Wyniki wyszukiwania - Biblioteka Nauki

1

Oxalic acid degradation by a novel fungal oxalate oxidase from Abortiporus biennis

100%

Grąz M. , Rachwał K. , Zan R. , Jarosz-Wilkołazka A.

Acta Biochimica Polonica

|

2016

|

tom 63

|

nr 3

595-600

EN

Oxalate oxidase was identified in mycelial extracts of a basidiomycete Abortiporus biennis strain. Intracellular enzyme activity was detected only after prior lowering of the pH value of the fungal cultures by using oxalic or hydrochloric acids. This enzyme was purified using size exclusion chromatography (Sephadex G-25) and ion-exchange chromatography (DEAE-Sepharose). This enzyme exhibited optimum activity at pH 2 when incubated at 40°C, and the optimum temperature was established at 60°C. Among the tested organic acids, this enzyme exhibited specificity only towards oxalic acid. Molecular mass was calculated as 58 kDa. The values of Km for oxalate and Vmax for the enzyme reaction were 0.015 M and 30 mmol min-1, respectively.

2

Direct reuse of rare earth oxalate precipitation mother liquor for rare earth leaching

100%

Wu X. , Zhou F. , Feng J. , Liu X. , Zhang Z. , Chi R.

Physicochemical Problems of Mineral Processing

|

2019

|

tom Vol. 55, iss. 3

760--769

EN

In the recovery process of rare earth (RE) from the weathered crust elution-deposited rare earth ore, ammonium sulfate is used as the leaching liquor to leach RE, and then the leachate containing RE3+ can be precipitated by oxalic acid and the RE oxalate precipitation mother liquor is reused for RE leaching process after removing the residual oxalic acid by precipitation with calcium hydroxide. However, the reuse process of precipitation mother liquor cannot proceed in the strong acid and alkali restricted areas and the discharge of mother liquor which contains a large amount of ammonium salt will cause ammonia-nitrogen waste and pollution. In order to realize the reuse of the precipitation mother liquor in this area, the direct reuse of RE oxalate precipitation mother liquor for RE leaching was investigated in this study. The RE oxalate precipitation process and the RE leaching process with oxalic acid were studied. The results showed that the residual oxalic acid concentration in the mother liquor can be controlled lower than 0.8 g/dm3 at pH 2-3 when the RE concentration in the leachate was 0.1- 1.5 g/dm3 and the RE precipitation rate reached to 94%. In addition, RE leaching efficiency was up to 90% while the oxalic acid concentration in the prepared mother liquor was 0.2-0.8 g/dm3, pH 2-3. Therefore, the precipitation mother liquor with oxalic acid concentration less than 0.8 g/dm3 could be directly reused for RE leaching. However, considering the different performance of RE ores, the recommended oxalic acid concentration in the direct used precipitation mother liquor was lower than 0.6 g/dm3.

3

Quantum chemical studies of the double proton transfer in oxalic acid dimer

100%

Chojnacki H.

Polish Journal of Chemistry

|

1998

|

tom Vol. 72, nr 2

421-425

EN

The double proton transfer process has been studied for the oxalic acid dimer in the gaseous state and for crystalline form at the non-empirical level. The correlation energy corrections have been taken into account at the MP2 level as well as crystal field effects were considered. The results of our calculations enable a reasonable interpretation of low potential barriers, observed in NMR experimental studies of some molecular crystals involving carboxylic dimers. The possible mechanisms of the double proton transfer are considered.

4

Leaching kinetics of iron from coal-series kaolin by oxalic acid solutions

100%

Shao H. , Ji M. , Yu M.

Physicochemical Problems of Mineral Processing

|

2020

|

tom Vol. 56, iss. 1

134--146

EN

Removal of iron from coal-series kaolinite and its kinetics by chemical leaching were investigated in this paper. The optimal removal rate of iron reaches 29.09% (the content of Fe2O3 decreased from 0.55 to 0.39%) under the conditions of 100 °C, 0.4 M C2H2O4, and liquid-to-solid ratio of 4 cm3/g for 120 min. The leaching process was successfully described by the Avrami model and mainly controlled by internal diffusion control of shrinking core model, the apparent activation energy is 18.46 kJ/mol. The experimental results were consistent with the internal diffusion control of shrinking core model, improving acid concentration and leaching temperature could promotes the removal of iron from coal-series kaolin.

