Determination of acoustic fields in acidic suspensions of peanut shell during pretreatment with high-intensity ultrasound

Polachini, Tiago Carregari; Carvalho, Gisandro Reis de; Telis-Romero, Javier

doi:10.1590/0104-6632.20170342s20150549

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Bioprocess Engineering • Braz. J. Chem. Eng. 34 (2) • Apr 2017 • https://doi.org/10.1590/0104-6632.20170342s20150549 copy

Determination of acoustic fields in acidic suspensions of peanut shell during pretreatment with high-intensity ultrasound

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The benefits of high-intensity ultrasound in diverse processes have stimulated many studies based on biomass pretreatment. In order to improve processes involving ultrasound, a calorimetric method has been widely used to measure the real power absorbed by the material as well as the cavitation effects. Peanut shells, a byproduct of peanut processing, were immersed in acidified aqueous solutions and submitted to an ultrasonic field. Acoustic power absorbed, acoustic intensity and power yield were obtained through specific heat determination and experimental data were modeled in different conditions. Specific heat values ranged from 3537.0 to 4190.6 J·kg^-1·K^-1, with lower values encountered for more concentrated biomass suspensions. The acoustic power transmitted and acoustic intensity varied linearly with the applied power and quadratically with solids concentration, reaching maximum values at higher applied nominal power and for less concentrated suspensions. A power yield of 82.7% was reached for dilute suspensions at 320 W, while 6.4% efficiency was observed for a concentrated suspension at low input energy (80 W).

Keywords
acoustic intensity; biomass pretreatment; ultrasonic hydrolysis; specific heat; power yield

