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- Study of antioxidant and antitumoral activity of cork processing wastewaters components fractionated by ultrafiltration membranesPublication . Gomes, Luís; Borges, C.; Serralheiro, M.L.M.; Pacheco, Rita; Minhalma, MiguelCork processing wastewater present a severe environmental problem due to its high content in organic matter, such as sugars and non-biodegradable compounds like polyphenols (PPs), namely tannins. In this work, the assessment of the biological activity and identification of valuable polyphenolic compounds was envisaged. These compounds were obtained using membrane technology, leading to the valorisation of the wastewater components and simultaneously leading to the decrease of its pollutant content.
- The ultrafiltration performance of cellulose acetate asymmetric membranes: a new perspective on the correlation with the infrared spectraPublication . Figueiredo, Ana Sofia; Garcia, Ana Rosa; Minhalma, Miguel; ILHARCO, LAURA; Pinho, Maria deIntegral asymmetric cellulose acetate (CA) membranes were casted by phase-inversion with formamide varying content - 22, 30 and 34% - as pore promoter. These membranes, CA-22, CA-30 and CA-34, were analyzed by infrared spectroscopy in attenuated total reflection mode (ATR-FTIR) to investigate the porous membrane matrix influence on the polymer/water/solute interactions and the selective ultrafiltration of salts. The membranes covered a wide range of hydraulic permeabilities, from 3.5 to 81.0 kg.m-2.h-1.bar-1, and of molecular weight cut-offs, from 4.17 to 31.43 kDa. The experimental apparent rejection coefficients of neutral solutes of increasing molecular weight are related to their intrinsic rejection coefficients through the film model. The surface average pore radius, estimated by an iterative algorithm, ranges from 2.1 to 4.5 nm. The tighter membrane, CA-22, displays experimental apparent rejection coefficients to the Na2SO4, CaSO4, MgSO4 of 50% or higher values and this is in contrast with the lower values, between 14 and 18%, to the NaCl, CaCl2 and MgCl2 salts. The ATR-FTIR evidences that in the membranes with larger pores, CA-30 and CA-34, the water molecules are organized with a liquid-water-like structure, in which most molecules are hydrogen bonded to four or to two others; nevertheless, a fraction of water molecules is strongly bonded to the CA carbonyl groups. For the CA-22 membrane, there are more free carbonyl groups and a larger fraction of free water, both able to interact with solutes, such as the hydrated sulphate ions. Therefore, this ultrafiltration membrane has the capability of differentiating anionic species.
- Nanofiltration of surface water for the removal of endocrine disruptorsPublication . Salvaterra, Ana Filipa; Sarmento, Georgina; Minhalma, Miguel; de Pinho, Maria NorbertaThe assessment of surface water nanofiltration (NF) for the removal of endocrine disruptors (EDs) Nonylphenol Ethoxylate (IGEPAL), 4-Nonylphenol (NP) and 4-Octylphenol (OP) was carried out with three commercial NF membranes - NF90, NF200, NF270. The permeation experiments were conducted in laboratory flat-cell units of 13.2 x 10(-4) m(2) of surface area and in a DSS Lab-unit M20 with a membrane surface area of 0.036 m2. The membranes hydraulic permeabilities ranged from 3.7 to 15.6 kg/h/m(2)/bar and the rejection coefficients to NaCl, Na2SO4 and Glucose are for NF90: 97%, 99% and 97%, respectively; for NF200: 66%, 98% and 90%, respectively and for NF270: 48%, 94% and 84%, respectively. Three sets of nanofiltration experiments were carried out: i) NF of aqueous model solutions of NP, IGEPAL and OP running in total recirculation mode; ii) NF of surface water from Rio Sado (Settibal, Portugal) running in concentration mode; iii) NF of surface water from Rio Sado inoculated with NP, IGEPAL and OP running in concentration mode. The results of model solutions experiments showed that the EDs rejection coefficients are approximately 100% for all the membranes. The results obtained for the surface water showed that the rejection coefficients to natural organic Matter (NOM) are 94%, 82% and 78% for NF90, NF200 and NF 270 membranes respectively, with and without inoculation of EDs. The rejection coefficients to EDs in surface water with and without inoculation of EDs are 100%, showing that there is a fraction of NOM of high molecular weight that retains the EDs in the concentrate and that there is a fraction of NOM of low molecular weight that permeates through the NF membranes free of EDs.