5

Application of oxalic acid as an efficient leaching agent of aluminum from industrial waste

100%

Pospiech B. , Warzecha M.

Physicochemical Problems of Mineral Processing

|

2020

|

tom Vol. 56, iss. 2

264--270

EN

The leaching with acids is one of many methods used for recovery of valuable components from industrial wastes. The processing and neutralization of this type of waste is very difficult due to toxic properties. This work shows the results of aluminum leaching from industrial black dross with oxalic acid depending on temperature, acid concentration, effect of liquid to solid ratio (L/S) and time process. The oxalic acid has not been used so far for processing of aluminum black dross. The main purpose of this work was to determine the optimal conditions of this process. The results show that the maximum leaching efficiency of aluminum (75.2 %) was obtained with a liquid to solid ratio of 20:1 using 0.5 mol·dm-3 oxalic acid at 75 °C for 3 h.

6

Spectrophotometric determination of oxalic acid using zirconium(IV)-(p-acetylarsenazo) system

88%

Zhai Q. Z.

Chemia Analityczna

|

2008

|

tom Vol. 53, No. 4

609-615

EN

A new spectrophotometric method for determination of oxalic acid has been developed. It is based on the property that in 0.40 mol L-1 HC1 solution oxalic acid forms complexes with zirconium by replacing p-acetylarsenazo in zirconium-(p-acetylarsenazo) complex. The formed complex makes the absorbance of the solution increase. Over a specified range, the measured absorbance was proportional to the concentration of oxalic acid in the range of 3.0 x 10-5-6.0 x 10-4 mol L-1, according to Beer's law. The apparent molar absorptivity was ε540=1,02. The detection limit of the method was 2.5 x 10-5 mol L-1. The proposed method was satisfactorily applied to the determination of trace amount of oxalic acid in spinach and strawberry samples.

PL

Opracowano nową, spektrofotometryczną metodę oznaczania kwasu szczawiowego. W metodzie wykorzystano zdolność kwasu szczawiowego do wypierania p-acety loarsenazo z kompleksu cyrkon-p-acetyloarsenazo i tworzenie, w środowisku roztworu kwasu solnego 0,40 mol L-1, kompleksów z cyrkonem. Utworzony kompleks powoduje wzrost absorbancji roztworu proporcjonalnie do stężenia kwasu szczawiowego, spełniając prawo Beera w zakresie stężeń od 3.0 x 10-5-6.0 x 10-4 mol L-1. Absorbancja molowa wynosiła ε540=1,02 = 1,02 x 10-5 L mol-1. Granicę wykrywalności oznaczono na 2.5 x 10-5 mol L-1. Proponowana metoda została z powodzeniem zastosowana do oznaczania śladowych ilości kwasu szczawiowego w próbkach truskawek i szpinaku.

7

Effect of sucrose concentration on oxalic acid biosynthesis by Aspergillus niger

88%

Walaszczyk E. , Gasiorek E. , Podgorski W.

Zeszyty Problemowe Postępów Nauk Rolniczych

|

2017

|

tom 588

EN

The aim of the work was to determine the influence of initial sucrose concentration in fermentation medium on oxalic acid synthesis by Aspergillus niger W78C in submerged batch culture. Cultivations were conducted in synthetic medium containing sucrose in the concentration of 100, 125, 150, 175 or 200 g·dm⁻³. As the result of the present investigation, the optimal sucrose concentration was found at the level of 125 g·dm⁻³. In medium containing this amount of carbon source, 70.2 g·dm⁻³ of oxalic acid was obtained. When substrate concentration was the highest, 200 g dm⁻³, the amount of product was only 5.2 g·dm⁻³ higher than in medium with 125 g·dm⁻³ of sucrose. Moreover, an increase of the initial sucrose concentration resulted in process time extension, an increase of citric and gluconic acids concentration and a decrease of productivity and oxalic acid yield.

