Studies on internal and external water treatment at a paper and cardboard factory

The treatment of effluent from a paper/board factory that produced 280 tons of cardboard and consumed 1200 m³ of water per day was carried out. Wastewater analysis showed that the mill effluent contained 3000 mg dm^?3 suspended solids, 1400 mg dm^?3 COD (chemical oxygen demand) and 500 mg dm^?3 BOD (biochemical oxygen demand). An internal treatment cycle is suggested that involves recirculation of paper‐machine wastewater (white‐water) and may be accomplished by installing a flotation saveall (fiber recovery) unit. This arrangement reduced fresh water use by about 90%, reduced fiber loss by 80–90%, and increased board production by 13%. An external treatment process for the effluent was assessed by conducting laboratory coagulation tests (alum, ferric chloride, ferrous sulfate, and polyelectrolyte) on the whole mill effluent. Oxidation of the mill effluent using calcium hypochlorite before discharging the effluent to a lagoon offers the benefits of killing the harmful bacteria and reducing the pollution load. Copyright © 2003 Society of Chemical Industry     

Residence time distribution and oxygen transfer in a novel constructed soil filter

BACKGROUND: The constructed soil filter (CSF), also known as soil biotechnology is a system for water renovation, which makes use of formulated media, culture of soil micro‐ and macro‐organisms, additives and plantation to purify water and wastewater. The process gives benefits in terms of applicability across very small to large scale, natural aeration, absence of moving parts, no biological sludge generation, odor free green aesthetic ambience. RESULTS: Residence time distribution (RTD) studies were carried out using laboratory scale CSF. Pulse potassium bromide tracer tests were carried out to determine RTD, and the Peclet number found to be 9–13 for a 2 m bed, and 2–3 for a 0.30 m bed with oxygen transfer of 0.08 h^?1. CONCLUSION: The two‐channel dispersion model for flow behavior shows a good fit to the experimental data, indicating a reactor Peclet number 9–13 for a 2 m bed and 2–3 for a 0.3m bed. Oxygen transfer studies carried out using various methods gave an oxygen transfer coefficient of about 0.08 h^?1. Wastewater purification studies indicate overall COD removal rate of around 50 mg L^?1 h^?1, suggesting that highly aerobic conditions are prevalent in the CSF system. Copyright © 2009 Society of Chemical Industry     

Hydration of a low‐grade magnesium oxide. Lab‐scale study

BACKGROUND: Low grade magnesium oxide (LG‐MgO) is a by‐product from the calcination of natural magnesite that is currently hydrated to magnesium hydroxide by storing it in the open for up to 6 months. It is eight to ten times cheaper than pure magnesium oxide and therefore the revalorization of this by‐product is very attractive for those applications requiring great quantities of magnesium hydroxide for which high purity is not required. Here the hydration of LG‐MgO is studied as a function of two parameters: hydrating agent and temperature. RESULTS: Addition of acetic acid during the hydration of LG‐MgO improved the effectiveness of treatment. At 50 °C, the maximum percentage hydration was 40% in pure water and increased to 65% and 70% using aqueous solutions of 0.5 and 1.0 mol L^?1 acetic acid. Increase of temperature also had a positive effect on the final degree of hydration. When the treatment was carried out with 0.5 mol L^?1 acetic acid, the hydration increased from 50 to 65 and 80% at 25, 50 and 90 °C respectively. Accordingly under the optimum conditions of 90 °C and 0.5 mol L^?1 acetic acid 80% hydration was achieved within 8 h. CONCLUSIONS: The results showed that much shorter hydration times are possible and therefore an industrial alternative to the spontaneous process could satisfy an increasing demand for magnesium hydroxide. Moreover, agitation is not needed as the reaction is chemically controlled. Copyright © 2012 Society of Chemical Industry     

Separation of Acetic Acid‐Water Mixtures through Poly(Vinyl Alcohol)/Poly(Acrylic Acid) Alloy Membranes by Using Evapomeation and Temperature Difference Evapomeation Methods

