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•Phenomenological adsorption modeling was successfully applied.•Kinetics, equilibrium and thermodynamics assessed through interdependent approach.•Adsorption on the adsorbent sites ...controls the overall process.•Electrostatic forces identified as the main interaction in the adsorption process.•High adsorption capacity of DOSD-2 adsorbent was achieved.
This work focused in the assessment of the potential of reactive blue dye 5G (RB5G) adsorption by polymeric adsorbent Dowex Optipore SD-2 (DOSD-2) in closed batch system by a phenomenological investigation of the adsorption process by both experimental data and mathematical modeling of kinetics, equilibrium and thermodynamics. The kinetic model of adsorption on the adsorbent sites described experimental data, consequently the adsorption itself is the rate-limiting step of the overall process, instead of diffusional steps. This kinetic model reduces to Langmuir isotherm in equilibrium condition, which in turn adequately described the solid-liquid interface equilibrium. Both kinetic, namely, adsorption kinetic constant (ka), and isotherm parameters: maximum adsorption capacity (qmax) and adsorbent-adsorbate affinity (b) provided data to the thermodynamics investigation, which was evaluated by means of: (i) activation energy (Ea) calculated Arrhenius equation; and (ii) enthalpy of adsorption (ΔH) determined by the Henry constant with the estimated parameters. In this sense, the proposed model presents a theoretical investigation of the entire process by an interdependent approach. Results showed higher adsorption capacity in acidic pH values (i.e. pH=2 – lower than adsorbent’s zero point charge: 4<pHzpc<10) suggesting electrostatic interactions as the main intermolecular forces in adsorption’s mechanism. The positive and low values of ΔH and Ea suggested to a physical nature and endothermic sorption process. Morphological and chemical characteristics of the adsorbent-adsorbate system indicated the possibility of aggregates formation and hence sterical limitations for the dye in the DOSD-2 adsorbent pores, on spite of that high adsorption yield of RB5G dye presented by DOSD-2 (≈700mgg−1) was achieved demonstrating its great potential for textile effluents containing reactive dyes.
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•9 commercial membranes were tested for OSN of extracts from wet olive pomace.•Industrially interesting phenolic compounds can be recovered by OSN.•High purification of valuable ...hydroxytyrosol and tyrosol has been achieved.•Molecular weight is not enough to predict rejection values in OSN.
Organic-solvent nanofiltration (OSN) has been applied to purify and fractionate the phenolic compounds present in wet olive pomace, which is the main by-product of olive mills. Nine commercial OSN membranes have been tested: DuraMem® 150, DuraMem® 300, DuraMem® 500, PuraMem® 600 (Evonik), NFS, NFX (Synder), oNF-1 and oNF-2 (Borsig) and NF270 (FilmTec). Their stability in ethanol/water 50:50 (v/v) and their effectiveness to treat a model solution of a solvent-based extract of wet olive pomace have been studied. To that end, a METcell cross-flow system (Evonik) has been utilized. DuraMem® 500, NFX and NF270 membranes displayed satisfactory values of permeate flux (10–100 L·h−1·m−2) compared to the other tested membranes. Measurements of the contact angle of the membranes after their conditioning and after the nanofiltration process allowed the comprehension of the interaction between the ethanol/water 50:50 (v/v) solution and the membrane. The solvent contact angle was also examined. AFM was employed to understand the modification of membrane morphology. To characterize the samples, liquid chromatography coupled to mass spectrometry (and/or refractive index detector) was employed. The selected membranes exhibited low rejection values for the aimed phenolic compounds (less than 10 % for hydroxytyrosol) and high rejection (50–100 %) of the undesired compounds, such as sugars and organic acids. Therefore, the purification of the target phenolic compounds was accomplished.
