Effect of radial impeller size in the presence and absence of baffles on the copper exchange on zeolite NaX

Effect of hydrodynamics on ion exchange in a batch reactor is still not appropriately studied even though proper mixing parameters may considerably affect the process of solid suspension and its costs. In this work, hydrodynamic conditions generated by straight blade turbine (SBT) impellers on suspension in the batch reactor with and without baffles were investigated. The aim of this work was to analyze influence of impeller diameter and zeolite mass on just suspended impeller speed, (NJS) power consumption, maximum amount of copper exchanged onto zeolite NaX and copper exchange kinetics as well. All experiments were conducted at the same temperature, initial concentration of the copper solution and zeolite particle size. The obtained results showed that just suspended impeller speed decreases as impeller diameter increases in the reactor with and without baffles but this trend is considerably more pronounced in the reactor with baffles. The increase in zeolite mass causes a slight increase of NJS in the both reactor. In the reactor with the baffles this increment became noticeably higher as impeller diameter decrease. Power consumption, at the state of complete zeolite suspension, decreases as impeller diameter increases and its values in the reactor without baffles are considerably lower as well. Kinetics results indicated that the amount of copper ion increases significantly in the initial stage and then gradually until the equilibrium is reached for all hydrodynamics conditions and mass of zeolite examined

Investigation on the effects of process variables on copper exchange on NaX in a batch stirred reactor

The aim of this work was to determine the effects of anion type (A), time (t), impeller off-bottom clearance (C/H) and solute concentration (c) on copper exchange on zeolite NaX in a batch stirred reactor. The experiments were carried out at constant temperature (300 K) and at the same impeller speed (250 rpm). The amount of exchanged copper at examined conditions was measured by UV/Vis spectrophotometer. In order to find the optimal process conditions for copper exchange on the basis of experimental data, Taguchi’s method for experimental design were used, applying larger-the-better approach. Beside the optimum experimental conditions this method allowed to define the influence of each process variable on the process conducted. Applied method has shown that the highest copper exchange is achieved at increased solute concentration, when sulphate anion was used, and impeller is positioned at standard position (C/H =0.33). It was also found that solute concentration and anion type have more pronounced impact on process investigated than impeller position and process duration (c > A > c/H > t). For the optimum experimental condition, kinetic data for copper exchange were obtained and tested using the Elovich and the Ritchie kinetic models

Primjene različitih metala kao elektrodnog materijala u obradi kompostne procjedne vode

In this paper, different metallic materials (alloys of Fe, Al, and Zn) were investigated as sacrificial anodes during electrocoagulation (EC) for the treatment of compost leachate. Taguchi’s L9 orthogonal array design was applied to investigate the four controllable factors (different metallic material, initial pH value, stirring speed, and contact time) on decrease of chemical oxygen demand (COD) and electrodes mass loss. COD decrease reached values in the range of 75.72–92.97 %. The Taguchi optimisation results showed that the most effective factor for decrease of COD is the duration of the experiment, while the electrode material was for electrodes mass loss. The zinc electrode showed the lowest potential for use in the EC process for treatment of compost leachate, while the Al and Fe electrodes could be used in an acid or slightly acidic environment. The following decreasing order of energy consumption was recorded: Zn > Al > Fe. The measured values of metal electrode mass loss exceeded the theoretical values calculated using Faraday’s law in EC experiments with Al electrodes, while in experiments with Fe and Zn electrodes, those differences were insignificant.U ovom radu različiti metalni materijali (legure Fe, Al, Zn) ispitivali su se kao žrtvene anode tijekom elektrokoagulacije (EK) za obradu kompostne procjedne vode. Taguchijev L9 ortogonalni niz primijenjen je za ispitivanje četiriju kontroliranih čimbenika (različiti metalni materijali, početne pH vrijednosti, brzine vrtnje miješala i vremena kontakta) na uklanjanje organske tvari izražene preko kemijske potrošnje kisika (KPK) i gubitak mase elektroda. Učinkovitost uklanjanja organske tvari izražene preko KPK-a dosegla je vrijednosti u rasponu od 75,72 do 92,97 %. Rezultati optimizacije Taguchi pokazali su da je najučinkovitiji čimbenik za uklanjanje organske tvari, izražene preko vrijednosti KPK-a, trajanje eksperimenta, dok je gubitak mase elektroda za materijal elektrode. Cinkova elektroda pokazala je najmanji potencijal za uporabu u EK procesu za pročišćavanje kompostne procjedne vode, dok se Al i Fe elektroda mogu upotrebljavati u kiselom ili blago kiselom području. Zabilježen je sljedeći opadajući redoslijed potrošnje energije: Zn > Al > Fe. Izmjerene vrijednosti gubitka mase metalne elektrode premašuju teorijske vrijednosti izračunate Faradayevim zakonom u EK eksperimentima s Al elektrodama, dok su u eksperimentima s Fe i Zn elektrodama te razlike manje

