Remediation of methyl green dye from aqueous solution via adsorption and degradation using silica gel modified with hydrated zinc oxide catalyst

Abstract

a b s t r a c tThe modification of silica via incorporation of hydrated zinc oxide (HZnO) with different loadings was achieved using wet precipitation technique. After drying at room temperature, the obtained samples calcined at 105°C and characterized using X-ray powder diffractometer, scanning electron microscopy, electron diffraction X-ray, transmission electron microscopy, Fourier transform infrared spectroscopy and BET. The data of characterizations indicated the well-distributed HZnO particles inside the silicate matrix with average particle size were lower than the detection limit of some characterization instruments. Furthermore, the modification with HZnO led to a noticeable decrease in BET surface area and the energy band gap due to the occupation of ZnO for interstitial positions inside the silicate matrix. The modified samples were successfully utilized in the adsorption and photocatalytic degradation of Methyl green dye as one of the cationic hazardous organic pollutants. The adsorption capacity of the sorbent catalyst was found to be 24.91 mg g -1 , while complete degradation of the (2 × 10 -4 mol L -1 ) dye was fulfilled in no more than 16 min. The influence of different experimental parameters as pH, temperature, concentration of the dye and dose of the catalyst was examined. The results obtained indicate that both adsorption and degradation of MG were a pH, dose and temperature dependent. The easiness of regeneration of the exhausted catalyst and its successive reuse confirmed remarkable economic efficiency.

Efficient Catalytic Degradation of Azo Dyes from Textile Wastewater by Nano and Micro Amorphous Alloys

“…Among these techniques, coagulation may successfully decolorize insoluble colors, but it has little impact on soluble dyes [31] . The transformation of contaminants from aqueous to solid phase was done by using adsorption technique, but adsorption is ineffective in complete elimination of the dyes [32] . Another highly effective technique is membrane filtration [33] in which a membrane is used to separate the dye particles from the clean water after dye effluent has passed over it, and it requires costly initial investment and it also produces concentrated sludge [34] .…”

“…The transformation of contaminants from aqueous to solid phase was done by using adsorption technique, but adsorption is ineffective in complete elimination of the dyes. [32] Another highly effective technique is membrane filtration [33] in which a membrane is used to separate the dye particles from the clean water after dye effluent has passed over it, and it requires costly initial investment and it also produces concentrated sludge. [34] Oxidation processes (such as ozonation [35] and Fenton [36] ) are another high-cost techniques, which can be effective in decolorization of azo dyes.…”