PHENOL RECOVERY WITH SLM USING “CYANEX 923”

The study of the phenol separation-concentration process with the hollow fiber supported liquid membrane technology has been performed. Mixtures of kerosene and CYANEX 923 were used as liquid membrane. The extractant CYANEX 923 is characterized by a high phenol selectivity and an extremely low solubility in the aqueous phase. The introduction of CYANEX 923 in the membrane composition decreases the extractant losses from the pores of the support.

The phenol separation and simultaneous concentration process has been checked. The influences of the initial concentration of phenol in the feed solution and sodium hydroxide in the stripping phase and the membrane composition on the separation rate have been investigated in a single-pass mode. The analysis of the membrane composition influence has been performed according to the steady-state mass transfer conservation equation and the associated boundary conditions, leading to the mass transfer parameters of the process     

Comparison study of a chiral stationary phase based on cellulose derivatives prepared by “grafting from” and “grafting to” methods

Chiral stationary phase (CSP) with cellulose derivatives was synthesized using the “grafting from” and “grafting to” methods. The “grafting to” method involves the bonding of a preformed end‐functionalized polymer to reactive surface amine groups on the silica gel. The “grafting from” involves the immobilization of initiator onto the aminated silica gel followed by atom transfer radical polymerization (ATRP) to generate the chiral polymer chains. The successful preparation of the CSP with cellulose derivatives prepared by ATRP was confirmed by FE‐SEM, XPS, EA, and thermal analysis. The chiral resolution of the CSP with cellulose derivatives was evaluated by high‐performance liquid chromatography using 10 racemates with various mobile phases that consisted of hexane/alcohol, hexane/THF, and hexane/chloroform. Furthermore, the CSP with cellulose derivatives prepared by “grafting from” and “grafting to” were compared and discussed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Properties of PMMA/Carbon nanotubes nanocomposites prepared by “grafting through” method

A number of batch polymerizations were performed to study the effect of multi‐walled carbon nanotubes (MWCNTs) on the properties of PMMA/MWCNTs nanocomposites. To improve the dispersion of nanotubes in PMMA matrix, MWCNTs were functionalized with methacrylate groups via a four‐step modification process and the modified nanoparticles were used to synthesize the nanocomposites. The prepared samples were characterized by Raman spectroscopy, thermogravimetric analysis, dynamic mechanical thermal analysis, differential scanning calorimetry, gel permeation chromatography, UV–visible, and TEM techniques. According to the results, modified nanotubes improved thermal and mechanical properties better than the pristine MWCNTs. The main improvement in the mechanical and thermophysical properties was achieved for the nanocomposite containing 0.5 wt% of MWCNTs. POLYM. COMPOS., 2012. © 2011 Society of Plastics Engineers     

Polymerization reactor: The influence of “gel effect” in batch and continuous solution polymerization of methyl methacrylate

This article describes the influence of gel effect in the free radical polymerization of methyl methacrylate. A mathematical model has been developed which tries to predict the performance of batch and continuous polymerization reactors under dynamic and steady-state conditions. The influence of diffusion phenomena on the process kinetics (gel effect) is very important. The autoacceleration in the polymerization rate of the batch reactor and the mulitple steady state for the continuous stirred tank reactor (CSTR) are connected with the attainment of critical conditions in the system. Such a model is useful for the design of the reactor and the choice of the control system.     

Optimum Values of Process Parameters of the “Wet Limestone Flue Gas Desulfurization System”

In this article the method of cost optimization of the “Wet Limestone Flue Gas Desulfurization System” is presented. The optimization calculations include process and cost models. The process model describes the most important stage of SO₂ removal that runs in the absorber and in the holding tank. It includes absorption of sulfur dioxide, oxidation of SO^2–₃, dissolution of limestone, and crystallization of gypsum. The model was applied to calculate indispensable parameters for estimating costs and then to minimize capital and operating costs. Costs of all important equipment were estimated, such as SO₂ removal systems with the absorber and the holding tank, reagent feed system with the ball mill and dewatering gypsum slurry system. Optimum values of the process parameters for different conditions of running flue gas desulfurization system were found. The process and cost model can be useful when designing the wet limestone FGD systems and carrying out economic analysis of the flue gas desulfurization plants.     

