• 분석과학
• /
• 제14권4호
• /
• pp.306-310
• /
• 2001

황상용액 매질에서 요오드 음이온을 흡착제에 흡착시킨 후 황산용액에 남아있는 요오드 음이온을 정량하기 위해 이온 크로마토그래피를 적용하였다. 산화제 작용을 하는 황산의 농도를 0.25 M, 0.5 M, 1 M로 변화시키고 요오드 음이온을 각각 첨가한 후 시간변화에 따라 요오드 음이온이 산화되는 정도를 측정하였다. 황산농도가 진할수록 요오드 음이온은 산화되어 휘발하므로 적게 검출되었다. 수산화나트륨 용액을 사용하여 환산매질을 중화하였다. 중화된 0.5 M $Na_2SO_4$ 매질 중 요오드 음이온의 농도범위가 0-20 mg/L인 구간에서 검정곡선의 직선성이 좋게 나타났다(r=0.99999).

• 자원리싸이클링
• /
• 제32권3호
• /
• pp.38-44
• /
• 2023

국내산 흑연정광으로부터 불순물을 제거하기 위해 황산용액 및 수산화나트륨용액을 이용하여 침출실험을 진행하였다. 황산용액과 수산화나트륨용액을 각각 사용하여 침출실험을 진행한 결과, 수산화나트륨과 황산의 농도가 2 mol/L 이상에서 제거효과의 차이가 미미하고, 황산용액침출에서 온도가 증가함에 따라 고정탄소함량이 증가하는 것에 비해 수산화나트륨용액에서는 150℃ 이상에서 큰 차이가 나타나지 않았다. 수산화나트륨용액침출은 2 mol/L NaOH, 200℃, 1시간의 조건으로 선정하고, 황산용액침출은 2 mol/L H₂SO₄, 100℃, 1 시간의 조건으로 선정하여 5회까지 반복하여 침출을 진행하였다. 황산용액침출 후 수산화나트륨용액침출을 5회 반복했을 때 고정탄소는 99.95 %까지 증가하였고, 회분은 0.048 %까지 감소하였다. 수산화나트륨용액침출 후 황산용액침출을 5회 반복한 결과, 고정탄소는 99.98 %, 회분은 0.018까지 감소하여 수산화나트륨용액 침출 후 황산용액침출을 수행한 결과가 다소 높게 나타났다.

• Korean Chemical Engineering Research
• /
• 제55권1호
• /
• pp.7-12
• /
• 2017

황산에 의한 바이오매스의 당화 후 황산의 회수는 매우 중요하다. 본 연구에서는 전기투석 방법에 의해 황산과 글루코스 혼합용액으로부터 황산을 분리하는 연구를 하였다. 전기투석은 음이온막과 양이온막을 사용한 3실 방식이 일반적인데 본 연구에서는 음이온막 만을 사용한 2실 방식을 실험했다. 글루코스 10~30% 황산농도 1~3 M 농도 범위의 용액에서 2실 방식의 전기투석으로 황산을 완전 분리할 수 있었다. 실험한 3종류의 음이온 막 중에서 확산과 대류의 영향이 작은 음이온 막에서는 전류밀도에 비례해 황산분리 속도가 증가하였다. 전기를 가하지 않고 확산과 대류에 의해 황산분리 45%를 달성할 수 있었다.

• 한국신재생에너지학회:학술대회논문집
• /
• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
• /
• pp.179.1-179.1
• /
• 2011

