Isabel C Escobar

University of Kentucky | UKY · Department of Chemical and Materials Engineering

Many materials traditionally used for polymeric membrane fabrication incur significant environmental impacts and limit sustainability of the process; therefore, more eco‐friendly materials are needed in membrane fabrication. In this study, recycled polyethylene terephthalate (rPET) and a solvent blend of Rhodiasolv® PolarClean (PolarClean) and gamm...

Protection against airborne viruses has become very relevant since the outbreak of SARS-CoV-2. Nonwoven face masks along with heating, ventilation, and air conditioning (HVAC) filters have been used extensively to reduce infection rates; however, some of these filter materials provide inadequate protection due to insufficient initial filtration eff...

Microcystin-LR (MC-LR) is a toxin produced by cyanobacteria that can bloom in freshwater supplies. This study describes a new strategy for remediation of MC-LR that combines linearization of the toxin using microcystinase A, MlrA, enzyme with rejection of linearized byproducts using membrane filtration. The MlrA enzyme was expressed in Escherichia...

The outbreak of the COVID-19 pandemic, in 2020, has accelerated the need for personal protective equipment (PPE) masks as one of the methods to reduce and/or eliminate transmission of the coronavirus across communities. Despite the availability of different coronavirus vaccines, it is still recommended by the Center of Disease Control and Preventio...

(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-der...

Nanomaterials with tunable properties show promise because of their size-dependent electronic structure and controllable physical properties. The purpose of this research was to develop and validate environmentally safe nanomaterial-based approach for treatment of drinking water including removal and degradation of per- and polyfluorinated chemical...

The design and understanding of rejection mechanisms for both positively and negatively charged nanofiltration (NF) membranes are needed for the development of highly selective separation of multivalent ions. In this study, positively charged nanofiltration membranes were created via an addition of commercially available polyallylamine hydrochlorid...

The state-of-the-art manufacturing process of making lithium ion batteries (LIBs) uses a toxic organic and petroleum-derived solvent, N-methylprrolidone (NMP), to dissolve poly vinylidene fluoride (PVDF) to form a slurry consisting of active materials and conductive agents. By using viscosity and electrochemical measurements, scanning electron micr...

Phosphorene is a promising candidate as a membrane material additive because of its inherent photocatalytic properties and electrical conductance which can help reduce fouling and improve membrane properties. The main objective of this study was to characterize structural and morphologic changes arising from the addition of phosphorene to polymeric...

Nonsolvent induced phase separation has been widely used to fabricate polymeric membranes. Common solvents, such as dimethylacetamide (DMAc) and N-Methyl-2-pyrrolidone (NMP), are toxic and not environmentally friendly; therefore, eco-friendly alternatives are needed. Eco-friendly solvents, such as Rhodiasolv® PolarClean (PolarClean) and γ-valerolac...

Silver nanoparticles (AgNPs) have been widely studied for the control of biofouling on polymeric membranes due to their antimicrobial properties. However, nanoparticle leaching has posed a significant impediment against their widespread use. In this study, a one-step method of chemically embedding AgNPs on cellulose acetate (CA) membranes via their...

Petroleum‐derived solvents commonly used in membrane fabrication are often hazardous and toxic, so the investigation of safer alternatives is important. In this study, two low‐hazard solvents, methyl 5‐(dimethylamino)‐2‐methyl‐5‐oxopentanoate (Rhodiasolv® PolarClean) and gamma‐valerolactone (GVL), were investigated as sole‐ and as co‐solvents to ca...

Functional polymers or copolymers have been added to separations membranes by incorporating them in the membrane dope prior to casting, by in situ polymerization, and by postsynthesis surface modification of existing membranes. Here, a postsynthesis membrane functionalization that targeted decreasing the molecular weight cutoff (MWCO) and increasin...

Various types of channel proteins, broadly named porins, present in the cell membrane of gram‐negative bacteria have specific functionalities depending on their selectivity toward different nutrients or toward water. The high selectivity of porins has led to their incorporation into synthetic systems, in a field called biomimetics. An example is th...

Aquaporins are water channel proteins in cell membrane, highly specific for water molecules while restricting the passage of contaminants and small molecules, such as urea and boric acid. Cysteine functional groups were installed on aquaporin Z for covalent attachment to the polymer membrane matrix so that the proteins could be immobilized to the m...