Konkurentno uklanjanje teških metala iz binarne otopine

The removal of copper and cobalt ions from binary metal solutions on zeolite NaX by ion exchange process was investigated. Experiments were conducted in unbaffled glass reactor with a Rushton turbine as a stirrer. The dependence of ion exchange kinetics and the amount exchanged were tested using different initial concentrations of metal ions in mixtures. The results obtained indicate that the removal efficiency depends on the initial heavy metal concentrations in binary solutions. Experimental kinetics data were analysed using Ritchie and Weber-Morris models. According to AARD values, the rate in this study was reaction-controlled. This work is licensed under a Creative Commons Attribution 4.0 International License.Ispitano je uklanjanje iona bakra i kobalta iz binarnih otopina metala ionskom izmjenom na zeolitu NaX. Eksperimenti su provedeni u staklenom kotlastom reaktoru bez razbijala virova. Kao miješalo upotrijebljena je Rushtonova turbina. Ovisnost kinetike izmjene iona i izmijenjene količine iona metala ispitana je pri različitim početnim koncentracijama iona metala u smjesama. Prema dobivenim rezultatima, učinkovitost uklanjanja iona metala iz otopina ovisi o početnim koncentracijama metala u binarnim otopinama. Kinetički podatci dobiveni eksperimentom analizirani su Ritchievim i Weber-Morrisovim modelom. Prema vrijednostima AARD-a, ukupna brzina procesa u ovoj studiji kontrolirana je reakcijom. Ovo djelo je dano na korištenje pod licencom Creative Commons Imenovanje 4.0 međunarodna

Modelling the supercritical CO2 extraction kinetics of soybean oil

Different empirical models were used to describe the supercritical CO2 extraction of soybean oil obtained at series of operational parameters namely pressure, temperature, solvent flow rate and characteristic particle size. Process yields obtained by supercritical CO2 were up to 19.33%. Several kinetic models: Brunner, Kandiah and Spiro, Tan and Liou, Martinez et al. and Esquivel et al. were used to test the experimental yield data. All models were analysed using nonlinear regression method. Also a new model, modified Esquivel et al., was proposed and analysed using nonlinear regression method as well. According to the obtained results for extraction yield of soybean oil, the modified Esquivel et al. model show the best agreement between experimental and model calculated data

INFLUENCE OF ZEOLITE PARTICLE SIZE AND INITIAL LEAD CONCENTRATION ON SORPTION KINETIC STUDY BY BATCH EXPERIMENTS

The effect of particle size and initial lead concentration on the kinetics of lead ions uptake onto natural zeolite has been examined by batch experiments. The uptake rate of lead ions increases with decreasing particle size and has no effect on the zeolite removal capacities. Also the removal capacities are not affected by initial lead concentrations. To identify the rate rate-determining step, experimental data have been tested by the Lagergren pseudo-first order, Ho pseudo-second order and Elovich reaction kinetic models, Vermeulen’s, Parabolic and Homogeneous diffusion models. For different lead concentrations and particle sizes the kinetic constants obtained have been changed and have consequently been excluded as relevant for the description of kinetics. Vermeulen´s and Homogeneous diffusion models have shown the best fitting with the experimental data, what confirms that intraparticle diffusion is rate-determining step of uptake process of lead ions onto natural zeolite

The Garden Candytuft (Iberis umbellata L.): At the Crossroad of Copper Accumulation and Glucosinolates

The copper accumulation ability and its impact on the glucosinolate content of the garden candytuft were studied. Different copper sources (adsorbents or solution) were used. Generally, the seedlings copper uptake from the adsorbents was in the amount needed for its growth and development with the beneficial or no impact on the glucosinolate content. The lowest copper concentration was detected in the total seedlings biomass which grew in the humus with the addition of Cu-exchanged zeolite NaX (27.88 μg g−1 DW) having glucosinolate content of 9757.81 µg g−1 DW (23.86 µmol g−1 DW). The highest copper concentration among all the garden candytuft samples was detected in the seedlings watered with CuSO4∙5H2O solution (514.63 μg g−1 DW) with a sharp decrease of the glucosinolate content 3103.33 µg g−1 DW (7.59 µmol g−1 DW). Based on the results obtained, the garden candytuft can be considered as a copper accumulator plant

