Thermal,chemical and thermo‐chemical pre‐treatment of waste activated sludge for anaerobic digestion

The influence of different pre‐treatments was studied in order to observe the effects of temperature, pH and treatment time on Waste Activated Sludge (WAS) solubilization, and anaerobic digestion of pre‐treated sludge. Results showed that thermo‐chemical pre‐treatments were the most efficient on Chemical Oxygen Demand (COD) solubilization, which could reach 83% at 170 °C with pH = 12. Yet, increase in COD solubilization in thermo‐chemical pre‐treatment was not linked to an increase in soluble Volatile Solids (VS) as optimal conditions were 170 °C, and 130 °C with pH = 10, for this criterion. So, temperature was found to be the most influential parameter on COD and VS solubilization. Biodegradability batch anaerobic tests confirmed results obtained on WAS solubilization, that is to say that 170 °C and 130 °C with pH = 10 were optimal conditions, with respectively 45% and 21% of anaerobic digestion enhancement. Thus these two conditions were chosen for sludge treatment before continuous anaerobic digestion. Results, after stabilization have shown a better efficiency of 170 °C compared with 130 °C with pH = 10 pre‐treatment, since after anaerobic digestion it led to 71% of COD degradation and 59% of Total Solids (TS) degradation, with an improvement of 54% in biogas production. The main differences between those two pre‐treatments could be due to the pre‐treatments themselves more than to an effect on anaerobic digestion, because the first one led to a partial loss of WAS COD (near 17% of initial COD) and the second one to an increase in TS due to addition of base. Copyright © 2004 Society of Chemical Industry     

Solubilization of calfskin collagen in citrate buffer with the use of automated equipment

An automated collagen solubilizing apparatus that maintains constant electrolytic conditions during solubilization is described. It was used in solubilization of 6.95% of a calfskin corium as monomeric collagen in citrate buffer at pH 3.44 and ionic strength of 0.44 and a temperature of 8°C. It is shown that this is the limit of solubilization for undenatured collagen in this buffer.     

Solubilization of nitrogen‐containing heterocyclic compounds in reactive solvents

A reactive solvent was obtained by reacting 1 mol of cyclohexanone with 5 mol of formaldehyde. The structure of the solvent was studied by using ¹H‐NMR and IR spectroscopy. It was used for solubilization of melamine and other heterocyclic compounds containing ? NH? groups, such as adenine, carbazole, cytozine, guanine, thymine, and uracyl, as well as isocyanuric, barbituric, and uric acids. The solubilization involved the reaction of formaldehyde (liberated at an elevated temperature) with amino groups of the compound. Melamine was the compound with the best solubility in the reactive solvent. Preliminary attempts of curing the solutions have also been made. The oligomers cured at 120°C in the presence of acidic catalysts. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 2650–2659, 2002     

Sesame cake protein hydrolysis by alcalase: Effects of process parameters on hydrolysis, solubilisation, and enzyme inactivation

We investigated the effects of process parameters (substrate concentration, enzyme concentration, temperature and pH) on the hydrolysis and solubilization of sesame cake protein as well as enzyme stability. The sesame cake protein was hydrolyzed by Alcalase enzyme (a bacterial protease produced by a selected strain of Bacillus Licheniformis) that was chosen among five commercial enzymes examined. The optimum process conditions for hydrolysis and solubilization were obtained as 15 g L^?1 substrate concentration, 3 ml L^?1 enzyme concentration, 50 °C and pH 8.5. Under these conditions, the values of degree of hydrolysis and solubilization were found as 26.3% and 82.1%, respectively, and enzyme lost its activity by approx. 56% at the end of 120 min processing time. Modeling studies were performed to determine the kinetics of hydrolysis, solubilization and enzyme inactivation. The relationship between hydrolysis and solubilization was found linear for all experimental conditions examined. The inactivation energy of Alcalase at the temperature range of 45–55 °C was determined to be 25544 J mol^?1.     