Water pollution is one of the greatest challenges around the world. Nanocomposite membranes are a promising modified version of traditional polymeric membranes for water treatment, with three main characteristics of enhanced permeation, improved rejection and reduced fouling. For novel nanocomposite membranes, there is a strong connection between t...

Petroleum-derived solvents used for membrane fabrication through the nonsolvent induced phase separation (NIPS) process are known for their toxicity. Therefore, bio-derived and low-toxicity solvents are starting to be investigated. Examples of bio-derived, low-toxicity solvents include methyl-5-(dimethylamino)-2-methyl-5-oxopentanoate (PolarClean)...

Phosphorene is a two-dimensional material exfoliated from bulk phosphorus and it possesses a band gap. Specifically, relevant to the field of membrane science, the band gap of phosphorene provides it with potential photocatalytic properties, which could be explored in making reactive membranes that can self-clean. The goal of this study was to deve...

A 1980s cholera outbreak in Latin America, an inspirational university professor and one not-so-inspirational professor, and an Environmental Protection Agency STAR Fellowship were all pivotal experiences in my evolution as an environmental engineer, at the University of Kentucky where I am a full professor in the Department of Chemical and Materia...

Organic solvents, such as N-methyl-2-pyrrolidone (NMP) and dimethylacetamide (DMAc), have been traditionally used to fabricate polymeric membranes. These solvents may have a negative impact on the environment and human health; therefore, using renewable solvents derived from biomass is of great interest to make membrane fabrication sustainable. Met...

This study shows the results of low-biofouling nanocomposite membranes, loaded with casein-coated silver nanoparticles (casein-Ag-NPs). Membranes were cast and imbedded with Ag-NPs using two approaches, physical blending of Ag-NPs in the dope solution (PAg-NP/CA membranes) and chemical attachment of Ag-NPs to cast membranes (CAg-NP/CA membranes), t...

This study was directed at the investigation of technologies for treatment of water containing algal toxins at basic pH values. Ozonation, biofiltration and membrane filtration were examined for the removal of algal toxins, specifically microcystin-LR (MC-LR). Results indicate that, as expected, ozonation completely destroyed MC-LR in water, while...

Scaling up from a laboratory batch process to a continuous manufacturing process can result in unexpected changes in membrane morphology and performance. To understand how processing effects the structure and performance of cellulose acetate filtration membranes, membranes were produced using laboratory-scale doctor blade and industrial/production-...

This study shows the results of low-biofouling nanocomposite membranes, when using batch-scale fabrication and testing techniques, and when using continuous-scale fabrication and testing techniques. This holistic study begins with nanoparticle manufacturing and selection, then focuses on nanocomposite membrane synthesis and fabrication, and ends wi...

“When and Where I Enter…,” an effort to assist women of color in science, technology, engineering, mathematics, and medicine (STEMM) in the Midwest to become successful and sustaining members of the academy, was designed by a multicultural and multiethnic committee from The University of Toledo (UT). The goal was to provide professional development...

The accumulation of micro-organisms, along with the presence of nutrients, forms biofilms. Biofoulants that are typically encountered in desalination systems include cellular organisms (e.g. bacteria or algae) and organic debris, including algae organic matter. The accumulation of these micro-organisms is problematic to membranes by causing irrever...

Membrane fouling occurs when there is reversible or irreversible accumulation of macrosolutes present in the water on the membrane surface or within the pores. Membrane cleaning and eventual replacement due to fouling can add to the operational costs of membrane systems. Reversible fouling can be minimized by crossflow operation and/or backflushing...

The huge efforts for the achievement of highly purified biomolecules are growing every day. A great number of efficient techniques, such as chromatography, are already available in laboratory for separation processes. However, membrane-based technologies are the best match to assure simplicity, efficiency and easy scale-up procedures. Herein we rep...

The huge efforts for the achievement of highly purified biomolecules are growing every day. A great number of efficient techniques, such as chromatography, are already available in laboratory for separation processes. However, membrane-based technologies are the best match to assure simplicity, efficiency and easy scale-up procedures. Herein we rep...

The development of technologies for water treatment, desalination and reuse became more personal to me when the city where I live, Toledo, Ohio, USA, found itself without safe drinking water for two days in August 2014. On August 2, 2014, the greater Toledo area woke up to a Do Not Drink or Boil Water Advisory. The advisory was due to the presence...

RNA is one of the main soluble contaminants that needs to be separated from plasmid DNA (pDNA) during its recovery process from fermentation broths. Although significantly different in molecular size, pDNA and RNA are difficult to separate by membrane filtration due to the fact that both types of molecules are highly deformable and therefore suffer...

