The effects of salt concentration and foulant surface charge on hydrocarbon fouling of a poly(vinylidene fluoride) microfiltration membrane.

The effects of inorganic salts and organic hydrocarbons on membrane fouling are often investigated independently. However, in many cases, these foulants are commonly found together, and such mixtures are rarely the subject of fouling studies. In this study, crude oil-in-water emulsions were formulated at three different added NaCl concentrations, 0, 10 and 10 M.

Chemical Modification of Butyl Rubber with Maleic Anhydride via Nitroxide Chemistry and Its Application in Polymer Blends.

Butyl rubber (isobutylene⁻isoprene⁻rubber, IIR) was functionalized in solution with a nitroxide moiety taking advantage of the unsaturations present in the isoprene units of IIR, and was further grafted with maleic anhydride (MA) or styrene⁻MA (SMA) to produce IIR--MA and IIR--SMA. In one of the functionalization techniques used, the molecular structure of the IIR was preserved as the chain-breaking reactions are prevented from occurring. The resulting graft copolymers were tested as compatiblizers/impact modifiers blended with Nylon-6, and one of them was preliminarily tested as a coupling agent in the preparation of nanocomposites of IIR and an organo-clay.

Predicting Salt Permeability Coefficients in Highly Swollen, Highly Charged Ion Exchange Membranes.

This study presents a framework for predicting salt permeability coefficients in ion exchange membranes in contact with an aqueous salt solution. The model, based on the solution-diffusion mechanism, was tested using experimental salt permeability data for a series of commercial ion exchange membranes. Equilibrium salt partition coefficients were calculated using a thermodynamic framework (i.

Surface Modification of Water Purification Membranes.

Polymeric membranes are an energy-efficient means of purifying water, but they suffer from fouling during filtration. Modification of the membrane surface is one route to mitigating membrane fouling, as it helps to maintain high levels of water productivity. Here, a series of common techniques for modification of the membrane surface are reviewed, including surface coating, grafting, and various treatment techniques such as chemical treatment, UV irradiation, and plasma treatment.

Partitioning of mobile ions between ion exchange polymers and aqueous salt solutions: importance of counter-ion condensation.

Equilibrium partitioning of ions between a membrane and a contiguous external solution strongly influences transport properties of polymeric membranes used for water purification and energy generation applications. This study presents a theoretical framework to quantitatively predict ion sorption from aqueous electrolytes (e.g.

Specific ion effects on membrane potential and the permselectivity of ion exchange membranes.

Membrane potential and permselectivity are critical parameters for a variety of electrochemically-driven separation and energy technologies. An electric potential is developed when a membrane separates electrolyte solutions of different concentrations, and a permselective membrane allows specific species to be transported while restricting the passage of other species. Ion exchange membranes are commonly used in applications that require advanced ionic electrolytes and span technologies such as alkaline batteries to ammonium bicarbonate reverse electrodialysis, but membranes are often only characterized in sodium chloride solutions.

A crossflow filtration system for constant permeate flux membrane fouling characterization.

Membrane fouling is often characterized using a crossflow filtration apparatus. Typically, the transmembrane pressure (TMP) difference is fixed, and the flux is allowed to decline as the membrane fouls and the resistance to mass transfer increases. However, as flux varies, so too does the rate at which foulants are brought to the membrane surface, so the observed fouling behavior is not solely the result of membrane∕foulant interactions.

Short-term adhesion and long-term biofouling testing of polydopamine and poly(ethylene glycol) surface modifications of membranes and feed spacers for biofouling control.

Ultrafiltration, nanofiltration membranes and feed spacers were hydrophilized with polydopamine and polydopamine-g-poly(ethylene glycol) surface coatings. The fouling propensity of modified and unmodified membranes was evaluated by short-term batch protein and bacterial adhesion tests. The fouling propensity of modified and unmodified membranes and spacers was evaluated by continuous biofouling experiments in a membrane fouling simulator.

Elucidating the structure of poly(dopamine).

Herein we propose a new structure for poly(dopamine), a synthetic eumelanin that has found broad utility as an antifouling agent. Commercially available 3-hydroxytyramine hydrochloride (dopamine HCl) was polymerized under aerobic, aqueous conditions using tris(hydroxymethyl)aminomethane (TRIS) as a basic polymerization initiator, affording a darkly colored powder product upon isolation. The polymer was analyzed using a variety of solid state spectroscopic and crystallographic techniques.