Effect Of Ultrasonic Pretreatment Research Articles

Effect of ultrasonic pretreatment on biomethane potential of two-phase olive mill solid waste: kinetic approach and process performance.

The effect of ultrasound (US) pretreatment on two-phase olive mil solid waste (OMSW) composition and subsequent anaerobic biodegradation was evaluated by chemical oxygen demand solubilization and biochemical methane potential (BMP) tests. OMSW was ultrasonically pretreated at a power of 200 W and frequency of 24 kHz for time periods of 20, 40, 60, 90, 120, and 180 minutes, corresponding to specific energies of 11367, 21121, 34072, 51284, 68557, and 106003 kJ/kg total solids, respectively. In order to evaluate the US pretreatment, a low, medium, and high exposure time, that is, 20, 90, and 180 min, were selected for BMP tests. Methane yields of 311 ± 15, 393 ± 14, and 370 ± 20 mL CH4/g VSadded (VS: volatile solids) were obtained for 20, 90, and 180 minutes, respectively, while the untreated OMSW gave 373 ± 4 mL CH4/g VSadded. From a kinetic point of view, the BMP tests showed a first exponential stage and a second sigmoidal stage. In the first stage, the kinetic constant obtained for US pretreated OMSW at 20 minutes was 46% higher than those achieved for the pretreated OMSW at 90 and 180 minutes and 48% higher than that for untreated OMSW. The maximum methane production rate achieved was 12% higher than that obtained for untreated OMSW.

Conversion of Cornstalk to Bio-oil in Hot-Compressed Water: Effects of Ultrasonic Pretreatment on the Yield and Chemical Composition of Bio-oil, Carbon Balance, and Energy Recovery

An ultrasonic pretreatment method was developed to enhance the yield of bio-oil obtained from the liquefaction of cornstalks in hot-compressed water at different reaction temperatures (260-340 °C) and residence times (0-40 min). Influences of ultrasonic pretreatment on the physicochemical properties of cornstalks and bio-oil yields were investigated. The results show that ultrasonic pretreatment obviously increases surface areas of cornstalks, decreases crystallinities, and erodes the structures of lignin, leading to more exposure of cellulose and hemicellulose. The yield of bio-oil was increased remarkably by 10.1% for 40 min sonicated cornstalks under the optimum liquefied conditions (300 °C for 0 min of residence time). Carbon balance indicates that ultrasonic pretreatment increases the carbon conversion of cornstalks to heavy oil and water-soluble oil. Energy balance indicates that the sonicated cornstalks have positive energy efficiencies. GC-MS analyses demonstrate ultrasonic pretreatment increases the contents of the phenols in heavy oil and water-soluble oil.

Enhancing biofuel production by ultrasonics

This work evaluated the use of high-powered ultrasonics to enhance biofuel production in terms of efficiency and costs. A wide range of feed stocks, including switch grass, corn stover, and soft wood, were studied. The effect of ultrasonic pretreatment on the removal of lignin for hydrolysis of starches and cellulose to fermentable sugars was studied. It was found that many of the pretreatments were very successful in enhancing lignin removal. For example, time of dissolution of lingo-cellulosic biomass in ionic liquids was reduced from hours to minutes accompanied by a significant decrease in energy consumption compared to mechanical stirring. In addition, it was found that hydrolysis of corn starch could be greatly accelerated utilizing ultrasonics. Economic models showed that the technology, once implemented, would have a payback period of less than one year. The work also focused on biodiesel production. It was seen that ultrasonics accelerated the transesterification process so that soy bean oil could be converted to biodiesel in less than a minute, compared to 45 min using traditional methods. It was shown that yeast grown from glycerin, a co-product of biodiesel production, could be extracted and simultaneously converted to biodiesel with ultrasonics in less than a minute, compared to traditional techniques that require multiple processes and relatively long cycle times (+1 h).

COMPOSITE VEGETABLE DEGRADATION AND ELECTRICITY GENERATION IN MICROBIAL FUEL CELL WITH ULTRASONIC PRETREATMENT

Vegetable waste was used as the fuel of a two-chamber microbial fuel cell (MFC) for simultaneous power recovery and waste degradation. Effects of ultrasonic pretreatment, organic loadings, anolyte pH adjustment on the MFC performance were investigated. Results showed that higher power generation and organic compounds removal efficiency were achieved in the MFCs with the vegetable waste pretreated with ultrasonication at >1.0W/mL compared to the un-pretreated control. A maximum voltage of 491 mV (1000 external resistor), power density of 10.19 W/m3 and 7-d TCOD removal rate of 62.5% were attained for the ultrasonic pretreated samples, while the corresponding parts for the un-pretreated control were 430 mV, 5.96 W/m3 and 35.1%, respectively. For stable power generation and effective removal of the waste in the MFC system, the raw waste required a certain dilution and the anode solution should be adjusted to improve system buffering capacity.