Aquaporin is a highly selective water channel protein, which allows water molecules to pass through in single file while the transport of ions, protons and hydroxyl ions is prevented. Biomimetic membranes attempt to combine of ultra-efficient functioning of biological molecules, such as aquaporins, with the productivity of synthetic water purificat...

The goal of this project was to develop low-biofouling membranes through the functionalization of cellulose acetate (CA) membranes with metal chelating ligands charged with biocidal metal ions, i.e. copper ions. To this end, glycidyl methacrylate (GMA),1 an epoxy, was used to attach a chelating agent, iminodiacetic acid (IDA),2 to facilitate the ch...

The need to control membrane fouling by microorganisms, also known as biofouling, is crucial in water separations applications. The purpose of this project was to investigate the charging of membrane surfaces with copper (Cu+2) to control biofouling by developing anti-microbial membranes. The use of anti-microbial membranes would reduce the cost as...

Hollow fiber membranes were made from two different dope solutions by using a dry-jet wet spinning process. One dope solution contains cellulose acetate (CA)/N-methyl-2-pyrrolidone (NMP) with a mass ratio of 20/80 and the other contains polysulfone (PS)/NMP with a mass ratio of 15/85. The hollow fiber membranes were heated in a water bath to invest...

Despite the availability of new detection and monitoring methods, a complete understanding of biofouling is still lacking. Therefore, this study employed a combination of biofilm characterization protocols macro, micro, and nano (meter) scales to provide insight into the early stages of biofilm formation using cellulose acetate ultrafiltration memb...

The need to control membrane fouling by microorganisms, also known as biofouling, is crucial in water separations applications. The purpose of this project was to investigate the charging of membrane surfaces with copper (Cu+2) to control biofouling by developing anti-microbial membranes. The use of anti-microbial membranes would reduce the cost as...

Responsive Ultrafiltration Cellulose Acetate Membranes Containing N-Isopropylacrylamide (NIPAAm) and Superparamagnetic Iron Oxide (SPIO) Nanoparticles Sneha Chede1, Geoffrey D. Bothun2 and Isabel C. Escobar1 1Chemical and Environmental Engineering, The University of Toledo, Toledo, OH 2Department of Chemical Engineering, University of Rhode I...

Implementation of nanofiltration (NF) and reverse osmosis (RO) processes in treating traditional water sources can provide a steady‐state level of removal that eliminates the need for regeneration of ion exchange resins or granular activated carbon. Moreover, RO can help meet future potable water demands through desalination of seawater and brackis...

Polybenzimidazole (PBI) is a material with excellent chemical resistance, and thermal and mechanical stabilities. However, significant drawbacks of PBI that prevent its use as a membrane for water purification applications include hydrophobicity and neutral surface charge at neutral pH values. Surface functionalization was investigated as a means t...

The demanding ever-increasing quantities of highly purified biomolecules by bio-industries, has triggered the development of new, more efficient, purification techniques. The application of membrane-based technologies has become very attractive in this field, for their high throughput capability, simplicity of operation and scale-up. Herein we repo...

Glycidal Methacrylate (GMA) has been found to be a useful epoxy in the attachment of chelating agents onto the surface for polymer membranes. Flat sheet membranes were cast from a dope solution of cellulose acetate (CA), N-methyl-2-pyrrolidone (NMP), and GMA in a 21/77/2 wt% ratio. Half of the membranes were subjected to a treatment to attach the c...

Microfiltration and ultrafiltration operations were used in tandem to isolate and purify a 6050 bp plasmid DNA (pDNA). To achieve primary isolation of the plasmid from fermentation broths, immediately after cell lysis, a 0.2 μm microfiltration membrane was selected for solid/liquid separation, which was performed in a diafiltration mode, as an alte...

The possible use of membrane filtration in the recovery process of plasmid DNA (pDNA) from fermentation broths, for applications in gene therapy and DNA vaccine applications, has been studied in recent years. Application has been made to achieve efficient clarification from suspended solids after cell lysis and also to remove hydrophobic soluble co...

Title: Responsive Ultrafiltration Membranes Composed of N-isopropylacrylamide (NIPAAM) and Cellulose Acetate Abstract: The purpose of this study is to develop stimuli responsive membranes to control fouling using membrane casting dopes made of cellulose acetate with N-isopropylacrylamide (NIPAAM). NIPAAM is a stimuli-responsive polymer, which...

