D.Phil. (Chemistry) / Please refer to full text to view abstract

Orientador: Miriam Dupas Hubinger / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos / Made available in DSpace on 2018-08-27T10:07:35Z (GMT). No. of bitstreams: 1 Rabelo_RenataSantos_M.pdf: 54735801 bytes, checksum: 79deeea44988fbcfd818411f5b804573 (MD5) Previous issue date: 2015 / Resumo: A alcachofra (*Cynara scolymus L.*) é uma herbácea perene pertencente à família *Asteraceae. *A espécie, rica em compostos fenólicos, é originária de regiões subtropicais, mas também é cultivada no Brasil, onde maior parte da produção se concentra no interior paulista e é voltada à indústria de conservas*,* que geralmente descarta como resíduo, brácteas externas e internas da planta. Em vista disso, o presente trabalho teve como objetivo, desenvolver extratos ricos em compostos bioativos, principalmente fenólicos, a partir dos resíduos de alcachofra, por meio do estudo do processo de extração assistida por ultrassom e da avaliação do desempenho do processo de concentração por membranas. Inicialmente, foram estudadas as variáveis da extração hidroalcoólica assistida por ultrassom como potência do ultrassom, composição do solvente e razão sólido/solvente. Após esta etapa, dois dos extratos, nas melhores condições de extração, foram concentrados por nanofiltração, usando três membranas de poliamida (NF270, DK e DL), em um sistema de filtração tangencial operado a 20 bar. Os processos foram avaliados quanto ao rendimento de compostos fenólicos (Folin-Ciocauteau), ácido clorogênico (CLAE-DAD) e capacidade antioxidante (DPPH e FRAP). Os rendimentos obtidos com a integração das etapas de extração e concentração, a partir de um fator de redução de volume de 2,5 foram de 559,59 ± 32,09 mg de ácido gálico equivalente/g de extrato seco para fenólicos totais, e 22,95 ± 0,35 mg de ácido clorogênico/g de extrato seco, para ácido clorogênico. Os resultados para capacidade antioxidante foram de 198,88 ± 15,15 mg Trolox equivalente/g de extrato seco, para o método de DPPH, e de 385,70 ± 0,35 mg Trolox equivalente/g de extrato seco para o método FRAP. O declínio do fluxo de permeado no processo de nanofiltração foi causado pela formação de torta, e a membrana que apresentou menor resistência ao fluxo, maior estabilidade ao longo do processo de filtração e maior retenção dos compostos de interesse, foi a DK, sendo esta a mais indicada para concentração dos extratos avaliados nesse trabalho / Abstract: The artichoke (Cynara scolymus L.) is a perennial herb belonging to the family Asteraceae. The species, rich in phenolic compounds, is originally from subtropical regions, but is also cultivated in Brazil, where most of its production is concentrated in the interior of São Paulo, and is geared to the canning industry, where external and internal bracts of plant are usually discarded as waste. The present study aimed to develop extracts rich in bioactive compounds, mainly phenolics, from artichoke waste by the study of the extraction process assisted by ultrasound and the assessment of the performance of the membrane concentration process. Initially, the variables of water-alcohol extraction assisted by ultrasound (ultrasound power, solvent composition and solid/solvent ratio) were studied, after this, two extracts in the best extraction conditions were concentrated by nanofiltration, using three polyamide membranes (NF270, DK, DL), in a tangential filtration system operated at 20 bar. Process yields were evaluated for phenolic compounds (Folin-Ciocauteau), chlorogenic acid (HPLC-DAD) and antioxidant capacity (DPPH and FRAP). The yield obtained with the integration of extraction and concentration processes, from a volume reduction factor of 2.5 were of 559.59 ± 32.09 mg of gallic acid equivalent/g dry extract for total phenolics, and 22.95 ± 0,35 mg of chlorogenic acid/g of dry extract, for chlorogenic acid. The results for antioxidant capacity were of 198.88 ± 15.15 mg Trolox equivalent/g of dry extract to the DPPH method, and 385.70 ± 0.35 mg Trolox equivalent/g of dry extract for the FRAP method. The decline of the permeate flux in nanofiltration process is due to cake formation. The membrane that showed less resistance to flow, greater stability over the filtration process and more retention of the compounds of interest was DK, which is the most suitable for concentration of the extract evaluated in this work / Mestrado / Engenharia de Alimentos / Mestra em Engenharia de Alimentos

