• Title/Summary/Keyword: citric acid

Search Result 1,385, Processing Time 0.133 seconds

Studies on Wet Etching of PHEMT with Citric acid based solutions (Citric acid 조성 비율에 따른 식각 특성에 관한 연구)

  • 설우석;이복형;김성찬;이성대;김삼동;신동훈;이진구
    • Proceedings of the IEEK Conference
    • /
    • /
    • pp.33-36
    • /
    • 2001
  • In this paper, we have studied the characteristics of wet etching using citric acid based wet etchant. We have used the citric acid / hydrogen peroxide solution, citric acid / hydrogen peroxide / D.I. water solution. From our experimental result, a volumetric 1:3 ratio of citric acid and hydrogen peroxide and 1 : 3 : 1 ratio of citric acid, hydrogen peroxide, and D.I. water is shown to be a better wet etchant of PHEMT's system.

  • PDF

Effects of Temperature and pH on the Production of Citric Acid from Cheese Whey by Aspergillus niger (Aspergillus niger를 이용한 유청으로부터 구연산의 생산에 있어서 온도와 pH의 영향)

  • Lee, Jung-Hoon;Yun, Hyun-Shik
    • The Korean Journal of Mycology
    • /
    • v.27 no.6
    • /
    • pp.383-385
    • /
    • 1999
  • Effects of temperature and initial pH of the medium on production of citric acid from cheese whey permeate by Aspergillus niger were investigated. A. niger was cultivated at four different temperatures (27, 30, 33, $36^{\circ}C$) and four different pHs (2, 3, 4, 5) for 15 days. During the fermentation the concentrations of lactose and citric acid in the culture broth were measured. The maximum production of citric acid which was 33.9 g/l (68.26% yield based on lactose utilized) was obtained at $33^{\circ}C$ and pH 3. The production of citric acid was not much affected by shaking speed. However, the shaking speed was found to influence the form of pellets during cell growth.

  • PDF

Screening and Identification of the Yeasts for Orange Wine and Their Citric Acid Decomposition (밀감양조주 생산용 효모의 선별, 동정 및 Citric Acid 분해)

  • Ko, Young-Hwan;Kim, Jae-Ha;Koh, Jeong-Sam;Kim, Chang-Jin
    • Korean Journal of Food Science and Technology
    • /
    • v.29 no.3
    • /
    • pp.588-594
    • /
    • 1997
  • Yeast strains useful for the production of wine using mandarine orange, Citrus unshiu, as a main substrate were screened, and their primary ability to decompose citric acid that affects directly wine quality was investigated. Total eleven strains were selected for brewing orange wine. Five wild strains were from soil-based collections and identified: four of them were Saccharomyces cerevisiae and one of them was S. ellipsoideus. The rest of six strains were from among eighteen laboratory strains: three of them were S. cerevisiae, and the other three were S. coreanus, S. uvarum, and S. sake. Two strains of S. cerevisiae out of these selections were chosen and their decomposition of citric acid was investigated. Citric acid was not utilized as sole carbon source for cellular growth. However, when both citric acid and glucose were added together as carbon sources, decrease of citric acid concentration was observed after incubation. Shaking incubation was more effective for the reduction of citric acid than standing incubation. Utilization of citric acid did not contribute to the increase of ethanol concentration during fermentation. On the other hand, it appeared that citric acid caused partial inhibition of cellular growth of the yeasts.

  • PDF

Bonding Performance of Maltodextrin and Citric Acid for Particleboard Made From Nipa Fronds

  • Santoso, Mahdi;Widyorini, Ragil;Prayitno, Tibertius Agus;Sulistyo, Joko
    • Journal of the Korean Wood Science and Technology
    • /
    • v.45 no.4
    • /
    • pp.432-443
    • /
    • 2017
  • Maltodextrin and citric acid are two types of natural materials with the potential as an eco-friendly binder. Maltodextrin is a natural substance rich in hydroxyl groups and can form hydrogen bonds with lignoselulosic material, while citric acid is a polycarboxylic acid which can form an ester bond with a hydroxyl group at lignoselulosic material. The combination of maltodextrin and citric acid as a natural binder materials supposed to be increase the ester bonds formed within the particleboard. This research determined to investigate the bonding properties of a new adhesive composed of maltodextrin/citric acid for nipa frond particleboard. Maltodextrin and citric acid were dissolved in distillated water at the ratios of 100/0, 87.5/12.5, 75/25 and 0/100, and the concentration of the solution was adjusted to 50% for maltodextrin and 60% citric acid (wt%). This adhesive solution was sprayed onto the particles at 20% resin content based on the weight of oven dried particles. Particleboards with a size of $25{\times}25{\times}1cm$, a target density $800kg/m^3$ were prepared by hot-pressing at press temperatures of $180^{\circ}C$ or $200^{\circ}C$, a press time of 10 minute and board pressure 3.6 MPa. Physical and mechanical properties of particleboard were tested by a standard method (JIS A 5908). The results showed that added citric acid level in maltodextrin/citric acid composition and hot-pressing temperature had affected to the properties of particleboard. The optimum properties of the board were achieved at a pressing temperature of $180^{\circ}C$ and the addition of only 20% citric acid. The results also indicated that the peak intensity of C=O group increased and OH group decreased with the addition of citric acid and an increase in the pressing temperature, suggesting an interreaction between the hydroxyl groups from the lignocellulosic materials and carboxyl groups from citric acid to form the ester groups.