Microemulsion formation and detergency with oily soils: II. Detergency formulation and performance

In part I of this series (J. Surfact. Deterg. 6, 191–203, 2003), the mixed surfactant system of sodium dioctyl sulfosuccinate (AOT), alkyl diphenyl oxide disulfonate (ADPODS) and sorbitan monooleate (Span 80) was shown to form Winsor type I and type III microemulsions with hexadecane and motor oil. In addition, high solubilization and low interfacial tension were obtained between the oils and surfactant solutions both in the supersolubilization region (Winsor type I system close to type III system) and at optimal conditions in a type III system. In the present study, this mixed surfactant system was applied to remove oily soil from fabric (a polyester/cotton blend), and detergency results were correlated to phase behavior. Dynamic interfacial tensions were also measured between the oils and washing solutions. In the supersolubilization and in the middle-phase regions (type III), much better detergency performance was found for both hexadecane and motor oil removal than that with a commercial liquid detergent product. In addition, the detergency performance of our system at low temperature (25°C) was close to that obtained at high temperature (55°C), consistent with the temperature robustness of the microemulsion phase behavior of this system.     

Solubilization of fatty soils by a radiotracer technique

A technique for measurement of solubilized radiotagged triolein and tristearin fatty soils is described. By using surfactant solutions under standardized conditions of temperature and agitation, the solubilized soils are removed from emulsified materials by filtration through 0.1 and 0.01 micron-pore size of filters. The radiotagged fat is recovered by solvent extraction from the clear filtrate by salting-out under centrifugal force and is measured by conventional counting technique. The nonionic alkanol- and alkylphenol-ethylene oxide (EO) adducts solubilized up to 0.058% triolein (weight percentage at 75°C.) while anionic surfactant and sodium tripolyphosphate solubilization was negligible. These findings suggest for these nonionics that solubilization is one of the main, if not the controlling factor in the mechanism of soil removal. Nonionic solubilization was at a maximum for 10 molar EO adducts and at near cloud-point temperatures. For the same surfactant more triolein than tristearin was solubilized, possibly on account of spatial considerations. For tridecanol-10 EO at 0.25% the heat of solubilization of triolein, ΔH_s, was 15 kcal/mole while the heat of micellization of the adduct was 1.3 kcal/mole of adduct. Differences in the colloidal ion lengths of the micelles and their aggregation numbers may explain the differences in solubilization between the anionic and nonionic surfactants tested.     

Aqueous Hydrotropic Solution as an Efficient Solubilizing Agent for Andrographolide from Andrographis paniculata Leaves

Abstract

An aqueous solution based extraction process for andrographolide from Andrographis paniculata leaves has been developed using alkyl benzene sulfonates and carboxylates as hydrotropes. The plant cells are permeabilized by the hydrotrope solutions followed by solubilization of andrographolide into the solutions. The extraction and solubilization of andrographolide is affected by structure and concentration of hydrotrope, temperature and particle size. Sodium cumene sulfonate (Na‐CS) shows the most efficient solubilization of andrographolide amongst the hydrotropes studied. The solubility of andrographolide increased by two orders of magnitude in Na‐CS aqueous solutions and ～96% andrographolide extraction was achieved in just 20 min.     

Generalized correlations for the aqueous liquefaction of lignocellulosics

This paper shows that liquefaction (i.e. solubilization) of lignocellulosics in aqueous phase and in the absence of catalysts results in two general correlations. The extents of solubilization of both holocellulose and lignin are linearly related to overall conversion within the temperature range 150–270°C and up to conversions of 83%.     

Solubilization of Illinois bituminous coal: the critical importance of methylene group cleavage

The extent of solubilization of an Illinois bituminous coal achieved by hydroliquefaction at various temperatures with and without catalyst was determined. The coal was also solubilized by treatment in suspension in THF with potassium in the presence of naphthalene. The original coal was also extracted with THF without prior treatment. After removal of solvent the soluble fractions were examined by ¹H n.m.r. spectroscopy. It is concluded that there are two temperature regimes which affect coal conversion: in the 350–400 °C region, hydroliquefaction proceeds principally by ether cleavage; whereas in the 400–450 °C range, hydroliquefaction results in additional cleavage of methylene groups joining aromatic or heteroaromatic units. Comparison of solubilization by hydroliquefaction with solubilization achieved with potassium in THF seems to indicate the initial degradation of coal by both techniques proceeds by ether cleavage and that further degradation is achieved in both cases by attack at the methylene bridge. The n.m.r. studies on hydroliquefaction products indicate that Illinois bituminous coal is structurally quite homogeneous because the product composition is largely independent of the degree of solubilization. Thus, solubilization results from molecular weight degradation rather than from preferential-degradation to different structural units.     

