Enzymatic hydrolysis of autohydrolyzed barley husks

BACKGROUND: Barley husks were subjected to non‐isothermal autohydrolysis of different severities, yielding a liquid phase rich in hemicellulose‐derived compounds and a solid phase, composed mainly of cellulose and lignin. This solid phase was subjected to enzymatic hydrolysis in order to assess the effects of severity on the susceptibility of substrates to enzymatic hydrolysis. The effects of the liquid to solid ratio (LSR, in the range 6 to 18 g g^?1) and cellulase to substrate ratio (CSR, in the range 3.3 to 8.2 FPU g^?1) on the enzymatic hydrolysis were assessed. RESULTS: Up to 25.8 g oligomers per 100 g raw material were present in liquors from the hydrothermal processing. Enzymatic hydrolysis of solid phases obtained under selected conditions (log Ro = 4.14, LSR = 6 g g^?1 and CSR = 5.8 FPU g^?1) yielded glucose concentrations up to 67 g L^?1 (corresponding to cellulose to glucose conversions close to 100%). CONCLUSION: It was shown that autohydrolysis is an effective method for improving the enzymatic susceptibility of barley husks. High cellulose conversions resulting in high glucose yields were achieved by enzymatic hydrolysis at low LSR and CSR. The liquid fraction obtained upon autohydrolysis contained large amounts of hemicellulose‐derived compounds. Copyright © 2010 Society of Chemical Industry     

Manufacture of fibrous reinforcements for biodegradable biocomposites from Citysus scoparius

BACKGROUND: Cytisus scoparius samples were processed with hot, compressed water (autohydrolysis treatments) to obtain both fiber‐containing solids (suitable as reinforcements for composites) and a liquid phase containing sugar oligomers derived from hemicelluloses. The solid phase from autohydrolysis, mainly made up of cellulose and lignin, was employed for manufacturing polylactic acid (PLA)‐based biodegradable composites. The mechanical properties, water uptake and thermal properties of composites were assessed. RESULTS: The hydrolysis of the major hemicellulose polysaccharide components of Cytisus scoparius was interpreted using kinetic models based on sequential pseudo‐homogeneous first‐order, irreversible reactions. Operating under non‐isothermal conditions, the autohydrolysis experiment carried out at up to 215 °C led to the maximum concentration of sugar oligomers (accounting for about 71% of the initial xylan). These compounds can be employed for a variety of purposes, including applications as prebiotics. Composites containing autohydrolyzed fibers presented both improved impact strength and reduced water absorption ability. CONCLUSIONS: Autohydrolysis of Cytisus scoparius led to a liquid phase containing xylooligosacharides with commercial value, and to a solid phase suitable as a reinforcement for PLA‐based composites with reduced water retention ability. Copyright © 2010 Society of Chemical Industry     

Paulownia as a raw material for the production of pulp by soda–anthraquinone cooking with or without previous autohydrolysis

BACKGROUND: A central composite experimental design and multiple regression were used to model the production of pulp and paper sheets from a Paulownia fortunei × tormentosa × elongata trihybrid clone. Also, the same experiments were carried out with the solid phase after autohydrolysis of the raw material. RESULTS: The results were compared with those obtained from the solid phase remaining after autohydrolysis of the raw material with a view to optimizing the use of hemicelluloses and cellulose by fractionation. Pulp and paper sheets from the trihybrid clone surpass those from other Paulownia species such as P. fortunei and P. elongata in physical properties such as tensile index (11.6–49.1 Nm g^?1), burst index (0.23–2.41 MPa m² kg^?1), tear index (0.71–3.03 mN m² g^?1) and intrinsic viscosity (427–958 cm³ g^?1). CONCLUSIONS: The solid phase obtained by autohydrolysis of the Paulownia trihybrid provides pulp and paper sheets comparable in strength‐related properties with those of pulp directly produced from the raw material, but using substantially milder operating conditions and with the added advantage that the autohydrolysis treatment provides highly valorizable liquor. Copyright © 2011 Society of Chemical Industry     

