Nazanin Niknezhad; Neda Azimi; Shahin Ahmadi
Abstract
The purpose of this study was numerical and experimental investigations on the influence of ultrasound on Cr (VI) removal from aqueous solution by adsorption onto activated carbon nanoparticles. The effect of key factors on Cr (VI) elimination like media pH, absorbent mass, initial concentration of Cr ...
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The purpose of this study was numerical and experimental investigations on the influence of ultrasound on Cr (VI) removal from aqueous solution by adsorption onto activated carbon nanoparticles. The effect of key factors on Cr (VI) elimination like media pH, absorbent mass, initial concentration of Cr (VI) and the location of ultrasound transducers were considered. To perform CFD modeling of ultrasound propagation, the vibrations of 1.7 MHz piezoelectric transducers (PZTs) were defined based on the dynamic mesh model. The experimental results indicated that by pH raising from 2 to 8, Cr (VI) removal efficiency had a decreasing trend and at pH=8, it had the lowest value. The adsorption rate increased by augmentation in the adsorbent mass (AM) due to the enhancing its specific surface area. In comparison with using a shaker, ultrasound showed lower needed contact time for Cr (VI) elimination at identical conditions. In addition, CFD results depicted that the acoustic streams were induced in the direction of ultrasound propagation, which is caused to reach the better mixing and Cr (VI) removal efficiency. Finally, the experimental data were adopted with the Langmuir and Freundlich isotherms. The comparison of these models showed that both models were well suited to experimental findings and the data compatibility with Langmuir model was greater.
Zakie Rostami; Masoud Rahimi; Neda Azimi
Abstract
In this study, Ni+2 removal from aqueous solution was investigated by concurrent usage of Fe3O4 nanoparticles and a high frequency ultrasound (1.7 MHz). In addition to Ni+2 removal, presence of the high frequency ultrasound led to being cooled photovoltaic (PV) module. Studied variables were pH and adsorbent ...
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In this study, Ni+2 removal from aqueous solution was investigated by concurrent usage of Fe3O4 nanoparticles and a high frequency ultrasound (1.7 MHz). In addition to Ni+2 removal, presence of the high frequency ultrasound led to being cooled photovoltaic (PV) module. Studied variables were pH and adsorbent dose (AD). Results indicated that the Ni+2 removal efficiency increased with an increase in the pH ranging from 2 to 9. Furthermore, the Ni+2 removal efficiency boosted by an increase in the AD. However, no significant enhancement in Ni+2 removal efficiency was observed at the AD above 9 g. Generally, the maximum Ni+2 removal efficiency was about 79 % for contact time of 50 min at pH=9 and AD=9 g in the presence of ultrasound. At the efficient condition (pH=9, AD=9 g and contact time=50 min), using ultrasound showed 16-20 % enhancement in Ni+2 removal efficiency compared to no ultrasound usage. From heat transfer view, it was observed that propagation of 1.7 MHz ultrasound into nanofluid significantly has cooled the photovoltaic (PV) module. Moreover, an increase in concentration of nanofluid (AD) showed a positive effect on reduction of heat from the PV module surface and maximum generated power. Obtained data demonstrated that agitating nanofluid by 1.7 MHz ultrasound decreased temperature of the PV module up to 15.5 % compared to no cooling system.
Tahereh Mansouri Jalilian; Neda Azimi; Shahin Ahmadi
Abstract
The effect of ultrasound on cobalt adsorption from aqueous solution onto Fe3O4/Bentonite nanocomposite is investigated. Two layouts of using shaker and sono-separator equipped with ultrasound are considered. The effect of pH on Co(II) ions removal is investigated. Co(II) removal rate increased with increasing ...
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The effect of ultrasound on cobalt adsorption from aqueous solution onto Fe3O4/Bentonite nanocomposite is investigated. Two layouts of using shaker and sono-separator equipped with ultrasound are considered. The effect of pH on Co(II) ions removal is investigated. Co(II) removal rate increased with increasing pH from 2 to 10, and it reduced after pH=10. For the shaker, the contact time (t) of 50 min is selected as the most effective case. However, for sono-separator the maximum value of Co(II) removal rate is 78% at t=10 min, and it decreased after 10 min. The effect of the adsorbent mass (AM) is investigated and Co(II) removal increased by increasing the specific surface area of the adsorbent. The highest Co(II) removal rates are 83.3% and 86% for the shaker and the sono-separator, respectively. No significant increase for Co(II) removal is observed for increasing AM more than 3 g. The effect of the transducer locations and initial concentration of Co(II) ions (C0) at pH=10 and AM =3 g are investigated. The results showed that the activation of all transducers had the best performance. Initially, with increasing C0 from 0.05 to 0.1 g/L, Co(II) removal rate increased from 84% to 86%, respectively, but with increasing C0 from 0.1 to 0.15 and 0.2 g/L, cobalt removal has been decreased. Finally, the experimental data are adopted with Langmuir and Freundlich isotherms. The comparison of these models showed that both models are well suited to experimental data and data compatibility with the Langmuir model is greater.