- Cork industry wastewater partition by ultra/nanofiltration: A biodegradation and valorisation studyPublication . Bernardo, Marisa; Santos, Ana; Cantinho, Paula; Minhalma, MiguelWastewater from cork processing industry present high levels of organic and phenolic compounds, such as tannins, with a low biodegradability and a significant toxicity. These compounds are not readily removed by conventional municipal wastewater treatment, which is largely based on primary sedimentation followed by biological treatment. The purpose of this work is to study the biodegradability of different cork wastewater fractions, obtained through membrane separation, in order to assess its potential for biological treatment and having in view its valorisation through tannins recovery, which could be applied in other industries. Various ultrafiltration and nanofiltration membranes where used, with molecular weight cut-offs (MWCO) ranging from 0.125 to 91 kDa. The wastewater and the different permeated fractions were analyzed in terms of Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD), Total Phenols (TP), Tannins, Color, pH and Conductivity. Results for the wastewater shown that it is characterized by a high organic content (670.5-1056.8 mg TOC/L, 2285-2604 mg COD/L, 1000-1225 mg BOD/L), a relatively low biodegradability (0.35-0.38 for BODs/COD and 0.44-0.47 for BOD20/COD) and a high content of phenols (360-410 mg tannic acid/L) and tannins (250-270 mg tannic acid/L). The results for the wastewater fractions shown a general decrease on the pollutant content of permeates, and an increase of its biodegradability, with the decrease of the membrane MWCO applied. Particularly, the permeated fraction from the membrane MWCO of 3.8 kDa, presented a favourable index of biodegradability (0.8) and a minimized phenols toxicity that enables it to undergo a biological treatment and so, to be treated in a municipal wastewater treatment plant. Also, within the perspective of valorisation, the rejected fraction obtained through this membrane MWCO may have a significant potential for tannins recovery. Permeated fractions from membranes with MWCO lower than 3.8 kDa, presented a particularly significant decline of organic matter and phenols, enabling this permeates to be reused in the cork processing and so, representing an interesting perspective of zero discharge for the cork industry, with evident environmental and economic advantages. (C) 2010 Elsevier Ltd. All rights reserved.
- Nanofiltration of Cork Wastewaters and Their Possible Use in Leather Industry as Tanning AgentsPublication . Geraldes, V.; Minhalma, Miguel; de Pinho, M. N.; Anil, A.; Ozgunay, H.; Bitlisli, B. O.; Sari, O.Cork processing wastewater is a very complex mixture of vegetal extracts and has, among other natural compounds, a very high content of phenolic/tannic colloidal matter that is responsible for severe environmental problems. In the present work, the concentration of this wastewater by nanofiltration was investigated with the aim of producing a cork tannin concentrate to be utilized in tanning. Permeation results showed that the permeate fluxes are controlled by both osmotic pressure and fouling/gel layer phenomena, leading to a rapid decrease of permeate fluxes with the concentration factor. The rejection coefficients to organic matter were higher than 95%, indicating that nanofiltration has a very good ability to concentrate the tannins and produce a permeate stream depleted from organic matter. The cork tannin concentrate obtained by nanofiltration and evaporation had total solids concentration of 34.8 g/l. The skins tanned by this concentrate were effectively converted to leather with a shrinking temperature of 7 degrees C.
- Optimized Production of Hydroxamic Acid Derivatives with Antioxidant and Anticholinergic Potential by Immobilized Pseudomonas aeruginosa CellsPublication . Bernardo, Marisa; Reis, Telma; Minhalma, Miguel; Karmali, Amin; Serralheiro, Maria Luísa; Pacheco, RitaIn this study were investigated, the synthesis, acetylcholinesterase inhibition and antioxidant activity of a series of hydroxamic acid derivatives (HAD), with different chemical group characteristics, such as aliphatic (acetohydroxamic acid and butyryl hydroxamic acid), aromatic (benzohydroxamic acid and phenylalanine hydroxamic acid) and amino acid (glycine hydroxamic acid and alanine hydroxamic acid). It was observed that these HAD compounds present very promising activity as acetylcholinesterase (AChE) inhibitors and as antioxidants. The aliphatic HAD demonstrated to have a higher inhibitory activity of AChE than amino acid or aromatic HAD. As for the antioxidant activity, a high antioxidant potential was found for all the compounds with EC50 values ranging from 0.19 µM to 1.65 µM. Aiming these applications, a biocatalysis approach was used to obtain these HADs with optimal reactional conditions. In this study, reverse micelles with immobilized Pseudomonas aeruginosa intact cells containing amidase were used as a biocatalyst to catalyze the acyltransferase reaction of the corresponding substrate amide and hydroxylamine to obtain various HAD and this was achieved for the first time with yields of approximately 100 %.
