Implementation of the waste reduction (WAR) algorithm utilizing flowsheet monitoring

Environmental metric software can be used to evaluate the sustainability of a chemical based upon data from the chemical process used to manufacture it. An obstacle to the development of environmental metric software for use in chemical process modeling software has been the inability to obtain information about the process directly from the model. There have been past attempts to develop environmental metrics that make use of the process models, but there has not been an integrated, standardized approach to obtaining the process information required for calculating metrics. As a result, environmental evaluation packages are largely limited to use in a single simulation package, further limiting the development and adoption of these tools.This paper proposes a standardized mechanism for obtaining process information directly from a process model using a strongly integrated interface set, called flowsheet monitoring. The flowsheet monitoring interface provides read-only access to the unit operation and streams within the process model, and can be used to obtain the material flow data from the process streams. This material flow data can then be used to calculate process-based environmental metrics. The flowsheet monitoring interface has been proposed as an extension of the CAPE-OPEN chemical process simulation interface set.To demonstrate the capability of the flowsheet monitoring interfaces, the US Environmental Protection Agency (USEPA) WAste Reduction (WAR) algorithm is demonstrated in AmsterCHEM's COFE (CAPE-OPEN Flowsheeting Environment). The WAR add-in accesses the material flows and unit operations directly from the process simulator and uses flow data to calculate the potential environmental impact (PEI) score for the process. The WAR algorithm add-in is included in the latest release of COCO Simulation Environment, available from http://www.cocosimulator.org/.     

Poly(ether imide)‐modified benzoxazine blends: Influences of phase separation and hydrogen bonding interactions on the curing reaction

Polymer blends of polybenzoxazine (PBZ)/poly(ether imide) (PEI) were prepared by the in situ curing reaction of benzoxazine (BZ) resin in the presence of PEI. Phase separation induced by the polymerization of BZ resin was observed. The rheological behaviors, morphologies, and their evolution process of BZ/PEI blends were investigated by rheometer and scanning electron microscope. Phase separation that took place at the early stage of the curing reaction effectively reduced the dilution effect of PEI. Fourier transform infrared (FTIR) results suggested that hydrogen bonds between PBZ and PEI existed during the whole curing process, although weakened with phase separation. The decrease of isoconversion activation energy indicated that the polymerization of BZ resin was facilitated in the presence of such kind of hydrogen‐bonding interactions. By changing the weight fraction of PEI, extensive phase separation was obtained in PBZ blends with 5 and 20 wt % of PEI, in which systems, the crosslinking density and glass transition temperature (T_g) of PBZ‐rich phase were greatly improved compared to this single PBZ system. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Improvement in polyetherimide gas separation membranes through the incorporation of nanostructured metal complexes

Polyetherimide (PEI) gas separation membranes were tailored, at the molecular scale, by the incorporation of nanostructured metallic complexes into the PEI network. The influence of these additives on the micropore size distributions of the membranes produced and on their performance for oxygen/nitrogen separation was investigated. Changing the metal within the same ligand had a significant influence on the microporosity and gas separation performance of these membranes. Magnesium (II) phathalocyanine (MgPc) in PEI membranes was found to be an excellent additive to increase membrane performance for air separation. The performance of these membranes increases with increasing additive concentrations. Membranes with this additive also exhibit an improved stability as determined through the annealing process. Annealing these membranes caused a slight decrease in their gas permeance and total micropore volume but a significant increase in their gas selectivity. The results show that the properties of the nanophase additive and nanophase-polymer interactions play a pivotal role in stabilizing and determining membrane performance for air separation.     

Adsorption performance of amine functionalized cellulose grafted epichlorohydrin for the removal of nitrate from aqueous solutions

Cellulose grafted epichlorohydrin (Cell-g-E) copolymer was synthesized and functionalization carried out using polyethylenimine (Cell-g-E/PEI). Characterization studies using FTIR, XRD and TGA, confirmed the grafting and functionalization process. Batch adsorption reaction was carried out for removal/recovery of nitrate ions and maximum adsorption capacity was obtained at pH 4.5. Kinetic studies explained pseudo-second-order as the best fit. Isotherm studies conducted at different temperatures revealed applicability of Freundlich isotherm model. Comparative studies proved effectiveness of Cell-g-E/PEI to other reported adsorbents. The adsorption process was spontaneous and exothermic. Batch adsorption/desorption studies for over six cycles showed the repeatability and regeneration capability of the adsorbent.     