Abstract

Separation of acetic acid‐water mixtures by using evapomeation (EV) method were carried out over the full range of compositions at temperatures varying from 30 to 55°C using poly(vinyl alcohol)/poly(acrylic acid) (PVA/PAA) (75/25) (v/v) alloy membranes. PVA/PAA membranes gave separation factors of 110–5711 and permeation rates of 2.3×10^?4–1.53×10^?1 kg/m²h, depending on the operation temperature and feed mixture composition. The temperature dependence of the permeation in EV was expressed by the Arrhenius type expression and the activation energy was calculated as 9.15 kcal/mol. More efficient EV technique, which is called temperature difference evapomeation method (TDEV) was also applied to PVA/PAA membranes to separate acetic acid‐water mixtures; high permeation rates (1.7×10^?3–3.0×10^?1 kg/m²h) and separation factors (1335–8924) were obtained for each of the studied feed compositions. Azeotropic mixture of acetic acid and water was also separated by TDEV method with a separation factor of 297 and permeation rate of 1.50×10^?1 kg/m²h.     

Biological treatment of a contaminated gaseous emission from a paint and varnish plant—from laboratory studies to pilot‐scale operation

A Vapour‐Phase Bioreactor (VPB), namely a biotrickling filter, was scaled‐up and operated in‐situ for the treatment of gaseous emissions from a paint and varnish industrial plant. A microbial culture able to degrade the target compounds was enriched and a laboratory‐scale VPB was established in order to evaluate the treatment's performance. The VPB presented removal efficiencies higher than 90% when exposed to Organic Loads (OL) of ca 50 g h^?1 m^?3 of reactor. The VPB was exposed to dynamic conditions often found in‐situ (eg night and weekend shutdown periods) and showed a fast capacity to recover, with and without mineral medium recirculation. After a prolonged interruption period (10 months), the VPB was not able to cope with OL of ca 25 g h^?1 m^?3 of reactor and re‐inoculation was required in order to recover the treatment performance. The VPB also showed limited treatment when exposed to higher OL (ca 500 g h^?1 m^?3 of reactor). The VPB was then scaled‐up and a 3 m³ VPB was operated in‐situ, showing removal efficiencies higher than 50% when exposed to an OL of c 5 g h^?1 m^?3 of reactor, thus complying with current legal demands. The addition of a maintenance feed was shown to be a useful tool for VPB pilot‐scale operation when shutdown periods occurred. A factorial design of experiments was carried out, which allowed reduction to one‐tenth of the initial supply of the main mineral medium constituents, namely phosphate buffer, ammonium and magnesium salts, and also elimination of the metal supplement. Overall, the VPBs were shown to be robust equipment, being able to respond actively to dynamic treatment scenarios, particularly night and weekend shutdown periods. Copyright © 2003 Society of Chemical Industry     

Photocatalytic degradation of 17α‐ethynylestradiol in environmental samples by ZnO under simulated solar radiation

BACKGROUND: Recently, the fate of emerging micro‐contaminants in environmentally relevant samples has attracted considerable attention. Semiconductor photocatalysis may offer an appealing methodology to treat such contaminants; in this respect, the degradation of synthetic estrogen 17α‐ethynylestradiol (EE2) employing simulated solar radiation and ZnO as the photocatalyst was investigated. RESULTS: A factorial design approach was adopted to evaluate the effect of estrogen concentration (100–500 µg L^?1), ZnO concentration (50‐500 mg L^?1 in suspension), treatment time (2‐10 min), photon flux (4.93 × 10^?7–5.8 × 10^?7 einstein L^?1 s^?1) and the water matrix (ultrapure water and treated wastewater) on EE2 removal. The first four variables had a statistically important, positive effect on degradation, while the water matrix introduced a negative effect presumably due to the competition between EE2 and the effluent organic and inorganic matter for hydroxyl radicals and other oxidizing species. Moreover, second‐order interactions of estrogen concentration with time and the water matrix were also significant. EE2 degradation follows first‐order kinetics with the respective rate constants in wastewater and water being 9.2 ± 0.7 × 10^?2 and 41 ± 8 × 10^?2 min^?1 at the maximum ZnO concentration and photon flux. On the other hand, the removal rate of effluent's overall estrogenicity (as assessed by the yeast estrogen screening bioassay) was an order of magnitude lower than that of EE2, implying the presence of persistent estrogenic compounds in the photocatalyzed effluent. CONCLUSIONS: An effective treatment process is demonstrated which benefits from the use of renewable energy and a stable and highly active photocatalyst. Copyright © 2012 Society of Chemical Industry     