Effects of ultrasonic pre-treatment on sludge characteristics and anaerobic digestion

In this work, the influence of an ultrasonic pre-treatment on anaerobic digestion of waste activated sludge is studied. Attention is paid to the solubilisation of the main organic (proteins, carbohydrates) and inorganic (heavy metals) sludge components during ultrasonic treatment and the influence of the dry solids content (DS) on the degree of solubilisation. The second part of the paper focuses on the relationship between the applied specific energy of the ultrasonic treatment and methane production. In general, a higher specific energy and a higher DS content are beneficial for the release of organic matter, resulting in an increased methane production. The efficiency of the subsequent anaerobic digestion is similar for both sludge types (2.1 and 3.2% DS). However, at lower DS contents (2.1%), the methane production increase was more significant.

Effect of Ultrasonic Pretreatment for the Anaerobic Digestion of Sewage Sludge

Anaerobic digestion is an economic and environmentally friendly technology for treating the biomass material-sewage sludge, but has some limitations, such as the low efficient biogass production. In this paper ultrasound was proposed as pre-treatment for effective sludge anaerobic digestion. Sludge anaerobic digestion experiments with ultrasonic pretreatment was investigated. It can be seen that this treatment effectively leaded to the increase of soluble chemical oxygen demand(SCOD) and volatile fatty acids(VFA)concentration. High concentration of VFA leaded to a increase in biogas production. Besides, the SV of sludge was reduced and the settling characteristics of sludge was improved after ultrasonic pretreatment. It can be concluded that sludge anaerobic digestion with ultrasonic pretreatment is an effective method for biomass material transformation.

The effects of ultrasonic pretreatment and structural changes during the osmotic dehydration of the ˈStarkingˈ apple (Malus domestica Borkh)

During the osmotic dehydration (OD) of fruit, the cell membrane displays a high resistance to mass transfer, thereby reducing the dehydration rate. To reduce thermal damage to cell membranes, alternative methods have recently been introduced to reduce the initial moisture content and/or modify the structure of fruit tissue. The aim of this work was to evaluate the effects of an ultrasound (US) pretreatment for OD on the effective diffusion coefficients and to observe the changes in the molecular structure of Starking apple cubes by Fourier-transform infrared spectroscopy (FTIR) during a 3 h process using a 45°Bx sucrose solution at 60°C. In the pretreatment step, apple samples were immersed in an ultrasonic bath at 45 kHz for 20 min. The effective diffusion coefficients for water (Dew) and solids (Des) were calculated from the observed osmotic kinetics according to Fick´s second law for the transient state. The solids coefficients were higher than the water coefficients in both processes due to the concentration difference (Des= 7.7×10-9 and 9.7×10-9 m2 s-1 for ODUS).The structural changes were determined by FTIR by measuring the molecular vibration frequency for sucrose. The 1,500–900 cm-1 region of the infrared spectra was used to monitor the effect of sucrose concentration on fruit structure. We observed that the first bonds formed were C-H and C-O-C stretching (at 920 and 1,129 cm−1, respectively) in the sucrose skeleton and glycoside bonds among sucrose molecules. The water concentration affected the diffusion coefficient significantly due to its dependence on the physical structure of the food.

Effect of ultrasonic pretreatment on the composition of lignocellulosic material in biotechnological processes

The ultrasonic impact and possibilities of using its damaging effect on lignocellulosic material in order to increase the reactivity of plant biomass are studied. The main aim of pretreatment is the disruption of the crystalline, highly ordered structures of cellulose and lignin, or the removal of the latter. At the selected optimum parameters of ultrasonic pretreatment (frequency, 30 kHz) of the raw material, degradation of cellulose reaches 16% of a.d.s. (absolutely dry substance) while that of lignin is 11.4 % of a.d.s. Pretreatment of a substrate with ultrasound changes the rate and depth of the destruction of the initial material in the course of cultivation and can be used to accelerate the bioconversion of lignocellulosic substrates in biodiesel fuel production.