Organically modified layered-silicates facilitate the formation of interconnected structure in the reaction-induced phase separation of epoxy/thermoplastic hybrid nanocomposite

We incorporated organic modified layered silicates (OLS) into the mixture of epoxy and poly(ether imide) (PEI) to obtain a ternary hybrid nanocomposite and investigated its reaction-induced phase separation behavior. We found that OLS had dramatic impact to the phase separation process and the final phase morphology. The onset of phase separation and the gelation or vitrification time were greatly brought forward and the periodic distance of phase-separated structure was reduced when OLS was incorporated. Phase separation of the unfilled specimens was greatly suppressed at temperatures higher than 190 °C, and no etch hole of PEI-rich phase could be observed in the SEM images. An interconnected, or bicontinuous morphology could only be observed at cure temperatures lower than 140 °C. On the contrary, the OLS-filled hybrid nanocomposites carried out obvious phase separation at cure temperatures ranging from 120 to 220 °C. Even at cure temperatures higher than 190 °C, the hybrid nanocomposites had an interconnected phase-separated microstructure. These phenomena were related to the preferential wettability, chemical reaction of OLS with epoxy oligomer and the enhanced viscosity of the mixture.     

Effect of tertiary polysiloxane on the phase separation and properties of epoxy/PEI blend

Epoxy functional siloxane (DMS-E09) was blended with epoxy resin (DGEBA) and thermoplastic polyetherimide (PEI). The results of morphology monitoring indicated that the reaction induced phase separation for all blends followed the spinodal phase separation mechanism. The microstructure changed from co-continuous of 25 wt% epoxy/PEI system to phase-inversion structure of 30 wt% epoxy/PEI system regardless of the content of the tertiary component DMS-E09. By comparing the onset time of phase separation between the two designated systems, the sequential occurrence of primary macrophase separation in co-continuous phase and secondary microphase separation in PEI-rich phase for 25 wt% epoxy/PEI system was identified. Studies of the thermomechanical properties of the DGEBA/PEI/DMS-E09 blends found that storage modulus increased with the addition of PEI but decreased with DMS-E09 monotonically. The value of T_g decreased with the addition of the tertiary DMS-E09 but was offset partially by the presence of PEI.     

Effect of Stabilization Condition on PEI/PVP-Based Carbon Hollow Fiber Membranes Properties

The concept of carbon membrane fabrication has attracted a great deal of attention among membrane researchers around the world in recent years. Stabilization is one of the important steps involved during the fabrication of the carbon membranes. The stabilization of PEI/PVP membrane was carried out in a tubular furnace under two types of environments (air and N₂). The resulting set of experiments from thermogravimetry analysis (TGA), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and X-ray diffraction (XRD) was used to investigate the effect of stabilization environments on the properties of the prepared carbon hollow fiber membranes (CHFM)s in terms of their morphological structure, thermal property, chemical structure, and microstructure. The detailed studies with regard to the chemical reaction mechanism occurring during the heat treatment process of the PEI/PVP-based CHFMs were explored. During the heat treatment process, PEI/PVP membranes underwent various physical and chemical changes, such as coloration, shrinkage, crosslinking reaction, and random scission. Based on overall properties, the stabilization step under air environment prior to carbonization step showed the best condition for the preparation of CHFMs derived from PEI/PVP.     