Surfactant Synthesis via Lipase Esterification of Methyl α-d-Glucopyranoside with Selected Aliphatic Carboxylic Acids

Lipase‐catalyzed esterification and properties of synthesized carbohydrate esters were investigated. Methyl α‐d ‐glucopyranoside was the acyl group acceptor and different carbon atom chain lengths of aliphatic carboxylic acids (C12, C14 and C16) as the acyl group donors were applied in the esterification. Physico‐chemical studies on the synthesized carbohydrate esters were carried out. It was found that melting point for the methyl 6‐O‐hexadecanoyl‐α‐d ‐glucopyranoside was the highest consecutively followed by methyl 6‐O‐tetradecanoyl‐α‐d ‐glucopyranoside and methyl 6‐O‐dodecanoyl‐α‐d ‐glucopyranoside. Liquid crystal properties of the synthesized carbohydrate ester synthesized were evaluated via optical polarized microscopy. It was found that the liquid crystal textures for mono‐substituted carbohydrate esters were of the smectic phase. In a quaternary system (carbohydrate ester/n‐butanol/n‐hexadecane/water), a maximum 34 % of water (by mass) was contained in the monophasic region of methyl 6‐O‐tetradecanoyl‐α‐d ‐glucopyranoside and a maximum of 52 % water (by mass) was contained in a monophasic methyl 6‐O‐dodecanoyl‐α‐d ‐glucopyranoside. For methyl‐6‐O‐dodecanoyl‐α‐d ‐glucopyranoside, its concentration at aggregation was 5.2 × 10^?4 mM, with minimum air/water surface tension of 26 mN m^?1. The Gibbs energy of micellization was calculated at ?50 kJ mol^?1. The maximum adsorption density of methyl 6‐O‐dodecanoyl‐α‐d ‐glucopyranoside was determined at 4 × 10^?6 mol m^?2 while its minimum area per surfactant molecule at the air/water surface was 47 Ų.     

Activity of horseradish peroxidase in aqueous and reverse micelles and back‐extraction from reverse‐micellar phases

Studies on the activity of the enzyme horseradish peroxidase (HRP) have been carried out in micellar as well as reverse‐micellar media. The activity of the enzyme was studied in the presence of different classes of surfactants – ionic as well as non‐ionic. In aqueous media, the activity of the enzyme varied depending on whether the concentration of the surfactant used was above or below the critical micellar concentration (CMC). The enzyme was also studied in reverse‐micellar systems. HRP was introduced into the reverse micellar phase by the injection method and its activity within the reverse micelles was determined. The effect of water to surfactant ratio (W_o) on activity within reverse micelles was studied, and an almost two‐fold increase in activity was seen when the enzyme was encapsulated within reverse micelles of aqueous phase fractional hold‐up (?) of 0.0072 (v/v) consisting of sodium bis‐(2‐ethylhexyl) sulfosuccinate (AOT) in isooctane at a W_o of 20. The activity of HRP was measured over a wide range of AOT concentrations having different W_o values. Back‐extraction of HRP from these reverse micelles was carried out at varying ionic strengths of phosphate buffer. Back extraction was found to be highest at pH 7.0 in 40 mol m^?3 phosphate buffer and 100 mol m^?3 sodium chloride. © 2001 Society of Chemical Industry     

Deactivation kinetics of a HZSM‐5 zeolite catalyst treated with alkali for the transformation of bio‐ethanol into hydrocarbons