Retrofit design of a pharmaceutical batch process considering “green chemistry and engineering” principles

Considering the capital intensive nature of the chemical industry, redesign of existing production plants is a strategic decision. In this study, retrofitting is performed using a systematic path flow decomposition method, enriching it with hazard assessment and life cycle analysis path flow indicators and proposing a classification scheme for coupling these new path flow indicators with relevant heuristics for process alternative generation. The developed methodology is applied in a batch production plant from the pharmaceutical industry. The method highlights solvent recovery or substitution as important retrofitting actions, generates diverse process layout structures to achieve this task and evaluates them from cost, hazard and life cycle assessment point of view. Extractive distillation using glycol as an entrainer is identified as the multiobjective optimal option for separating the THF/Water azeotrope with improvement up to 40% for the various objectives compared with a base case where the waste solvent is incinerated. © 2015 American Institute of Chemical Engineers AIChE J, 61: 3423–3440, 2015     

Polymer waste recycling over “used” catalysts

Catalytic degradation of high-density polyethylene (HDPE) was carried out under nitrogen using a laboratory fluidised bed reactor operating at 360 °C with catalyst to polymer feed ratio of 2:1 and at 450 °C with catalyst to polymer feed ratio of 6:1 under atmospheric pressure. The catalysts used in this study were ZSM-5, US-Y, ASA, fresh FCC (fluid catalytic cracking) commercial catalyst (Cat-A) and equilibrium FCC catalysts with different levels of metal poisoning were studied. The initial results for polymer degradation at 360 °C (catalyst to polymer ratio of 2:1) in a fluidised bed reactor in terms of the yield of volatile hydrocarbon products were: model catalysts>commercial FCC catalyst>E-Cats. However, when the process conditions more closely resembled to FCC conditions, the fresh commercial FCC catalyst was more favourable in terms of the yield of volatile hydrocarbon products. The degradation of HDPE over E-Cats although reduced was similar to ASA in product selectivity and yield, and the level of metal contamination did not affect the product stream generated. A simple economic evaluation of polymer recycling process is reported showing that a catalytic system based on E-Cats appears comparable in costs to a commercial thermal cracking plant.     

An environmentally friendly clay‐based polymer composite “paper”

The paper industry is closely related to our daily life. Vast quantities of paper requirement worldwide lead to astonishing lumber consumption and environmental pollution. So the exploration of alternative paper‐like material should be of great importance. Here, we reported the preparation of a kind of environmentally friendly clay‐based polymer composite paper‐like film by incorporation of a kind of nanometer sized natural clay crystals, in this case attapulgite (ATP), into degradable poly(vinyl alcohol) (PVA) only though a simple blending and subsequently casting method. X‐ray analysis shows that no changes in the crystalline structure of ATP were observed in the PVA matrix. Even with a high content of clay crystals in composites (50 wt %), the resulting ATP‐PVA composite films (named as APCF) show excellent flexibility and tensile strength up to 22.19 MPa. The doping of ATP also results in flame retardant of composites, making it ideal candidate for packing and also building decoration applications. Interestingly, the APCF are printable and also much tough and tensile. Due to the simple fabrication, nearly no pollution emission process and easily to be scaled up, the APCF have great potentials as a kind of alternative for paper materials for diverse applications. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45128.     

Electrolytic Generation “In-Situ” of Sodium Hypochlorite

In-situ production of sodium hypochlorite is one of the oldest electrochemical processes of the chemical industry. During the past twenty years a new “in-situ” hypochlorite industry has developed. Construction and performance of present-day cells are considered in detail. Modern cells are fed with seawater or similar weak brines and yield solutions suitable for disinfection, e. g. in breweries, laundries, etc., or for treatment of municipal sewage. Particular importance attaches to units for chlorination of cooling water for power stations or on board ships, thus hindering growth of organisms leading to operating failures. The article closes by considering development trends.     

Cellular Changes in “Hass” Avocado Mesocarp During Cold‐Pressed Oil Extraction

The aim of this study was to understand factors affecting oil release from “Hass” avocado cells during the cold‐pressed oil extraction process. Early‐season “Hass” avocado fruit and pulp were sampled from a commercial extraction process. Light microscopy and electrical impedance spectroscopy were used to examine avocado flesh structure at defined steps during the extraction process (destoning, grinding, malaxing, and decanting). Most parenchyma cells were ruptured during destoning, grinding, and mixing before malaxing. In contrast, the other oil bearing cells, idioblast cells, appeared to remain unruptured and intact during the extraction process. The greatest reduction in electrical resistance was observed after the destoning step. There were also significant differences between the resistances of flesh after destoning, grinding, and prior to malaxing samples. Malaxing for two hours assisted the process of oil aggregation, which led to a greater oil yield. These findings will help to develop methods to enhance oil extraction from early‐season “Hass” avocado fruit.     