Biomass concentration (%)	T (K)	c_p (J·kg^-1 ·K^-1 )
Biomass concentration (%)	T (K)	pH=3	pH=4	pH=5	pH=6	pH=7
0	274.13	4164.5 ± 2.4 ^a	4174.7 ± 2.4 ^a	4176.1 ± 2.7 ^a	4175.2 ± 12.0 ^a	4176.4 ± 2.1 ^a
	283.13	4164.4 ± 4.7 ^a	4174.4 ± 1.3 ^a	4174.7 ± 2.9 ^a	4174.8 ± 12.0 ^a	4174.8 ± 8.5 ^a
	293.13	4165.3 ± 1.0 ^a	4175.0 ± 2.7 ^a	4175.9 ± 1.6 ^a	4175.5 ± 12.0 ^a	4176.8 ± 2.1 ^a
	303.13	4166.7 ± 2.7 ^a	4177.5 ± 1.4 ^b	4179.1 ± 3.4 ^b	4177.8 ± 6.7 ^b	4178.5 ± 0.6 ^b
	313.13	4170.7 ± 2.9 ^a	4180.4 ± 1.4 ^a	4181.3 ± 2.1 ^a	4181.4 ± 0.6 ^a	4181.5 ± 2.1 ^a
	323.13	4174.2 ± 1.0 ^b	4183.5 ± 5.7 ^a,b	4184.5 ± 1.8 ^a	4184.3 ± 12.0 ^a	4184.6 ± 9.1 ^a
	333.13	4179.9 ± 3.4 ^b	4188.6 ± 10.7 ^a,b	4190.0 ± 2.0 ^a	4190.6 ± 4.4 ^a	4189.7 ± 9.1 ^a,b
4	274.13	3901.4 ± 6.6 ^a	3938.4 ± 12.7 ^a	3916.9 ± 6.0 ^a	3883.2 ± 15.1 ^a	3858.4 ± 17.5 ^a
	283.13	3914.2 ± 13.1 ^a	3940.1 ± 3.1 ^a	3879.7 ± 11.1 ^a	3882.9 ± 10.6 ^a	3879.8 ± 11.0 ^a
	293.13	3929.1 ± 3.1 ^a	3924.5 ± 8.7 ^a	3923.8 ± 5.3 ^a	3880.5 ± 11.1 ^a	3858.8 ± 23.4 ^a
	303.13	3898.6 ±7.3 ^a	3877.6 ± 12.7 ^a	3926.0 ± 5.1 ^a	3925.6 ± 5.2 ^a	3887.4 ± 12.5 ^a
	313.13	3931.8 ± 3.4 ^a	3915.6 ± 8.1 ^a	3915.1 ± 7.3 ^a	3890.1 ±14.2 ^a	3881.4 ± 20.7 ^a
	323.13	3951.8 ± 8.5 ^a	3914.7 ± 7.3 ^a	3920.6 ± 7.1 ^a	3888.7 ± 11.3 ^a	3915.7 ± 8.0 ^a
	333.13	3937.9 ± 7.4 ^a	3919.5 ± 7.8 ^a	3957.4 ± 6.4 ^a	3925.2 ±7.1 ^a	3920.5 ± 8.2 ^a
6	274.13	3885.5 ± 11.0 ^a	3834.4 ± 6.6 ^a	3885.5 ± 1.2 ^a	3835.4 ± 5.8 ^a	3849.8 ± 6.4 ^a
	283.13	3871.2 ± 1.2 ^a	3885.4 ± 11.9 ^a	3888.4 ± 2.0 ^a	3789.7 ± 20.8 ^a	3859.8 ± 2.7 ^a
	293.13	3788.0 ± 12.1 ^a	3881.8 ± 4.1 ^a	3882.8 ± 9.0 ^a	3790.4 ± 13.4 ^a	3860.5 ± 7.4 ^a
	303.13	3881.3 ± 2.2 ^a,b	3799.2 ± 12.1 ^b	3857.5 ± 3.3 ^a,b	3899.8 ± 12.2 ^a,b	3872.0 ± 6.9 ^a,b
	313.13	3890.4 ± 3.8 ^a	3900.1 ± 4.1 ^a	3887.2 ± 5.0 ^a	3887.7 ± 21.3 ^a	3887.3 ± 9.0 ^a
	323.13	3887.9 ± 2.2 ^a	3805.5 ± 11.8 ^a	3891.3 ± 11.0 ^a	3812.0 ± 11.2 ^a	3843.8 ± 6.0 ^a
	333.13	3899.0 ± 4.6 ^a	3894.7 ± 4.1 ^a	3872.5 ± 12.2 ^a	3816.7 ± 11.3 ^a	3855.4 ± 5.4 ^a
8	274.13	3802.6 ± 6.7 ^a	3812.4 ± 7.9 ^a	3671.4 ± 28.0 ^a	3813.5 ± 4.4 ^a	3800.0 ± 8.6 ^a
	283.13	3706.5 ± 19.0 ^a	3809.3 ± 3.2 ^a	3808.9 ± 8.7 ^a	3804.7 ± 8.3 ^a	3809.0 ± 2.7 ^a
	293.13	3795.7 ± 7.8 ^a	3741.3 ± 12.5 ^a	3813.8 ± 8.2 ^a	3737.5 ± 8.4 ^a	3803.3 ± 0.7 ^a
	303.13	3804.7 ± 5.8 ^a	3807.1 ± 1.4 ^a	3808.1 ± 10.6 ^a	3807.1 ± 2.6 ^a	3739.2 ± 8.3 ^a
	313.13	3793.9 ± 17.9 ^a	3809.8 ± 7.6 ^a	3804.3 ± 1.7 ^a	3812.0 ± 1.3 ^a	3804.6 ± 0.3 ^a
	323.13	3808.4 ± 4.7 ^a	3822.2 ± 6.5 ^a	3808.2 ± 5.1 ^a	3817.7 ± 6.5 ^a	3815.7 ± 1.4 ^a
	333.13	3815.9 ± 3.0 ^a	3811.9 ± 10.9 ^a	3812.8 ± 4.0 ^a	3826.5 ± 12.4 ^a	3818.1 ± 2.2 ^a
10	274.13	3657.0 ± 6.1 ^a	3692.2 ± 11.9 ^a	3672.2 ± 5.6 ^a	3640.6 ± 14.2 ^a	3617.4 ± 16.4 ^a
	283.13	3669.0 ± 12.2 ^a	3693.8 ± 2.9 ^a	3637.3 ± 10.4 ^a	3640.3 ± 10.0 ^a	3637.4 ± 10.3 ^a
	293.13	3682.9 ± 2.9 ^a	3679.3 ± 8.1 ^a	3678.7 ± 5.0 ^a	3638.1 ± 10.4 ^a	3617.7 ± 21.9 ^a
	303.13	3654.4 ± 6.8 ^a	3635.3 ± 11.9 ^a	3680.7 ± 4.8 ^a	3680.4 ± 4.9 ^a	3644.6 ± 11.8 ^a
	313.13	3685.5 ± 3.2 ^a	3670.9 ± 7.6 ^a	3670.5 ± 6.9 ^a	3647.1 ± 13.4 ^a	3638.9 ± 19.4 ^a
	323.13	3704.3 ± 8.0 ^a	3670.0 ± 6.9 ^a	3675.7 ± 6.6 ^a	3645.7 ± 10.6 ^a	3671.1 ± 7.5 ^a
	333.13	3691.3 ± 7.0 ^a	3674.5 ± 7.3 ^a	3710.1 ± 6.0 ^a	3680.0 ± 6.7 ^a	3675.6 ± 7.7 ^a
12	274.13	3642.9 ± 5.3 ^a	3610.2 ± 11.6 ^a	3590.6 ± 11.6 ^a	3559.7 ± 9.8 ^a	3537.0 ± 16.0 ^a
	283.13	3593.2 ± 12.1 ^a	3611.8 ± 2.9 ^a	3556.5 ± 13.7 ^a	3559.4 ± 10.3 ^a	3556.6 ± 10.1 ^a
	293.13	3625.3 ± 1.8 ^a	3597.5 ± 8.0 ^a	3597.0 ± 6.2 ^a	3557.3 ± 10.0 ^a	3537.3 ± 20.8 ^a
	303.13	3619.3 ± 2.5 ^a	3554.5 ± 11.6 ^a	3599.0 ± 10.8 ^a	3598.6 ± 12.0 ^a	3563.6 ± 9.5 ^a
	313.13	3647.5 ± 3.6 ^a	3589.3 ± 7.4 ^a	3589.0 ± 12.3 ^a	3566.1 ± 9.9 ^a	3558.1 ± 14.2 ^a
	323.13	3639.1 ± 6.5 ^a	3588.5 ± 6.7 ^a	3594.0 ± 6.5 ^a	3564.7 ± 10.2 ^a	3589.5 ± 7.5 ^a
	333.13	3659.7 ± 3.8 ^a	3573.9 ± 9.9 ^b	3627.7 ± 5.9 ^a,b	3598.2 ± 6.5 ^a,b	3593.9 ± 8.0 ^a,b

