Ultrasound-assisted method for determination of chemical oxygen demand

Canals, Antonio; Hernández, Maria del Remedio

doi:10.1007/s00216-002-1578-2

Cited by 35 publications

(13 citation statements)

References 29 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When a large amount of ultrasonic power enters a system, a much larger quantity of ultrasonic cavitation bubbles are generated in the reaction mixture. Excessive bubbles are likely to merge and form larger and more stable bubbles and, thus, create a barrier to acoustic energy transfer [43].…”

Section: Effect Of Powermentioning

confidence: 99%

See 1 more Smart Citation

Ultrasound assisted synthesis of methyl butyrate using heterogeneous catalyst

Dange

Kulkarni

Rathod

2015

Ultrasonics Sonochemistry

View full text Add to dashboard Cite

Ultrasound assisted esterification of butyric acid with methanol was investigated in an ultrasound irradiated isothermal batch reactor using acid ion-exchange resin (amberlyst-15) as a catalyst. Effect of parameters such as temperature (323-353 K), catalyst loading (0-8.5%w/w), alcohol to acid ratio, M (2-6), ultrasound power (0-145 W), duty cycle (0-85%) and amount of molecular sieves added (0-11%w/w) on the rate of reaction was studied. At optimized parameters, a maximum conversion of 91.64% was obtained in 120 min in presence of ultrasound. Experimental kinetic data were correlated by using Eley-Rideal (ER) and Langmuir-Hinshelwood-Hougen-Watson (LHH W) models taking into account reverse reaction. Studies showed that single site LHHW with reactants and products both adsorbing on catalyst surface was most suited for the obtained experimental data. Activation energy determined based on heterogeneous kinetics was in the range 49.31-57.54 kJ/mol while it was 18.29 kJ/mol using homogeneous model.

show abstract

Section: Effect Of Powermentioning

confidence: 99%

“…These bubbles are likely to coalesce and form larger and more stable bubbles. This creates a barrier to dissipative energy transfer inhibiting effective diffusion of reactant species [43]. Hence the optimum duty cycle was taken at 75%.…”

Section: Tablementioning

confidence: 99%

Ultrasound assisted synthesis of methyl butyrate using heterogeneous catalyst

Dange

Kulkarni

Rathod

2015

Ultrasonics Sonochemistry

View full text Add to dashboard Cite

show abstract

“…[14] or ultrasound-assisted oxidation. [15] Other alternative assays have also been developed such as electrocatalytic determination using PbO 2 or Cu sensors in thin-cell reactors, [16,17] and photocatalytic and photoelectrocatalytic methods based on TiO 2 nanomaterial sensors. [18,19] However, all these modified K 2 Cr 2 O 7 methods are still plagued by the secondary pollution caused by highly toxic Cr(VI) ions, and moreover, the PbO 2 sensors pose the risk of the potential release of hazardous Pb during the preparation and disposal of the active material of the sensors.…”

mentioning

confidence: 99%

Self‐Organized TiO₂ Nanotube Array Sensor for the Determination of Chemical Oxygen Demand

et al. 2008

View full text Add to dashboard Cite

The principal impetus for the fabrication of functional nanotube materials comes from the promise of discovering unique structure-dependant properties and superior performance that are derived from their intrinsic nanotubular architecture. [1][2][3][4] 1D TiO 2 nanotube arrays prepared by the electrochemical anodization of self-organized porous structures on Ti foil [5][6][7] have attracted great research interest in recent years owing to their peculiar architecture, remarkable properties, and potential for wide-ranging applications. Uniform TiO 2 nanotubes are quite remarkably different in structure from other forms of TiO 2 , and are highly ordered, high-aspect-ratio structures with nanocrystalline walls perpendicular to electrically conductive Ti substrates, thereby naturally forming a Schottky-type contact. Moreover, these structures can be directly used as electrodes for photoelectric applications since the size of the nanotubes is very precisely controllable. The technological applications of TiO 2 nanotube arrays are still at an early stage, but these remarkable structures have already been shown to be very promising for applications in sensing, [8] catalysis, [9] photovoltaics, [10] photoelectrolysis, [11] and nanotemplating. [12] The electrical resistance of the TiO 2 nanotubes changes by almost 7 orders of magnitude upon exposure to 1000 ppm H 2 , [13] the largest ever reported sensitivity of a material to a gas. Furthermore, the H 2 evolution rate of TiO 2 nanotube arrays has been reported to be 76 mL hw -1 , [11] which is the highest reported H 2 generation rate for any oxide system upon photoelectrolysis. TiO 2 nanotube arrays have also attracted great interest for enhancing the photocatalytic degradation of various organics, which makes them promising materials for the detection of pollutants. Given the increasing quantities of pollutants that are being dumped into water bodies, environmental monitoring and control have become issues of global concern. Chemical oxygen demand (COD) is one of the most widely used metrics in the field of water-quality analysis in many countries, and is frequently used as an important index for controlling the operation of wastewater treatment plants, wastewater effluent monitoring, and taxation of wastewater pollution. [14] or ultrasound-assisted oxidation.[15]Other alternative assays have also been developed such as electrocatalytic determination using PbO 2 or Cu sensors in thin-cell reactors, [16,17] and photocatalytic and photoelectrocatalytic methods based on TiO 2 nanomaterial sensors. [18,19] However, all these modified K 2 Cr 2 O 7 methods are still plagued by the secondary pollution caused by highly toxic Cr(VI) ions, and moreover, the PbO 2 sensors pose the risk of the potential release of hazardous Pb during the preparation and disposal of the active material of the sensors. As compared to traditional analytical methods, photoelectrocatalytic approaches are more promising because of the superior oxidative abilities of illuminated TiO 2 . Furthermore, TiO 2 ...

show abstract

“…These include increased efficiency and shortened reaction times. These are the oxidation of inorganic species in CCl 4 -saturated aqueous media [14][15][16], the degradation of organometallic compounds prior to the determination of the target metal [17][18][19][20], oxidation of organic matter for the determination of the chemical oxygen demand (COD) [21,22], and the fast oxidation of oils for correlating the time required with long-time oxidative stability [23]. Processing times were dramatically shortened in all instances.…”

Section: Redox Reactionsmentioning

confidence: 99%