탈황더스트를 활용한 중탄산나트륨 제조시 탄산나트륨이 미치는 효과

임채현 국립순천대학교대학원 2024 국내박사

기후변화는 사람의 활동으로 인하여 온실가스의 농도가 변함으로써 상당 기간 관찰되어 온 자연적인 기후변동에 추가적으로 일어나는 기후체계의 변화를 말한다. 이산화탄소(CO2)는 기후변화를 야기하는 주범으로 알려져 있다. 전 세계적으로 이산화탄소를 저감시키고 2050년까지 탄소중립(Net-Zero)을 실현 시키기 위해 다각적으로 많은 노력을 기울이고 있다. 이를 달성하기 위한 핵심 기술로 탄소 포집, 이용 및 저장(CCUS, Carbon Capture, utilization and storage)이 각광을 받고 있다. 다양한 산업공정 중 중탄산나트륨(NaHCO3) 생산은 이산화탄소 감소와 경제 적 이윤을 통시에 충족시키는 대표적인 탄소 포집, 이용 및 저장 기술이다. 최근 철강 산업은 배가스 중에 포함된 황산화물(SO2)을 처리하기 위하여 중탄산나트륨을 사용하고 있다. 중탄산나트륨으로 황산화물을 제거하고 나면 부산물로 탈황더스트가 발생하게 되는데 현재까지 마땅한 처리 방법이 없어 대부분 매립처리 되고 있는 실정이다. 탈황더스트의 주 성분은 황산나트륨(Na2SO4) 이며 15%의 염류 및 중금속을 불순물로 함유하고 있다. 지속적인 환경규제 강화 및 환경설비 운영비용의 증가로 탈황더스트 재생에 대한 관심은 점차 증대되고 있다. 황산나트륨은 탄소 포집, 이용 및 저장 방법으로 중탄산나트륨을 생산하기 위한 적합한 원료이나 기타 나트륨(Na+) 원료와 비교하면 생산효율이 낮아 현재까지 개발된 상용 공정은 전무하다. 본 연구에서는 탈황더스트를 물에 용해시켜 불순물을 제거하고 이산화탄소와 암모니아를 활용하여 중탄산나트륨을 재생하는 공정을 개발하였다. 탈황더스트는 순수 황산나트륨보다 pH가 높은 특성을 보여 이산화탄소를 용해 시키기 용이하다. 추가적으로 생산된 중탄산나트륨 일부를 가열하여 탄산나트륨(Na222CO3)을 생산하고 반응 용액에 재투입하게 되면 값비싼 암모니아 사용을 대체 할 수 있어 운영 비용 을 저감 할 수 있다. 본 연구에서 탈황더스트에 탄산나트륨 20%를 투입하게 되면 암모니아 사용량을 50% 감소 시키는 것과 동시에 중탄산나트륨 생산 효율을 20% 이상 증진 시킬 수 있음을 확인 하였으며 재생된 중탄산나트륨은 기존의 상용 중 탄산나트륨과 비교하여 우수한 황산화물 제거능을 보이는 것을 확인 하였다. CO2 is the primary greenhouse gas emitted through human activities which cause global warming. Many countries and international regulations aim to reduce CO2 and encourage development of a net-zero society by 2050. thus, CCUS (carbon capture, utilization, and storage) can be considered as a key technology for achieving this goal. Among the many industrial processes, NaHCO3 production is a representative CCUS technology which satisfies both CO2 reduction and economic incentive. Recently, Na2SO4 waste, containing 15% impurities (i.e., various heavy metals), produced as a by-product generated from desulfurized processes in steel industry has received a great deal of attention since landfilling has been the only way to treat it. Na2SO4 could be a suitable source of NaHCO3 production as CCUS; however, there are no commercial processes for production of NaHCO3 using Na2SO4 as the raw material, since it has low production efficiency compared to other Na+ sources. This study evaluates the regeneration of NaHCO3 using Na2SO4 waste and our results show that a combination of Na SO2 waste and the addition of 20% NaHCO3 can sharply increase the yield of NaHCO3 while minimizing the consumption of expensive NH3.

