composting of mixture of dairy manure and rice straw. The reactors with thermocouples, oxygen sensor and datalogger were aerated at four different rates of 0.09, 0.18, 0.90 and 1.79ℓmin^(-1) ㎏ dry solids^(-1). The higher aeration rates were, the faster the rates of increase and decrease in composting temperature were in both of initial and turnover stage, and the smaller the temperature difference between exhaust air and composting materials. Composting temperature of initial stage increased suddenly in all aeration rates, then stationary phase of temperature in materials and exhaust air showed at 50∼53℃ for 5 hours and at 45℃ between 5 and 15 hours, respectively. In initial stage the maximum temperature was decreased with increasing aeration rates but in the stage after turnover it was the opposite except for 1.79ℓmin^(-1)㎏^(-1). Time arrived at the maximum temperature of composting materials was later in low-aeration rates than high-aeration rates at both stages. Time maintained high-temperature more than 45℃ was rapidly decreased with increasing aeration rates. In initial stage of composting maintaining time of 65℃ or more was the longest in the treatments of 0.09 and 0.18ℓmin^(-1)㎏^(-1), while those of 55∼65℃ and 45∼55℃ was in 0.90 and 1.79ℓmin^(-1)㎏^(-1), respectively. The minimum oxygen content and the maximum oxygen consumption rate in exhaust air through composting materials showed the increased trends with increasing aeration rates. In initial stage the minimum oxygen content was ranged from 0.9% to 7.4% for 32 to 59.5 hours and the maximum oxygen consumption rate was 1.89∼6.48gh^(-1)㎏VS^(-1). In the stage after turnover their levels were 2.1∼19.9% and 1.76∼3.49g/h-㎏ VS, respectively, for 16 to 49.5 hours.

Biological Treatment of Kitched Food Waste with Sequencing Batch Reactors

Kim, Sang Hun,Zhang, Ruihong 한국농업기계학회 2003 Agricultural and Biosystems Engineering Vol.4 No.1

The performance of an integrated ASBR-SBR(Anaerobic Sequencing Batch Reactor-Sequencing Batch Reactor) system was studied for treating the kitchen food waste(KFW). A simulated KFW was a mix of boiled rice, cooked meat, and fresh Chinese cabbage at weight percentage ratio of 10:10:80. The biogas yield was 0.88, 0.66, 1.00 L/g VS for Chinese cabbage, boiled rice, and cooked meat, respectively. A solid retention time (SRT) of at least 15 days should be provided in the reactor to obtain 95% of biogas production. The ASBR was highly effective in treating KFW, achieving up to 70% TS removal and 84% VS removal. The biogas yield was 0.51 to 0.64 L/g VSfed for the loading rate of 0.9 to 3.5 gVS/L/day. The SBR was capable of oxidizing 83% of ammonia nitrogen into nitrite and nitrate.

Microstructure and Properties of 2Cr13-xMo Stainless Steels Fabricated by Direct Laser Deposition

Jing Liang,Ziyang Lin,Xiuyuan Yin,Suiyuan Chen,Changsheng Liu,Ruihong Chai,Hongwei Zhang,Guangquan Tang,Kun Tian 대한금속·재료학회 2022 METALS AND MATERIALS International Vol.28 No.1

In this paper, 2Cr13 stainless steels with diferent Mo contents (x=0 wt%, 0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%) were fabricated by Direct Laser Deposition (DLD) technology. The efects of Mo element on the microstructure evolution and comprehensive properties such as corrosion resistance and wear resistance of 2Cr13 stainless steel were investigated in detail. The results showed that the microstructure for the DLD 2Cr13 stainless steel was mainly composed of martensite, ferrite,and a small amount of Mo2C and Cr23C6 carbides. With the content of Mo increased from 0.5 to 1.5 wt%, the martensiticmicrostructure was refned and more dispersed Mo2C and Cr23C6 carbides were formed. The average microhardness andcorrosion resistance of the DLD 2Cr13-xMo were increased with the Mo content increased from 0 to 1.0 wt%, and thendecreased when the Mo content exceeded 1.0 wt%. For the DLD 2Cr13-1.0 wt% Mo, the average microhardness reachedup to 620 HV0.2, and the highest corrosion resistance (self-corrosion potential − 0.34 V) was obtained, in which the selfcorrosion potential was 0.05 higher than that of DLD 2Cr13 stainless steel. The wear resistance of the DLD 2Cr13-xMogradually increased with the increase of the Mo, the wear mass loss of DLD 2Cr13-xMo (x=1.0 wt%) was only 37% thatof DLD 2Cr13 stainless steel.