Forward osmosis involves the movement of water across a selectively permeable membrane. Unlike pressure driven processes, such as reverse osmosis (RO), the driving force for water permeation through the membrane in FO is the difference in osmotic pressure between the feed and draw solutions. Recently, a hollow fiber nanofiltration (NF) forward osmo...

Membrane biofouling is a complicated process and can include both abiotic and biotic fouling. The objective of this research was to determine the contribution of conditioning layer in the presence of active cells to early stage membrane biofouling. Membranes were operated for 4, 11, and 24 h using buffered synthetic water composed of a conditioning...

A potentially low fouling membrane was developed by attaching a stimuli-responsive polymer layer on the surface, which offered the potential to collapse or expand the polymer layer with change in temperature. The phase change arose from the existence of a lower critical solution temperature (LCST) such that the polymer precipitated from solution as...

Membranes are capable of separating species as a function of their physical and chemical properties when a driving force is applied, which enables filtration for removal of colloids, cells and molecules. In this work, flat sheet polysulfone ultrafiltration membranes were cast due to polysulfone's high mechanical strength, thermostability and stabil...

Forward osmosis (FO) involves the movement of water across a selectively permeable membrane. Unlike pressure driven processes, such as reverse osmosis (RO), the driving force for water permeation through the membrane in FO is the difference in osmotic pressure between the feed and draw solutions. Recently, a hollow fiber nanofiltration (NF) forward...

@font-face { "ＭＳ 明朝"; }@font-face { "ＭＳ 明朝"; }@font-face { "Calibri"; }@font-face { "Cambria"; }p.MsoNormal, li.MsoNormal, div.MsoNormal { margin: 0in 0in 0.0001pt; font-size: 12pt; ; }span.st { }.MsoChpDefault { ; }div.WordSection1 { page: WordSection1; } The purpose of this research is to investigate properties of hollow fiber membranes based o...

A mass transfer model is proposed for predicting sieving coefficients, S(obs), of supercoiled plasmid DNA (pDNA), in the presence of a salt, in membranes with narrow pores, i.e., pores smaller than the gyration radii of the plasmids to be considered for a certain application. The model assumes that permeation occurs due to plasmid suction at the me...

Early detection of bacteria in water treatment is desired to mitigate system biofouling and potential human health impacts. This research involved the development of an antibody-based sensor, which was attached to a hydroxypropyl cellulose (HPC) modified cellulose acetate ultrafiltration membrane surface, to target bacteria. HPC was chosen because...

Gas separation is an application area for membrane technology with a long history. As a consequence, several membrane-based gas separations are now mature, although there is still a steady improvement in performance of membranes, and membrane functionalities. During the last decade, membrane gas separation had a new impulse mainly due to emerging e...

Water is one of the basic requirements for the survival of life on this planet. However, the total quantity of fresh water on the planet is finite while the world population and its water usage are fast increasing due to industrialization and urbanization (Kirby, A. http://news.bbc.co.uk/2/hi/ science/nature/3747724.stm). Only 1% of the water avail...

Forward osmosis is the movement of water across a selectively permeable membrane. The driving force for water permeation through the membrane is the difference in osmotic pressure between the feed and draw solutions. Polybenzimidazole (PBI) is a material with excellent chemical resistance and high mechanical and thermal stability that is a promisin...

Biofouling of membranes used in high-pressure applications has been and will continue to be a problem that must be addressed in industry as well as academia. Many of these applications use membranes in a spiral wound configuration that contains a feed spacer. When anti-biofouling properties were imparted to these feed spacers, through copper chelat...

The complexity and variability of solute chemistry which forms the conditioning layer with the membrane surface (i.e., instantaneous fouling) makes it hard to distinguish between abiotic and biotic fouling behaviors. Moreover, the role of membrane chemical heterogeneities and morphology in biofouling and their effect on solute chemistry has receive...

This chapter focuses on the challenges facing desalination and water reuse. Membrane fouling is one of the most important factors that limit greater use of desalination membranes. Fouling occurs due to particulate matter, organic matter, microorganisms forming biofilms, and inorganic scaling. Electrodialysis reversal (EDR) is generally most attract...

This chapter presents an overview of the global water situation. In the United States and Europe, the average individual uses between 200 and 600 liters of water per day. A significant cause of water scarcity is agriculture since crop production requires up to 70 times more water than is used in drinking and other domestic purposes. IWMI approximat...