Optimization of Citric Acid Production by Immobilized Cells of Novel Yeast Isolates

  • Hesham, Abd El-Latif;Mostafa, Yasser S.;AlSharqi, Laila Essa Omar
    • Mycobiology
    • /
    • v.48 no.2
    • /
    • pp.122-132
    • /
    • 2020
  • Citric acid is a commercially valuable organic acid widely used in food, pharmaceutical, and beverage industries. In this study, 260 yeast strains were isolated from soil, bread, juices, and fruits wastes and preliminarily screened using bromocresol green agar plates for their ability to produce organic acids. Overall, 251 yeast isolates showed positive results, with yellow halos surrounding the colonies. Citric acid production by 20 promising isolates was evaluated using both free and immobilized cell techniques. Results showed that citric acid production by immobilized cells (30-40 g/L) was greater than that of freely suspended cells (8-19 g/L). Of the 20 isolates, two (KKU-L42 and KKU-L53) were selected for further analysis based on their citric acid production levels. Immobilized KKU-L42 cells had a higher citric acid production rate (62.5%), while immobilized KKU-L53 cells showed an ~52.2% increase in citric acid production compared with free cells. The two isolates were accurately identified by amplification and sequence analysis of the 26S rRNA gene D1/D2 domain, with GenBank-based sequence comparison confirming that isolates KKU-L42 and KKU-L53 were Candida tropicalis and Pichia kluyveri, respectively. Several factors, including fermentation period, pH, temperature, and carbon and nitrogen source, were optimized for enhanced production of citric acid by both isolates. Maximum production was achieved at fermentation period of 5 days at pH 5.0 with glucose as a carbon source by both isolates. The optimum incubation temperature for citric acid production by C. tropicalis was 32 ℃, with NH4Cl the best nitrogen source, while maximum citric acid by P. kluyveri was observed at 27 ℃ with (NH4)2 SO4 as the nitrogen source. Citric acid production was maintained for about four repeated batches over a period of 20 days. Our results suggest that apple and banana wastes are potential sources of novel yeast strains; C. tropicalis and P. kluyveri which could be used for commercial citric acid production.

Effect of Citric Acid Treatment on Wrinkle Recovery and Mechanical Properties of Ramie Fabrics (Citric Acid 처리가 모시직물의 주름 회복성과 기계적 성질에 미치는 영향)

  • 정유진;박종신
    • Textile Science and Engineering
    • /
    • v.35 no.9
    • /
    • pp.584-591
    • /
    • 1998
  • Citric acid was used to improve the wrinkle recovery of ramie fabrics. The effect of curing conditions, citric acid concentration, and triethanolamine (TEA) amount on the wrinkle recovery of the fabrics were investigated. The wrinkle recovery increased with the curing time, curing temperature, and citric acid concentration and changed little up to 5% of TEA amount but decreased afterwards. FT-IR was used to study the degree of reaction between ramie cellulose and citric acid. Ester carbonyl band absorbance ratio and carbonyl band intensity ratio showed that the ester crosslinking increased with the curing time, curing temperature, and citric acid concentration and changed little up to 5% of TEA amount but decreased afterwards. The mechanical properties of treated fabrics such as breaking strength, tearing strength, and abrasion resistance were also investigated. The mechanical properties were deteriorated seriously with the citric acid treatment. One reason for the deterioration could be uneven distribution of crosslinking due to some structural characteristics such as nodes in ramie fibers. The deterioration of mechanical properties, however, could be prevented to a certain degree by using TEA.

Sorption Kinetics of $Sr_{2+}$in Citric Acid-Water systems (Citric acid-water 혼합시스템에서 $Sr_{2+}$의 흡착특성)

  • 김계남;김진완;한운우;원휘준;오원진
    • Proceedings of the Korean Society of Soil and Groundwater Environment Conference
    • /
    • /
    • pp.133-136
    • /
    • 2000
  • Soil decontamination process was conducted to study adsorption and modeling characteristic of Sr$^{2+}$ ion using citric acid and water system with TRIGA soil. When the concentration of citric acid was increased, the BTC of Sr$^{2+}$ ion was to be closed to the BTC of $^3$$H_2O$ at experiments of soil adsorption. Beside, when the concentration of citric acid was under 0.01M Sr$^{2+}$ ion, BTLs was asymmetry. It was characteristic of nonequilibrium adsorption. R and $K_{p}$ , were decreased to be increased the concentration of citric acid. Asymmetry modeling was nearly the same to be compare with symmetry modeling in decontamination process, when the concentration of citric acid was decreased. Result of experiment was agree with asymmetry and symmetry model, when the concentration of citric acid was increased.eased.