PL

Celem badań było określenie wpływu początkowego stężenia sacharozy, będącej jedynym źródłem węgla, na proces biosyntezy kwasu szczawiowego przez Aspergillus niger metodą wgłębnej hodowli okresowej. W badaniach stosowano szczep A. niger W78C. Hodowle prowadzono w podłożach syntetycznych zawierających sacharozę w stężeniu 100, 125, 150, 175 lub 200 g·dm⁻³. W podłożu o najniższym początkowym stężeniu sacharozy, tj. 100 g·dm⁻³, uzyskano najniższe stężenie kwasu szczawiowego, tj. 59,3 g·dm⁻³. Podwyższenie stężenia substratu do 125 g·dm⁻³ spowodowało zwiększenie ilości produktu do 70,8 g·dm⁻³, czyli o 19,1%. Dalszy wzrost stężenia cukru w podłożu nie był już tak skuteczny, gdyż w wariancie z najwyższym początkowym stężeniem sacharozy, tj. 200 g·dm⁻³, uzyskano tylko o 5,2 g·dm⁻³ (czyli o 7,4%) więcej kwasu szczawiowego niż w podłożu, w którym ilość substratu była równa 125 g·dm⁻³. Wzrost początkowego stężenia substratu ze 100 do 200 g·dm⁻³ powodował wydłużenie czasu procesu, wzrost stężenia kwasów towarzyszących: cytrynowego i glukonowego, oraz spadek wydajności kwasu szczawiowego i szybkości jego tworzenia. Na podstawie uzyskanych stężeń produktu w podłożach z różnym początkowym stężeniem substratu oraz po analizie parametrów procesu (wydajności kwasu szczawiowego i objętościowej szybkości jego produkcji) uznano, że najkorzystniejsze stężenie sacharozy w tym procesie wynosi 125 g·dm⁻³.

8

A study on the dissolution kinetics of iron oxide leaching from clays by oxalic acid

75%

Arslan V.

Physicochemical Problems of Mineral Processing

|

2021

|

tom Vol. 57, iss. 3

97--111

EN

Clay is widely used in a number of industries due to its special properties like fine particle size, brightness and whiteness, chemical inertness, platy structure, etc. In this study, the general characteristics of clays have been investigated by XRF, XRD, FT-IR, TG-DTA and SEM. The presence of iron as an impurity decreases its commercial value due to giving unwanted colors to clay mineral. Therefore, the dissolution capacity of clay ore was investigated by oxalic acid leaching. Under optimized leaching conditions (0.8 M oxalic acid concentration, 85°C reaction temperature, 1.75 ambient pH, 106+75 µm particle size, 15% w/v solids concentration and 150 min. leaching time) with 250 rpm stirring, 83.90% of Fe2O3 was removed. The amount of iron oxide, the main impurity in the clay, has been reduced from 2.70 to 0.40%. The iron dissolution kinetics was mainly controlled by internal diffusion control of shrinking core model and activation energy, Ea, of 26.29 kJ/mol was obtained for the process. The results also showed that the studied clays have adequate characteristics for ceramics industry, earthenware and porcelain production.

9

Jiroft refractory manganese ore leaching using oxalic acid as reducing agent in sulfuric acid solution

75%

Sobouti A. , Shafaat N. , Abdollahzadeh A. A.

Physicochemical Problems of Mineral Processing

|

2020

|

tom Vol. 56, iss. 2

374--385

EN

Leaching process of Jiroft refractory manganese ore was investigated. The effects of operating parameters such as liquid to solid ratio, pulp temperature, sulfuric acid concentration, and oxalic acid concentration were studied and the optimization was done through the response surface methodology (RSM) based on central composite design (CCD) model. The recoveries of Mn, Fe and Si were selected as response of design. The optimum condition was determined by ANOVA, indicating that the liquid to solid ratio, oxalic acid concentration and pulp temperature for Mn recovery and liquid to solid ratio, pulp temperature and sulfuric acid concentration for Fe recovery and liquid to solid ratio for Si recovery were the most effective parameters, respectively. Under the optimum conditions of liquid to solid ratio= 11.8%, pulp temperature= 70 ℃ sulfuric acid concentration= 40 g/L and oxalic acid concentration= 35 g/L, 71.1%, 4.67% and 0.6% of Mn, Fe and Si were recovered, respectively.