The kinetics of deactivation by coke of a HZSM‐5 zeolite catalyst in the transformation of bioethanol into hydrocarbons has been studied. To attenuate deactivation, the following treatments have been carried out: (i) the zeolite has been subjected to a treatment with alkali to reduce the acid strength of the sites and (ii) it has subsequently been agglomerated into a macro and meso‐porous matrix of bentonite and alumina. The experimental study has been conducted in a fixed bed reactor under the following conditions: temperature, between 300 and 400°C; pressure, 1 atm; space‐time, up to 1.53 (g of catalyst) h (g of ethanol)^?1; particle size of the catalyst, between 0.3 and 0.6 mm; feed flowrate, 0.16 cm³ min^?1 of ethanol+water and 30 cm³ (NC) min^?1 of N₂; water content in the feed, up to 75 wt %; time on stream, up to 31 h. The expression for deactivation kinetics is dependent on the concentration of hydrocarbons and water in the reaction medium (which attenuates the deactivation) and, together with the kinetics at zero time on stream, allows the calculation of the evolution with time on stream of the yields and distribution of products (ethylene, propylene and butenes, C₁‐C₃ paraffins, and C₄‐C₁₂). By increasing the temperature in the 300–400°C range the role of ethylene on coke deposition is more significant than that of the other hydrocarbons (propylene, butenes and C₄‐C₁₂), which contribute to a greater extent to the formation of coke at 300°C. © 2011 American Institute of Chemical Engineers AIChE J, 58: 526–537, 2012.     

Defluoridation performance and mechanism of nano‐scale aluminum oxide hydroxide in aqueous solution

BACKGROUND: The present study has concentrated on investigating the fluoride removal potential of nano‐scale aluminum oxide hydroxide (nano‐AlOOH). A series of batch adsorption experiments were carried out to assess parameters that influence the adsorption process. The different parameters investigated include the effect of contact time, initial fluoride concentration, adsorbent dose, pH of the solution and co‐existing anions. RESULTS: Most of the adsorption took place during the first 30 min and kinetic and equilibrium adsorption data show that the process obeys a pseudo‐second‐order kinetic equation and the Langmuir adsorption model. The fluoride removal efficiency is greater than 90% between pH 6 and 8 and decreases as pH values increase to 11. The presence of SO₄^2? or PO₄^3? in aqueous solution was found to reduce the fluoride uptake. Desorption studies showed that the fluoride can easily be desorbed at pH 13. CONCLUSION: Nano‐AlOOH possesses a maximum fluoride capacity of 3259 mg F^? kg^?1, which is comparable with that of activated alumina. Maximum adsorption occurred at around pH 7, which makes nano‐AlOOH a potential adsorbent for drinking water treatment. Copyright © 2009 Society of Chemical Industry     

Antibacterial,flame retardant,and physico‐chemical properties of cotton fabric graft copolymerized with a binary mixture of acrylonitrile and 4‐vinylpyridine

Modification of cotton fabric has been carried out through chemically induced graft copolymerization of binary mixture of acrylonitrile (AN) and 4‐vinyl pyridine (4‐VP) using ceric ammonium nitrate, (CAN) as initiator. Maximum percentage of grafting (151.28%) has been obtained at [4‐VP] = 0.376 mol L^?1 and [AN] = 1.221 mol L^?1, [CAN] = 0.0255 mol L^?1 and [HNO₃] = 0.9585 mol L^?1 in 25mL of water at 70°C in 180 min. Post quarternization and phosphorylation reactions of the grey and grafted cotton fabrics have been carried out to study their antibacterial and flame retardant properties respectively. The fabrics have been characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). The physico‐chemical properties such as wettability, moisture regain, crease recovery and tensile strength of the grey and grafted cotton fabric have also been evaluated. The modified fabric has been shown to exhibit excellent antibacterial and flame retarding properties with improved physico‐chemical properties except for the mechanical properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40415.     