Nanofiltration and seawater reverse osmosis desalination are still considered energy-intensive processes. Seawater desalination can be 25 times more energy-intensive compared to conventional water treatment processes. Biofouling is a significant problem in achieving sustainable desalination, as it increases the energy demands and the overall water cost. Limiting the biodegradable substrate concentration in the feed water is proposed as a suitable approach to control biofouling in desalination membranes. Until now, nutrient manipulation studies have not fully elucidated to which extent this technique affects biofilm morphology and if the manipulated biofilms are easier to control and remove with a chemical-free approach. The main objective of this Ph.D. study is to provide a comprehensive assessment of the effect of nutrient manipulation on the physical properties of the developed biofilm to decrease the impact of biofouling on system performance and enhance the cleanability of biofilms in membrane systems. The aspects of the study included biofilm development and related system performance under varying feed water biodegradable carbon and phosphorous concentrations and the impact of permeation. The results of this study indicate that lowering the assimilable organic carbon and phosphorus concentration in the feed water controls biofilm formation and prolongs membrane system performance. A strategy of enhancing the hydraulic cleanability of biofilms in RO systems could involve avoiding the increase of the phosphorus concentration by eliminating the use of phosphonate-based antiscalants. The higher detachment for biofilms grown at a lower phosphorus concentration was explained by more soluble polymers in the EPS, resulting in a lower biofilm cohesive and adhesive strength. We demonstrated that the phosphorus concentration in the feed water affected the microbial and EPS composition. A homogenous bacterial community composition was found over the biofilm height. Permeation played a role in shaping biofilm localization, and therefore, the observed impact on the system performance parameters. This Ph.D. dissertation represents an exciting advance towards greener desalination by controlling and enhancing the cleanability of biofilms through feed water nutrient manipulation.

Membrane processes are considered energy-efficient for water desalination and treatment. However most membranes are based on polymers prepared from fossil petrochemical sources. The development of multilayer membranes for nanofiltration and ultrafiltration, with thin selective layers of naturally available cellulose, has been hampered by the availability of non-aggressive solvents. We propose the manufacture of cellulose membranes based on two approaches: (i) silylation, coating from solutions in tetrahydrofuran, followed by solvent evaporation and cellulose regeneration by acid treatment; (ii) casting from solution in 1-ethyl-3-methylimidazolum acetate ([C2mim]OAc), an ionic liquid, followed by phase inversion in water. In the search for less harsh, greener membrane manufacture, the combination of cellulose and ionic liquid is of high interest. Due to the abundance of OH groups and hydrophilicity, cellulose-based membranes have high permeability and low fouling tendency. Membrane fouling is one of the biggest challenges in membrane industry and technology. Accumulation and deposition of foulants onto the surface reduce membrane efficiency and requires harsh chemical cleaning, therefore increasing the cost of maintenance and replacement. In this work the resistance of cellulose 5 membranes towards model organic foulants such as Suwanee River Humic Acid (SRHA) and crude oil have been investigated. Cellulose membrane was tested in this work for oil-water (o/w) separation and exhibited practically 100 % oil rejection with good flux recovery ratio and membrane resistivity. The influence of anionic, cationic and ionic surfactant as well as pH and crude oil concentration on oil separation was investigated, giving a valuable insight in experimental and operational planning.

In the last decades, there has been a trend towards bio-inspired approaches for the formation of nanocoatings as well as to accomplish energy-intensive industrial separations in a more sustainable fashion. Solvent Resistant Nanofiltration (SRNF) is a pressure driven technology where the operation conditions are moderate and additional waste streams are minimized, making this a favorable energy efficient approach for challenging molecular separations such as purification of active pharmaceutical ingredients, production of specialty chemicals and in the petrochemical industry just to mention a few examples, where this technology can be currently applied. The overall performance of SRNF membranes is determined by solute/solvent interactions with the membrane top layer. Therefore, the modification of the membrane surface becomes crucial to obtain high-performance SRNF membranes, as well as exploring novel and green approaches to improve the separation properties of SRNF membranes, without sacrificing their permeation properties. One alternative for the fabrication of the thin-films in SRNF membranes proposed in this work is the use of biopolyphenolic molecules. Among the many classes of phenolic biomolecules, plant phenols are capable of binding and cross-linking due to their strong interfacial activity. Here, the successful optimization of the interfacial polymerization reaction for the manufacture of SRNF membranes is demonstrated by replacing the common toxic amines used for this method with natural occurring bio-polyphenols such as dopamine, tannic acid, morin hydrate and catechin. These bio-polyphenols can be found in mussels, date fruits, guava fruits and green tea respectively and they were used to form a selective thin film on top of a crosslinked polyacrylonitrile or a cellulose support. These membranes have shown an exceptional performance and resistance towards harsh solvent environments. Due to the incorporation of natural compounds for the manufacture, they provide a cost-effective alternative for industrial separations due to the ease of chemical modification and preparation, which is potentially easy to scale up at low cost taking advantage of the natural compounds for their manufacture.

