Abstract
Microscopic and acoustic emission analysis and sound patterns recognition techniques were applied for the characterization of granular activated carbon (GAC). A new and improved methodology has been developed to characterize the exhaustion degree of GAC used in rum production: (1) based on the acoustic emission analysis of the sound produced by water flooded on GAC; and (2) based on the microscopic analysis of bubbles formed by immersion into glycerol. Acoustic measurements are made in a specific set-up, bubble detection and analysis is performed using dedicated software developed in MATLAB® for circular shape pattern detection based on the Hough transform. Both have been correlated with data of GAC characteristics based on thermogravimetric analysis (TGA) and Thermal Desorption-Gas Chromatography Mass Spectrometry (TD-GC/MS). Eight samples of GAC used in the rum production, obtained at different depths within the fixed-bed filter, have been evaluated. Good correlations are found between the immersion “bubble-metric” technique and the acoustic measurement data from the original signal processed by Band-Pass (BP) filtering at 1.3 kHz and weight loss amounts of adsorbed compounds on the GAC. The found relationship gives the possibility to determine the exhaustion degree of GAC applying these methods and to evaluate high-porosity materials.
Highlights
Activated carbon (AC) adsorption is the most common technique for removing various pollutants due to its extended surface area, high pore volume, well-developed porous structure and specific surface functional groups [1,2]
The acoustic emission of different samples of activated carbons used in the rum production process were studied by applying a non-professional set-up; it was observed that the best correlation between granular activated carbon (GAC) parameters, SBET and total volume of pores with the acoustic measurements were obtained when the signal is processed at 1 kHz [7]
TheThe acoustic emission results are are highly correlated with immersion total volume of the. This confirms the results presented are highly correlated immersion volume the GAC. This confirms the results presented highly correlated withwith immersion total total volume of theofGAC
Summary
Activated carbon (AC) adsorption is the most common technique for removing various pollutants due to its extended surface area, high pore volume, well-developed porous structure and specific surface functional groups [1,2]. This paper gives an improved approach of earlier findings [7,8], describing a new method for the characterization of activated carbons based on flooding a GAC sample with water It results in a sound emission by bubbles escaping through the bulk water and exploding at the liquid surface. The acoustic emission of different samples of activated carbons used in the rum production process were studied by applying a non-professional set-up; it was observed that the best correlation between GAC parameters, SBET and total volume of pores with the acoustic measurements were obtained when the signal is processed at 1 kHz [7]. Rum production, and confirms the GAC acoustic emission results, as both phenomena are directly associated with each other (bubbling process and acoustic emission)
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