REACTION KINETICS OF OZONE GAS IN WHEAT FLOUR

Paes, Juliana L.; Faroni, Lêda R. A.; Martins, Marcio A.; Cecon, Paulo R.; Heleno, Fernanda F.

doi:10.1590/1809-4430-Eng.Agric.v37n3p520-528/2017

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Scientific Papers, Post-Harvest Science and Technology • Eng. agríc. 37 (03) • May-Jun 2017 • https://doi.org/10.1590/1809-4430-Eng.Agric.v37n3p520-528/2017 copy

REACTION KINETICS OF OZONE GAS IN WHEAT FLOUR

Authorship SCIMAGO INSTITUTIONS RANKINGS

ABSTRACT

The implementation of the ozonation process in the milling industry to control insect pests and improve wheat flour qualities requires understanding the behavior of ozone during ozonation. Therefore, this study aimed to investigate the reaction kinetics of ozone gas in wheat flour. Wheat flour ozonation at concentrations of 0.54, 1.07, 1.61 and 2.14 mg L⁻¹ was used in a prototype consisting of a cylinder and a mixing system with a helical thread. The iodometric titration method was used to quantify the ozone concentration in the air stream. The reaction kinetics were characterized by determining the saturation time and the decomposition kinetics (decay rate and half-life time). With increasing ozone concentration, less time was required to saturate the wheat flour. The saturation times were 812, 434, 370 and 342 min for ozone concentrations of 0.54, 1.07, 1.61 and 2.14 mg L⁻¹, respectively. Increasing the ozone concentration did not influence the constant decay rate and half-life time. The ozone decomposition kinetics could be represented by a first-order model, with a decay rate constant of 0.23±0.008 min⁻¹ and a half-life time of 3.02±0.081 min.

KEYWORDS:
ozonation; saturation; decay rate; half-life time

Models	Differential equation	Integrated and linearized equations
Zero order	$\frac{dC}{dt} = - k$	$C = C_{0} - kt$	(1)
First order	$\frac{dC}{dt} = - kC$	$\ln C = \ln C_{0} - kt$	(2)
Second order	$\frac{dC}{dt} = - {kC}^{2}$	$\frac{1}{C} = \frac{1}{C_{0}} + kt$	(3)

Concentration (mg L⁻¹)	Intervals of exposure period (min)	Equation	Determination coefficient (r²)
0.54	x_i <812 812≤x_i≤1040	ŷ = -0.0239+1.47 10⁻⁴ x_i ŷ = 0.096	0.88
1.07	x_i <434 434≤x_i≤880	ŷ = -0.0248+3.38 10⁻⁴ x_i ŷ = 0.1219	0.88
1.61	x_i <370 370≤x_i≤735	ŷ = 0.0096+3.30 10⁻⁴ x_i ŷ = 0.1315	0.96
2.14	x_i <342 342≤x_i≤630	ŷ = 0.0256+3.42 10⁻⁴ x_i ŷ = 0.1425	0.98

Saturation concentration (mg L⁻¹)	Intervals of decomposition period (min)	Equation	Determination coefficient (r²)
0.10	x_i <5.1472 5.1472≤x_i≤9	ŷ = 0.0976–0.016 x_i ŷ = 0.0152	0.97
0.12	x_i <5.7550 5.7550≤x_i≤9	ŷ = 0.1142–0.016x_i ŷ = 0.0211	0.90
0.13	x_i <5.6929 5.6929≤x_i≤10	ŷ = 0.1356–0.02 x_i ŷ = 0.0206	0.98
0.14	x_i <5.4235 5.4235≤x_i≤10	ŷ = 0.139–0.022 x_i ŷ = 0.0212	0.96

Saturation concentration (mg L⁻¹)	Models	Integrated and linearized equations	Determination coefficient (r²)
0.10	Zero order	C = 0.084 - 0.009t	0.84
	First order	ln C = −2.357 - 0.237t	0.91
	Second order	$\frac{1}{C} = 4.571 + 7.548 t$	0.89
0.12	Zero order	C = 0.102 - 0.011t	0.87
	First order	ln C = −2.168 - 0.23t	0.90
	Second order	$\frac{1}{C} = 4.214 + 5.895 t$	0.87
0.13	Zero order	C = 0.116 - 0.012t	0.86
	First order	ln C = −2.033 - 0.226t	0.92
	Second order	$\frac{1}{C} = 2.706 + 5.504 t$	0.91
0.14	Zero order	C = 0.115 - 0.012t	0.81
	First order	ln C = −2.084 - 0.222t	0.85
	Second order	$\frac{1}{C} = 4.889 + 5.311 t$	0.81

Associação Brasileira de Engenharia Agrícola SBEA - Associação Brasileira de Engenharia Agrícola, Departamento de Engenharia e Ciências Exatas FCAV/UNESP, Prof. Paulo Donato Castellane, km 5, 14884.900 | Jaboticabal - SP, Tel./Fax: +55 16 3209 7619 - Jaboticabal - SP - Brazil
E-mail: revistasbea@sbea.org.br

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[1] *Corresponding author. Universidade Federal de Viçosa/ Viçosa - MG, Brasil. E-mail: lfaroni@ufv.br