The Adsorptive and Photocatalytic Performance of Granite and Basalt Waste in the Discoloration of Basic Dye

Abstract

The present work explored the adsorptive capacity and catalytic activity of rock powders from basaltic and granitic rocks in the discoloration of synthetic and industrial effluents containing the yellow dye Basic Yellow 96. The rock powders were characterized with scanning electron microscopy associated with energy-dispersive spectroscopy, photoacoustic spectroscopy, N2 physisorption and X-ray diffraction, the latter confirming the abundant presence of silica in the four materials studied. The basaltic powders presented specific surface areas between 7 and 10 times greater than those of granitic materials, which allowed up to 92% removal of the dye in 3 h of test using the basaltic powder. Despite the smaller area, the granitic materials showed considerable photocatalytic activity in 3 h, 94%, the same as that of the basaltic materials in the photocatalysis. Granitic and basaltic photocatalysts proved to be efficient in the discoloration of synthetic and industrial effluents, although TOC analyses indicated that it was not possible to promote the pollutant mineralization in the industrial effluent. Both artificial light and sunlight were effective in the photocatalysis of the dye, although the former was slightly faster.

Sustainable and Green Synthesis of Iron Nanoparticles Supported on Natural Clays via Palm Waste Extract for Catalytic Oxidation of Crocein Orange G Mono Azoic Dye

“…The mineralization efficiency of COG was further studied by measuring COD removal rate under previously established optimal conditions: [H 2 O 2 ] = 5 × 10 –4 mol/L, [COG] = 20 mg/L, dose catalyst = 0.2 g/L, pH = 3, t = 180 min, room temperature or 30 °C. It is widely known that the total discoloration of organic dyes does not necessarily indicate that they have completely mineralized into carbon dioxide and water . Indeed, during the discoloration of dyes, several colorless intermediates with a COD value might be formed .…”

“…It is widely known that the total discoloration of organic dyes does not necessarily indicate that they have completely mineralized into carbon dioxide and water. 100 Indeed, during the discoloration of dyes, several colorless intermediates with a COD value might be formed. 101 Therefore, in addition to the discoloration, we focused on the COD removal of the COG solution after oxidation rather than the identification of reaction intermediates, which will be the subject of further studies.…”

“…This type of adsorption is considered physical adsorption that requires a low activation energy amount of 5− 40 kJ/mol, 99 thus confirming the physically diffusioncontrolled reaction in the degradation of COG dye using HB-NZVI. 100 Indeed, during the discoloration of dyes, several colorless intermediates with a COD value might be formed. 101 Therefore, in addition to the discoloration, we focused on the COD removal of the COG solution after oxidation rather than the identification of reaction intermediates, which will be the subject of further studies.…”

Mining Waste as an Eco-Friendly Adsorbent in the Removal of Industrial Basazol Yellow 5G Dye and Incorporation in Mortars

“…These elements are generally in the form of oxides and are common in granitic rock samples [9]. The predominance of oxygen, silicon, and aluminum classifies these materials as aluminosilicates [45]. The samples demonstrated similar compositions, implying that the dye did not incorporate elements that could be potentially toxic into the samples, enabling the subsequent use of the material after adsorption, such as in mortars.…”

“…Considering that the BY5G dye has a cationic nature and the zero charge point of granitic rocks is close to pH 7 [45], values below pHpcz facilitate the desorption process.…”