Low-Temperature Dilute Acid Hydrolysis of Oil Palm Frond

Oil palm frond (OPF) fiber, a lignocellulosic waste from the palm oil industry, contains high cellulose and hemicellulose content, thus it is a potential feedstock for simple sugars production. This paper describes the two-stage hydrolysis process focusing on the use of low-temperature dilute acid hydrolysis to convert the hemicellulose in OPF fiber to simple sugars (xylose, arabinose, and glucose). The objective of the present study was to evaluate the effect of operating conditions of dilute sulfuric acid hydrolysis undertaken in a 1 L self-built batch reactor on xylose production from OPF fiber. The reaction conditions were temperatures (100–140°C), acid concentrations (2–6%), and reaction times (30–240 min). The mass ratio of solid/liquid was kept at 1:30. Analysis of the three main sugars glucose, xylose, and arabinose were determined using high-pressure liquid chromatography. The optimum reaction temperature, reaction time, and acid concentration were found to be 120°C, 120 min, and 2% acid, respectively. Based on the potential amount of xylose (10.8 mg/mL), 94% conversion (10.15 mg/mL) was obtained under the optimum conditions with small amount of furfural (0.016 mg/mL). To enhance the effectiveness of dilute acid hydrolysis, the hydrolysis of OPF fiber was also performed using ultrasonic-pretreated OPF fiber. The effects of ultrasonic parameters power (40–80%) and ultrasonication times (20–60 min) were determined on sugar yields under optimum hydrolysis conditions (2% acid sulfuric, 120°C and 120 min). However, the use of ultrasonication was found to have detrimental effect on the yield of simple sugars due to the 10-fold increase in the formation of furfural.     

Liquid Radial Dispersion in Liquid-solid Circulating Fluidized Beds with Viscous Liquid Medium

Liquid dispersion in the radial direction was investigated in the riser of a viscous liquid-solid fluidized bed 0.102 m in diameter and 3.5 m in height. Pressure fluctuations in the riser were also measured and analyzed to examine the behavior of fluidized particles. Effects of liquid velocity (0.15–0.45 m/s), solid circulation rate (2–8 kg/m²s), particle size (1–3 mm), and liquid viscosity (0.96–38 mPas) on pressure fluctuations and the liquid radial dispersion coefficient were determined. The infinite space model was employed to obtain the radial dispersion coefficient from the radial concentration profiles of the tracer. The pressure fluctuations were analyzed by means of autocorrelation coefficient as well as power spectral density function. The dominant frequency obtained from the autocorrelation coefficient or power spectral density function of pressure fluctuations decreases with increasing liquid viscosity or liquid velocity, but it increases with increasing particle size. The liquid radial dispersion coefficient decreases with increasing liquid velocity or viscosity, but it increases as the solid circulation rate or particle size increases. The liquid radial dispersion coefficient is related closely to the resultant behavior of fluidized particles. The radial dispersion coefficient has been well correlated with operating variables in terms of dimensionless groups.     

Pretreatment of lignocellulosic biomass by autohydrolysis and aqueous ammonia percolation

A two-stage biomass pretreatment process-a combination of autohydrolysis and aqueous ammonia percolation-was experimentally studied as a method to remove and recover hemicellulose from lignocellulosic biomass. Hemicellulose was completely separated from the biomass after 1 hr of autohydrolysis at 200‡C. As reaction temperature and/or time of autohydrolysis was increased in the range of 170-200‡C and 1–2.5 hr, respectively, the amount of hemicellulose solubilization was increased ; however, more sugars were decomposed. Most of the extracted hemicellulose was recovered as xylose oligomer. Hemicellulose was found to inhibit the enzymatic hydrolysis of cellulose. When the biomass was consecutively pretreated with pure water at 180‡C for 30 min and with 10 wt% ammonia solution at 180‡C for 30 min, about 62% of the hemicellulose was extracted. The enzymatic digestibility of the pretreated biomass was as high as 95 %.     