10

Kwas szczawiowy

75%

Puchalska H. , Patelska B. , Skowroń J.

Podstawy i Metody Oceny Środowiska Pracy

|

1998

|

tom Nr 18

129--149

11

Dobór szczepów Aspergillus niger do biosyntezy kwasu szczawiowego z trakcji glicerynowej

75%

Musiał I. , Rymowicz W.

Inżynieria i Aparatura Chemiczna

|

2009

|

tom Nr 3

71-72

PL

Wszystkie badane szczepy A. niger były zdolne do produkcji kwasu szczawiowego z frakcji glicerynowej jako jedynego źródła węgla. Końcowe stężenie kwasu szczawiowego wahało się od 28,4 do 48,7 g dm3. Produktywność i wydajność biosyntezy kwasu szczawiowego zależała od użytego szczepu. Szczepem, który prowadził najbardziej efektywnie badany proces biosyntezy był szczep XP, który produkował tylko kwas szczawiowy.

EN

All tested A. niger strains were able to utilize glicerin waste as the sole carbon source for oxalic acid production. A final oxalic acid concentration ranged from 28.4 to 48.7 g dm3. Oxalic acid productivity and yield were different depending on the strain used. A. niger XP which produced only oxalic acid was found to be the most suitable for oxalic acid production from glycerin waste.

12

Wpływ stężenia glukozy na syntezę kwasu szczawiowego przez Aspergillus niger

63%

Walaszczyk E. , Dawidowicz K. , Gasiorek E. , Podgorski W.

Acta Scientiarum Polonorum. Biotechnologia

|

2014

|

tom 13

|

nr 4

PL

Celem pracy było zbadanie wpływu stężenia glukozy, jako jedynego źródła węgla, na tworzenie produktu w procesie syntezy kwasu szczawiowego przez Aspergillus niger we wgłębnej hodowli okresowej. Badania prowadzono w podłożach syntetycznych zawierających glukozę rozcieńczoną do poziomu 100, 125, 150 i 175 g·dm-3. Najwyższe stężenie produktu, wynoszące 64,2 g·dm-3, uzyskano w podłożu zawierającym glukozę w ilości 150 g·dm-3. W wariancie tym stwierdzono także obecność kwasów towarzyszących: cytrynowego w stężeniu 15,4 g·dm-3 i glukonowego w stężeniu 28,7 g·dm-3. Współczynnik homofermentatywności procesu wyniósł 59,2%. Najwyższą szybkość tworzenia produktu i najwyższą wydajność substratową, wynoszące odpowiednio 2,9 g·dm-3·d-1 i 61,6%, uzyskano w podłożu ze stężeniem substratu na poziomie 100 g·dm-3. Uznano, że optymalne stężenie glukozy w podłożu, ze względu na maksymalizację stężenia produktu, wynosi 150 g·dm-3.

EN

The aim of the work was to examine the influence of glucose concentration as a sole carbon source on oxalic acid synthesis by Aspergillus niger in submerged fer- mentation. Cultivations were conducted in synthetic medium containing glucose di- luted to 100, 125, 150 and 175 g·dm-3. The highest product concentration 64,2 g·dm-3 was obtained in medium containing 150 g·dm-3 of glucose. There were also 15,4 g·dm-3 of citric acid and 28,7 g·dm-3 of gluconic acid present. Chemical selectivity of the process was 59,2%. The highest productivity and the highest substrate yield equalled respective- ly 2,9 g·dm-3·d-1 and 61,6% was obtained in medium containing 100 g·dm-3 of substrate. In conclusion, optimal glucose concentration in medium was recognised as 150 g•dm-3 be- cause of the highest product concentration.

13

Evaluation of soluble oxalates content in infusions of different kinds of tea and coffee available on the Polish market

63%

Rusinek E.