Uptake of sodium chloride by mixture of weakly acidic and weakly basic ion exchange resins: equilibrium and kinetic studies

The equilibrium and kinetic behaviour of weakly acidic resin (WAR) with alkali and weakly basic resin (WBR) with acids have been studied by many research teams. But little work is reported in literature regarding equilibrium and kinetic behaviour of mixture of WAR and WBR.In the present study, detailed analysis of equilibrium and kinetic behaviour of mixed resins with sodium chloride has been undertaken. From equilibrium studies, no adsorption is observed taking place, when salt solution is brought in contact with WAR or WBR individually; however adsorption is observed taking place, when salt solution is brought in contact with the mixture of WAR and WBR. The salt uptake depends on the concentration of salt solution, the amounts of individual ion-exchange resins as well as their proportion.Mixture of resins and salt solution has three phases interacting with each other and a number of resistances can influence salt uptake rate either individually or in combination. A series of possible resistances to the salt uptake are identified, namely, diffusion across films surrounding the resin particles, diffusion inside the resin particles, and dissociation of carboxylic group (-COOH) in WAR.To minimize the mathematical complexity, limiting case approach is adopted in this study. The underlying assumption in this approach is that resistance to the entire process lies in that limiting step.It is finally concluded that generation of H⁺ ions (by interaction of WAR particles and salt solution) followed by adsorption of acid by WBR governs the salt uptake process in mixed resin systems.     

Viscoelastic effects on the phase separation in thermoplastics modified cyanate ester resin

A high temperature thermosetting bisphenol-A dicyanate, BADCy was blended with a thermoplastic poly(ether imide) (PEI). The phase separation behavior of the blend was investigated by scanning electron microscopy (SEM) and time resolved light scattering (TRLS). It was found by SEM that the blend with 20 and 25 wt% PEI had a phase inversion structure. The results of TRLS displayed clearly that the phase separation took place according to a spinodal decomposition (SD) mechanism and the evolution of both scattering vector q_m and the maximum scattering intensity I_m followed Maxwell-type relaxation equation. The temperature-dependent relaxation time τ for the blends can be described by the Williams-Landel-Ferry equation. It demonstrated experimentally that the phase separation behaviors in PEI/BADCy blends were affected by viscoelastic effect.     

Morphology profiles obtained by reaction‐induced phase separation in epoxy/polysulfone/poly(ether imide) systems

The reaction‐induced phase separation in epoxy/aromatic diamine formulations simultaneously modified with two immiscible thermoplastics (TPs), poly(ether imide) (PEI) and polysulfone (PSF), has been studied. The epoxy monomer was based on the diglycidyl ether of bisphenol A (DGEBA) and the aromatic diamine was 4,4′‐methylenebis(3‐chloro 2,6‐diethylaniline) (MCDEA). Phase‐separation conversions are reported for various PSF/PEI proportions for blends containing 10 wt% total TP. On the basis of phase‐separation results, a conversion–composition phase diagram at 200 °C was compiled. This diagram was used to design particular cure cycles in order to generate different morphologies during the phase‐separation process. It was found that, depending on the PSF/PEI ratio employed, a particulate or a morphology characterized by a distribution of irregular PEI‐rich domains dispersed in an epoxy‐rich phase was obtained for initially miscible blends. Scanning electron microscopy (SEM) characterization revealed that the PEI‐rich phase exhibits a phase‐inverted structure and the epoxy‐rich matrix presents a bimodal size distribution of TP‐rich particles. For PSF/PEI ratios near the miscibility limit, slight temperature change result in morphology profiles. Copyright © 2005 Society of Chemical Industry     

Evaluating and improving environmental performance of HC's recovery system: A case study of distillation unit

Waste solvents/valuable products in the effluent stream are one of the major environmental problems in the chemical industry if not properly controlled. Separation processes are vital for the recovery of waste solvent/valuable product from the effluent stream to reduce the pollution along with improvement in economic performance. Among the various separation processes, distillation is most widely used. A number of environmental indicators, each satisfying researchers own need, and methodologies such as life cycle assessment (LCA), minimum environmental impact assessment (MEIM), waste reduction algorithm (WAR) and environmental fate and risk assessment (EFRAT) are available for evaluation of environmental performance of chemical processes. In this article, a systematic procedure, introducing an environmental performance index (EPI) based on potential environmental impact (computed from waste reduction algorithm (WAR)), energy consumption, resource conservation and fugitive emission, for evaluating environmental performance is presented. Analytical hierarchy process (AHP) is used at two levels for the determination of weighting of individual categories. The procedure is applied for the study of environmental performance of distillation column (steam stripping column) from a real chemical plant for the recovery of acetone and HC's from the off gases of the distillation fraction (DF) plant. Alternatives are compared using environmental performance index and best alternative is selected.     