Improvements of the Tensile Properties of Recycled High Density Polyethylene (HDPE) by the Use of Carbonized Olive Solid Waste

Recycling of plastic poses several concerns to manufacturers. The most important concern is the unpredictable of their mechanical properties (modulus of elasticity, tensile strength and ductility). Olive solid waste, an abundant material usually thrown into land causing harms to environment was mixed with HDPE plastic and used as a filling material. The mixture was fed to a house made extruder operating at different speed and temperature. Two carbon particle sizes range (less than 150 µm and 180–250 µm) were used. The effect of carbon contents from 0 to 10% wt/wt and operating conditions were tested on the mechanical properties of the recycled HDPE plastic. It was found that up to 5% wt/wt carbon of less than 150 µm resulted in a noticeable improvement of modulus of elasticity and tensile strength. The optimum value of modulus at carbon particle size 180–250 µm was found at 2.5 olive solid carbon content. Increasing screw speed was found to increase tensile modulus and strength of used plastic. This was related to melt viscosity and reduction in particle size. An increase in processing temperature was found to improve tensile properties up to certain point where degradation of polymeric matrix begins to occur and therefore tensile properties deteriorate.     

TCF BLEACHED PULPS FROM MISCANTHUS SINENSIS BY THE IMPREGNATION RAPID STEAM PULPING (IRSP) PROCESS

ABSTRACT

The production of bleached cellulose pulps from elephant grass (Miscanthus sinensis) via a two-stage soda pulping process and a TCF bleaching sequence is evaluated in this work. The impregnation rapid steam pulping process (IRSP) involves impregnating of the lignocellulosic material with the pulping liquor, withdrawing the excess liquor and rapidly steaming the impregnated material at 180–200°C for a short time. In this paper the process variables and their effect on the kappa number, yield and viscosity of the unbleached pulps are discussed. Bleaching by an ozone-based TCF sequence was tested, and the papermaking properties of the bleached pulp were determined. A kappa number of 19 was obtained by impregnating at an alkali charge of 30 + 0.1% anthraquinone carboxylic acid (AQCA) and pulping at 180°C for only 15 min. Kappa was reduced to 16 by extending pulping time to 26 min. The alkali consumption during impregnation and pulping was 10.2 g NaOH/100 g of dry Miscanthus. Screened pulp yield, viscosity and brightness for this pulp were 54.6%, 913 mL/g and 37.3%, respectively. After bleaching, the pulp had an ISO brightness of 87.4% and a viscosity of 700 mL/g. Refining in a PFI mill provided optimal strength properties of the bleached pulp at 4500 revolutions (71°SR): breaking length 7.2 km, tensile index 72 N m/g, and burst index 4.3 kN/g. Tear index was 7.9 mN m²/g at this degree of refining.     

PHENOLIC WASTEWATER TREATMENT BY SUPPORTED LIQUID MEMBRANE USING DIFFERENT COOKING OILS AS LIQUID MEMBRANE

Transport of phenol through a flat sheet supported liquid membrane (SLM) containing cooking oil as liquid membrane (LM) was investigated. Factors affecting permeation of phenol such as membrane phase, support material, feed phase pH, stripping phase concentration, stirring speed, and initial concentration of phenol were studied. It was found that these parameters strongly influence phenol removal efficiency; PTFE membrane as support material, grape seed oil as liquid membrane, feed pH of 2.0, initial phenol concentration of 100 mg/L, stirring speed of 350 rpm, and 0.2 M sodium hydroxide as effective stripping agent were found as the best conditions for greater phenol transport. Under these conditions, permeability was found to be 7.46 × 10^?6 m/s. After 10.5 h, phenol was completely removed from the feed phase to strip phase. According to stability experiments, it was observed that the SLM is stable after 22 h. Thus, the use of cheap, nontoxic, and naturally oil as a novel and green membrane for recovery of phenol from wastewater was demonstrated.     