Equation	Model	Parameters	R ² _adj	MRE (%)
(6)	c_P = a ₁ + a ₂ X	a₁ = 4149.3 J·kg^-1·K^-1 a₂ = -47.42 J·kg^-1·K^-1	0.959	0.85
(7)	c_P = a ₁ + a ₂ X + a₃ T	a₁ = 4125.1 J·kg^-1·K^-1 a₂ = -47.42 J·kg^-1·K^-1 a₃ = 0.07 J·kg^-1·K^-1	0.959	0.85
(8)	c_P = a ₁ + a ₂ X^M + a ₃ T	a₁ = 4149.8 J·kg^-1·K^-1 a₂ = -75.73 J·kg^-1·K^-1 a₃ = 0.07 J·kg^-1·K^-2 M = 0.82	0.967	0.74

	P (W)				I (W∙cm^- ²)
Parameters	Coefficient	p _value	R²_adjsub>	MRE (%)	Coefficient	p _value	R²_adjsub>	MRE (%)
Intercept	32.96	-	0.999	2.090	8.67	-	0.999	2.090
U	0.84	< 1×10^-28			0.22	< 1×10^-28
X	-8.25	< 1×10^-28			-2.17	< 1×10^-28
X²	0.09	1.23×10^-4			0.02	1.23×10^-4
U×X	-0.01	3.69×10^-28			-0.002	3.69×10^-28

	Power yield (%)
Parameters	Coefficient	p _value	R²_adjsub>	MRE (%)
Intercept	102.15	-	0.977	6.410
U	0.12	< 1×10^-28
U²	-5.40×10^-4	< 1×10^-28
X	-9.86	< 1×10^-28
U×X	0.024	< 1×10^-28

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