Wyniki wyszukiwania - BazTech

Ograniczanie wyników

Znaleziono wyników: 2

Liczba wyników na stronie

Wyniki wyszukiwania

Wyszukiwano:
w słowach kluczowych: uzdatnianie ścieków

Sortuj według:

Ogranicz wyniki do:

Do we still need a laboratory to study advanced oxidation processes? A review of the modelling of radical reactions used for water treatment

Wacławek Stanisław

Ecological Chemistry and Engineering. S

2021

Vol. 28, nr 1

11--28

Environmental pollution due to humankind’s often irresponsible actions has become a serious concern in the last few decades. Numerous contaminants are anthropogenically produced and are being transformed in ecological systems, which creates pollutants with unknown chemical properties and toxicity. Such chemical pathways are usually examined in the laboratory, where hours are often needed to perform proper kinetic experiments and analytical procedures. Due to increased computing power, it becomes easier to use quantum chemistry computation approaches (QCC) for predicting reaction pathways, kinetics, and regioselectivity. This review paper presents QCC for describing the oxidative degradation of contaminants by advanced oxidation processes (AOP, i.e., techniques utilizing •OH for degradation of pollutants). Regioselectivity was discussed based on the Acid Blue 129 compound. Moreover, the forecasting of the mechanism of hydroxyl radical reaction with organic pollutants and the techniques of prediction of degradation kinetics was discussed. The reactions of •OH in various aqueous systems (explicit and implicit solvation) with water matrix constituents were reviewed. For example, possible singlet oxygen formation routes in the AOP systems were proposed. Furthermore, quantum chemical computation was shown to be an excellent tool for solving the controversies present in the field of environmental chemistry, such as the Fenton reaction debate [main species were determined to be: •OH < pH = 2.2 < oxoiron(IV)]. An ongoing discussion on such processes concerning similar reactions, e.g., associated with sulphate radical-based advanced oxidation processes (SR-AOP), could, in the future, be enriched by similar means. It can be concluded that, with the rapid growth of computational power, QCC can replace most of the experimental investigations related to the pollutant’s remediation in the future; at the same time, experiments could be pushed aside for quality assessment only.

Models of adsorption of natural contaminants from treated water for municipal purposes on powdered activated carbon

Bielski Andrzej

Technical Transactions

2020

Vol. 117, iss. 1

art. no. e2020006

The paper investigates whether time and doses of powder activated carbon (PAC) effect adsorption rates of organic contaminants from water and proposes a new model of volume adsorption. Depending on the nature of the organic compounds present in water, a general description of the adsorption process may require a linear combination of adsorption models running at different rates and at different parameters of adsorption isotherms. The model showed a good fit with the measured data and could be used in designing adsorption units at water or wastewater treatment plants. The proposed set of model equations enables to predict the effects of PAC adsorption in both plug flow reactors and homogeneous reactors.

Artykuł bada, w jaki sposób czas i dawki proszku węgla aktywnego (PAC) wpływają na szybkość adsorpcji zanieczyszczeń organicznych z wody, i proponuje nowy model adsorpcji objętościowej. W zależności od charakteru związków organicznych obecnych w wodzie ogólny opis procesu adsorpcji może wymagać liniowej kombinacji modeli adsorpcji działających z różnymi prędkościami i przy różnych parametrach izoterm adsorpcji. Model, na którym przeprowadzono badania, wpasował się w przykładowe dane, więc można go wykorzystać do projektowania jednostek adsorpcyjnych w oczyszczalniach wody lub ścieków. Proponowany zestaw równań modelowych pozwala przewidzieć skutki adsorpcji PAC zarówno w reaktorach z przepływem tłokowym, jak i reaktorach homogenicznych.