Sonication Pretreatment Research Articles

Diamond deposition on fine vapour grown carbon filament

A fine carbon filament has been used as substrate in a microwave plasma enhanced chemical vapour deposition (MPECVD) process. The carbon filaments were severely etched to form carbon dusts which then served as nucleation seeds. Polycrystalline diamond coatings on the carbon dust and the diamond dust, which was used during the sonication pre-treatment, were obtained at temperatures below 1000°C. A mini-explosion that formed a 120-μm diamond sphere occurred at a temperature of 950°C. As the processing temperature further increased, several explosions occurred to form protrusions, including glassy carbon spheres with volumes greater than 22 mm3, and thick glassy carbon coatings, at an average rate as high as 270 μm per 17 h, on the entire surface. These thick coatings occurred on the untreated surface of a Si coupon, which was used to support the carbon filaments. The explosion has been explained to be as a result of energy absorption from the microwave and plasma.

A procedure for partitioning bulk sediments into distinct grain-size fractions for geochemical analysis

A method to separate sediments into discrete size fractions for geochemical analysis has been tested. The procedures were chosen to minimize the destruction or formation of aggregates and involved gentle sieving and settling of wet samples. Freeze-drying and sonication pretreatments, known to influence aggregates, were used for comparison. Freeze-drying was found to increase the silt/clay ratio by an average of 180 percent compared to analysis of a wet sample that had been wet sieved only. Sonication of a wet sample decreased the silt/clay ratio by 51 percent. The concentrations of metals and organic carbon in the separated fractions changed depending on the pretreatment procedures in a manner consistent with the hypothesis that aggregates consist of fine-grained organic- and metal-rich particles. The coarse silt fraction of a freeze-dried sample contained 20–44 percent higher concentrations of Zn, Cu, and organic carbon than the coarse silt fraction of the wet sample. Sonication resulted in concentrations of these analytes that were 18–33 percent lower in the coarse silt fraction than found in the wet sample. Sonication increased the concentration of lead in the clay fraction by an average of 40 percent compared to an unsonicated sample. Understanding the magnitude of change caused by different analysis protocols is an aid in designing future studies that seek to interpret the spatial distribution of contaminated sediments and their transport mechanisms.

Sonically enhanced beneficiation of Illinois no. 6 coal

Laboratory tests were performed to investigate the effects of sonic energy on the selective removal of ash-forming minerals from Illinois No. 6 coal. The net effect of exposure to sonic energy was elucidated by using wet-sieved narrowly sized coal samples free of undersize material loosely clinging to particle surfaces. A 10-kHz near-field array processor, configured for continuous rinsing of coal in the presence of sonic waves, was used. Results for sonically treated, then wet-sieved coal and the initial wet-sieved sample showed ash content removals ranging from 11.6 to 31.3% by weight, as a result of exposure to pulsed sonic energy for a 50-second total time of sonic treatment. Calculated recoveries of heating value ranged from 97.6 to as high as 99.8%, depending on the particle size of coal treated. Ash content of the sonically dislodged undersize material ranged from 55.0 to 86.9% by weight. Exposure to sonic energy also enhanced the floatability of Illinois No. 6 coal. Lower ash-content float fractions resulted from sonic pretreatment of the coal feed, compared to float fractions of wet-sieved coal not exposed to sonic energy. Separate tests with specific gravity fractions of Illinois No. 6 coal have shown that exposure to sonic energy promotes separation of coal-mineral composite particles.

Pretreatment Effect on Dispersion of Carbonates in Calcareous Soils

AbstractA pH‐stat procedure was previously developed to determine the effective particle‐size distribution of soil carbonates. The results obtained by the pH‐stat procedure are influenced by the accessibility of carbonate surface sites to the titrant and, therefore, provide a methodology for the comparison of carbonate dispersion treatments. In this study, the influence of dispersion treatment on the determination of effective particle‐size distribution of soil carbonates was examined. The treatments consisted of agitation, sonication, or Na saturation of clay cation‐exchange sites of calcareous soils representing three series (Austin: fine‐silty, carbonatic, thermic Entic Haplustoll; Rio Grande: coarse‐silty, mixed (calcareous), hyperthermic Typic Ustifluvent; Victoria: fine, montmorillonitic, hyperthermic Udic Pellustert). Shaking and sonication pretreatments resulted in increases in the experimentally determined proportion of effective fine‐clay size soil carbonates and corresponding decreases in the effective silt‐ and sand‐size carbonates, when compared with the untreated soils. As the intensity of either of these pretreatments was increased, the proportion of effective clay‐size carbonates increased. Scanning electron microscopy indicated that the longer and more intense sonication treatments resulted in a higher degree of disruption or grinding of carbonate aggregates. Sodium saturation of the clay cation‐exchange sites resulted in the most effective disaggregation of the phyllosilicate‐carbonate complex, as indicated by the greatest proportion of effective clay‐size and lowest proportions of effective silt‐ and sand‐size carbonates. Sodium saturation may also result in a lower degree of disruption of carbonate particles or carbonate‐cemented aggregates than may occur with intense sonication. An initial Na saturation is, therefore, recommended as a pretreatment for the determination of effective particle‐size distribution of soil carbonates.

