Photocatalytic degradation of methylene blue dye in aqueous solution by MnTiO3 nanoparticles under sunlight irradiation

This study investigated the degradation of methylene blue dye with ZnO-CuO/RHA, a synthesised agro waste-based photocatalyst under solar irradiation at ambient temperature. Preliminary screening of the methylene blue degradation facilitated the selection of the best ZnO-CuO/RHA combination. The photocatalytic degradation was done by taking varying weights of catalyst in 100 mL of dissolved 10-30 ppm MB solutions. The sample was magnetically stirred at 500 rpm in darkness before being exposed to sunlight irradiation. The suspension was magnetically stirred continuously and 5 ml was withdrawn intermittently, centrifuged and analysed with UV-Vis spectrophotometer. The effect of catalyst dosage, initial concentration and irradiation time on the photodegradation were studied using the one-variable-at-a-time method. The result showed that the degradation percentages of the catalyst with 1, 2, 3, 4, and 5 wt. % of RHA were 80.31%, 88.23%, 99.94%, 91.06 % and 81.12% respectively after 180 minutes. These results showed that degradation percentage was directly proportional to the irradiation time up to 3 wt. % thereafter, there was a decline in the percentage degradation. Hence, as the irradiation time increases, there was a significant increase in the degradation of methylene blue dye. ZnO-CuO/RHA catalyst was found to possess a higher photocatalytic activity in the presence of sunlight in comparison to bare ZnO-CuO since using RHA as a base for ZnO-CuO increased the surface area resulting in more active sites under visible light irradiation. ZnO-CuO/RHA may serve as an efficient-photocatalyst for industrial applications with excellent prospects. Keywords: Photocatalytic degradation, Sunlight irradiation, One-variable-at-a-time

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Using of modified-bentonite as low-cost sorbent for removal of methylene blue dye from aqueous solution

Association of Arab Universities Journal of Engineering Sciences ◽

10.33261/jaaru.2020.27.2.005 ◽

2020 ◽

Vol 27 (2) ◽

pp. 45-54

Author(s):

Saraa Muwafaq Ibrahim ◽

Ziad T. Abd Ali

Keyword(s):

Aqueous Solution ◽

Methylene Blue ◽

Silanol Group ◽

Infrared Spectrometry ◽

Blue Dye ◽

Ammonium Bromide ◽

Vibration Band ◽

Order Kinetic ◽

Methylene Blue Dye ◽

Modified Bentonite

Batch experiments have been studied to remove methylene blue dye (MB) from aqueous solution using modified bentonite. The modified bentonite was synthesized by replacing exchangeable calcium cations in natural bentonite with cationic surfactant cetyl trimethyl ammonium bromide (CTAB). The characteristics of modified bentonite were studied using different analysis such as Scanning electronic microscopy (SEM), Fourier transform infrared spectrometry (FTIR) and surface area. Where SEM shows the natural bentonite has a porous structure, a rough and uneven appearance with scattered and different block structure sizes, while the modified bentonite surface morphology was smooth and supplemented by a limited number of holes. On other hand, (FTIR) analysis that proved NH group aliphatic and aromatic group of MB and silanol group are responsible for the sorption of contaminate. The organic matter peaks at 2848 and 2930 cm-1 in the spectra of modified bentonite which are sharper than those of the natural bentonite were assigned to the CH2 scissor vibration band and the symmetrical CH3 stretching absorption band, respectively, also the 2930 cm-1 peak is assigned to CH stretching band. The batch study was provided the maximum removal efficiency (99.99 % MB) with a sorption capacity of 129.87 mg/g at specified conditions (100 mg/L, 25℃, pH 11 and 250rpm). The sorption isotherm data fitted well with the Freundlich isotherm model. The kinetic studies were revealed that the sorption follows a pseudo-second-order kinetic model which indicates chemisorption between sorbent and sorbate molecules.

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