The objective of this study was to assess the predictive value of a lung ultrasound (LUS) score in the development of moderate-severe bronchopulmonary dysplasia (sBPD). This was a prospective ...observational diagnostic accuracy study in a third-level neonatal intensive care unit. Preterm infants with a gestational age below 32 weeks were included. A LUS score (range 0-24 points) was calculated by assessing aeration semiquantitatively (0-3 points) in eight lung zones on the 7th day of life (DOL) and repeated on the 28th DOL. ROC curves and logistic regression were used for analysis. Forty-two preterm infants were included. The LUS on the 7th DOL had an area under the receiver operating characteristic curve (AUROC) of 0.94 (95% CI: 0.87-1) for the prediction of sBPD (optimal cutoff of ≥8 points: sensitivity 93%, specificity 91%). The LUS score was independently associated with sBPD OR 2.1 (95% CI: 1.1-3.9), p = 0.022, for each additional point in the score. Conclusions: Lung aeration as assessed by LUS on the 7th DOL may predict the development of sBPD.
The fissility is the ability of some rocks to split along relatively smooth surfaces parallel to the bedding. This property observed mostly in fine-grained rocks is particularly expressed in ...outcrops, where rocks are subjected to weathering processes. Most authors associate the fissility to the abundance of clay minerals and their orientation parallel to the bedding. The horizontal fabric can be promoted by depositional conditions such as sediment composition, quantity of total organic carbon content (TOC) and depositional mechanisms, giving rise to a primary fissility. Alternatively, the alignment of platy minerals can be linked to the burial history of the rock, by processes such as mechanical compaction or secondary mineral growth, resulting in a secondary fissility. The present study aims to identify the main controls of fissility development at the micro- and macroscopic scale in rocks of the Vaca Muerta Formation exposed in the Cerro Mulichinco area and in a 121-meter-long core extracted from a well within the Neuquén Basin. In outcrops, fissility is related to fine-grained laminated facies with low carbonate content, revealing the strong control exerted by lithology. The TOC measurements allow establishing a positive correlation between organic matter content and fissility intensity. Moreover, the analysis of the transgressive-regressive cycles shows that fissility is higher around the maximum flooding surfaces. Regarding their mechanical characteristics, the different interfaces observed in core are classified into first and second-order, the last one including fissility planes. Some of these interfaces evolve from potential (partially open) to effective (totally open) discontinuities in response to changes of stress conditions during the core extraction and due to the stress relaxation through time: weeks (T1), months (T2) and years (T3) after extraction. The time evolution of the effective core discontinuities points out rock intervals that are variably broken and core segments that remain intact. The Drying Alcohol Discontinuities (DAD) methodology reveals potential discontinuities within apparently intact core segments. By using this technique, a 4-class index is established as a proxy for fissility degree. When integrated with geological, petrophysical and geomechanical data, this index enables characterizing the main mechanisms controlling rock fissility that express through discontinuities promoting the loss of competence of a rock. Consequently, this mechanical property is considered to influence the efficiency of hydraulic fracture in shale reservoir completion.
In this work Hermia's models adapted to crossflow ultrafiltration were used to investigate the fouling mechanisms involved in the ultrafiltration of polyethylene glycol (PEG). Although PEG has been ...very often used as a standard macromolecule in ultrafiltration experiments to test flux decline models, it has not been used to test Hermia's models adapted to crossflow ultrafiltration. This work analyses the different fouling mechanisms that may occur at different stages of the ultrafiltration process. Fitted Hermia's models parameters are also analyzed for the experimental conditions tested on the basis of their physical meaning.
Ultrafiltration experiments were performed with ceramic membranes supplied at different experimental conditions: feed flow rates and transmembrane pressures (TMPs). The results showed that the phenomenon controlling fouling was intermediate blocking for the highest TMP and the lowest crossflow velocity tested. For lower TMPs and/or higher a crossflow velocities, complete blocking or intermediate blocking controlled the fouling process. The analysis of the fouling mechanisms performed dividing the filtration curves in different regions revealed that complete blocking was dominant for a TMP of 0.3
MPa and a crossflow velocity of 1
m/s and in the case of a TMP of 0.4
MPa and a crossflow velocity of 2
m/s.