Roczniki Państwowego Zakładu Higieny

|

2012

|

tom 63

|

nr 1

PL

Background. Tea and coffee are the potentially rich source of oxalic acid, which can act as a antinutrient. Objective. The aim of this study was to determine and evaluate the content of soluble oxalates in teas and coffees available on the Polish market. Material and method. The green, red and black teas, and black natural ground and instant coffees were used for preparing the infusions. The manganometric method was used for the determination of the oxalates in the infusions. Results. The mean oxalates content in the infusions from 3 g of black teas was 115.68 mg/100cm3 and was higher as compared to red teas (101.91 mg/100cm3) and green teas (87.64 mg/100cm3). Disregarding the variety of analyzed teas, the largest oxalates content was in infusions of pure one-component tea - “Sir Roger” (164.82-174.22 mg/100cm3), while the lowest oxalates content was noted in the tea containing the components from other plants (“Bio-Active” with grapefruit juice – reaching as low level as 39.00 mg/100cm3). Instant coffees contained larger amount of oxalates than natural ground coffees. Irrespective of the kind of the tested coffees, the lowest oxalates content was found in the infusions from the following coffees: Tchibo Exclusive - 19.62 mg/100cm3, Gala ulubiona - 37.32 mg/100cm3, and Maxwell House - 38.40 mg/100cm3, while the highest oxalates content in instant coffee - Nescafe Espiro 51.80 mg/100cm3. Conclusions. The results revealed a significant relation between phytochemical composition of analyzed teas and coffees and the level of soluble oxalates in infusions prepared from the tested products.

EN

Wprowadzenie. Herbata i kawa stanowią potencjalnie bogate źródło kwasu szczawiowego, który ma działanie antyodżywcze. Cel badań. Celem badań było zbadanie i ocena zawartości rozpuszczalnych szczawianów w naparach z różnych gatunków herbat zielonych, czerwonych i czarnych oraz naturalnych kaw mielonych i rozpuszczalnych dostępnych na polskim rynku. Materiał i metoda. Z herbat zielonej, czerwonej i czarnej oraz kaw naturalnych mielonych i rozpuszczalnych przygotowywano napary. Oznaczenia zawartości rozpuszczalnych szczawianów w naparach wykonywano metodą manganometryczną. Wyniki. Wykazano, że średnia zawartość szczawianów w naparach uzyskanych z 3,0 gramów herbat czarnych (115,68 mg/100 cm3) jest wyższa, w porównaniu do herbat czerwonych (101,91 mg/100 cm3) i herbat zielonych (87,64 mg/100 cm3). Największą zawartość szczawianów zawierały napary z herbat czystych, jednoskładnikowych - „Sir Roger” (164,82- 174,22 mg/100 cm3), natomiast najmniejszą odnotowano w herbacie z komponentem roślinnym („Bio-Active” z sokiem grejpfrutowym - 39,00 mg/100 cm3). Kawy rozpuszczalne zawierały istotnie większą zawartość szczawianów niż naturalne kawy mielone. Najniższą zawartość szczawianów odnotowano w naparach z kaw: Tchibo Exclusive - 19,62 mg/100 cm3, Gala ulubiona - 37,32 mg/100 cm3 i Maxwell House - 38,40 mg/100 cm3, natomiast najwyższą zawartość w kawie rozpuszczalnej Nescafe Espiro - 51,80 mg/100 cm3. Wnioski. Wykazano istotny wpływ składu fitochemicznego badanych próbek herbaty i kawy na zawartość rozpuszczalnych szczawianów w naparach przygotowanych z badanych produktów.

14

Comparison of different strains of Aspergillus niger for oxalic acid production from lipid substrates

63%

Rymowicz W. , Lenart D.

Electronic Journal of Polish Agricultural Universities. Series: Biotechnology

|

2004

|

tom 07

|

nr 2

15

Porównanie efektów rozdzielania mieszaniny kompleksów Al(III) z kwasami octowym i szczawiowym na podłożach kationitowych z wykorzystaniem metody "ligand exchange"

63%

Gasińska E.