Thermally crosslinkable poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion-exchange fibers

The aim of this study was to prepare poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion-exchange fibers using the electrospinning technique and a post-thermal treatment. First, intermediate PSSA-MA/PVA fibers were prepared from solutions of PSSA-MA/PVA combined at ratios of 0.2/1 to 1/1; the fibers were subsequently crosslinked at 80–150 °C for 0.25–7 h. The effect of the crosslinking time, the temperature and the PSSA-MA/PVA ratio on various properties of the obtained ion-exchange fibers was investigated. When the PSSA-MA/PVA ratios were greater than 0.4/1, bead formation was observed. Thus, only smooth fibers without beads prepared from PSSA-MA/PVA mixed in ratios up to 0.4/1 were subjected to the thermal crosslinking treatment. When the crosslinking time and temperature were increased, the degree of crosslinking increased, which caused a decrease in the water solubilization and water uptake and an increase in the Young’s modulus. These parameters also appeared to significantly affect the ion-exchange capacity value. The temperature and time for successful crosslinking were 120–140 °C and 1–7 h, respectively.     

Preparation of SiO2/epoxy nanocomposite via reverse microemulsion in situ polymerization

Reverse water/oil (w/o) microemulsions composed of epoxy resin (EP) (the oil phase) and nonionic surfactant and ammonia aqueous solutions (the water phase) were used in the synthesis of SiO2/EP nanocomposites. The stability of reverse microemulsion was evaluated by measuring water solubilization of the microemulsion. Effects of surfactant type and content, ammonia concentration and temperature on the water solubilization were systematically investigated. Higher water solubilization capacity was obtained by nonionic surfactant TX‐100 compared with other two surfactants, Span‐80 and Tween‐80. Ammonia concentration of 5 wt% and preparation temperature at 35°C were favorable for forming a stable microemulsion and enabling the subsequent hydrolysis and condensation reaction of inorganic precursor tetraethoxysilane (TEOS). SiO2/ epoxy nanocomposites were prepared via in situ polymerization of TEOS within the nanoscale reverse microemulsion “water pool”. FTIR, SEM, and universal testing machine were used to characterize the structural and mechanical properties of the composite. The results revealed that the optimal mechanical properties were obtained at 3 wt% TEOS content. Compared with neat epoxy resin, the tensile and flexural strength of the composite were 40% and 12% higher, respectively. The formation of the silica structure in the hybrid was investigated with FTIR. The SEM and optical observations showed a ductile fracture morphology and good miscibility between inorganic and organic phases. POLYM. COMPOS., 35:1388–1394, 2014. © 2013 Society of Plastics Engineers     

Detergency study of the synergism between oily and particulate soil on polyester/cotton fabric

The removal of multiphase, multicomponent soils from fibrous substrates depends upon the nature of the soil mixture, the order of application, wash temperature, and type of detergent formulation. By studying these factors, we investigated the synergism between residual oil (triolein) and particulate soil (clay) on a durable press polyester/cotton fabric after laundering with four different detergents at wash temperatures of 27 and 49 C. To probe the interaction between clay and oil, fabric specimens were soiled with clay only, triolein only, clay followed by an application of triolein, and triolein followed by an application of clay. Four detergent formulations were used to launder the soiled fabrics, including one unbuilt liquid and three powdered detergents with different builder systems. The amount of residual oil (triolein) was determined by radiotracer technique, and the quantities of clay were determined by measuring aluminum by neutron activation. Reflectance measurements were used to calculate fabric whiteness. The soil distributions on and within the textile structure were obtained by scanning electron microscopy using backscattered electron images, secondary electron images and X-ray mapping. Osmium tetroxide was used to tag the oil, while silicon was the elemental tag for clay in the microscopic analysis. Results of the four factors studied can be summarized as follows. (i) In agreement with observations by previous researchers, a mixture of clay and oil is more difficult to remove than either the oil or the clay applied singly. It appears that oil acts as a matrix to bind clay, forming a composite soil. (ii) The specimens that were soiled first with oil and then clay had more soil removed by laundering than the specimens soiled with clay and then oil. Detergency was limited by the encapsulation of clay by the oil and adsorbtion of oil by the clay. (iii) The built powdered detergents were temperature sensitive, while the unbuilt liquid detergent was not. (iv) The built powdered detergents removed more soil (oily and clay) than the unbuilt liquid detergent.     