Kinetic resolution of 1‐phenylethanol integrated with separation of substrates and products by a supported ionic liquid membrane

BACKGROUND: In the present study, the kinetic resolution of rac‐1‐phenylethanol by transesterification with several vinyl esters catalysed by a commercial immobilized Candida antarctica lipase B (Novozym 435) was carried out in n‐hexane at different water contents. The subtrates and products involved in the kinetic resolution were separated using a membrane bioreactor containing a supported liquid membrane based on the ionic liquid 1‐butyl‐3‐methylimidazolium tetrafluoroborate [bmim⁺][BF₄^?]. RESULTS: Variables affecting the kinetic resolution performance of the enzyme were studied. First, the influence of water content of the medium on the synthetic activity, selectivity and enantioselectivity of the enzyme was analysed in order to establish the optimal amount of water. The use of vinyl esters of different alkyl chain length (vinyl propionate, vinyl butyrate and vinyl laurate) as acyl donors to kinetic resolution was studied. Finally, the integrated reaction/separation process for the resolution of rac‐1‐phenylethanol was carried out in the optimal conditions found. CONCLUSION: These investigations demonstrate that the coupling of lipase enantioselectivity with the selective separation of supported liquid membranes based on ionic liquids provides a promising basis for practical production of enantiomerically pure or enriched compounds. Copyright © 2008 Society of Chemical Industry     

Ice‐Templated Poly(vinyl alcohol): Enhanced Strength and Low Thermal Conductivity

The freeze‐casting technique has been used for a variety of materials to tailor their pore structure. The growing ice crystals act as a template for the subsequent voids present in the body. While it is mostly used for inorganic oxide materials, the method is also applicable to polymers like poly(vinyl alcohol) (PVA). The synthesized materials have an aligned anisotropic pore structure which significantly influences the mechanical behavior and the thermal conductivity. Glutaraldehyde (GA) can be used as a cross‐linking agent to reduce the water solubility of the PVA samples. The composition‐dependent thermal conductivities are measured, and found to be 0.055–0.078 W m^?1 K^?1 parallel to the freezing direction and 0.048–0.058 W m^?1 K^?1 in the transverse direction. The scaffold‐like structure resembling the hydroxyapatite structures in bones yields high strength values in the axial direction well exceeding that of common unsupported building insulation materials.     

Efficient acetoin production by optimization of medium components and oxygen supply control using a newly isolated Paenibacillus polymyxa CS107

BACKGROUND: Acetoin is a natural flavor commonly used in wine, buffer, honey, garnet berry and strawberry as a food additive. It also has been widely applied in cosmetics, pharmacy and chemical synthesis. Culture medium optimization and process control were carried out for efficient production of acetoin by a newly isoliated P. polymyxa CS107. RESULTS: An acetoin high producing strain, designated as CS107, was newly isolated and identified as P. polymyxa based on its physiological and biochemical characteristics as well as the 16S rDNA sequence. The medium composition was optimized in shake flask fermentations by a sequential statistical experimental design. Under the optimized conditions, acetoin concentration of 30.98 g L^?1 was achieved with 71.83% of theoretical glucose conversion efficiency. Fed‐batch fermentation based on a suitable agitation speed was carried out in a 5 L jar, the maximum acetoin concentration of 55.3 g L^?1 was obtained with the productivity of 1.32 g L^?1 h^?1 and the yield of 75.62%. CONCLUSION: A new strain for efficient production of acetoin, designated as P. polymyxa CS107, was obtained. The optimization of fermentation variables and fed‐batch culture resulted in a maximum acetoin concentration of 55.3 g L^?1 in 5 L jar. Copyright © 2012 Society of Chemical Industry     

Kinetics of reactions between chlorine or bromine and the herbicides diuron and isoproturon

