Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "chemical oxidation" wg kryterium: Temat


Wyświetlanie 1-3 z 3
Tytuł:
Treatment of evaporative water from brewer’s yeast concentration by Fenton and Fenton-like processes
Oczyszczanie wody wyparnej z zatężania gęstwy drożdżowej w procesie Fentona
Autorzy:
Michel, M. M.
Reczek, L.
Siwiec, T.
Rudnicki, P.
Powiązania:
https://bibliotekanauki.pl/articles/204618.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
chemical oxidation
COD removal
industrial water
TOC removal
water reuse
utlenianie chemiczne
usuwanie ChZT
woda przemysłowa
usuwanie OWO
ponowne wykorzystanie wody
Opis:
Evaporative water from yeast slurry concentration is acidic, low mineralized and contains large amounts of dissolved organic contaminants. The treatment of evaporative water from yeast slurry concentration by Fenton (Fe(II)/H2O2) and Fenton-like (Fe(III)/H2O2) reactions has been studied. The processes in terms of system variables have been compared: catalyst and oxidant doses, initial pH, temperature of reaction, and the reaction kinetic. For determination of mineralization efficiency the total organic carbon (TOC) in water before and after reactions was measured. The Fenton reaction was more efficient for mineralization of organic compounds: the highest efficiency of TOC removal was 45–50%, while for the Fenton-like it was 20–30%. The pH adjustment of evaporative water in the range of 2–5 did not change the efficiency of treatment. Temperature of 30°C was the most favorable for both reactions. The Lumped Kinetic Model fitted very well the experimental results. The reaction rate analysis indicated that the rate of direct mineralization of organic compounds is similar to the rate of its oxidation to organic intermediates, its selectivity factor was more favorable to the Fenton reaction. The strong correlation between chemical oxygen demand (COD) and TOC in evaporative water after the Fenton and Fenton-like reactions has been determined, providing a simple tool for calculating COD on the basis of values of TOC measurement.
Woda wyparna z zatężania gęstwy drożdżowej jest kwaśna, nisko zmineralizowana i zawiera dużą ilość rozpuszczonych związków organicznych. W pracy badano oczyszczanie wody wyparnej w reakcji Fentona (Fe(II)/H2O2) i pokrewnej (Fe(III)/H2O2). Porównywano procesy przy następujących zmiennych: dawki katalizatorów i utleniacza, pH początkowe, temperatura i kinetyka reakcji. Efektywność oceniano poprzez pomiar ogólnego węgla organicznego przed i po reakcji. Związki organiczne były bardziej skutecznie mineralizowane w reakcji Fentona: najwyższa efektywność usuwania OWO wynosiła 45–50%, a w reakcji pokrewnej jedynie 20–30%. Korekta odczynu wody wyparnej w zakresie 2–5 pH nie wpłynęła na efektywność oczyszczania. Temperatura 30°C była najbardziej korzystna dla obydwu reakcji. Model kinetyczny o parametrach skupionych bardzo dobrze opisywał wyniki badań eksperymentalnych. Analiza szybkości reakcji wykazała, że jest ona zbliżona w przypadku mineralizacji organicznych składników oraz utleniania do produktów pośrednich, a współczynnik selektywności reakcji był korzystniejszy dla procesu Fentona. Określono silną korelację pomiędzy parametrami ChZT i OWO w wodzie po reakcji Fentona i pokrewnej, co może być przydatnym do obliczania ChZT na podstawie pomiaru OWO.