Hydrolysis of o- and p-nitrochlorobenzene with aqueous sodium hydroxide to the corresponding nitrophenols

The hydrolysis of o- and p-nitrochlorobenzene with aqueous sodium hydroxide was studied at temperatures of 100–160°C and at a pressure corresponding to the vapour pressure of the aqueous solution, so that the system was maintained in the liquid phase. The rate of reaction, as well as the yield and quality of the product, were poor when no catalyst was used. The use of cuprous oxide and manganese dioxide as catalysts was found to be suitable for the process. The effects of temperature, amount of caustic soda, ratio of aqueous phase to organic phase, type and amount of catalyst, speed of agitation and period of reaction on the conversion and yield of nitrophenols were studied with a view to obtaining the most suitable conditions for the production of o- and p-nitrophenol.     

Hydrolysis of o- and p-nitrochlorobenzene with aqueous sodium hydroxide to the corresponding nitrophenols

The hydrolysis of o- and p-nitrochlorobenzene with aqueous sodium hydroxide was studied at temperatures of 100–160°C and at a pressure corresponding to the vapour pressure of the aqueous solution, so that the system was maintained in the liquid phase. The rate of reaction, as well as the yield and quality of the product, were poor when no catalyst was used. The use of cuprous oxide and manganese dioxide as catalysts was found to be suitable for the process. The effects of temperature, amount of caustic soda, ratio of aqueous phase to organic phase, type and amount of catalyst, speed of agitation and period of reaction on the conversion and yield of nitrophenols were studied with a view to obtaining the most suitable conditions for the production of o- and p-nitrophenol.     

Modeling and Drying of Carton Packaging Waste in a Rotary Dryer

This research aims at modeling the rotary drying of carton packaging waste and analyzing the energy performance of the process. Drying data were obtained in a semi-pilot rotary dryer, 0.45 m diameter and 2.7 m rotating drum long, operating with an air velocity of 1 m/s and air inlet temperature of 90°C and 10 rpm. Under the operating conditions employed, the analysis of the data showed that the energy performance of the drying process increased from 5 to 75% as the inlet wet solid feed rate increased from 1.8 to 19 kg/h. In addition, at this latter wet-solid feed rate, the reduction of the air velocity in the dryer to 0.8 m/s also led to an increase in the performance of drying process from 80 to 94%. Furthermore, with a 95% confidence interval, the model used was adequate to predict the air and solid temperature as well as the air humidity and the solids moisture content.     

MEASUREMENT OF CONTINUOUS PHASE VELOCITIES IN A CONFINED SOLID-LIQUID JET USING LDV

A two-component LDV was used to investigate how flow structures in a liquid jet are influenced by the presence of solid particles. Solid glass spheres with a density of 2.5 kg/dm³ and three different sizes (0.5 mm, 1 mm, and 2 mm) at different solids loading (0–6.2 vol.%) were used as particles, while water served as continuous phase. No significant influence of the solid particles on the rate of decrease in the centerline liquid velocity or the jet expansion ratio could be observed. Two flow regimes were identified: a stable jet characterized by a symmetric shear layer close to the nozzle, and a flow dominated by large-scale instabilities farther from the nozzle. The spreading of particles was dominated by interparticle collisions in the region close to the nozzle and by jet instability in the region farther from the nozzle. With increased solids loading increased liquid RMS values in the region close to the nozzle could be found. The effect on RMS values was larger with larger particles. For the 1 mm particles the RMS increased in this region, but decreased in the region farther from the nozzle. The presence of 2 mm particles acted to stabilize the jet, and the instability moved farther downstream. Suspensions with smaller particles had no effect on the instability, strength, or location.     

Autohydrolysis of Tropical Harowodos

Abstract

Eight tropical hardwoods (Malaysian) were subjected to autohydrolysis at 195°C for 10 – 100 Min, followed by extraction with 90% dioxane. A linear relationship was obtained between the % of water soluble extract, after autohydrolysis, and the % of hemicellulose present in the respective woods. Comparison of the different woods for their response to autohydrolysis was made, based on the % of maximum extractable lignin obtained. It was found that the effectiveness of autohydrolysis was not related to the density of the wood, or to the taxonomic type, but to a certain extent to the content of lignin present in the wood.     