Effect of deaeration processing on the behavior of an acrylonitrile–acrylamide copolymer and carbon fiber precursors

The effect of the deaeration process on the behavior of acrylonitrile–acrylamide copolymer solutions was demonstrated experimentally in detail. The corresponding mechanical properties and morphology of the resultant precursors were also been examined. It was found that the viscosity of the copolymer solutions at rest increased continuously with the deaeration time prolonged at every fixed temperature stage, but it considerably increased when the deaeration temperature decreased. The changes in the viscosity of the solutions at 80°C were less prominent than those of the solutions at 20°C in the beginning stage; beyond 60 min, the changes became remarkable. In concentrated copolymer solutions, the dimethyl sulfoxide composition weight percentage decreased with an increase in the deaeration temperature; the increasing temperature reduced the solvent power continuously at a high deaeration temperature, so more solid–elastic gels were formed in the solutions with an increase in time. At the same degree of vacuum, when the temperature varied from 20 to 80°C and, in particular, the deaeration temperature was beyond 60°C, the products from the copolymer seemed to have slightly narrower molecular weight distributions. With the deaeration temperature increasing, the tensile strength, elongation at break, and bulk density of the resultant precursors increased, but their fineness and coefficient of variation decreased. The morphology of the precursors was more compact and more round beyond 60°C than below 60°C. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Influence of roasting temperature on reactions between ferruginous blende and copper(II) oxide

Thermal treatment in an oxidizing atmosphere of a mixture of raw blende (ZnS) and copper(II) oxide enhanced the formation of a mixed ferrite phase at temperature about 600°C. The composition established at 900°C was approximately (0.8 ZnO · 0.2 CuO)Fe₂O₃. For the mixture ZnS–CuO, with 5 to 15% CuO by weight, less than 15% copper was involved in the formation of the spinel phase. The increasing copper content in the mixture, roasted above 1000°C, favoured solubilization of iron, even in a weakly acid medium.     

Hydrolysis and solubilization of corn gluten by Neutrase

Hydrolysis and solubilization of corn gluten were performed using a commercial protease preparation Neutrase. The effects of substrate concentration, enzyme concentration, temperature, pH and hydrolysate amount on the degree of hydrolysis and solubility of corn gluten were investigated depending on processing time. Trials were conducted in a batch reactor and degrees of hydrolysis were computed using a pH‐stat method. Results show that solubility and degree of hydrolysis were almost linearly related in all process conditions applied except in the case of hydrolysate addition. Optimum conditions for hydrolysis and solubilization were obtained as 10 g L^?1 protein concentration, 4 mL L^?1 enzyme concentration, 45 °C and pH 6.5. The mechanism of the kinetics was explained by taking into consideration association binding between the enzyme and substrate. The kinetics of hydrolysis and solubilization for all experiments performed were represented by exponential association equations that have not been used in the literature before. Also, to illustrate the effect of process variables on hydrolysis and solubilization, some modelling studies were performed. Copyright © 2007 Society of Chemical Industry     

Strength of Zirconium Diboride to 2300°C

The strength of zirconium diboride (ZrB₂) ceramics was measured up to 2300°C, which are the first reported measurements above 1500°C since 1970. ZrB₂ ceramics were prepared from commercially available powder by hot pressing. A mechanical testing apparatus capable of testing material in the ultra‐high temperature regime with atmosphere control was built, evaluated, and used. Four‐point bend strength was measured as a function of temperature up to 1600°C in air and between 1500°C and 2300°C in argon. Strength between room temperature and 1200°C was ~390 MPa, decreasing to a minimum of ~170 MPa between 1400°C and 1500°C, with strength increasing to ~220 MPa between 1600°C and 2300°C.     