Effect of ultrasonic pretreatment on chlorine dioxide disinfection efficiency

Ultrasound (US) and chlorine dioxide (ClO 2) were combined sequentially in an aim to improve wastewater disinfection. Results demonstrated that the combined effect of US and ClO 2 on Escherichia coli ( E. coli) and total coliform (TC) inactivation in raw wastewater was synergistic involving high removal of bacteria from the solution. A sequential combination of US (150 or 300 W/L) and ClO 2 (2 mg/L) provided about 3.2–3.5 log reduction in the number E. coli and TC in raw wastewater, while the sum of log reductions by the individual treatments were 1.4–1.9. However, the measured inactivation rate with the combination of ultrasound and ClO 2 in synthetic wastewater or secondary effluent was the same as the sum of the log inactivations with individual treatments. The enhancement attained by combined US and ClO 2 disinfection methods was attributed to the presence of high concentration of particles in raw wastewater and their break up under shock sound waves.

Effect of ultrasonic pre-treatment on low temperature acid hydrolysis of oil palm empty fruit bunch

Various pre-treatment techniques change the physical and chemical structure of the lignocellulosic biomass and improve hydrolysis rates. The effect of ultrasonic pre-treatment on oil palm empty fruit bunch (OPEFB) fibre prior to acid hydrolysis has been evaluated. The main objective of this study was to determine if ultrasonic pre-treatment could function as a pre-treatment method for the acid hydrolysis of OPEFB fibre at a low temperature and pressure. Hydrolysis at a low temperature was studied using 2% sulphuric acid; 1:25 solid liquid ratio and 100 degrees C operating temperature. A maximum xylose yield of 58% was achieved when the OPEFB fibre was ultrasonicated at 90% amplitude for 45min. In the absence of ultrasonic pre-treatment only 22% of xylose was obtained. However, no substantial increase of xylose formation was observed for acid hydrolysis at higher temperatures of 120 and 140 degrees C on ultrasonicated OPEFB fibre. The samples were then analysed using a scanning electron microscope (SEM) to describe the morphological changes of the OPEFB fibre. The SEM observations show interesting morphological changes within the OPEFB fibre for different acid hydrolysis conditions.

The influence of ultrasonic treatment on the bleaching of CMP revealed by surface and chemical structural analyses

Effects of ultrasonic pretreatment on the bleaching of chemimechanical pulp (CMP) fiber of triploid Chinese white Poplar were investigated. Before single-stage hydrogen peroxide bleaching, CMP was sonicated at 1.5% pulp consistency and 50oC for 20min with 90% amplitude and 20s pulse; these conditions showed the most favorable effect of a 3.5% ISO increase of brightness, reaching a final value of 80.2% ISO. The benefit may be because the ultrasound can accelerate heterogeneous reactions, which arise from the impingement of microjets and shockwaves on the solid surface, which are then capable of inducing striking changes in surface morphology, composition, and reactivity. To prove the theory, the surface structure and surface morphology were investigated by SEM and AFM, and the crystalline structure and characteristics of the cellulose in terms of XRD and FT-IR were also evaluated.

THE INFLUENCE OF ULTRASONIC TREATMENT ON THE BLEACHING OF CMP REVEALED BY SURFACE AND CHEMICAL STRUCTURAL ANALYSES

Effects of ultrasonic pretreatment on the bleaching of chemimechanical pulp (CMP) fiber of triploid Chinese white Poplar were investigated. Before single-stage hydrogen peroxide bleaching, CMP was sonicated at 1.5% pulp consistency and 50oC for 20min with 90% amplitude and 20s pulse; these conditions showed the most favorable effect of a 3.5% ISO increase of brightness, reaching a final value of 80.2% ISO. The benefit may be because the ultrasound can accelerate heterogeneous reactions, which arise from the impingement of microjets and shockwaves on the solid surface, which are then capable of inducing striking changes in surface morphology, composition, and reactivity. To prove the theory, the surface structure and surface morphology were investigated by SEM and AFM, and the crystalline structure and characteristics of the cellulose in terms of XRD and FT-IR were also evaluated.

