Ultrasonically induced ZnO–biosilica nanocomposite for degradation of a textile dye in aqueous phase

Abstract

In the present study, a porous clay-like support with unique characteristics was used for the synthesis and immobilization of ZnO nanostructures to be used as sonocatalyst for the sonocatalytic decolorization of methylene blue (MB) dye in the aqueous phase. As a result, the sonocatalytic activity of ZnO-biosilica nanocomposite (77.8%) was higher than that of pure ZnO nanostructures (53.6%). Increasing the initial pH from 3 to 10 led to increasing the color removal from 41.8% to 88.2%, respectively. Increasing the sonocatalyst dosage from 0.5 to 2.5 g/L resulted in increasing the color removal, while further increase up to 3g/L caused an obvious drop in the color removal. The sonocatalysis of MB dye over ZnO-biosilica nanocomposite was temperature-dependent. The presence of methanol produced the most adverse effect on the sonocatalysis of MB dye. The addition of chloride and carbonate ions had a negligible effect on the sonocatalysis, while the addition of persulfate ion led to increasing the color removal from 77.8% to 99.4% during 90 min. The reusability test exhibited a 15% drop in the color removal (%) within three consecutive experimental runs. A mineralization efficiency of 63.2% was obtained within 4h.

Copper(I) sulfide (Cu 2 S) nanoparticles from Cu(II) diethyldithiocarbamate: Synthesis, characterization and its application in ultrasound-assisted catalytic degradation of organic dye pollutants

“…Although, the exact mechanism for this sonocatalytic degradation reaction over Cu2S nanoparticles is not very clear and intermediates were not observed directly; on the basis of the above observations and previously reported mechanisms [45][46][47][48][49][50][51][52], the following mechanism was…”

Adsorption of Cr(VI) by Natural Clinoptilolite Zeolite from Aqueous Solutions: Isotherms and Kinetics

“…Another problem with conventional treatment technologies is production of considerable amounts of toxic sludge which makes the overall treatment and disposal incompatible with the environmental friendly processes 6 . Considering the above-mentioned statements 7 , the removal of toxic heavy metals in an environmentally friendly and cost-effective manner is very important 2 . The use of adsorbents such as activated carbon, inorganic materials such as zeolite and clay, biological adsorbents and industrial wastes for removal of metal ions has been increasingly studied 8,9 .…”

Visible light photocatalysis of a textile dye over ZnO nanostructures covered on natural diatomite

“…The porous structure improves the reaction area, thereby exhibiting highly efficient catalytic activity. 20 The formation of OH · during the photocatalysis of AR88 over ZnO-diatomite nanocomposite is shown in the following equations:…”

“…14−18 Among the semiconductors being used for photocatalysis, ZnO, in nanosize, has attracted extensive interest because of its availability, low cost, wide band gap (E g = 3.37 eV), high photosensitivity, large area-to-volume ratio, and large excitation binding energy (60 meV). 11,12,19,20 However, several difficulties using suspended photocatalysts have also been observed as follows: (1) the aggregation of fine particles in the bulk solution, (2) difficulty in the separation of nanoparticles from the solution after the * Correspondence: darvishi@arakmu.ac.ir process, (3) the small amount of absorbed photons in the visible light region, (4) the high recombination rate of the generated electron-hole pairs, and (5) difficulty in the application of fine particles in continuous flow mode reactors. 14,16 Another disadvantage in using suspended nanoparticles is associated with their fine size, which can adversely affect human health and the environment.…”