Zeszyty Naukowe. Chemia Spożywcza i Biotechnologia / Politechnika Łódzka

|

2000

|

tom Z. 62

53-61

PL

Metodą ligandową rozdzielano mieszaninę kwasów octowego i szczawiowego na silnie kwasowych kationitach: Dowex 50 WX-10 i Amberlite IRA-120 w formie Al(III). Badano wpływ stopnia usieciowania i wielkości ziaren kationitu oraz szybkości przepływu eluentu na efekt rozdzielania. Stwierdzono, że w wyniku zastosowania złoża Dowex 50 WX-10 (stopień usieciowania 10%, wielkość ziaren 20-50 mesh), uzyskuje się lepsze parametry rozdzielenia (zdolność rozdzielcza, współczynnik rozdzielenia) mimo dłuższego czasu retencji - niż w przypadku rozdzielania na złożu Amberlit IRA-120 (stopień usieciowania 8%, wielkość ziaren 150-200 mesh) [6,7]. Stwierdzono także, że wskutek oddziaływań kompleksujących w układzie jon metalu-kwas organiczny uzyskuje się znacznie lepszy efekt rozdzielenia badanej mieszaniny niż w przypadku metody zwykłej wymiany jonowej.

EN

A mixture of acetic acid and oxalic acid was resolved by the ligand method using Al³+ forms of strougly acidic ion-exchange resins: Dowex 50 WX-10 and Amberlite IRA 120. The influence of the cross-linking degree, particle size and velacity of elution on the effectiveness of the resolution were investigated The best results were achieved using Dowex 50 WX-10 (10% cross-linking, 20-50 mesh).

16

Plasma degradation of organic compounds: oxidation of oxalic and maleic acids

63%

Bellakhal N. , Brisset J.-L.

Polish Journal of Applied Chemistry

|

1999

|

tom Vol. 43, nr 1-2

23-28

EN

Solid Oxalic and Maleic acid pellets are exposed to an inductively coupled oxygen plasma to investigate the oxidizing properties of the plasma on organic powders in view of ageing studies. Both acids degrade to carbon dioxide according to pseudo 1 st order reactions with kinetic constants k= 0.250 min- 1 and k=0.098 min-I respectively, relevant to the experimental conditions. Models involving the oxygen atoms present in the plasma phase are proposed [or the degradation mechanism.

17

Zroznicowanie polskich i chinskich izolatow Sclerotinia sclerotiorum de Bary pod wzgledem zdolnosci do wytwarzania kwasu szczawiowego.

63%

Starzycka E. , Kachlicki P. , Starzycki M.

|

2002

|

tom 23

|

nr 2

385-390

18

Physiochemical properties of cocoyam starch extracted in two media

63%

Ishiwu C. , Onoh I. M. , Nwanya P. O. , Agulanna A. C.

International Letters of Natural Sciences

|

2017

|

tom 64

EN

Starch was extracted (isolated) from cocoyam with the aid of water solution of oxalic acid and ammonium oxalate in 8 samples of ratios, 1:3, 1:1, 3:1, 2:3, 2:1, 1:2 and 0:0 respectively. The physiochemical properties were investigated in order to unveil its characteristics and unravel the potentials for industrial applications of the cocoyam starch. The physiochemical properties investigated includes; Amylose and Amylopectin contents, water binding capacity, particle size distribution, swelling power and solubility. The results obtained showed that swelling power and solubility of the starch were temperature dependent. The solubility was found to increase with temperature increase as the cocoyam starch showed highest solubility within the 70-90°C temperature range. The swelling power was found fluctuating between the temperatures of 25-90°C. The swelling power starch sample isolated with blending ratios of 2:1 and 1:2 were temperature dependent. The Amylose content ranges from 3.06 to 31.21%.

19

A method for estimation of enzymatic browning and its suppression in apple slices

63%

Kuczynski A. , Varoquaux P.

International Agrophysics

|

1996

|

tom 10

|

nr 1

20

Application of replicated 2 3 full factorial central composite circumscribed design of experiment [CCC DOE] for optimization of oxalate biosynthesis by Aspergillus niger W78C

63%

Forys E. , Podgorski W.

Acta Scientiarum Polonorum. Biotechnologia

|

2004

|

tom 03

|

nr 1-2