An efficient extraction and clean‐up procedure for pesticide determination in olive oil

This work reports a simple, rapid, and effective extraction method based on liquid–liquid extraction (LLE) followed by matrix solid‐phase dispersion‐sonication for detection, identification and quantification of multiclass pesticides in virgin olive oil using liquid chromatography mass spectrometry (LC‐QTOF‐MS). LLE to extract pesticide residues in virgin olive oil was performed in order to study the centrifugation efficiency to obtain high recovery yield and low co‐extract fat residue in the final extract. Different suitable parameters of MSPD procedure were evaluated, such as nature of dispersing phase, clean‐up adsorbent, and volume of eluting solvent (acetonitrile) in different extraction conditions, with or without sonication. The best results were obtained using 5 g of virgin olive oil, 2 g of PSA as dispersant sorbent, 2 g of Florisil/GCB (70:30 w/w) as clean‐up sorbent, and 15 mL of acetonitrile as eluting solvent under conditions of 15 min ultrasonic bath at RT. Method validation was performed in order to study sensitivity, linearity, precision, and accuracy. Average recoveries ranged between 73.7 and 104.2% with relative SDs 5.3–13.4% at three concentration levels (25, 50, and 100 µg/kg). Detection and quantification limits ranged from 1.5 to 5 µg/kg and 3 to 9 µg/kg, respectively.     

PDA measurements in a three‐phase bubble column

Phase Doppler anemometry was used to quantify the flow characteristic of a three phases (liquid, solid, and bubbles) cylindrical bubble column driven by a point air source made of a 30‐mm diameter perforated air stone centrally mounted at the bottom. The cylindrical bubble column had an inner diameter of 152 mm and was filled with liquid up to 1 m above the point source. Acrylic beads with a nominal diameter of 3 mm were used as the solid phase. To match the density of the solid phase which was 1.05 kg/m³, the liquid density was raised to about 1.0485 kg/m3 by added salt. The bubble diameters generated were within the range of 600–2400 µm. The detailed turbulent characteristics of the liquid‐phase velocity, bubble diameter, bubble velocity, and solid velocity were measured at three different air rates, namely 0.4, 0.8, and 1.2 L/min (corresponding to average gas volume fraction of 0.0084, 0.0168, and 0.0258, respectively) for the homogeneous bubble column regime. With the addition of the solid phase, the flow field was found to be relatively steady compared to the two‐phase column referencing the probability density functions for both the liquid and bubble velocities. An analysis based on the determination of the drag forces and transversal lift forces was performed to examine the flow stability in the three‐phase bubble column. The analysis illustrated that how the added solid phase effectively stabilized the flow field to achieve a steady circulation in the bubble column and a generalized criterion for the flow stability in the three‐phase bubble column was derived. Further investigation for the transition and the heterogeneous bubble column regime with air rates at 2.0 and 4.0 L/min shown that this criterion can also be used as a general prediction of flow stability in this three‐phase bubble column. © 2013 American Institute of Chemical Engineers AIChE J, 59: 2286–2307, 2013     

Heat Treatment and Chemical Composition of Fatty Acids and Rosin Acids Mixtures: Effects on Their Thermal Properties and Morphology

Mixtures of fatty acids and rosin acids are industrially important products utilized as a raw material for several purposes. Their thermal properties, especially cold stability and crystallization behavior is also important. Several fatty acid and rosin acid mixtures both from industrial products and from commercially available fatty and rosin acids were prepared and treated for 30 min at 80 °C under an inert atmosphere. Thereafter, the mixture was cooled to the desired temperature. Determination of the cloud point, chemical analysis of liquid and solid phase, thermal analysis by differential scanning calorimetry as well as morphology analysis by scanning electron microscopy were performed. The results revealed that crystallization was more rapid when it occurred at 10 °C compared to 25 °C. The crystal sizes increased with decreasing the crystallization temperature. Furthermore, crystals were of irregular shape and agglomerated when rapid cooling of the mixture occurred. Chemical analysis revealed that liquid phase was enriched with stearic acid, whereas crystals contained large amounts of abietic, dehydroabietic and linoleic acids. The cloud point of the mixtures increased with increasing amount of stearic and rosin acids. Dehydroabietic acid addition improved the cold stability of the synthetic fatty acid–rosin acids mixture.     