Effects of ultrasonic pretreatment on sludge dewaterability and extracellular polymeric substances distribution in mesophilic anaerobic digestion

Effect of ultrasonic pretreatment on sludge dewaterability was determined and the fate of extracellular polymeric substances (EPS) matrix in mesophilic anaerobic digestion after ultrasonic pretreatment was studied. Characteristics of proteins (PN), polysaccharides (PS), excitation-emission matrix (EEM) fluorescence spectroscopy and molecular weight (MW) distribution of dissolved organic matters (DOM) in different EPS fractions were evaluated. The results showed that after ultrasonic pretreatment, the normalized capillary suction time (CST) decreased from 44.4 to 11.1 (sec·L)/g total suspended solids (TSS) during anaerobic digestion, indicating that sludge dewaterability was greatly improved. The normalized CST was significantly correlated with PN concentration ( R 2 = 0.92, p < 0.01) and the PN/PS ratio ( R 2 = 0.84, p < 0.01) in the loosely bound EPS (LB-EPS) fraction. Meanwhile, the average MW of DOM in the LBEPS and tightly bound EPS (TB-EPS) fractions also had a good correlation with the normalized CST ( R 2 > 0.66, p < 0.01). According to EEM fluorescence spectroscopy, tryptophan-like substances intensities in the slime, LB-EPS and TB-EPS fractions were correlated with the normalized CST. The organic matters in the EPS matrix played an important role in influencing sludge dewaterability.

The use of ultrasound for enzymatic preparation of ACE-inhibitory peptides from wheat germ protein

Abstract The effects of ultrasonic treatment during proteolysis on kinetic characterisation of the hydrolysis of defatted wheat germ protein (DWGP), and on ACE-inhibitory activity of the hydrolysate, were investigated. The effects of ultrasonic pretreatment on the release of peptides with ACE-inhibitory were also studied. The results showed that the value of k A for DWGP hydrolysis under ultrasonic irradiation increased by about 22.2%, and K M decreased about 13.0%, compared with that obtained without ultrasound. Analysis of ACE-inhibitory activity indicated that ultrasound during enzyme treatments had less effect on the ACE-inhibitory activity, while ultrasonic pretreatment caused a 21.0–40.7% increase in ACE-inhibitory activity of DWGP hydrolysate. Analyses of hydrophobicity, microstructure, and amino acid composition revealed that ultrasonic pretreatment could accelerate the release of hydrophobic amino acids from DWGP during enzymatic hydrolysis. In conclusion, ultrasonic treatment during proteolysis could facilitate the enzymatic hydrolysis of DWGP, whereas ultrasonic pretreatment could promote the release of ACE-inhibitory peptides from DWGP during enzymatic hydrolysis.

Ultrasound as pre-treatment for drying of pineapple

Dehydration of fruits is an alternative to reduce post-harvest loss of fruits and also a process to produce dried fruits, which can be directly consumed or become part of foodstuffs like cakes, pastries and many others. The effect of ultrasonic pre-treatment and ultrasound-assisted osmotic dehydration, before air-drying, on dehydration of pineapple ( Ananas comosus) was investigated. This study allowed estimating the water diffusivity in the air-drying process for pineapples submitted to ultrasound. Results showed that the water diffusivity increased after application of ultrasound and that the overall drying time was reduced by 8% (over 1 h of air-drying time). During the ultrasonic treatment in distilled water the pineapples lost sugar (23.2% in 30 min), so in this condition the ultrasonic pre-treatment can be an interesting process to produce dried fruits with low sugar content. Results showed that the water loss increased with increasing soluble solids content of the osmotic solution and that the ultrasound-assisted osmotic dehydration incorporated more sugar than conventional osmotic dehydration. The water effective diffusivity of the pineapples during the air-drying process was influenced by the pre-treatment, increasing the water effective diffusivity when ultrasound was applied.

De‐agglomeration and Dispersion of Nano‐TiO2 in an Agitator Bead Mill

The de‐agglomeration and dispersion of nano‐TiO2 powder is little reported, although nano‐TiO2 powder has been widely used due to its unique optical properties. In this study, an agitator bead mill (MiniZETA 03E, Netzsch) accompanied with an ultrasonicator was employed to de‐agglomerate the nano‐TiO2 powder in butyl acetate, and the effects of ultrasonic pretreatment, dispersant dosage, agitation speed, solid content of TiO2 suspension, and bead diameter were systemically investigated. It is found that ultrasonic pretreatment leads to short grinding time to reach the limiting fineness, low specific energy input, and small limiting mean size. All other technical parameters have also some influence on the limiting fineness and grinding time. However, the former strongly depends on agitation speed while the latter on both agitation speed and dispersant dosage. A solvent‐borne nano‐TiO2 suspension with limiting mean size of 110 nm can be successfully result under the optimal technical conditions and showed excellent UV‐shielding property and transparence when it was incorporated into polyester/melamine coatings.