Abstract: The worldwide consumption of pharmaceuticals and personal care products for healthcare purposes has resulted in the occurrence of organic micropollutants (OMPs) in freshwater and wastewater resources. These pollutants are not entirely removed by conventional water and wastewater treatment plants, leading to potential human and animal health problems. Membranes are a promising technology capable of solving this problem. This study evaluated the ability of high-pressure driven membranes such as nanofiltration (NF) and reverse osmosis (RO) to remove OMPs. A total of 13 compounds were selected so that a broad range of molecular weights and octanol-water partition coefficients (log Kow) could be studied. Three commercial thin-film-composite polyamide membranes (NF1, NF6, and RO4) were tested. Filtration experiments were conducted using a cross-flow membrane system at pH 6 8 and 10. The membranes were characterized by atomic force microscopy and scanning electron microscopy that allowed a more profound understanding of the membrane surface structures. Experimental results showed that the permeate flux of NF6 is dependent on the pH of the feed solution. An increase in the feed pH from 6 to 10 resulted in an increase on the permeate flux from 14.5 to 24 L m-2 h-1 bar-1, which caused a drop in the rejection of some OMPs by NF6. Nevertheless, for most OMPs, as pH increased to 10, rejection increased for NF1 and RO4 due to electrostatic repulsion between the negatively charged membrane surface and the ionized OMPs. It was observed that ionic hydrophobic compounds could be highly rejected (> 95%) by NF1 and RO4. The study indicated that the rejection of non-ionic hydrophilic and hydrophobic OMPs were rejected effectively by RO4 (> 90%), and the rejection was mostly dominated by size exclusion and hydrophobic interactions between the membrane and the OMPs. Furthermore, the study revealed that the properties of the compounds, the intrinsic properties of the membrane, and the operating conditions have a significant influence on the rejection of OMPs.

Owing to the maldistribution of precipitation in the harsh climatic region has resulted in the deficit between freshwater demand and natural supply or water scarcity in these countries. Seawater desalination has emerged as one of the most reliable methods to bridge this gap. However, the thermal desalination (MED and MSF) process faces challenges related to surface scaling phenomena, such as temperature and seawater concentration. Innovative thermodynamic processes and technologies have the potential to overcome these limitations. On one hand, the top brine temperature (TBT) limit can be raised by partially removing the multivalent ions such as SO42-, Mg2+, Ca2+, Cl-, and Na+ dissolved in the seawater. One of the main drawbacks of the current MED processes is their vulnerability to scaling at temperatures above 70°C.. This limitation deprives the technology to be energy efficient and reduces its optimal productivity. However, by implementing an optimized pre-treatment of seawater feed using NF membranes, the efficiency of the process can be significantly improved. In the pilot plant, the experiment was conducted to investigate the efficacy of NF (nanofiltration) as a physical pre-treatment method for partially removing undesirable ions of dissolved salts in Red Sea water, thereby mitigating scaling issues beyond the upper TBT limit in thermal desalination systems. Utilizing the NF-270 membrane, the optimal operating feed pressure of 15 bar was determined to ensure effective ion removal while minimizing operational expenditures (OpEx). The results demonstrated high removal rates, with 97% removal of Sulfate (SO42-), 73% removal of Magnesium (Mg2+), 49% removal of Calcium (Ca2+), 17% removal of Sodium (Na+), and 16% removal of Chloride (Cl-). By employing NF as a pre-treatment method, the concentrations of these ions were significantly reduced, allowing for thermal desalination plants to operate at higher temperatures, with a maximum TBT of 120°C. This, in turn, has the potential to substantially increase water production yield in thermally driven plants by incorporating a greater number of stages in a green new design plant or by exploiting larger temperature differences in existing plants.