Pretreatment of cellulosic biomass is necessary before enzymatic saccharification and fermentation. The objective of this study was to evaluate the effect of combined aqueous ammonia-dilute sulfuric acid treatment on cellulosic biomass. Miscanthus was pretreated using aqueous ammonia and dilute sulfuric acid solution under high temperature and pressure conditions to be converted into bioethanol. Aqueous ammonia treatment was performed with 15 %(w/w) ammonia solution at $150^{\circ}C$ of reaction temperature and 20 minutes of reaction time. And then, dilute sulfuric acid treatment was performed with 1.0 %(w/w) sulfuric acid solution at $150^{\circ}C$ of reaction temperature and 10 minutes of reaction time. The compositional variations of this combined aqueous ammonia-dilute sulfuric acid treatment resulted in 68.0 % of cellulose recovery and 95.7 % of hemicellulose, 81.3 % of lignin, 89.1 % of ash removal respectively. The enzymatic digestibility of 90.5 % was recorded in the combined pretreated Miscanthus sample and it was 14.7 times higher than the untreated sample. The ethanol yield in the Simultaneous Saccharification and Fermentation was 90.4 % of maximum theoretical yield based on cellulose content of the combined pretreated sample and it was about 98 % compared to the ${\alpha}$-cellulose ethanol yield.

• 대한전자공학회:학술대회논문집
• /
• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
• /
• pp.421-426
• /
• 2001

The pneumatic classification and acidic leaching behaviors of phosphor sludge have been examined to establish the recycling system of rare earth components contained in waste fluorescent lamp. At first, separation characteristic of rare earth components and calcium phosphate in phosphor sludge was investigated by pneumatic classification. After pneumatic classification of phosphor sludge, rare earth components were leached in various acidic solutions and sodium hydroxide solution. For recovery of soluble component in leaching solution, rare earth components were separated as hydroxide and oxalate precipitations. The experimental results obtained are summarized as follows: (1) In classification process, rare earth components in phosphor sludge were concentrated to 29.3% from 13.3%, and its yield was 32.9%. (2) In leaching process, sulfuric acid solution was more effective one as a leaching solvent of rare earth component than other solutions. Y and Eu components in phosphor sludge were dissolved in sulfuric acid solution of 1.5 k㏖/㎥, and other rare earth components were rarely dissolved in leaching solution. Leaching degrees of Y and Eu were respectively 92% and 98% in the following optimum leaching conditions; sulfuric acid concentration is 1.5 k㏖/㎥ , leaching temperature 343 K, leaching time 3.6 ks and pulp concentration 30 kg/㎥. (3) Y and Eu components of phosphor sludge contained in waste fluorescent lamp were, effectively recovered by three processes of pneumatic classification, sulfuric acid leaching and oxalate precipitation methods. Their recovery was finally about 65 %, and its purity was 98.2%.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2000년도 제18회 학술발표회 논문개요집
• /
• pp.165-165
• /
• 2000

Glass slides were chemically etched with sulfuric acid using five different methods. we investigated the effects of the chemical etching conditions on such properties as chemical composition, surface roughness, and the thermal stability of the glass. Sodium and carbon atoms in the surface of the glass are effectively eliminated by chemical etching with sulfuric acid. The glass slides were boiled for 30 min in 95% sulfuric acid and were depth profiled at room temperature with X-ray photoelectron spectroscopy (XPS), the Na ls signal was not detected in the detection limit of XPS. Surface morphology of the glass was very different depending on the concentration of sulfuric acid. The surface of the glass etched with 50% sulfuric acid was rougher than that of glass etched with 95% sulfuric acid. The sodium concentration of the glass boiled for 30 min in 95% sulfuric acid was nearly zero at the glass surface, and the sodium composition changed very little with annealing temperatures up to 35$0^{\circ}C$ in a vacuum environment. However the sulfur concentration at the glass surface due to the sulfuric acid increased with increasing temperature.

• Korean Chemical Engineering Research
• /
• 제53권4호
• /
• pp.417-424
• /
• 2015

본 연구에서는 목질계 바이오매스인 돼지감자 줄기에 대한 전처리 공정을 수행하였다. 공정은 효소 당화 수율을 높이기 위하여 흐름형 침출 전처리 공정에 2단 전처리 공정으로 적용하였다. 전처리 용매로 암모니아수에 의한 탈 리그닌 효과와 황산 용액에 의한 헤미셀룰로오스의 분해가 효소당화 및 발효에 미치는 영향을 확인하였다. 암모니아수와 황산용액을 이용한 2단 전처리 공정을 수행하였다. 먼저 1단계 공정은 40분 동안 $163.2^{\circ}C$의 온도에서 암모니아수로 처리를 진행하였고 다음 2단계 공정은 $169.7^{\circ}C$에서 20분 동안 황산 용액으로 처리를 수행하여 물질수지를 구하였다. 그리고 앞의 공정과 반대의 순서로 황산 용액을 먼저 처리한 후 암모니아수를 처리한 2단 전처리 공정을 수행하였다. 이때 암모니아수를 먼저 처리한 공정에서 글루코오스 생산량은 30.7 g으로 72.4%의 수율이 나타났다. 반대로 황산 용액을 먼저 처리한 후 암모니아수를 처리한 2단 전처리 공정에서는 글루코오스 생산량이 20.9 g으로 49.3%의 수율을 보였다.