Solubilisation of waste-activated sludge by ultrasonic treatment

In order to enhance the efficiency of anaerobic digestion, the effects of ultrasonic pretreatment have been studied on waste-activated sludge. Solubilisation of chemical oxygen demand (COD), solid and nitrogen has been proved. Flocs were broken and compounds were made soluble. In the same time, particle size decreased with specific energy applied. In terms of biodegradability, ultrasound led to an increase in biogas production. Moreover, the relationship between biogas production and sludge fractions has been examined. For specific energy input lower than 3000 kJ/kg of total solids, biogas production linked to the particulate fraction of sludge was constant, even if the solids concentration decreased. On the other hand, biogas production linked to the soluble part of sludge increased with ultrasonic power.

CVD diamond nucleation enhanced by ultrasonic pretreatment using diamond and mixture of diamond and TaC powders

Effects of ultrasonic pretreatment on chemical vapor deposition (CVD) diamond nucleation on Si substrates were systematically studied. Pure 1.5–40 μm-diamond powder and mixtures of 1.5–5 μm-diamond as well as 5–20 μm-Tantalum Carbide (TaC) powder were used in ultrasonic pretreatment. The root-mean-square (Rms) surface roughness of the pretreated substrates, residual diamond and TaC powders left on the substrates were examined using atomic force microscopy (AFM), Raman spectroscopy and X-ray diffraction (XRD), respectively. It was observed that the Rms surface roughness increases with increasing diamond or TaC powder size, and there is some diamond or TaC powder left on the substrates after ultrasonic pretreatment. Diamond films were deposited using microwave plasma chemical vapor deposition (MPCVD) technique and characterized by field emission scanning electron microscopy (FE-SEM). It was found that CVD diamond nucleation density strongly depends on particle size of diamond or TaC powder used, the nucleation density increases with increasing diamond or TaC powder size. A mixture of diamond and TaC powders enhances CVD diamond nucleation much more significantly than that of pure diamond powder. A mixture of 1.5 μm-diamond and 20 μm-TaC powders has an equivalent nucleation enhancement efficiency, which could be caused by pure 40 μm-diamond powder.

Investigation on the Effect of Ultrasonic Pretreatment on Selective Separation of Iron Values from Iron Ore Tailings by Flocculation

Selective flocculation studies were carried out on Barsuan iron ore tailings having 50.5% iron, 7.2% alumina, and 7.8% silica in the absence and presence of ultrasonication at different experimental conditions using sodium hexametaphosphate as a dispersant and starch as a flocculant. The imposition of ultrasonication resulted in a marked improvement in grade as well as recovery. The results indicate that ultrasonication is able to mitigate the adverse effects of gangue materials. A concentrate assaying 59% iron with 75% recovery could be obtained without ultrasonication, while the application of ultrasonication led to an improvement in concentrate grade to 65% with a corresponding increase in recovery to 91%. The improvement is attributed to the disruption caused at a solid/liquid interface which results in favorable modification of the mineral surface, facilitating selective adsorption of flocculant on the iron ore fines. This, in turn, leads to enhancement in selectivity and recovery. In addition, ultrasonication also leads to effective dispersion, causing enhanced activity.

The effect of ultrasonic pre-treatment on nucleation density of chemical vapor deposition diamond

Using statistical design of experiments, the effect of ultrasonic pre-treatment on the nucleation density of diamond was studied. The parameters investigated included ultrasonic excitation power, concentration of diamond powder in water, duration of ultrasonic excitation, and duration of cleaning with water after ultrasonic excitation. Diamond films were deposited on silicon (100) substrates using microwave assisted plasma chemical vapor deposition. The nucleation density varied from 106 nuclei/cm2 to 109 nuclei/cm2. The results illustrated that the dominant effect in ultrasonic pre-treatment was seeding. Moreover, scratches caused by the seeds during the treatment enabled more seeds to be retained on the surface. Based on these results, an optimized ultrasonic pretreatment has been developed. The new procedure yields a uniform nucleation density of 109 nuclei/cm2 on silicon (100) substrates.