COMPARISON OF ELECTROCOAGULATION COUPLED WITH SYNTHETIC ZEOLITE, ULTRASOUND AND TWO STEPS ELECTROCOAGULATION

Due to the very complex composition of leachate wastewater, combining two or more physical, chemical, or biological processes, carried out simultaneously or sequentially, is highly needed in order to obtain effluent suitable for further discharge into sewage. In this paper, electrocoagulation coupled with synthetic zeolite (EC-NaX), electrocoagulation coupled with ultrasound (EC-US), and two steps electrocoagulation (EC-1st and EC-2nd) were tested for compost leachate treatment, with very high initial organic loading and acidic pH. The comparison of each process was done in regard to the following parameters: pH, electrical conductivity and temperature change, removal percentage of chemical oxygen demand (COD), turbidity, total solids change, settling ability, and electrode consumption. Results highlight the EC-NaX as the best option for the treatment of compost leachate, due to the highest removal percentage of COD (51.91%), satisfactory removal percentage of turbidity (97%), good settling abilities, and lowest electrode consumption. However, the final COD values in the effluent are still significantly high for further discharge into sewage systems, thus additional treatment needs to be applied. Also, the final acidic pH, high values of electrical conductivity, and high temperature of effluent need to be solved in further treatment steps

INFLUENCE OF CURRENT DENSITY ON LEACHATE TREATMENT EFFICIENCY BY ELECTROCOAGULATION WITH ZEOLITE ADDITION

The electrocoagulation with zeolite addition was used to treat compost leachate. The effects of different current densities and zeolite particle sizes on electrode dissolution, electrode surface condition, and removal efficiency were investigated. The surface of the electrodes was analysed by optical microscope, while the consumption of the aluminium electrodes was investigated by weighing. The results confirmed that the removal efficiency could be improved by conducting the experiment at higher current densities, but the electrodes used were significantly more damaged. Significant damage was also observed on the electrode used in the experiment with larger zeolite particles, which can be related to the stronger abrasion effect

Evaluation of the volatiles’ chemical profile and antibacterial activity of Lavandula stoechas L. extracts obtained by supercritical carbon dioxide

Funding Information: This project has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 101003396; European Union's Horizon 2020 (European Research Council) under grant agreement No ERC-2016-CoG 725034; National funds (FCT/MCTES, Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through the projects UIDB/50006/2020 and UIDP/50006/2020. The biological activity has been supported by research ID: 3105-12-21. The authors would like to thank Ana Jovanoski for her editorial support. Funding Information: This project has received funding from the European Union’s Horizon 2020 research and innovation program under the Marie Sklodowska-Curie grant agreement No 101003396 ; European Union’s Horizon 2020 ( European Research Council ) under grant agreement No ERC- 2016-CoG 725034 ; National funds (FCT/MCTES, Fundação para a Ciência e Tecnologia and Ministério da Ciência, Tecnologia e Ensino Superior) through the projects UIDB/50006/2020 and UIDP/50006/2020 . The biological activity has been supported by research ID: 3105-12-21. The authors would like to thank Ana Jovanoski for her editorial support. Publisher Copyright: © 2023 The AuthorsThe goal of this study was to establish a green methodology for obtaining safe, high-quality, and potent antibacterial extracts of Lavandula stoechas flowers. Supercritical carbon dioxide (scCO2) at different conditions (pressure 100–300 bar, temperature 40 and 60 °C, and CO2 flow 10–30) was applied. Moreover, the impact of the parameters on the extraction yield, chemical profile of the extracts, and the activity against Gram-positive and Gram-negative bacteria was investigated. ScCO2 extraction kinetics was investigated by modelling the extraction curves using the models described by Brunner, Martinez, and their modifications. In vitro assays were applied to estimate the susceptibility of Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis, and Staphylococcus aureus to extracts. A pattern recognition approach was applied to explore the correlations between the employed scCO2 parameters, detected volatile compounds, and extracts’ antibacterial properties. The achieved yield ranged from 1.17 to 2.4% (w/w), with oxygenated monoterpenes fenchone (5.76–22.72%) and verbenone (8.04.-18.65%) as the most abundant ones. The most significant susceptibility of Gram-positive and Gram-negative bacteria was attributed to extracts obtained at 200 bar, with minimal inhibitory concentration in the range 2.71 ± 1.31–20.69 ± 0.91 mgmL−1 and 3.39 ± 0.48–34.28 ± 5.94 mgmL−1, respectively. The obtained extracts represent safe, viable, and promising alternatives for tackling antimicrobial resistance. Moreover, by varying process conditions, it is possible to adjust the chemical profile and the activity of the extracts according to the target purpose. Furthermore, the requirements of clean and sustainable technologies, such as environmental preservation, rational use of renewable resources, and provision of natural, safe, and high-quality extracts can be met.publishersversionpublishe