聚醚酰亚胺/环氧树脂体系的固化及相分离行为研究

环氧树脂固化物本征的低韧性是限制其在复合材料应用的主要缺点之一。利用高性能热塑性树脂聚醚酰亚胺(PEI)与环氧树脂共混,系统研究了PEI在环氧树脂中的溶解行为、固化行为以及相分离行为。溶解试验表明:PEI与环氧齐聚物具有良好的相互溶解性;同时,PEI的加入降低了环氧树脂固化反应的活化能,但并没有改变其固化反应的机制。扫描电镜结果显示:随着PEI含量的增加,环氧/PEI浇铸体的相形貌从明显的分散颗粒相结构演变为双连续相结构和反转相结构。     

Effects of ultrasonication on glycerin separation during transesterification of soybean oil

The aim of this study was to determine the effects of high-intensity ultrasound irradiation and temperature on glycerin separation start time and separation rate during the transesterification of soybean oil. Response surfaces methodology was used to design the experiments. Reaction temperature, ultrasonication level and duration of ultrasonication at three levels were assigned as the control variables. The progressing transesterification reactions were monitored using a low-intensity ultrasound measurement system, which measures the ultrasound time of flight in glycerin as glycerin separates during the reaction. The effects of ultrasonication level, duration of ultrasonication and temperature on glycerin separation start time and separation rate were statistically significant at p < 0.01 level. The effect of the interaction between temperature and duration of ultrasonication on glycerin separation start time was also statistically significant at p < 0.05 level. The process conditions that provided the lowest starting times for glycerin separation were determined to be the reaction temperature of 50 °C, ultrasonication of 5 min and ultrasonication rate of 90%. Low-intensity ultrasound measurement techniques and response surfaces experimental design are useful tools in determining the effects of various variables on the transesterification of vegetable oils.     

Residue curve maps of reactive membrane separation

A batch reactive membrane separation process is analysed and compared with a batch reactive distillation process by means of residue curve maps. In both processes, the chemical reaction takes place (quasi-) homogeneously in the liquid bulk phase and vapour-liquid equilibrium is assumed to be established. Additionally, in the reactive membrane separation process, selective vapour phase permeation through a membrane is incorporated.A model is formulated which describes the autonomous dynamic behaviour of reactive membrane separation at non-reactive and reactive conditions when vacuum is applied on the permeate side. The kinetic effect of the chemical reaction is characterized by the Damköhler number Da, while the kinetic effect of multicomponent mass transfer through the membrane is characterized by the matrix of effective mass transfer coefficients. The process model is used to elucidate the effect of selective mass transfer on the singular points of reactive membrane separation for non-reactive conditions (Da=0), for kinetically controlled reaction (0<Da<∞), and for equilibrium controlled reaction (Da→∞). Scalar, diagonal and non-diagonal mass transfer matrices are considered. As examples, the simple reaction A⇔B+C in ideal liquid phase, and the cyclization of 1,4-butanediol to tetrahydrofurane in non-ideal liquid phase are investigated.     

Chain packing and phase transition of N-hexacosylated polyethyleneimine comb-like polymer: A combined investigation by synchrotron X-ray scattering and FTIR spectroscopy

In this paper, the chain packing and phase transition of comb-like polymer has been deeply analyzed with N-hexacosylated polyethyleneimine (PEI26C) as a template, fabricated through the reaction between n-hexacosyl bromide and PEI in a homogenous solution. The effect of long alkyl groups on the chain packing and phase transition of PEI26C was systematically investigated by synchrotron X-ray scattering and variable-temperature FTIR spectroscopy. PEI26C comb-like polymer exhibited an interesting structure-evolution process, and phase transformation from orthorhombic (β_O), monoclinic (β_M), to hexagonal (α_H) phase, and finally to amorphous state was demonstrated, indicating that large alkyl domains induced the complicated structures. Size-depended phase transition behavior provides an insight into the formation of metastable structure during the early stage of polymer crystallization.     

