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1
Content available Influence of the Method of Brewing Various Types of Coffee on the Content of Oxalates in Them®
Dąbrowska-Molenda Monika, Szyszka Izabela, Szwedziak Katarzyna, Hetmańczyk Ireneusz, Doleżal Petr
Postępy Techniki Przetwórstwa Spożywczego
|
2022
|
nr 2
35--41
EN
The aim of this study presented in the article, the influence of various brewing methods on the oxalate content in different types of coffee was examined. The level of these compounds was determined by permanganometric titration in two coffee species: Coffea arabica and Coffea robusta, using three brewing methods as well as different brewing times. In the experimental part, the content of oxalates in the prepared coffee infusions was determined and the results were analyzed and discussed by comparing the obtained values with the available literature data, and then conclusions were drawn based on them.
PL
Celem pracy zaprezentowanej w artykule było zbadanie wpływu sposobu parzenia różnych rodzajów kaw na zawartość w nich szczawianów. Poziom tych związków oznaczono metodą manganometryczną w dwóch gatunkach kawy: Coffea arabica oraz Coffea robusta, wykorzystując trzy metody parzenia, a także różny czas zaparzania. W części doświadczalnej oznaczono zawartość szczawianów w przygotowanych naparach kawowych oraz dokonano analizy i dyskusji wyników, porównując uzyskane wartości z dostępnymi danymi literatury, a następnie na ich podstawie wyciągnięto wnioski
2
Content available A study on the dissolution kinetics of iron oxide leaching from clays by oxalic acid
Arslan Volkan
Physicochemical Problems of Mineral Processing
|
2021
|
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.
3
Content available Leaching kinetics of iron from coal-series kaolin by oxalic acid solutions
Shao Hui, Ji Mengjiao, Yu Mingming
Physicochemical Problems of Mineral Processing
|
2020
|
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.
4
Content available Jiroft refractory manganese ore leaching using oxalic acid as reducing agent in sulfuric acid solution
Sobouti Arash, Shafaat Niosha, Abdollahzadeh Ali A.
Physicochemical Problems of Mineral Processing
|
2020
|
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.
5
Content available Application of oxalic acid as an efficient leaching agent of aluminum from industrial waste
Pospiech Beata, Warzecha Marek
Physicochemical Problems of Mineral Processing
|
2020
|
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
Content available Direct reuse of rare earth oxalate precipitation mother liquor for rare earth leaching
Wu Xiaoyan, Zhou Fang, Feng Jian, Liu Xueme, Zhang Zhenyue, Chi Ruan
Physicochemical Problems of Mineral Processing
|
2019
|
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.
7
Content available Nanoporous surface treatment of aluminium by anodisation in oxalic acid
Dass G., Kushwaha M. K.
Journal of Achievements in Materials and Manufacturing Engineering
|
2019
|
Vol. 93, nr 1-2
20--25
EN
Purpose: Well-ordered nanoporous anodic surface on aluminium substrate was obtained by anodisation method in 0.3 M of oxalic acid as an electrolyte. The objective of this perusal is to describe a system for the magnifying diameter of pores and resistance of demolition of the oxide layer at various voltages. The effect of voltage and time of anodisation process in which obtaining the required structure in AAO film. Design/methodology/approach: The experiments have been performed on a setup for anodisation considering variables parameters. In this study, AAO Templates were prepared in oxalic acid of 0.3 M concentration under the potential range of anodisation 30-40 V at relatively temperatures range from 20-30°C of an electrolyte. Anodic voltage, current density and temperature of electrolyte were adopted as electrical parameters during anodisation. Before anodisation starts two crucial pre-treatment i.e. annealing and electropolishing are finished. Findings: The diameter of pores and pitch of pores are well-proportional to anodisation voltage and process time. The pore diameters were 85 nm, 138 nm, 184 nm, 248 nm with having 9, 16, 27, 37 porosity % respectively. The thickness of AAO film in all cases has been found to be maximum or constant after one hour in second step anodisation. The anodisation parameters like voltage, the time duration of the anodisation process and temperature are very essential features which influencing the fabrication of an AAO film. Research limitations/implications: The anodisation process is very easy to perform but very complex to understand as there are many parameters which may affect it. Practical implications: After that, the second step anodisation for the next half hour, there will be no change in the thickness of AAO film but after that dissolution rate starts over the formation rate and finally thickness will be decreasing. Originality/value: Therein is numerous macropores in the membrane with the size of pores variation from 163 to 248 nm. The diameter of pores, thickness, and pore density of AAO film was determined through Scanning Electron Microscopy (SEM), which exhibited that homogeneous honeycomb-like structure has appeared on the entire surface where anodisation performed precisely.
8
Content available Dobór szczepów Aspergillus niger do biosyntezy kwasu szczawiowego z trakcji glicerynowej
Musiał I., Rymowicz W.
Inżynieria i Aparatura Chemiczna
|
2009
|
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.
9
Content available remote Spectrophotometric determination of oxalic acid using zirconium(IV)-(p-acetylarsenazo) system
Zhai Q. Z.
Chemia Analityczna
|
2008
|
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.
10
Content available remote Porównanie efektów rozdzielania mieszaniny kompleksów Al(III) z kwasami octowym i szczawiowym na podłożach kationitowych z wykorzystaniem metody "ligand exchange"
Gasińska E.
Zeszyty Naukowe. Chemia Spożywcza i Biotechnologia / Politechnika Łódzka
|
2000
|
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).
11
Plasma degradation of organic compounds: oxidation of oxalic and maleic acids
Bellakhal N., Brisset J.-L.
Polish Journal of Applied Chemistry
|
1999
|
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.
12
Quantum chemical studies of the double proton transfer in oxalic acid dimer
Chojnacki H.
Polish Journal of Chemistry
|
1998
|
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.
13
Content available remote Kwas szczawiowy
Puchalska H., Patelska B., Skowroń J.
Podstawy i Metody Oceny Środowiska Pracy
|
1998
|
Nr 18
129--149
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