Phenolic compounds from a hydroalcoholic extract of wet olive pomace were purified and concentrated by an integrated membrane process in organic media. First, UF010104 (Solsep BV) and UP005 (Microdyn ...Nadir) membranes were tested to be implemented in the ultrafiltration stage, with the aim of purifying the extract and obtaining a permeate enriched in phenolic compounds. Despite the high flux observed with the UF010104 membrane (20.4 ± 0.7 L·h
·m
, at 2 bar), the UP005 membrane was selected because of a more suitable selectivity. Even though some secoiridoids were rejected, the permeate stream obtained with this membrane contained high concentrations of valuable simple phenols and phenolic acids, whereas sugars and macromolecules were retained. Then, the ultrafiltration permeate was subjected to a nanofiltration step employing an NF270 membrane (DuPont) for a further purification and fractionation of the phenolic compounds. The permeate flux was 50.2 ± 0.2 L·h
·m
, working at 15 bar. Hydroxytyrosol and some phenolic acids (such as vanillic acid, caffeic acid, and ferulic acid) were recovered in the permeate, which was later concentrated by reverse osmosis employing an NF90 membrane. The permeate flux obtained with this membrane was 15.3 ± 0.3 L·h
·m
. The concentrated phenolic mixture that was obtained may have important applications as a powerful antioxidant and for the prevention of diabetes and neurodegenerative diseases.
To contribute to the circular economy in olive mills, wet olive pomace can be employed as a source of valuable phenolic compounds. These compounds are efficiently extracted with ethanol/water 50:50 ...(v/v), at 40 °C. Here, the ultrafiltration membranes UF010104, UF010801v3 (from SolSep BV), and UP005 (Microdyn Nadir) have been tested to purify the phenolic compounds present in the hydroalcoholic extracts of the pomace. Several membrane conditioning protocols were explored, being the most adequate a short pre-treatment consisting of soaking the membrane in the working solvent for 2 h. All the considered membranes permitted the recovery of the biophenols of interest in the permeate stream, being most of the organic matter retained. A powerful analytical methodology based on liquid chromatography coupled to mass spectrometry (LC-ESI-QToF-MS) allowed the evaluation of the individual rejection of 43 compounds. The UF010104 membrane displayed the highest permeate flux (15 L h−1·m−2, at 2.5 bar) and high rejection of the total solids (67 ± 3%, at 2.5 bar), thus achieving the purification of the phenolic compounds in the permeate stream. The cleaning of the membranes used in organic solvent media was also investigated.
•Organic solvent ultrafiltration of wet olive pomace extracts has been performed.•Commercial ultrafiltration membranes resisted the contact with ethanol at 50% (v/v).•Several pretreatments of the membranes were studied.•Valuable phenolic compounds were recovered in the permeate stream.•43 individual compounds were monitored by LC-ESI-qTOF-MS.
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•Different NF membranes were evaluated for a possible second stage of OMW treatment.•2D fluorescence and FTIR techniques were used to analyse membrane fouling.•All tested compounds ...have an effect on membrane surfaces (confirmed with PCA).•NF achieved a concentrate of OMW polyphenols and a suitable permeate for reuse.
The presented work tries to solve the problem of the large volumes of oil mill wastewater (OMW). For this, nanofiltration is presented as a possible second stage of treatment. Different membranes were tested under different operating conditions, varying cross flow velocity (CFV) and transmembrane pressure (TMP), in order to obtain a concentrate rich in phenolic compounds and also an adequate permeate able to be returned to the process as machinery cleaning water. The NF270 membrane under the conditions of 1 ms−1 CFV and 10 bar of TMP was observed to be the best to concentrate the phenolic compounds, with high permeate flux and low fouling. Different types of tests were performed: membrane adsorption tests with different compounds, nanofiltration tests with a model solution (MS) to analyse fouling and check the effectiveness of the cleaning protocol and, finally, the selected NF270 membrane was tested with OMW. Also, for the first time, 2D fluorescence spectroscopy and Fourier-transform infrared spectroscopy (FTIR) were used together as tools to study membrane fouling. From the adsorption tests it was observed that all the considered compounds had an effect on the membrane surfaces, which was also confirmed from the nanofiltration tests (with the DM900 membrane the most affected). After cleaning, the membranes fouled with MS and OMW did not recover the spectra of the pristine membranes but, instead, matched the spectra presented by the new membranes subjected to the cleaning protocol. Finally, the following a suitable membrane for this purpose is selected In addition, it has been proved that the used spectroscopic techniques are a feasible option for the study of both fouling and efficiency of cleaning protocols.
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