3127. Neurological effects of cyanide toxicity: Brierley, J. B., Brown, A. W. & Calverley, J. (1976). Cyanide intoxication in the rat: physiological and neuropathological aspects. J. Neurol. Neurosurg. Psychiat. 39, 129.

The objective of this study was to evaluate the effect of dioctyl sodium sulphosuccinate (DOSS, a surfactant) on lysis rate of sludge and specific energy required for sonic pretreatment of waste activated sludge (WAS). Different ultrasonic power levels, WAS concentrations, DOSS dosages, and specific energy levels were used to compare pretreatment efficiencies. At an optimum time of 10 min with ultrasonic power level of 160 W, DOSS coupled sonic pretreatment resulted in better lysis rate (24.7%) of sludge than sonic pretreatment (17.6%). Biodegradability estimation through non-linear regression modeling revealed that DOSS coupled ultrasound pretreatment of sludge showed better biodegradability with higher hydrolysis constant (about 0.25 d−1) than sonic pretreatment (0.19 d−1). Nearly six times less energy was required for DOSS coupled ultrasound pretreatment compared to that required for sonic pretreatment. Therefore, DOSS coupled ultrasound pretreatment makes the pretreatment process energetically positive.

Presence of micro-aggregates containing sulfate-reducing bacteria in a paddy-field soil

Micro-aggregates containing sulfate-reducing bacteria in a paddy-field soil were examined by enumerating the number of sulfate-reducing bacteria liberated when the soil was subjected to repeated washings with and without pretreatment by sonication. Soils sampled from both an oxidized surface-layer and a reduced plough-layer were subjected to repeated washings. The liberation of sulfate-reducing bacteria, expressed as log n, were calculated according to the equation N i = N 0 (1/ n) i . Where i is the number of repeated washings; N 0 is the number of cells per 1 ml supernatant of original soil suspension; N i is the number of cells per 1 ml supernatant of the i-th wash, and n is the reciprocal of dilution rate. Ideally log n is 1.0 with our conditions. In the case of soils without sonic pretreatment, the values of log n were 0.009–0.018 for sulfate-reducing bacteria, indicating that almost constant numbers of sulfate-reducing bacteria were newly liberated by every wash, and 0.35–0.55 for aerobic bacteria, indicating that a direct wash-out of cells took place. With sonicated soils we obtained the values 0.26–0.38 and 0.39–0.55 respectively. Based on these results we conclude that sulfate-reducing bacteria were present in aggregates which were decomposed by sonic treatment, whereas aerobic bacteria were not.

Action of pure distilled water, with or without electrolytes, on metals

In this investigation, the application of citric acid was explored for the removal of extracellular polymeric substance (EPS) from waste activated sludge (WAS), followed by ultrasonic pretreatment, which enhanced the subsequent anaerobic biodegradability. EPS was removed with 0.05 g/g SS of citric acid. The chemical oxygen demand (COD) solubilization and suspended solids (SS) reduction that occurred for specific energy input of 171.9 kJ/kg TS, in deflocculated (EPS removed and ultrasonically pretreated) sludges were found to be 22.70% and 20.28% and was comparatively higher, than the flocculated (with EPS and ultrasonically pretreated). The biogas yield potential of flocculated and deflocculated sludges (specific energy input – 171.9 kJ/kg TS) was found to be 0.212 L/(g VS) and 0.435 L/(g VS), respectively. Accordingly, the deflocculation and ultrasonic pretreatment improved the anaerobic biodegradability efficiently. Thus, this chemo mediated sonic pretreatment is an effective method for enhancing biodegradability and improving clean energy generation from WAS.

Deflocculation of artificial graphite

In this investigation, the application of citric acid was explored for the removal of extracellular polymeric substance (EPS) from waste activated sludge (WAS), followed by ultrasonic pretreatment, which enhanced the subsequent anaerobic biodegradability. EPS was removed with 0.05 g/g SS of citric acid. The chemical oxygen demand (COD) solubilization and suspended solids (SS) reduction that occurred for specific energy input of 171.9 kJ/kg TS, in deflocculated (EPS removed and ultrasonically pretreated) sludges were found to be 22.70% and 20.28% and was comparatively higher, than the flocculated (with EPS and ultrasonically pretreated). The biogas yield potential of flocculated and deflocculated sludges (specific energy input – 171.9 kJ/kg TS) was found to be 0.212 L/(g VS) and 0.435 L/(g VS), respectively. Accordingly, the deflocculation and ultrasonic pretreatment improved the anaerobic biodegradability efficiently. Thus, this chemo mediated sonic pretreatment is an effective method for enhancing biodegradability and improving clean energy generation from WAS.