成纤型聚醚酰亚胺的熔融聚合

聚醚酰亚胺(PEI)是在聚酰亚胺链上引入醚键而形成的一类高聚物。通过设计的四步法进行了PEI聚合所需单体双酚A型二醚二酐(BPDEDA)的合成,并运用哈克转矩流变仪进行BPDEDA与间苯二胺的熔融聚合,所得PEI树脂与美国GE公司的Ultem4000树脂在红外光谱、13C核磁共振、DSC、TG图谱的比较上具有较好的一致性。     

Creep behaviour of polymer blends based on epoxy matrix and intractable high Tg thermoplastic

Polymer blends based on intractable, high temperature‐resistant thermoplastic polyetherimide (PEI) and epoxy‐amine (EA) were processed by dissolution of the thermoplastic into the epoxy‐amine precursors, followed by subsequent reaction. Because the PEI concentration was higher than the critical concentration, phase separation produced a dispersion of crosslinked thermoset (EA) in a PEI matrix. The creep behaviour of the blends were investigated in the temperature range near the glass transition of the thermoset phase. To account for the experimental data, two ways of modelling were explored, assuming (1) perfect coupling between phases (2) total debonding. Comparison between experimental data and modelling results indicates that a strong debonding process takes place even at low stress. This conclusion is in fair agreement with the low value of the estimated interfacial adhesion at the PEI matrix–EA particles interface. Copyright © 2004 Society of Chemical Industry     

Morphology and thermal behavior of dicyanate ester‐polyetherimide semi‐IPNS cured at different conditions

A high‐temperature thermosetting bisphenol‐A dicyanate, BADCy was modified with polyetherimide, PEI, at various compositions. Phase separation and rheokinetics through curing were studied by optical microscopy, dynamic and isothermal differential scanning calorimetry, and rheological measurements. The PEI phase separated at the early stages of curing, well before gelation, and did not affect the polycyclotrimerization kinetics. The phase structure and thermal properties of the final network were investigated as a function of the PEI content and cure temperature. For this purpose, dynamic mechanical analysis, scanning electron microscopy studies, and thermogravimetrical analysis were carried out. The morphological changes were interpreted in terms of a spinodal decomposition mechanism in the composition range studied. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1037–1047, 2000     

Post sulfonation of bisphenol A poly(arylene ethers)

In this study, bisphenol A polyetherimide (PEI) was sulfonated by a novel postsulfonation route using trimethylsilylchlorosulfonate. Different degrees of sulfonation were achieved by varying the mole ratio of the sulfonating agent to the PEI repeat unit and the reaction time. Comparison was made with respect to bisphenol A polysulfone (PSU) to study the influence of electron withdrawing group in the sulfonated poly(arylene ethers) (SPAE) backbone on sulfonation. Structural characterization of SPAE was conducted by ¹H‐NMR and FTIR spectroscopy. The enhanced reaction rate with PSU compared to PEI was attributed to the deactivation of bisphenol A unit due to the stronger electron withdrawing effect of imide group. The sulfonation of PEI was also carried out with chlorosulfonic acid for comparative study. The effects of degree of sulfonation on thermal and mechanical properties of SPAE‐s were studied by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and a tensile testing machine. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Pervaporative separation of bioethanol produced from the fermentation of waste newspaper

In this study, a hydrophobic polymeric polydimethylsiloxane (PDMS) membrane was used for the pervaporative separation of bioethanol produced from fermentation of lignocellulosic biomass (waste newspaper) and glucose. As a preliminary study, the pervaporation permeation performance showed strong dependence on feed concentration and temperature. The pervaporation of bioethanol produced by the fermentation of waste newspaper by Saccharomyces cerevisiae decreased process performance. However, the process performance was restored reversibly by water cleaning. The pervaporative separation of bioethanol from the fermentation of waste newspaper was carried out without any significant decreasing process performance in the study.