Źródło:
Archives of Environmental Protection; 2018, 44, 3; 11-18
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study of catalytic processes for biodiesel production wastewater treatment
Autorzy:
Borralho, Teresa
Coelho, Solange
Estrelo, Andreia
Powiązania:
https://bibliotekanauki.pl/articles/205024.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
cobalt
chemical oxygen demand
Fenton process
biodiesel production wastewater
catalytic advanced oxidation process
potassium monopersulphate
Opis:
The study of the possibility of removing organic compounds from wastewater originating from the biodiesel purification stage by two catalytic processes, HSO5-/transition metal and Fenton method has been presented. The source of the ion HSO5-is potassium monopersulphate (2KHSO5∙KHSO4∙K5SO4) (Oxone) that may be decomposed into radicals (OH., SO4-., SO5-.) by means of transition metal as Co(II). Different concentrations were used for both compounds and the combination ([Co2+] = 1.00μM/[HSO5-] = 5.00·10-2 M) achieved the highest COD removal (60%) and complete decomposition of the oxidant was verified for contact times of 45 min. This process has some advantages comparing to the conventional Fenton method such as the absence of the costly pH adjustment and the Fe(III) hydroxide sludge which characterize this treatment process. The Fenton process showed that the combination of [H2O2] = 2.00M/[Fe2+] = 0.70 M was the best and archived COD removal of 80%. The treatments studied in this research have achieved high COD removal, but the wastewater from the biodiesel purification stage presents very high parametric values of Chemical Oxygen Demand (667,000 mgO2/L), so the final COD concentration reached is still above the emission limit of discharge in surface water, according the Portuguese Law (Decree-Law 236/98). However, both treatments have proved to be feasible techniques for the pre-oxidation of the wastewater under study and can be considered as a suitable pre-treatment for this type of wastewaters. A rough economic analysis of both processes was, also, made.
Źródło:
Archives of Environmental Protection; 2019, 45, 2; 66-72
2083-4772
2083-4810
Pojawia się w:
Archives of Environmental Protection
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of modified atmosphere packaging on the course of physical and chemical changes in chilled muscle tissue of silver carp (Hypophthalmichthys molitrix, V.)
Autorzy:
Jezek, F.
Buchtova, H.
Powiązania:
https://bibliotekanauki.pl/articles/31515.pdf
Data publikacji:
2012
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
modified atmosphere packaging
physical change
chemical change
chilled muscle
muscle tissue
silver carp
Hypophthalmichthys molitrix
freshwater fish
fish
meat oxidation
freshness
oxidative process
Opis:
The effect of two types of modified atmosphere (MA1: 69% N2, 25% CO2, 5%O2, 1% CO; MA2: 70% N2, 30% CO2) on changes in physical and chemical parameters (pH, aw - water activity, TVBN - total volatile basic nitrogen, TMA - trimethylamine, FFA - free fatty acids, PV - peroxide value, TBA - thiobarbituric acid) in muscle tissues of the silver carp was monitored in the study. The samples were stored at temperatures +2 ± 2oC for 18 days. Changes in gas volumes (CO2 and O2) in MAs were also monitored. CO2 levels increased in MA1 but decreased in MA2. At the end of 18 days of storage, a significantly (P < 0.01) lower water activity (aw) levels were found in samples packaged under MA1, in contrast to samples packaged under MA2 where water activity values showed considerable fluctuation. Variations in pH values in the two types of MA showed similar trends. Sample pH gradually decreased until day 9 of storage. On day 11, muscle tissue pH increased markedly and then began to decrease again. The overall decrease in pH values was more profound in samples packaged under MA1. TVBN and TMA levels in samples packaged under the two types of MAs remained almost identical until day 9 of the experiment. Later, however, significantly (P < 0.01) higher levels of both parameters were found in muscle tissues packaged under MA1. FFA concentrations in silver carp samples in MA1 were significantly lower (P < 0.01) throughout the experiment. The PV increased significantly in both muscle samples tested. Greater fluctuations in this parameter’s values throughout the experiment were observed in samples packaged under MA2. Faster rates of oxidation (P < 0.01) were found in samples packaged under MA1 starting on day 9. Maximum TBA values in MA1 and MA2 were observed on days 14 and 18 of the experiment, respectively. From the course of proteolytic and oxidative changes point of view, the more appropriate combination of gases for silver carp storage seems to be the mixture of 70% N2 and 30% CO2 (MA2), which allows for muscle storage of up to 9 days. We recommend TVBN as a suitable indicator of freshness, and TBA assay as a suitable indicator of the extent of oxidative processes.
Źródło:
Polish Journal of Veterinary Sciences; 2012, 15, 3
1505-1773
Pojawia się w:
Polish Journal of Veterinary Sciences
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-3 z 3

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies