John Pellegrino

University of Colorado Boulder | CUB · Department of Mechanical Engineering (ME)

Direct glucose fuel cells (DGFCs) and direct methanol fuel cells (DMFCs) commonly supply the reducing agent in liquid (aq.) form. In this work, we present key characteristics of implementing cellulose acetate (CA) coatings, which can subsequently be deacetylated toward cellulose, on carbon cloth used as a fuel diffusion layer in aqueous fuel-fed ce...

We conducted experiments to study the influence of material surface chemistry and morphology on the crystallization of calcium carbonate from supersaturated solution containing mixed electrolytes. The study evaluated ethylene vinyl alcohol (EVOH) co-polymers and fluorinated and non-fluorinated polyamide thin film composite membranes to evaluate how...

Herein, we report on the fabrication of a graphene-based, semi-permeable membrane electrode (gr-ME) using non-solvent phase inversion to confine a packed-layer of graphene nanosheets into a ≤1 µm thick surface layer that smoothly transitions into the microporous membrane, primarily using polysulfone. The gr-MEs have: (i) gas permeance on the order...

We have used shaken-jar testing to screen the influence of various commercial polymer films on the crystallization of calcium carbonate from a supersaturated mixture containing other salts. Such methodologies and data can inform designs of crystallizers and mixing devices used to increase water recovery during inland desalination, as well as, in co...

We present a methodology and results for measuring crystallization kinetics of sparingly soluble salt mixtures typical of reject/concentrate streams from membrane-based, inland water supply processes. More usable water can be recovered (and lower disposal costs incurred) from these concentrate streams through efficient crystallization. In this work...

The transport of micron-sized particles such as bacteria, cells, or synthetic lipid vesicles through porous spaces is a process relevant to drug delivery, separation systems, or sensors, to cite a few examples. Often, the motion of these particles depends on their ability to squeeze through small constrictions, making their capacity to deform an im...

BACKGROUND Converting abundant lignocellulosic biomass to sugars as fungible precursors to fuels and chemicals has the potential to diversify the supply chain for those products, but further process improvements are needed to achieve economic viability. In the current work, process intensification of the key enzymatic hydrolysis unit operation is d...

Nanoimprinting of a commercial, as supplied, polyethersulfone ultrafiltration membrane has been carried out for the first time using a roll-to-roll (R2R) process. To support this processing approach, we also developed a reusable flexible polyetherimide mold. We were able to pattern membrane at room temperature (∼21 °C) due to the high pressures (22...

To further the ability to design membranes for separation/fractionation of deformable particles (such as, cells, liposomes, vesicles, and droplets in emulsions and oil-water suspensions), we have developed a 2-d multiscale computational approach to study how the pressure drops and bulk flow within the depth of a porous "membrane" influences the mob...

One of the major challenges in applying membrane technology is how to mitigate fouling, which decreases membrane productivity and lifetime. We previously developed a technique for preparing thin-film composite (TFC) polyamide membranes with submicron-patterned surfaces (via nanoimprint lithography), using interfacial polymerization techniques consi...

With the development of the scanning tunneling microscope, and other high resolution “microscopies”, researchers could examine and adapt synthetic process to control particles on the nanometer scale. Since then there have been an explosion of techniques for fabricating nanoparticles. So called “top-down” synthetic techniques start with large partic...

Depth filtration with microporous membranes has been modeled by extending upon previous approaches of Polyakov[1-4][ to incorporate pore size distribution, tortuosity, and cake buildup. The model forecasts were benchmarked against filtration measurements performed with colloidal particles using three very different commercial membrane morphologies...

We are currently evaluating the feasibility of performing continuous enzymatic hydrolysis of lignocellulosic biomass to product sugars using a membrane-assisted reaction/separation process. The overarching technical goals are to continuously remove the sugars—this lowers product feedback inhibition—retain and recycle active enzyme, and continuously...

“Cradle-to-gate” life cycle analysis surrounding five algae-to-fuel/fuel precursor scenarios was studied. The different processes modeled were: an open pond producing either triacylglycerides (TAG) or free fatty acid methyl ester (FAME); a solar-lit photobioreactor producing either FAME or free fatty acids; and a light emitting diode irradiated (LE...

An ability to precisely regulate the quantity and location of molecular flux is of value in applications such as nanoscale 3D printing, catalysis, and sensor design. Barrier materials containing pores with molecular dimensions have previously been used to manipulate molecular compositions in the gas phase, but have so far been unable to offer contr...

We are currently evaluating the feasibility of performing continuous enzymatic hydrolysis of lignocellulosic biomass to product sugars using a membrane-assisted reaction/separation process. The overarching technical goals are to continuously remove the sugars—this lowers product feedback inhibition—retain and recycle active enzyme, and continuously...

We are developing a membrane-assisted reaction/separation process that performs continuous enzymatic hydrolysis of lignocellulosic biomass to product sugars. The continuous removal of sugars during the hydrolysis lowers product-feedback inhibition, and the membrane assisted separation helps retain and recycle active enzyme. Our earlier experiments...

Previous work has suggested that membrane patterning is a promising approach to fouling mitigation. In this systematic study, we describe performance metrics for the cross-flow filtration of colloidal suspensions through ultrafiltration membranes with lithographically patterned surfaces. The effects of particle size, cross-flow velocity, pattern si...

Numerous polypropylene hollow fiber microfiltration membrane modules were severely degraded after utilization as pretreatment in a military water purification system. To determine the plausible causes of degradation, thermal, chemical, and mechanical material properties were initially evaluated by using differential scanning calorimetry, thermograv...

To help elucidate the mechanisms for solute transport in polyamicle (PA) and cellulose acetate (CA) reverse-osmosis membranes, we have conducted temperature-variation permeation experiments with aqueous solutions containing NaCl and 3- and 4-carbon solutes that possess different numbers of hydroxyl groups. Mass transport metrics were calculated usi...

We are currently evaluating the feasibility of performing continuous enzymatic hydrolysis of lignocellulosic biomass to product sugars using a membrane-assisted reaction/separation process. The overarching technical goals are to continuously remove the sugars—this lowers product feedback inhibition—retain and recycle active enzyme, and continuously...

Many colloidal-sized particles encountered in biological and membranebased separation applications can be characterized as soft vesicles such as cells, yeast, viruses and surfactant micelles. The deformation of these vesicles is expected to critically affect permeation by accommodating pore shapes and sizes or enhancing the adhesion with a pore sur...

From a technical perspective, sustainability is a second law of thermodynamics analysis that has become synonymous with development of non-fossil fuel energy carriers. In that broad milieu, harvesting photons into biomass and converting these into different chemical forms has been a "grand challenge" for many decades. The challenge is having a "pro...

We evaluate giant magnetoresistance sensors to trap and count small concentrations of magnetic nanoparticles (MNPs) within microfluidic flow. The device presented takes the novel approach of capturing and detecting MNPs utilizing the strong fringe-fields present on the periphery of the patterned sensor. The presence of MNPs manifests as a field shi...

Microalgae are often cited as a sustainable source of energy and specialty products due to their ability to fix CO2 as biomass through photosynthesis. At present, however, the large material and energy inputs required to grow and process the cells using conventional methods make these processes infeasible from both an economic and environmental per...

Fouling is widely regarded as the bottleneck in membrane separation process. To address the fouling issues, different sort of pretreatments and cleaning protocols are being developed and followed in the process industry which rarely can avoid fouling resulting in huge energy consumption and sometime shutdown of the productivity and eventually repla...

Mitigating Fouling of Ultrafiltration Membrane with Nanoimprinted Surface Patterns Yifu Ding, Sajjad H. Maruf, John Pellegrino, Melissa Rickman, Liang Wang, John Mersch, and Alan R. Greenberg Membrane Science, Engineering and Technology Center Department of Mechanical Engineering University of Colorado Boulder, Boulder, CO 80309-0427, USA...

Efficient membrane fractionation of small, neutral organics from electrolytes could improve the sustainability of biofuel production from microorganisms, but the separations achieved are often insufficient. To rationally develop improved membrane materials for these fractionations, we need to better understand the mechanisms that govern solute tran...

Detailed design analysis of an ambient-pressure, membrane-based heat pump serves as a basis for examining the applicability of a variety of correlations used in coupled heat and mass transfer devices that include membranes and aqueous electrolyte streams. The transport phenomena were studied using scaling analysis and finite-volume numerical method...

Flux decline due to membrane fouling prevails in almost all pressure-driven liquid separations. The factors controlling fouling, ranging from surface chemistry to topographic roughness, have been extensively investigated. However, the role of surface patterns, particularly at a submicron scale, on membrane fouling remains unclear. Herein, we demons...

For many years, it has been suggested that mitigation of atmospheric carbon dioxide (CO2) emissions can be achieved by fixing CO2 as algal biomass. New EPA regulations limit greenhouse gas emissions from new power plants, and thus power plants have additional impetus to decide if co-location with algal ponds is a feasible strategy for CO2 mitigatio...

Gas–liquid porometry is a common method for characterizing microfiltration (MF) membranes. This paper provides a modified approach to analyze data from it. Herein, we combine porometry results with porosity measurements to improve prediction of the gas and liquid permeances through the membranes. Pore size distribution (PSD) and porosity measuremen...

Membranes act as selective barriers and play an important role in processes such as cellular compartmentalization and industrial-scale chemical and gas purification. The ideal membrane should be as thin as possible to maximize flux, mechanically robust to prevent fracture, and have well-defined pore sizes to increase selectivity. Graphene is an exc...

In this study we report changes in the glass transition temperature (Tg) of the polyamide barrier layer (PBL) of a commercial RO membrane as a function of chlorine treatment in which concentration and pH were systematically varied. The results indicate a monotonic decrease of Tg with increasing exposure time at a given chlorine concentration. Furth...

Harvesting of secreted fuel precursors is an alternative approach to sustainable biofuel production from algae, and relies on selective separation of growth media from algal suspensions. Membrane fouling and species fractionation for selected ultrafiltration (UF) and microfiltration (MF) membranes were investigated for this purpose. Suspensions wer...

Reverse osmosis (RO) membrane desalination is a well-known pressure-driven water purification process which removes inorganic electrolytes (salts) from sea water or brackish water effectively. A natural consequence of desalination is the flux decline due to crystallization of sparingly soluble salts on the membrane surface which decreases the water...

Harvesting of secreted fuel precursors is an alternative approach to sustainable biofuel production from algae, and relies on selective separation of growth media from algal suspensions. Membrane fouling and species fractionation for selected ultrafiltration (UF) and microfiltration (MF) membranes were investigated for this purpose. Suspensions wer...

Ceramic materials for microfiltration and ultrafiltration have a number of potential advantages over polymeric materials including chemical and thermal stability, physical strength, and a longer operational life. In this study an alumina composite ceramic membrane was compared to a polyethersulfone(PES) membrane for the filtration of bentonite and...

It is increasingly suggested that bioremediation of atmospheric carbon dioxide (CO2) can be achieved by fixing CO2 as algal biomass. This topic has been the subject of numerous life-cycle analyses (LCAs) in recent years, which have attempted to assess the environmental impacts of such processes, with mixed conclusions. Authors of techno-economic an...

Microalgae are unicellular organisms that offer a promising source of sustainable energy and specialty products. Hundreds of thousands of diverse species exist, but only a few are produced commercially today, primarily for high-value products. Today, algae are increasingly investigated for their ability to locally produce non-fossil-derived liquid...

Oftentimes, membrane morphology studies are done with scanning electron microscopy or transmission electron microscopy. One disadvantage of these techniques is that they retrieve only superficial information. To study the interior of a sample, the sample must be cut, and the integrity of the structure can be destroyed. In this contribution, we pres...

The economics surrounding five algae-to-fuels process scenarios were examined. The different processes modeled were as follows: an open pond producing either triacylglycerides (TAG) or free fatty acid methyl ester (FAME), a solar-lit photobioreactor producing either FAME or free fatty acids (FFA), and a light emitting diode irradiated (LED-lighted)...

A membrane absorption heat pump uses absorbent and refrigerant (solvent) flows separated by a membrane to create temperature gradients (aka temperature lifts) used for heating or cooling. Compared to vacuum absorption heat pumps, an atmospheric-pressure membrane heat pump provides more compact designs, potentially enabling applications such as ener...

Does pore-size distribution need to be considered to accurately model vapor transport in membrane distillation (MD)? This paper addresses that question from a theoretical perspective. Although some previous work has discussed pore-size distribution in MD, there has yet to be a comprehensive, general analysis of its effects on MD and its various con...

Virus filtration membranes are used to obtain virus clearance during the purification of biopharmaceutical products. These direct flow (also referred to as dead end or normal flow) filtration membranes are designed to reject virus particles and yield >98% product recovery for proteins less than 170 kDa. Virus filtration feed streams generally have...

In this paper, a membrane heat pump is proposed and analyzed. Fundamentally, the proposed heat pump consists of an aqueous CaCl2 solution flow separated from a water flow by a vapor-permeable membrane. The low activity of the solution results in a net flux of water vapor across the membrane, which heats the solution stream and cools the water strea...

A methodology for the assessment of the crown corrosion in concrete sewer pipes was developed based upon the principle that the surface roughness increases when concrete corrodes. The roughness was quantified by correlating the depths of the surface pits to the lengths of shadows produced in a single source of incident light. A computer program was...

Measurements of the diffusive permeances of water, NaCl, and ethanol through several, unoptimized membranes are presented. Such data can facilitate analysis and development of water recovery from highly impaired sources using hybrid processes based on forward (direct) osmosis (FO) with aqueous ethanol solutions as the “osmotic” agent. The membranes...

Electrolytes are an important component in determining the performance and cycle life of ultracapacitors. Good electrolytes should have high ionic conductivity, large electrochemical windows, and excellent thermal and chemical stability. Ionic liquids are possibly ideal electrolytes to satisfy these requirements. In the present work, we developed e...

This research attempted to identify characteristic coordinates responsible for significant flux decline in low pressure membrane filtration, and to explain relationships among those coordinates with a modeling approach. A Pearson's correlation matrix supported that significant flux decline over a short time frame (low delivered DOC) is highly corre...

The general formulation for the propagation of statistical uncertainties is presented for the dual volume pressure decay method of measuring sorption capacity in polymers and other solid sorbents. These relationships are then used to determine the percent uncertainty in the calculated sorption coefficient (or capacity) with respect to ranges of val...

Development of the lignocellulosic‐biomass‐based biorefinery for making transportation fuels requires the production of valuable byproducts, minimizing the chemical consumables, and efficient water recovery and reuse. Our focus is on a liquid stream containing a variety of soluble lignin species and alkalinity that is produced by a novel extrusion...

We have considered a speculative water desalination concept that combines high-pressure reverse osmosis (RO) and electrodialysis (ED) in intimate proximity to each other. In the concept model’s configuration, the RO membranes are hollow-fibers that form the spacer channels between the alternating anion and cation exchange membranes. The entire syst...

Electrolytes are an important component in determining the performance and cycle life of ultracapacitors. Good electrolytes should have high conductivity, large electrochemical windows, excellent thermal and chemical stability, and negligible electrolyte depletion. Ionic liquids are ideal electrolytes to satisfy these requirements. In the present w...

Ultrafiltration (UF) membranes may be used as both a primary water treatment and/or as a pretreatment for reverse osmosis or nanofiltration during desalination. Important operational issues continue to revolve around the choices of materials, nominal molecular mass cutoff (MWCO), and filtration hydrodynamics. To study the former two points, we isol...

Measurements are reported for the sorption equilibrium and transport of water vapor into polyaniline (PANI) powders and asymmetric, microporous hollow fibers. Equilibrium isotherms at 298 K were measured on powders doped with 13 different organic and inorganic acids to change the polyaniline from its emeraldine base, PANI-EB (insulating) form, to t...

An apparatus has been developed to accurately measure the unsteady permeation of pure water through permselective reverse osmosis (RO) and nanofiltration membranes under an osmotic pressure gradient (aka forward osmosis). The key component of the apparatus is a capacitance-based level sensor with a flowrate resolution of 15–50nL/s. The measurement...

Organic and inorganic micropollutants are rejected by high-pressure membranes, nanofiltration (NF) and reverse osmosis (RO), primarily as a consequence of solute-membrane interactions. These interactions include steric and electrostatic effects that depend on compound properties (e.g., molecular weight (MW) and ionic charge) and membrane properties...

Fabricating integrally-skinned asymmetric hollow fiber membranes from concentrated polyaniline solutions is technically challenging due to the complex issues associated with rapid gelation of the polymer solution and controlling the phase inversion process to create porous structures. Different processing parameters, such as solution composition, c...

Measurements are reported for the sorption equilibrium and transport of water into commercially produced polyaniline solid fibers from a 50% relative humidity air stream at ambient pressure of 0.1 MPa and 300 K. The data have been collected using a single solid fiber morphology, PANION, but with different acid dopants used to change the polyaniline...

A synthetic mixture of solutes (colloids, macromolecules, small organic molecules, and salts) was evaluated to facilitate consistent bench and small pilot-scale studies of membrane flux decline. In this paper, we present physical, chemical, and filtration resistance properties of inexpensive, commercial, off-the-shelf components—colloidal silica an...

Flow-Field Flow Fractionation (FI-FFF) is an idealization of the cross flow membrane filtration process in that, (1) the filtration flux and crossflow velocity are constant from beginning to end of the device, (2) the process is a relatively well-defined laminar-flow hydrodynamic condition, and (3) the solutes are introduced as a pulse-input that s...

We report the results of membrane filtration studies designed to measure the removal of humectant preservatives (expressed as total organic carbon) from new membrane samples. Membranes with different characteristic properties, that is, relative molecular mass cutoff and material chemistry, were filtered with deionized water under constant flux and...