Reverse osmosis (RO) and membrane distillation (MD), the two important applications associated with membrane-based desalination, are discussed in detail. Various RO process parameters, such as membrane synthesis, materials involved, and fouling control, play vital roles in the success of membrane filtration. The membrane synthesis process has a lar...

Polybenzimidizole (PBI) is a promising material for membrane separations due to its high mechanical and thermal stabilities. Two drawbacks that can hinder the use of PBI membranes in water applications are low hydrophilicity and neutral charge at neutral pH values. To investigate methods to increase hydrophilicity and charge, PBI membranes were cas...

Cellulose acetate (CA) ultrafiltration membranes were functionalized using a green chemistry approach. In the functionalization, an enzyme, Porcine pancreatic crude type II lipase (PPL), was used to polycondensate poly ethylene glycol (PEG) to the surface of the CA membranes. Modification was verified using structural and morphological analyses. Th...

The productivity of membrane filtration is severely lowered by fouling, which is the accumulation of foreign substances on the surface and/or within pores of membranes. Microbial fouling, or biofouling, is the growth of microorganisms on the membrane surface and on the feedspacer as present between the envelopes. The fouling of membranes has demand...

Microbial fouling, or biofouling, is the accumulation of microorganisms onto material surfaces. The goal of this project was to develop low-biofouling polypropylene (PP) films through the functionalization of PP by a spacer arm with metal chelating ligands charged with copper ions. Virgin and modified PP films were put in contact with 3.0 ×105Esche...

Recent efforts aimed at minimizing membrane fouling have emphasized an increasing demand for on-line monitoring in an effort to accurately predict membrane performance. To this end, an in situ bacterial monitoring system was developed that is integrated within the membrane. Because the target is bacterial monitoring, organic matter fouling must be...

Over the past several decades we have clearly observed the repercussions of releasing toxins into the environment. Though initial focus of treating this problem concentrated on treatment of wastes before their release into environment, since 1990 authorities concentrated on the prevention of the formation of waste at the source leading to the adven...

The presence of microorganisms in feed water can further exacerbate fouling due to the accumulation of microorganisms onto the membrane surface and on the feed spacer between the envelopes, or biofouling. Microorganisms transported to the membrane element can attach to the feed side of the membrane and the spacer. Attachment depends on Van der Waal...

Biofouling is the accumulation of microorganisms onto the membrane surface and on the feed spacer. Research and development of biofouling prevention has commonly focused on the pretreatment of the feed water, the improvement of cleaning solutions and procedures, and modifications to the membranes themselves. This research focuses on developing low-...

Numerous surface modification strategies have been developed to improve the fouling resistance of filtration membranes. A novel approach in which a temperature sensitive polymer gel is deposited on the surface is reported. The gel switches from an expanded, lower permeability, fouling-resistant hydrophilic state to a collapsed, higher permeability,...

A model is proposed for predicting the intrinsic rejections of linear flexible molecules, of high molecular dimensions, in microfiltration and ultrafiltration membranes. The developed model is based on the available theory of hindered transport of solutes through narrow pores, assuming that convection is the only relevant transport mechanism. For t...

Recent efforts aimed at minimizing membrane fouling have emphasized an increasing demand for on-line monitoring in an effort to accurately predict membrane performance. The development of an in-situ bacterial monitoring system that is integrated within the membrane can meet that need. Because the target is bacterial monitoring, organic matter fouli...

Ion beam irradiation has long been recognized as an effective method for the synthesis and modification of diverse materials, including polymers. Ion beam irradiation is the bombardment of a substance with energetic ions. When the ions penetrate through the surface of a membrane, they may eliminate tall peaks and deep valleys, resulting in an overa...

The presence of microorganisms in feed water can exacerbate fouling due to the accumulation of microorganisms onto the membrane surface and on the feed spacer between the envelopes, or biofouling. Microorganisms transported to the membrane element can attach to the feed side of the membrane and the spacer. Attachment depends on Van der Waals forces...

Cellulose acetate is widely used in the manufacture of commercial water purification membranes. Although commercially available cellulose acetate membranes have high flux through membrane, they suffer limitations such as susceptibility to microbial attack and low chlorine resistance due to the presence of naturally occurring cellulose acetate backb...

Biofouling, which is the accumulation of microorganisms onto the membrane surface and on the feed spacer, is a very prominent problem in the use of reverse osmosis (RO) membranes. In the past, research and development of biofouling prevention has commonly focused on the pretreatment of the feed water, the improvement of cleaning solutions and proce...