Theory of “Cohesive” vs “Adhesive” Separation in an Adhering System

It is shown that there is limited validitity to the doctrine that true interfacial separation, in an adhering system, is highly improbable. An analysis employing the Griffith-Irwin crack theory yields these results: The important parameters are, difference in elastic moduli, ΔE; differences in g, the energy dissipation per unit crack extension; thickness, Δ₁ or δ₂, of the region where dissipation occurs; and the presence or absence of strong interfacial bonds. If the forces across the interface are appreciably weaker than the cohesive forces in either phase, there is a strong minimum in g at the interface. For flaws of equal size, an interfacial flaw will be the site of initiation of failure. If strong interfacial bonds are present, then if Δg and ΔE have the same sign, failure is most probable, deep within one phase. If Δg and ΔE have opposite signs, failure may be initiated, and may propagate, at a distance δ from the interface, in the phase with lower g. This may be mistaken for weak-boundary layer failure.     

The “cold‐solutioning” phenomenon in cellulose triacetate–acetone mixtures

Direct mixing of cellulose triacetate (CTA) in acetone at room temperature produces only an opaque swollen gel at all concentrations. However, cycling the mixture between room temperature and ?78 ± 3°C results in a stable solution at room temperature, if the concentration is less than 6% (w/w). This process has been called “cold‐solutioning.” Such a process also produces a clear solution at concentrations between 6% (w/w) and 10% (w/w); however, in time, the solution separates slowly into at least two phases, a clear liquid and an opaque gel phase. At concentrations above 10% (w/w) and below 20% (w/w), the system exhibits two phases. A completely opaque swollen gel forms at concentrations of 20% (w/w) and above. The above‐described cold‐solutioning phenomena are shown to be the coupled kinetic and thermodynamic consequences of (1) the large thermal stresses that would result from thawing a swollen mixture of CTA and acetone, arising from the large differences in their thermal expansion coefficients; and (2) the “bimodal” composition of the cellulose derivative. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 1697–1707, 2003     

Inhibitor properties of “green” pigments for paints

Zinc chromate is one of the anticorrosive pigments most frequently used in the formulation of primers. However, its environmental aggressiveness and toxicity severely restrict its use, and different green alternatives have been proposed in order to replace zinc chromate. In the last decade, the behaviour of zinc phosphate as anticorrosive pigment has been intensively researched. During this time, various modifications have been made to this family of pigments to improve its properties, and a “second generation” of phosphate pigments, incorporating elements such as molybdenum, aluminium, or iron, has been produced. In this paper, the inhibitive properties of zinc phosphate and three second-generation phosphates have been investigated, using zinc chromate pigment as a reference. Pigment extract solutions, at different values of pH, have been used as corrosive media. Carbon steel samples were immersed in such solutions and their corrosion rates were measured using electrochemical techniques. The data obtained suggest that zinc chromate provides the highest percentage of inhibition in neutral and basic solutions, but phosphate-based pigments showed better results in acid solutions. Given this performance advantage, together with their less harmful environmental impact, these phosphate-based pigments can be proposed as realistic alternatives to chromates in the formulation of protective paints for use in acidic conditions.     

The reduction of reflective notches using “dyed” resist

Variation in line width caused by light scattered from the substrate (reflective notching) is a major problem in VLSI lithography. This paper demonstrates the reduction of reflective notches using a resist with increased absorptivity (a dyed resist). The optimal set of process conditions which minimize line width variations is explored.     

Investigation of “Zn2+ salt‐bondings” cross linked ENR with shape memory effect via ionic interactions

In this article, the method of using zinc ionomer as the vulcanizing agent and the addition of metal salt to form Zn²⁺ salt‐bondings is proposed. The formation of Zn²⁺ salt‐bondings in the elastomer causes further self‐aggregation of ion pair Zn²⁺, resulting in ionic cross linking network. This cross‐linking is very effective in increasing the strength of rubber. Additionally, dissipated energy during the loading‐unloading process also increases, and more importantly, T_g increases with the higher cross‐link density. The tunable and comparatively broad tanδ peak makes such materials potentially useful in the fabrication of damping material with multishape memory properties. Therefore this study opens up an efficient and easy way to improve the performance of rubber and functional applications. POLYM. ENG. SCI., 59:E367–E374, 2019. © 2018 Society of Plastics Engineers     

Industrieller Korrosionsschutz „Duplex-System”︁: Feurerverzinkung plus Kunststoffbeschichtung am Beispiel von Stahlrohr-Durchlässen