Effect of ultrasound- and pulsed electric field-assisted enzymatic treatment on the recovery and quality of sunflower oil

The aim of this study was to evaluate the effect of cavitation and electroporation on enzymolysis extraction of sunflower oil. The optimum extraction conditions during 2 h under enzyme-assisted extraction (EAE) with a maximum oil yield of ≈23.70 ± 0.11% were as follows: cellulase/pectinase ratio 2:1, enzyme concentration 2%, pH 4.5, liquid/solid ratio 6:1 ml/g, and extraction temperature 40°C. Under the optimized enzymatic conditions, the application of ultrasound- (250 W) and pulsed electric field- (1.2 kV/cm; 52.4 kJ/kg) assisted enzymatic extraction for 30 min significantly increased the oil extraction yield by 91.1% and 18.6%, respectively, as compared with EAE.     

Experimental evaluation of alkaline treatment as a method for enhancing the enzymatic digestibility of autohydrolysed Acacia dealbata

BACKGROUND: Acacia dealbata wood samples were subjected to hydrothermal processing in aqueous media, yielding a liquid phase (containing xylooligosaccharides) and a solid phase, enriched in cellulose, which was treated with alkaline solutions to obtain solids with improved susceptibility towards enzymatic hydrolysis. The effects of the most influential variables involved in the alkaline processing (sodium hydroxide concentration, temperature and reaction time) on solid yield, solid composition and kinetic parameters involved in the modelling of the enzymatic hydrolysis were assessed using the response surface methodology (RSM). RESULTS: Analysis of the RSM equations allowed selection of operational conditions (temperature = 130 °C, sodium hydroxide concentration = 4.5%, time of alkaline processing = 3 h), leading to selective removal of non‐cellulosic components and to a solid substrate highly susceptible to enzymatic hydrolysis. Operating at an enzyme loading of 20 FPU (filter paper units) g^?1 autohydrolysed, extracted solids (denoted AES) with a liquor to solid ratio of 30 g liquor g^?1 AES, solutions containing 29.7 g glucose L^?1 (corresponding to a yield of 47.3 g glucose per 100 g solids from autohydrolysis) were obtained after 48 h. CONCLUSION: Samples of Acacia dealbata wood were processed by autohydrolysis, sodium hydroxide treatment and enzymatic hydrolysis, yielding xylooligomers and processed solids highly susceptible to the enzymatic hydrolysis. Copyright © 2009 Society of Chemical Industry     

Synthesis,Characterization, and Application of Zn–Al Layered Double Hydroxide as a Nano-Sorbent for the Removal of Direct Red 16 from Industrial Wastewater Effluents

In this research, nano-structured zinc–aluminum layered double hydroxide (Zn–Al LDH) was successfully synthesized by a co-precipitation method and followed by thermal treatment. The structure and morphology of the obtained material was characterized by X-ray diffraction, transmission electron microscopy, nitrogen-adsorption–desorption isotherms, and Fourier transform infrared spectroscopy. The as-prepared LDH was applied as a solid phase extraction (SPE) sorbent for the removal of direct red 16 (DR16) from aqueous solutions. A spectrophotometric method was used for monitoring of the extracted DR16 at λ = 548 nm. The effect of several parameters such as pH, sample flow rate, amount of nano-sorbent, elution conditions, and sample volume on the removal percentage was investigated. The results showed that DR16 could be retained by Zn–Al(NO₃^?) LDH at pH 6 and stripped by 2.5 mL of 1.0 mol L^?1 NaOH. In the optimum experimental conditions, the limit of detection and relative standard deviation were 0.003 µg mL^?1 and 1.2%, respectively. The calibration graph using the presented SPE system was linear in the range of 0.01–2.00 µg mL^?1 of DR16 with a correlation coefficient of 0.9994. The method was successfully applied for the removal of DR16 from several industrial wastewater effluents.