The chemical oxidation of two herbicide derivatives of the phenylurea group—diuron and isoproturon—has been carried out by means of chlorine, in the absence and in the presence of bromide ion. Apparent second‐order rate constants for the reactions between chlorine and the herbicides were determined to be below 0.45 L mol^?1 s^?1. Hypobromous acid reacts faster with the investigated herbicides, especially with isoproturon (k_app = 24.8 L mol^?1 s^?1 at pH 7). While pH exerts a negative effect on the bromination rate, the maximum chlorination rate was found to be at circumneutral pH. In a second stage, the oxidation of each compound was conducted in different natural waters, in order to simulate the processes which take place in water purification plants. Again, chlorine was used as an oxidant, and bromide ion was added in some experiments with the aim of producing the more reactive HOBr oxidant. The herbicide oxidation rate was inversely proportional to the organic matter content of the natural water. However, the formation of trihalomethanes (THMs) was directly proportional to the organic matter content and constitutes a limitation for the application of chlorine during drinking water treatment. Finally, the evolution of herbicide concentration was modeled and predicted by applying a kinetics approach based on the rate constants for the reactions between the herbicides and the active oxidants. Copyright © 2007 Society of Chemical Industry     

Determination of potential methane production capacity of a granular sludge from a pilot‐scale upflow anaerobic sludge blanket reactor using a specific methanogenic activity test

A 450 dm³ pilot‐scale upflow anaerobic sludge blanket (UASB) reactor was used for the treatment of a fermentation‐based pharmaceutical wastewater. The UASB reactor performed well up to an organic loading rate (OLR) of 10.7 kg COD m^?3 d^?1 at which point 94% COD removal efficiency was achieved. This high treatment efficiency did not continue, however and the UASB reactor was then operated at lower OLRs for the remainder of the study. Specific methanogenic activity (SMA) tests were, therefore, carried out to determine the potential loading capacity of the UASB reactor. For this purpose, the SMA tests were carried out at four different initial acetate concentrations, namely 500 mg dm^?3, 1000 mg dm^?3, 1500 mg dm^?3 and 2000 mg dm^?3 so that substrate limitation could not occur. The results showed that the sludge sample taken from the UASB reactor (OLR of 6.1 kg COD m^?3 d^?1) had a potential acetoclastic methane production (PMP) rate of 72 cm³ CH₄ g^?1 VSS d^?1. When the PMP rate was compared with the actual methane production rate (AMP) of 67 cm³ CH₄ g^?1 VSS d^?1 obtained from the UASB reactor, the AMP/PMP ratio was found to be 0.94 which ensured that the UASB reactor was operated using its maximum potential acetoclastic methanogenic capacity. In order to achieve higher OLRs with desired COD removal efficiencies it was recommended that the UASB reactor should be loaded with suitable OLRs pre‐determined by SMA tests. © 2001 Society of Chemical Industry     

Role of thermodynamic and kinetic interaction of poly(vinylidene fluoride) with various solvents for tuning phase inversion membranes

An extensive study of thermodynamics and kinetics of non‐solvent induced phase separation was carried out for poly(vinylidene fluoride)/solvent/water system for four different solvents. Literature available on semicrystalline polymers was mostly based on experimental cloud points, obtained to a narrow range of polymer concentration (<10 wt%), much less than the working range for membrane preparation (20–25 wt%). Aim of this work was to model the thermodynamic phase diagram using extended Flory–Huggins theory which was used as a tool, along with the kinetic data to obtain tailor‐made membranes with desired morphology and properties. Interaction parameters involving solvent, nonsolvent, and polymer played an important role to tune the porosity of the membrane. Thermodynamic calculation showed solvent N,N‐dimethyl acetamide resulted in the most porous membrane (permeability 5.4 × 10^?11 m Pa^?1 s^?1) followed by N,N‐dimethyl formamide (permeability 4.2 × 10^?11 m Pa^?1 s^?1), N‐methyl pyrrolidone (permeability 3.8 × 10^?11 m Pa^?1 s^?1), and acetone (impermeable to water even at 1380 kPa), which was the densest one. Prepared membranes were characterized in terms of surface morphology, molecular weight cut‐off, tensile strength, pore volume distribution, crystallinity, and surface roughness, which were correlated to inferences based on thermodynamic and kinetic calculations. POLYM. ENG. SCI., 58:1062–1073, 2018. © 2017 Society of Plastics Engineers     

Degradation of Phosphonate‐Based Scale Inhibitor Additives in the Presence of Oxidizing Biocides: “Collateral Damages” in Industrial Water Systems