Protection against Corrosion in the Industry by ”?Duplex-System”?: Hot-Galvanization Plus Plastic-Coating on Steel-Pipe Passages The authors reports on the manufacture and economic application of hot-galvanized and plastic-coated steel-parts as pipe passages for road construction and underground construction. The advantages of the Duplex-System, i. e. hot-galvanization and plastic-coating, as a modern corrosion-protective measure against fluctuating chemical stress, mechanical wear and tear, and stress due water-leakage are shown. The plastic layer, consisting of a modified two-component epoxy-resin, is applied in a continuous spray-painting plant by the airless-spraying process to yield a 150 μ dry-film layer, which is then stoved in a circulating air-oven. Illustrations are presented to depict the coating process in the spray-painting plant and to show the transport as well as application of hot-galvanized, plastic-coated steel parts as pipe-passages.     

From “Strong” to “Much Stronger”: Utilization of Green Tea Extract Dispersant for SWCNT‐Reinforced Polymer Composites

PVA is reinforced with SWCNTs using green tea extract as a dispersant to achieve good dispersion of the SWCNTs in an organic solvent and finally high‐performance composite fibers. A combination of green tea extract/DMSO/SWCNT/PVA is found to disperse larger aggregates of SWCNTs to individual or thin bundles of a few nanotubes. Incorporation of 0.5 wt% SWCNTs into PVA fibers yields a tensile strength of 2.42 GPa, a Young's modulus of 46 GPa, toughness of 105 J · g^?1 at a failure strain of 11%, and a loop strength of 245 MPa, much higher than the values of commercial PVA fibers. The incorporation of highly dispersed SWCNTs suppresses the fibrillation tendency of the PVA fibers. The applied load is effectively transferred from the matrix to the SWCNTs.

     

Study of “gas fingering” behavior in gas-assisted injection molding

A common problem encountered in gas-assisted injection molding (GAIM) is “gas fingering,” i.e., gas bubbles penetrating outside designed gas channels and forming finger-shaped branches. Severe gas fingering can result in significant reductions in part stiffness. In this paper, nondestructive techniques have been used to quantitatively characterize gas bubble geometry in specially designed GAIM parts. Based on the quantitative measurements, the most crucial process parameters to control gas fingering have been identified through factorial design experiments. More detailed process studies reveal that there is an intrinsic relationship between gas fingering and cross-sectional gas bubble shape. By examining the effects of gas channel design and material type on the gas bubble shape, some useful gas channel design guidelines have been obtained.     

Thermal stability of “living” polymer–lithium systems

The thermal stabilities of polybutadienyllithium, polyisoprenyllithium, and polystyryllithium solutions have been determined in hydrocarbon solvents. Kinetic analysis indicated that a complex mechanism was involved in the thermolysis of polybutadienyllithium. The thermal stability was observed to increase with increasing lithium concentration, suggesting the presence of competitive reactions in addition to the expected elimination of lithium hydride. The thermal stability of the three systems studied was consistent with their reported degrees of association: dimeric polystyryllithium was less stable than tetrameric polyisoprenyllithium or hexameric polybutadienyllithium.     

Eggshell reinforced biocomposite—An advanced “green” alternative structural material

The need for bio‐based polymers as substitutes to recalcitrant petroleum sourced plastics is ever growing, because of increase in demand globally. Eggshell nanopowder (ENP) prepared using mechanical attrition and ultrasound irradiation was used to infuse a bio‐based polymer [Super Sap 100/1000 epoxy (SSE)] for possible enhancement of its mechanical properties. The ENP, neat SSE and SSE/ENP composites were characterized using X‐ray Diffraction, Transmission Electron Microscopy (TEM), Energy dispersive spectroscopy (EDS), Scanning Electron Microscopy, Thermogravimetic Analysis (TGA), Dynamic Mechanical Analysis (DMA), Thermomechanical Analysis (TMA) and flexure analysis. TEM and EDS analysis showed evidence of ENP in the SSE matrix whiles DMA and TMA analysis revealed significant improvements (7–22%) in the storage moduli and (3–17%) in coefficient of thermal expansion (CTE) respectively. Also, major delay in 5% decomposition temperatures and increases in char yields were observed in TGA analysis. The flexure strength, modulus, and toughness significantly improved by 6–31%, 11–37%, and 10–36%, respectively. Microstructure of fractured surfaces showed deflected crack paths which contributed to improve toughness. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43124.