Interactions and Solubilization of Disperse Dye with Modified Gemini Surfactants: Investigation Using the Taguchi Method

Since the interaction of a disperse dye with a surfactant in micelles plays an important role in textile industry, the purpose of this study was to find out the optimal conditions that describe the dye?Csurfactant interaction. The effects of temperature, gemini surfactant concentration and ethylene-oxide chain length of gemini surfactants were investigated and optimized using the Taguchi method. First, this method was adopted to carry out the parameter design, and the interaction parameters that would affect the absorbance of UV?Cvisible spectrum were chosen as the control factors. After the selection of an appropriate orthogonal array, an analysis of variance was applied to decide upon the optimal conditions of solubilization parameters and determine the significant factors of the UV?Cvisible absorbance. The optimized conditions were as follow: surfactant concentration 5.6 × 10^?4 M, length of ethylene oxide chain 20, and temperature 40 °C. Finally, the experimental results of confirmation tests with a confidence interval of 95%, indicated that the experiment is reliable and reproducible. Under these optimum conditions, it was also determined that the solubilization of disperse dye using modified gemini surfactants increased when the surfactant concentration and the ethylene oxide chain length increased.     

Temperature-dependent solubilization of PEO-PPO-PEO block copolymers and their application for extraction trace organics from aqueous solutions

The effect of temperature on naphthalene solubilization in aqueous PEO-PPO-PEO block copolymer solutions has been investigated. Increasing temperature would enhance the apparent solubility of naphthalene in aqueous PEO-PPO-PEO block copolymer solutions. The pseudo-phase model was employed to calculate thermodynamic parameters for naphthalene solubilization in aqueous PEO-PPO-PEO block copolymer solutions.     

Viscoelasticity of concentrated polyacrylonitrile solutions: effects of solution composition and temperature

The effects of solution composition and temperature on the viscoelasticity of concentrated polyacrylonitrile (PAN) solutions were studied using a variety of rheological measurements, such as steady‐state shearing, dynamic stress sweep and transient rheological tests. The first normal stress difference N₁ and the shear stress τ were found to increase with decreasing temperature and increasing PAN concentration and water content in the solutions. The crossover point of N₁ and τ, denoting the equal contribution of viscosity and elasticity to the viscoelasticity of the solutions, moved to lower shear rates at lower temperature, higher PAN concentration and higher water content. The values of the relaxation time (λ) were larger at 70 °C than at 40 °C. In addition, the changes of λ with PAN concentration and water content were different at the two temperatures, ascribed to the different states of the solutions. The PAN solutions were in the linear viscoelastic regime in the temperature range 40–70 °C when the shear stress was below 300 Pa. The creep compliance recovery rate decreased with increasing temperature, but increased with increasing PAN concentration and water content. Thixotropic tests showed that the thixotropy of the solutions was also affected by the solution composition and temperature. Gelation was found to influence the way the solution composition and temperature affected the viscoelastic properties of the PAN solutions. Copyright © 2011 Society of Chemical Industry     

Effect of low temperature on the microwave-assisted vacuum frying of potato chips

The objective of this study was to investigate the effect of low temperature on the microwave-assisted vacuum frying of potato chips. A newly built, in-house, microwave-assisted frying machine was developed and used in this study. The effect of low temperature on the microwave-assisted vacuum frying of potato chips was investigated via comparing sample properties prepared with frying temperatures of 90°C, 95°C, and 100°C. The experience was taken at the same vacuum degree in every frying process. Parameters of included moisture content, oil content, color parameters (lightness, redness, and yellowness), and textures (hardness, crispness) were used to evaluate the effect of different frying temperatures on the microwave-assisted vacuum frying of potato chips. Results showed that with lower temperature in microwave-assisted frying, the rate of moisture evaporation of potato chips was slowed down and the time of the ending of frying was prolonged from 10 min with a frying temperature of 100°C to 14 min with 90°C and 12 min with 95°C. Meanwhile, the oil content in fried potato chips was increased with lower temperature in microwave-assisted vacuum frying. The breaking force of final products are not significantly (p > 0.05) affected in different frying temperatures of microwave-assisted vacuum frying. Also, the frying temperature of 100°C in microwave-assisted vacuum frying had better preservation of natural color than the lower frying temperature with prolonged frying time. Results showed that the temperature is one of the main factors that affect the quality of microwave-assisted vacuum frying of potato chips and the producer could find suitable temperature conditions according to experience.