Abstract

Organic, phosphorus‐based additives are commonly used in water treatment technologies such as mineral scale and corrosion inhibitors, and dispersing agents. Phosphonates find extensive use as anti‐precipitation inhibitors for sparingly soluble salts such as calcium carbonates and phosphates, calcium/barium/strontium sulfates and others, commonly formed in supersaturated process waters in a wide spectrum of industrial applications. In open recirculating cooling water systems strong oxidizing biocides (eg. ClO^?, BrO^?, etc.) are also added to control microbiological growth but have detrimental effects on other water treatment chemicals that are sensitive to oxidative degradation. In this paper we report the effect of a hypobromite‐based biocide towards the scale inhibitor AMP (amino‐tris‐(methylene phosphonate)). AMP reacts rapidly with the biocide at room temperature. AMP degradation continues, but it slowly reaches a plateau after 1000 minutes. Even after 50 h the reaction time, only 20% of AMP has decomposed. AMP reacts with the biocide to give the orthophosphate much more rapidly at 43°C than at 25°C due to faster kinetics of decomposition. Results on various other oxidizing biocides on PBTC (2‐Phosphonobutane‐1,2,4‐Tricarboxylic acid) are also presented. PBTC is a very “robust” scale inhibitor. This is confirmed by our degradation studies using biocides such as chlorine (ClO^?), bromine (BrO^?), their stabilized analogs, BCDMH, and ClO₂. Degradation (reversion to orthophosphate) of only up to 5% is observed in our experiments. These results are compared to others reported in the literature showing that PBTC degradation can be up to 25% under “harsher” conditions of higher biocide dosage and temperature. PBTC is virtually stable to the effects of a variety of oxidizing microbiocides, including chlorine, bromine and others.     

Free radical polymerization kinetics of monomers functionalized with ?AsO(OH)2 in aqueous media

The free radical polymerization kinetics of the isomer sodium salts of o‐ and p‐methacryloylaminophenylarsonate in aqueous solution have been studied using a dilatometric method. The polymerizations, initiated with potassium persulfate, were carried out at a constant monomer initial concentration of 0.50 mol/L and the initiator initial concentration was fixed at one of the following: 1.00, 2.00, 5.00, 8.00, or 10.00 (× 10^?3 mol/L). Another set of polymerizations were carried out at a constant initiator initial concentration of 2 × 10^?3 mol/L and the monomer initial concentration was fixed at one of the following: 0.20, 0.30, 0.50, 0.70, or 1.00 (mol/L). The polymerization reactions were conducted isothermally at 70°C. The order with respect to initiator was consistent with the classical kinetic rate equation, while the order with respect to monomer was greater that unity. The effects of temperature on the polymerization rate were also investigated and the activation energy gave values of 20.66, 22.68, and 23.22 kcal mol^?1 K^?1 over a temperature range of 50–70°C. For the case of o‐methacryloylaminophenylarsonic acid monomer, its kinetic study was carried out in DMF as solvent and AIBN initiator. p‐Methacryloylaminophenylarsonic acid was too insoluble in DMF to be studied. The polymers obtained were characterized by H‐NMR, IR, and viscosity. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1662–1669, 2004     

Roll‐to‐roll nanoimprint lithography of ultrafiltration membrane

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 MPa) applied during the low contact times (<2 s) inherent to R2R imprinting. N₂ permeance (L m^?2 h^?1 bar^?1) testing was used as an indicator to verify retention of membrane porosity and to guide selection of imprinting parameters during initial screening studies. Further measurements showed the N₂ and (scaled) deionized water permeances to have a 0.97 correlation coefficient. We scaled up the size of patterned membranes to as large as 226 cm² area, thereby demonstrating the plausibility of continuously patterning commercial ultrafiltration membranes. We also investigated pattern stability versus aqueous heat treatment and found that time, temperature, and imparted strain (during patterning) may all influence stability, but no evidence of pattern loss was observed in electron micrographs after our filtration experiments. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 45993.