Organic solvent nanofiltration (OSN) is a membrane-based sustainable alternative to conventional separation techniques because it is non-thermal and energy-efficient. The fabrication of membranes usually includes fossil-based polymers and toxic solvents that present significant challenges. For example, its declining availability, concerns about its degradability and cross-contamination that involve toxicity risks. Nowadays, there is an increasing interest in the development of more sustainable membranes that maintain an optimum performance even in harsh solvents. The aim of my thesis research is to develop stable OSN membranes from cellulose acetate and explore the use of deacetylation reactions. The effect of the degree of acetylation on the membrane performance and stability in different organic solvents was investigated. The chemical composition and morphology were investigated using Fourier Transform Infrared (FTIR), Scanning Electron Microscope (SEM), and Atomic Force Microscopy (AFM). It was found that cellulose acetate membranes with less than 22% acetylation present a satisfactory solvent resistance and rejection in harsh solvents, such as DMF and acetone. In the performance tests were identified two main trends: one for polar protic solvents and one for polar aprotic solvents. This was attributed to their capacity to interact with the membrane via H-bond formation. The molecular weight cutoff (MWCO) was in the range of 735–325 g mol–1 in aprotic solvents and higher than 885 g mol–1 for polar protic solvents. The results found in this research can be translated into a reduce in costs, waste generated, energy required, and time employed in the fabrication of membranes. Also, it opens potential areas in the industry as it can be implemented in harsh solvent environments.

Organic solvent nanofiltration (OSN) is a low-energy alternative for continuous separations in the chemical industry. As the pharmaceutical sector increasingly turns toward continuous manufacturing, OSN could become a sustainable solution for chiral separations. Here we present the first comprehensive theoretical assessment of enantioselective OSN processes. Lumped dynamic models were developed for various system configurations, including structurally diverse nanofiltration cascades and single-stage separations with side-stream recycling and in situ racemization. Enantiomer excess and recovery characteristics of the different processes were assessed in terms of the solute rejection values of the enantiomer pairs. The general feasibility of stereochemical resolution using OSN processes is discussed in detail. Fundamental connections between rejection selectivity, permeance selectivity, and enantiomer excess limitations are revealed. Quantitative process performance examples are presented based on theoretical rejection scenarios and cases from the literature on chiral membranes. A model-based prediction tool can be found on www.osndatabase.com to aid researchers in connecting materials development results with early-stage process performance assessments.

This document details the results of a study that employed a single element, spiral-wound, thinfilm composite nanofiltration (NF) membrane pilot to assess the treatment effectiveness for aerated and unaerated groundwater supplies. Phase 1 consisted of using raw, unaerated groundwater with standard cartridge filtration (CF) and scale inhibitor (SI) as pretreatment to NF. During the first phase, four water recoveries and crossflow velocities were evaluated to observe how operational conditions affected permeate water quality. Phase 2 involved the simulation of a 70-foot transmission pipeline and sand filter (SF) pilot in series with CF and SI addition pretreatment, prior to NF. Phase 3 employed tray aeration prior to the SF pilot. The pilot was operated for 1,483 run-hours over the three phases, whereupon operational and water quality monitoring ensued to assess NF efficiency. Biological activity tests and foulant analyses were performed to further characterize source water. It was determined statistically that changes in operational conditions in Phase 1 such as crossflow velocity did not significantly affect constituent mass transfer. Phase 2 demonstrated that NF removed total dissolved solids and total organic carbon content greater than 96 percent (%) and 86%, respectively. Phase 3, which exhibited operational difficulties and flux decline, suggested that additional pretreatment is required for NF operation using aerated groundwater. Dimensional analysis (DA) and diffusionbased mass transfer models were employed to predict permeate chloride content for each testing phase; it was determined that the DA overpredicted chloride concentrations by 10 magnitudes and diffusion models were predictive when compared to actual values. The transient response to feed water perturbations within the single-stage membrane process was determined to cause a log-logistic two-and-a-half-minute delay.