  • PDF

The Investigation for the Effects of Citric Acid on the Uranium Transfer into the Plants by the Pilot Scale Feasibility Test (파일럿 규모의 실증실험 사례를 통한 구연산의 우라늄 식물 전이 효과 규명)

  • Han, Yikyeong;Lee, Minhee
    • Journal of Soil and Groundwater Environment
    • /
    • v.21 no.6
    • /
    • pp.146-155
    • /
    • 2016
  • The field feasibility tests for a phytoextraction process were performed to identify the effect of citric acid as a chelate on the uranium (U) transfer into the plant for the naturally U contaminated soil in Duckpyeongri, Korea. For the feasibility tests, lettuce and Chinese cabbage were cultivated for 49 days on four testing grounds ($1m{\times}1m{\times}0.5m$ in each) in 2016. The citric acid solution was added to two testing grounds (one for lettuce and the other for Chinese cabbage) increasing the U transfer in two crop plants and their results were compared to those without the citric acid solution. When without the citric acid solution, the U concentration of plant after the cultivation was low (< $45{\mu}g/kg$ for leaves and < $450{\mu}g/kg$ for roots). However, with the addition of 50 mM citric acid solution, the U concentration of lettuce leaves and roots increased by 24 times and 1.8 times, and the U concentration of Chinese cabbage leaves and roots increased by 86.7 times and 5.4 times. The absolute accumulated U amount (${\mu}g$) in lettuce and Chinese cabbage also increased by 8.7 times and 50 times, compared to those without citric acid solution. Less than 8% of the U amount of exchangeable/carbonate phases was removed by using the lettuce and Chinese cabbage when the citric acid solution was not applied. However 52% and 66% of the U amount in exchangeable/carbonate phases were removed by the lettuce and the Chinese cabbage when the citric acid solution was added. The effect of the citric acid on the U transfer capability into the plants was quantitatively investigated by the field feasibility test, suggesting that U existing as exchangeable/carbonate phase in soil can be successfully removed by the phytoextraction process using Chinese cabbage with citric acid.

Improvement of Quality and Prolongation in Chopped Ginger Storage (다진 생강의 저장성 증진에 관한 연구)

  • Lee, Sang-Bok;Kim, Myeong-Sook;Choi, Yoon-Hee
    • Applied Biological Chemistry
    • /
    • v.40 no.2
    • /
    • pp.123-127
    • /
    • 1997
  • To improve the quality and prolongation of chopped ginger, they were treated with NaCl, citric acid, ascorbic acid alone or combination of them at $5^{\circ}C$. The browning and stink of chopped ginger were prevented by adding 10% NaCl, $0.5{\sim}2.0%$ citric acid, but the control became severely browned and deteriorated after 1 month storage. The application of 0.5% citric acid maintained citrine color and decreased the activity of polyphenol oxidase(PPO) more significantly compared to 5.0% NaCl or 0.5% ascorbic acid. Ascorbic acid treatment become browned at $1.0{\sim}2.0%$ and easily deteriorated compared to citric acid. Citric acid(0.5%) or ascorbic acid (0.5%) treatment was largely variation of pH compared to NaCl(5.0%)+citric acid(0.5%) or NaCl(5.0%)+ascorbic acid(0.5%) treatment during 8 month storage. The activity of PPO in NaCl(5.0%)+ascorbic acid(0.5%) treatment was elevated after 4 month storage. In chopped ginger, NaCl(5.0%)+citric acid(0.5%)+ascorbic acid(0.25%) treatment was more effective than 5.0%+0.1%+0.1%, 5.0%+0.5%+0.1% during 12 month storage.

  • PDF

Preparation of Chitosan Films Containing Hydroxyapatite Nanoparticle by Citric Acid Addition (Citric Acid 첨가에 의한 Hydroxyapatite 나노입자 함유 키토산 필름의 제조)

  • 정용식;최충열;이근완;좌용호;박병기
    • Textile Science and Engineering
    • /
    • v.39 no.4
    • /
    • pp.383-389
    • /
    • 2002
  • Nano-structured hydroxyapatite(HAp)/chitosan composites and their transparent films were prepared by the co-precipitation and solvent casting method. According to TEM observation, HAp particles with 100~150nm in length and 10~20nm in width were formed in the composites. We investigated the role of citric acid in the HAp/chitosan film formation. The HAp/chitosan films were prepared at various concentrations of citric acid. HAp particles did not aggregate in the chitosan matrix above 50% citric acid concentration for the HAp content. The inhibition effects result from the adsorption of citric acid on the surface of HAp particles by ionic exchange of phosphate ions with citrate ions at the HAp/chitosan composite solution, which is caused by a higher affinity of citrate than phosphate species for the Ca-site on the HAp surface.