• Korean Membrane Journal
• /
• 제7권1호
• /
• pp.28-33
• /
• 2005

The feasibility of producing sulfuric acid and ammonia water from ammonium sulfate was investigated by an integrated process including ammonia stripping (AS) and electrodialysis with bipolar membrane (EDBM). It was suggested that the production of sulfuric acid using ammonia stripping-electrodialysis with bipolar membrane (ASEDBM) was effective in obtaining high concentration of sulfuric acid compared with EDBM alone. AS was carried out over pH 11 and within the range of temperatures, $20^{\circ}C{\~}60^{\circ}C$. Sodium sulfate obtained using AS was used as the feed solution of EDBM. The recovery of ammonia increased from $40\%$ to $80\%$ at $60^{\circ}C$ due to the increased mobility of ammonium ion. A pilot-scale EDBM system, which is composed of two compartments and 10 cell pairs with an effective membrane area of $200 cm^2$ per cell, was used for the recovery of sulfuric acid. The performance was examined in the range of 0.1 M${\~}$1.0 M concentration of concentrate compartment and of $25 mA/cm^2{\~}62.5 mA/cm^2$ of current density. The maximum current efficiency of $64.9\%$ was obtained at 0.1 M sulfuric acid because the diffusion rate at the anion exchange membrane decreased as the sulfuric acid of the concentrate compartment decreased. It was possible to obtain the 2.5 M of sulfuric acid in the $62.5 mA/cm^2$ with a power consumption of 13.0 kWh/ton, while the concentration of sulfuric acid was proportional to the current density below the limiting current density (LCD). Thus, the integrating process of AS-EDBM enables to recover sulfuric acid from the wastewaters containing ammonium sulfate.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
• /
• pp.43-48
• /
• 2002

This study is experiment results that carried out the sulfuric acid immersion of the mortar containing blast furnace slag powder, based ell the mechanism of the sulfuric acid corrosion for concrete which was caused by the H$_2$S gas. The used materials is OPC, slag powder and gypsum, and the proportion of cement is total 13 levels which are 0~70% of the contents of slag, 0~6％ of the contents of gypsum. The specimen is immersed by 5% H$_2$SO$_4$ solution after 28 days and its weight loss is measured at intervals of 7 days. The results of experiment showed that the substitution ratio of 70% slag was excellent at a point of view for the sulfuric acid resistance and the sulfuric acid resistance was not improved by tile increase of the blaine of slag(8, 000longrightarrow10, 000$\textrm{cm}^2$/g) and the addition of gypsum.

• 설비공학논문집
• /
• 제7권4호
• /
• pp.600-610
• /
• 1995

When combustion gas is cooled down below the dew point of sulfuric acid vapor in the heat recovery systems, condensation occurs. Since the condensed sulfuric acid solution causes low-temperature corrosion in materials, it is important to measure the SOx dew point by electric measurement. In this study, two kinds of probes having electric gaps of 1mm or 2mm were used. and experiments were carried out by the parameters of sulfuric acid vapor and water vapor concentration. The changes of electric current caused by sulfuric acid condensed on the surface of probe according to the cooling rate and the probe head surface temperature were sudied. The opimum cooling rate was decreased with the increasing of water vaper concentration regardless of sulfuric acid concentration. The sensitivity of electric current is improved for the narrower gap(1mm) of ring electrodes, but it rarely affects the SOx dew point measuring of different probes according to the change of cooling rate.