Changes in physicochemical properties and gaseous emissions of composting swine manure amended with alum and zeolite

Jusiedave Melendez Bautista,오영숙,Hyosun Kim,Dae-Hee Ahn,Ruihong Zhang 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.1

Ammonia emissions from composted swine manure and the resulting physicochemical changes were monitored to determine the effectiveness of adding alum and zeolite during the composting process, as well as the most effective addition method. The two amendments reduced ammonia emissions 85-92%, with the finished compost retaining three-fold more NH_4^+-_N than the unamended control. The addition of zeolite sequestered 44% of the retained NH_4^+-_N at zeolite exchange sites. The addition of amendments did not appear to significantly affect microbial activity, because the patterns of CO_2 emissions, total organic carbon (TOC) reduction, and the ratio of humic acid to TOC of amended and unamended composts were very similar. The final respiration rates and Solvita^® maturity index indicated that the finished compost was well matured and aged. Alum has a high potential to reduce ammonia emissions and concomitantly enhance fertilizer N value. Zeolite further reduces ammonia emissions, and improves fertilizer quality, by serving as a slow-release N source.

Immobilization of Diatom Phaeodactylum tricornutum with Filamentous Fungi and Its Kinetics

Barzee Tyler J.,El-Mashad Hamed M.,Burch Andrew R.,Franz Annaliese K.,Zhang Ruihong 한국미생물·생명공학회 2023 Journal of microbiology and biotechnology Vol.33 No.2

Immobilizing microalgae cells in a hyphal matrix can simplify harvest while producing novel mycoalgae products with potential food, feed, biomaterial, and renewable energy applications; however, limited quantitative information to describe the process and its applicability under various conditions leads to difficulties in comparing across studies and scaling-up. Here, we demonstrate the immobilization of both active and heat-deactivated marine diatom Phaeodactylum tricornutum (UTEX 466) using different loadings of fungal pellets (Aspergillus sp.) and model the process through kinetics and equilibrium models. Active P. tricornutum cells were not required for the fungal-assisted immobilization process and the fungal isolate was able to immobilize more than its original mass of microalgae. The Freundlich isotherm model adequately described the equilibrium immobilization characteristics and indicated increased normalized algae immobilization (g algae removed/g fungi loaded) under low fungal pellet loadings. The kinetics of algae immobilization by the fungal pellets were found to be adequately modeled using both a pseudo-second order model and a model previously developed for fungal-assisted algae immobilization. These results provide new insights into the behavior and potential applications of fungal-assisted algae immobilization.

Development of a Serial Bioreactor Systemfor Direct Ethanol Production from StarchUsing Aspergillus niger and Saccharomyces cerevisiae

안대희,박두현,전보영,Soo Jin Kim,Dae Hee Kim,Byung Kwan Na,Hung Thuan Tran,Ruihong Zhang 한국생물공학회 2007 Biotechnology and Bioprocess Engineering Vol.12 No.5

Aspergillus niger hyphae were found to grow with unliquefied potato starch under aerobic conditions, but did not grow under anaerobic conditions. The raw culture of A. niger catalyzed saccharification of potato starch to glucose, producing approximately 12 g glucose/L/day. The extracellular enzyme activity was decreased in proportion to incubation time, and approximately 64% of initial activity was maintained after 3 days. At 50℃, A. niger hyphae growth stopped, while the extracellular enzyme activity peaked. On the basis of the A. niger growth property and enzyme activity, we designed a serial bioreactor system composed of four different reactors. Fungal hyphae were cultivated in reactor I at 30℃, unliquefied starch was saccharified to glucose by a fungal hyphae culture in reactors II and III at 50℃, and glucose was fermented to ethanol by Saccharomyces cerevisiae in reactor IV. The total glucose produced by fungal hyphae in reactor I and saccharification in reactor II was about 42 g/L/day. Ethanol production in reactor IV was approximately 22 g/L/day, which corresponds to about 79% of the theoretical maximum produced from 55 g starch/L/day.

Development of a Serial Bioreactor System for Direct Ethanol Production from Starch Using Aspergillus niger and Saccharomyces cerevisiae

Jeon, Bo-Young,Kim, Soo-Jin,Kim, Dae-Hee,Na, Byung-Kwan,Park, Doo-Hyun,Tran, Hung Thuan,Zhang, Ruihong,Ahn, Dae-Hee Korean Society for Biotechnology and Bioengineerin 2007 Biotechnology and Bioprocess Engineering Vol.12 No.5

Aspergillus niger hyphae were found to grow with unliquefied potato starch under aerobic conditions, but did not grow under anaerobic conditions. The raw culture of A. niger catalyzed saccharification of potato starch to glucose, producing approximately 12 g glucose/L/day. The extracellular enzyme activity was decreased in proportion to incubation time, and approximately 64% of initial activity was maintained after 3 days. At $50^{\circ}C$, A. niger hyphae growth stopped, while the extracellular enzyme activity peaked. On the basis of the A. niger growth property and enzyme activity, we designed a serial bioreactor system composed of four different reactors. Fungal hyphae were cultivated in reactor I at $30^{\circ}C$, unliquefied starch was saccharified to glucose by a fungal hyphae culture in reactors II and III at $50^{\circ}C$, and glucose was fermented to ethanol by Saccharomyces cerevisiae in reactor IV. The total glucose produced by fungal hyphae in reactor I and saccharification in reactor II was about 42 g/L/day. Ethanol production in reactor IV was approximately 22 g/L/day, which corresponds to about 79% of the theoretical maximum produced from 55 g starch/L/day.