- Cork processing wastewaters components fractioned by ultrafiltration membranes–studies of antioxidant and antitumoral activityPublication . Gomes, Luís; Borges, Carlos; Serralheiro, Maria Luisa; Minhalma, Miguel; Pacheco, RitaBACKGROUND: Cork processing wastewater is an environmental problem due to its high content of organic matter, such as sugars and non-biodegradable compounds such as polyphenols (PPs), namely tannins. Membrane technology aimed at valorisation of the wastewaters components, concentrate stream, and simultaneously offer a pre-treatment of the wastewater, permeate stream. In this work, the identification of bioactive PPs was also envisaged. Several fractions of cork processing wastewaters were generated using two cellulose acetate ultrafiltration membranes of 3 kDa and 74 kDa for PPs isolation according to nature and molecular weights. The membranes were prepared by the phase inversion method and fractionation was made in concentration and diafiltration modes. The wastewater and the fractions were analyzed in terms of total organic carbon, total phenols, tannins and total polysaccharides content and the compounds present were identified by FTIR, LC–MS and quantified by HPLC-DAD. RESULTS: Compounds such as quinic, gallic, protocatechuic, brevifolin carboxylic and ellagic acids were identified as the major compounds in cork wastewater. The wastewater and the fractions were tested for antioxidant activity and for capacity to inhibit the proliferation of the growth of human breast carcinoma cell lines, MCF-7. The fractions revealed high antioxidant activity with EC 50 values ranging from 1.174 ± 0.069 to 1.943 ± 0.179 mg/mgDPPH. The fractions demonstrated to be efficient as cell proliferation inhibitors, with values of IC50 ranging from 0.20 ± 0.003 to 0.46 ± 0.02 mg mL-1. CONCLUSION: The process reported demonstrates that PPs compounds can be recovered from cork effluent and further reused as high-value bioactive compounds.
- Concentration polarization quantification and minimization in cork process wastewater ultrafiltration by an ozone pretreatmentPublication . Minhalma, Miguel; De Pinho, Maria Norberta; Dominguez, Joaquin R.Concentration polarization and membrane fouling have been identified as the main problems during the ultrafiltration treatment of cork processing wastewaters. These problems drastically reduce the permeate fluxes and, therefore, their potential applications. In this work, a soft ozonation pretreatment was applied to minimize these undesirable effects. A new systematic study was carried out for membranes with different molecular weight cut-offs and at different operating conditions to monitor and quantify the concentration polarization caused by the wastewater's remaining ozonated compounds. Film theory was used to correlate the mass transfer coefficient, k, and the intrinsic rejection coefficient, f ', with the resistance introduced by concentration polarization. The ultrafiltration treatment was carried out under varying hydrodynamic operating conditions (circulating flow rates of 100-200 L/h) and transmembrane pressures (1-3 bar) for a set of four cellulose acetate membranes covering a wide range of molecular weight cut-offs (5000-100,000 Da) and hydraulic permeabilities (25-110 kg/h/m(2)/bar). The ozone pretreatment (at wastewater pH) reduced the phenolic content selectively (direct oxidation) by more than 50%, reducing membrane fouling and concentration polarization and increasing permeate fluxes (by 22-45%) and mass transfer coefficients (up to six times).
- Tailoring of structures and permeation properties of asymmetric nanocomposite cellulose acetate/silver membranesPublication . Figueiredo, Ana Sofia; Sánchez-Loredo, María Guadalupe; Maurício, António; Pereira, Manuel F. C.; Minhalma, Miguel; Pinho, Maria Norberta deCellulose acetate (CA)-silver (Ag) nanocomposite asymmetric membranes were prepared via the wet-phase inversion method by dispersing polyvinylpirrolydone-protected Ag nanoparticles in the membrane casting solutions of different compositions. Silver nanoparticles were synthesized ex situ and added to the casting solution as a concentrated aqueous colloidal dispersion. The effects of the dispersion addition on the structure and on the selective permeation properties of the membranes were studied by comparing the nanocomposites with the silver-free materials. The casting solution composition played an important role in the adequate dispersion of the silver nanoparticles in the membrane. Incorporation of nanoscale silver and the final silver content resulted in structural changes leading to an increase in the hydraulic permeability and molecular weight cut-off of the nanocomposite membranes. (c) 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41796.
- Assessment of saccharide fractionation by ultrafiltration and nanofiltrationPublication . Catarino, Isabel; Minhalma, Miguel; Beal, Lademir L.; Mateus, Marília; Pinho, Maria Norberta deThis paper addresses the investigation of the fractionation of saccharide mixtures and saccharide mixtures with calcium using ultrafiltration (UF) and nanofiltration (NF). A set of cellulose acetate membranes covered a wide range of molecular weight cut-off (MWCO) ranging from 250 to 46,000 Da and the total feed concentration of saccharides mixtures varied from 1550 to 4700 ppm with the ratio of the two saccharides-solutes (glucose to raffinose) being kept constant at the value of 1.8. The evolution pattern of the saccharide concentration ratio in the UF/NF permeate streams displayed a dependence on the membrane MWCO, on the total sugar concentration and on the presence of calcium ions. For the highest total sugar content, the membranes with MWCO from 2000 to 7000 Da showed saccharide fractionation capability that was enhanced in the presence of calcium. The Steric Pore Flow Model was used to predict individual solute permeation behaviours and to assess the deviations to steric hindered transport of the solutes in multi-component saccharide solutions. (C) 2008 Elsevier B.V. All rights reserved.