Measurements of the rejection of perchlorate anion (ClO4 ) have been performed by using two thin‐film composite nanofiltration (NF) membranes and four ultrafiltration (UF) membranes. The latter four membranes are all from the same manufacturer and, ostensibly, from the same material family. These were chosen to systematically change the membranes s...

As a material family, pi-conjugated polymers (also known as intrinsically conductive polymers) elicit the possibility of both exploiting the chemical and physical attributes of the polymer for membrane-based separations and incorporating its electronic and electrochemical properties to enhance the separation figures-of-merit. This review article, a...

As a material family, π-conjugated polymers (also known as intrinsically conductive polymers) elicit the possibility of both exploiting the chemical and physical attributes of the polymer for membrane-based separations and incorporating its electronic and electrochemical properties to enhance the separation figures-of-merit. This review article, al...

Measurements of the rejection of perchlorate anion (ClO4−) were performed using nanofiltration (NF) and ultrafiltration (UF) membranes. Aqueous solutions of perchlorate (at a concentration of 100 μg/L of ClO4− by “spiking” with KClO4) were fed to the membrane test apparatus. Solutions contained only perchlorate, or an additional salt (KCl, K2SO4, o...

The diffusion of pure liquid water into a commercial polypropylene (PP) film at 278–348 K was studied with Fourier transform infrared attenuated total reflectance spectroscopy. Abnormal diffusion behavior was indicated by a significant deviation between the experimental data and a Fickian diffusion model with the conventional saturated boundary con...

We present an experimental method for measuring diffusion of lubricants (or any highly viscous fluid) in polymers using Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy. Unlike the conventional FT-IR ATR diffusion measurement, in which a polymer sample is sandwiched between the penetrant and an internal reflection e...

The spectrum of filtration separations runs from the millimeter scale (beach sand and activated carbon particles) using coarse filters, to the angstrom scale (metal ions and gas molecules) using reverse osmosis or gas separation membranes. Between there are microfiltration (bacteria and emulsions), ultrafiltration (proteins, viruses, and colloids),...

Electrokinetic analysis is a family of techniques for estimating the charge on solid surfaces, macroscopic particles, colloidal species, and macromolecular aggregates. Charges on surfaces are critical to the behavior of colloids, coatings, films, fibers, and many other materials in a variety of application areas. In addition to estimating the charg...

In this article, we present a simple method for improving the contact between a film sample and the internal reflection element (or crystal) when diffusion into thin polymer films is measured with attenuated total reflectance (ATR)-Fourier transform infrared spectroscopy. Intimate film/crystal contact is particularly important for making measuremen...

Three ultrafiltration membranes [thin-film composite, polyethersulfone (PES), and sulfonated PES] which have different chemistries and nominal relative molecular mass cut-offs (MWCO), were compared in terms of their characteristics of flux decline, rejection of natural organic matter (NOM), and the adsorbed foulants, with two very different (relati...

We studied natural organic matter (NOM) rejection and the membrane’s flux decline during natural water filtration using a charged ultrafiltration membrane based on thin-film-composite technology. NOM rejection mechanisms such as steric exclusion and aromatic/hydrophobic and charge interactions were considered. Water composition factors affecting NO...

We evaluated sources of variance in the measurement of the surface streaming potential of flat sheet specimens of cellulose di/triacetate membranes with a commercial electrokinetic analyzer. Two measurement methods were evaluated: the instrument's standard operating procedure, which continuously ramps the flow past the specimen, and a modified proc...

Two source waters containing natural organic matter (NOM) with different physical and chemical characteristics were crossflow-filtered using four types of membranes having different material and geometric properties. Transport measurements of NOM rejection and flux decline were made. A resistances-in-series model was used to represent and quantitat...

Contact angles, zeta potentials, and IR spectra of clean and NOM-fouled membranes were compared to demonstrate differences in hydrophobicity, surface charge, and functional groups, respectively. Contact angle increased and decreased for membranes fouled with hydrophobic and hydrophilic NOM, respectively. Zeta potential decreased negatively (less ne...

Contact angles, zeta potentials, and IR spectra of clean and NOM-fouled membranes were compared to demonstrate differences in hydrophobicity, surface charge, and functional groups, respectively. Contact angle increased and decreased for membranes fouled with hydrophobic and hydrophilic NOM, respectively. Zeta potential decreased negatively (less ne...

An homologous series of polyethylene-oxide surfactants, with either octylphenol or polypropylene oxide “head” groups, were applied to commercial cellulose acetate blend (CA) and polyamide (PA) reverse osmosis (RO) and nanofiltration (NF) membranes. The pressure-normalized permeate flow (NPF) and salt rejection were evaluated before and after foulin...