COSLIF법에 의한 바이오매스의 전처리 특성 및 가수분해 효율 향상에 관한 연구

김재우 순천대학교 대학원 2015 국내박사

Ethanol produced from renewable lignocellulosic biomass, being a 2nd-generation biomass, has a potential to play a leading role in transforming the current fossil-fuel-based economy to a renewable-carbon-based economy. Cellulose-derived ethanol has a strength over the ethanol produced otherwise in that it can be produced from various and abundant raw materials. In particular, cellulose-derived ethanol can reduce more than 85% of the global warming gas emissions from fossil fuel. The lignocellulosic biomass composed of cellulose, hemicellulose and lignin, however, has an important drawback; it is difficult to separate cellulose, which is the source material for the production of bio-ethanol, from hemicellulose and lignin, which act as interfering substances. This has caused high cost of pretreatment for the removal of hemicellulose and lignin and low productivity, leading to low economic feasibility compared to first-generation biomass materials. In this study, an efficient and economical method for pretreatment of various lignocellulosic biomass materials was evaluatead against a conventional pretreatment method. Waste biomass materials, such as rice straw, corn stalk, reed, and herbal medicine residue, were used as raw material samples. Two pretreatment methods, the dilute acid (DA) method and the cellulose solvent- and organic solvent-based lignocellulose fractionation (COSLIF) method were used to extract cellulose from lignocellulosic biomass and their efficiencies were compared. The composition analysis of the lignocellulose samples showed that the content of cellulose was in the order of corn stalk (37.5%), rice straw (35.1%), reed (31.0%), and herbal medicine residue (16.4%), that of hemicellulose was in the order of rice straw (25%), corn stalk (22.4%), reed (20.4%), and herbal medicine residue (8.8%), and that of lignin was in the order of herbal medicine residue (39.8%), reed (25%), corn stalk (17.6%), and rice straw (12.0%). The ash content was in the order of reed (18.9%), rice straw (16.1%), herbal medicine residue (6.6%), and corn stalk (5.59%). When dried samples of rice straw, corn stalk, reed, and herbal medicine residue were hydrolyzed using dilute H2SO4, the cellulose yield obtained was 35.1%, 37.5%, 31.0%, and 16.4%, respectively. On the other hand, when they were hydrolyzed using the COSLIF method, the cellulose yield was 40.5%, 41.8%, 32.1%, 22.6%, respectively. The COSLIF method provided higher cellulose yields than the DA method by 5.4% (rice straw), 4.3% (corn stalk), 1.1% (reed), and 6.2% (herbal medicine residue). The COSLIF method also showed a higher lignin removal efficiency than the DA method. For example, in the case of corn stalk, the lignin removal efficiency of the COSLIF method was 18.4%, whereas that of the DA method was 17.6%. Hemicellulose was also removed more efficiently by the COSLIF method than by the DA method; 23.5% of hemicellulose remained after the COSLIF pretreatment, whereas 22.4% remained after the DA pretreatment. Overall, the COSLIF method showed a better pretreatment performance than the DA method. During the COSLIF pretreatment, the following conditions must be satisfied: (1) phosphoric acid with a concentration higher than the threshold value (~83%) must play a role as a solvent for cellulose; ​​(2) reaction time must be long enough to dissolve biomass and must not be too long to prevent complete hydrolysis; and (3) reaction temperature must be lower than 60 ℃ to prevent the decomposition of xylose. The optimum reaction conditions for the COSLIF pretreatment of biomass found in this study were phosphoric acid concentration of 84%, reaction temperature of 50℃, and reaction time of 45 min. The digestion efficiency of glucan of corn stalk pretreated by the COSLIF method with a high enzyme dose was > 90% at 12 h and 94% at 24 h. When the COSLIF pretreatment time was reduced to 20 min, the hydrolysis rate and the digestion efficiency decreased. The hydrolysis rate of DA-pretreated corn stalk was lower than that of COSLIF-pretreated corn stalk and the digestion efficiency of glucan was 82% at 24 h. With a small enzyme dose (5 FPUs per gram of glucan), the final glucan digestion efficiencies of the COSLIF-treated and DA-treated biomass were 92% and 53% at 24 h, respectively. The results of this study indicates that the COSLIF method is a superior pretreatment method than the conventional DA method. Finally, Spirogyra. sp, one of algae from ocean is very enough to make bioethanol by COSLIF-pretreated and even better than that of corn stalk.

고로슬래그와 제지슬러지 소각회 혼합물의 알칼리활성반응에 의한 압축강도 특성

김학연 순천대학교 대학원 2016 국내석사

This research is a study on the alkali-activate reaction according to the chemical component construction of blast furnace slag. For this reason, it was mixed with sludge fly ash from Daebul Industrial Complex paper mill company to blast furnace slag. Blast furnace slag has a higher content of SiO2 component than paper mill sludge fly ash and fly ash has a higher content of CaO than blast furnace slag. From the experimental result, the mixing ratio with paper mill sludge fly ash to slag become higher, it means that content of CaO isI increased, the compressive strength become lower level. This means that the excessive alkali element has given an adverse effect on the alkali-activate reaction. Therefore, it is desirable to use only the slag for Alkali-Activate reaction without any mixing ratio of fly ash. On the other hand, compressive strengths of samples which were cured at room temperature (25℃) and high temperature(70℃) are almost same. it shows that the compressive strength did not have a lot of influence by the temperature and it was found to be economics to alkali activate reaction at room temperature. SEM analysis showed that the crystals are grown into alkali-activate reaction. In XRD analysis, it was confirmed that it have grown new crystals unlike slag.

토양에서 추출한 부식물질이 음식물 퇴비화에 미치는 영향

배연호 순천대학교 대학원 2011 국내석사

This study was estimated composting reaction rate and effect of loss weight by humic substance extracted from soil that increases activity of composting microorganism. And utilize as the data base for food wastes treatment by providing optimum operating conditions and processing. The experiment composted mixing food wastes, Sunchon compost and humic substance extracted from soil using produced composting reactor. In this processing, it found out optimum composting conditions for reducing organic matters by analyzing pH, temperature, C/N ratio, organic removal rate, moisture content, amounts of CO2 emission and total loss rate of composting matters. The result, humic substance extracted from soil affected ativity of composting microorganism. and estimated that should achieve high loss weight rate by ruducing organic matters in composting porocess.