N, S doped carbon quantum dots inside mesoporous silica for effective adsorption of methylene blue dye

Abstract

This study aimed to develop non-metal elements for doping carbon quantum dots (CQDs) with nitrogen and sulfur (N, S-CQDs), which loaded inside hexagonal mesoporous silica (HMS) in order to effectively remove methylene blue dye (MB) from an aqueous solution. The histidine and cysteine amino acids were used as the source for synthesis N, S-CQDs through the hydrothermal method. Morphology and structure of the N, S-CQDs, and adsorbent (N, S-CQDs/HMS) were characterized by using different microscopic and spectroscopic techniques. The adsorption parameters such as adsorbent dosage (0.25–1 g/L), pH (2–10), contact time (15–75 min), and initial MB dye concentration (20–300 mg/L) were investigated. The maximum adsorption capacity and removal efficiency of MB were determined at 370.4 mg/g and 97%, respectively, under optimum conditions at 303 K. The adsorption isotherm studies were fitted with the Freundlich isotherm equation, and the dye removal kinetics of the adsorbent followed the pseudo-second-order model. Thermodynamic studies showed that the adsorption process had exothermic and spontaneous behavior. The removal of MB next to the Rhodamine B and Reactive Black 5 dyes indicated that the N, S-CQDs/HMS had excellent selective behavior for MB absorption. This prepared adsorbent could be well recycled with suitable activity after four repeated adsorption–desorption cycles. Results revealed that the porous characters, surface area, charge properties, reduction in the bandgap, and quantum yield of the N, S-CQDs/HMS were essential factors that affected dye adsorption.

Synthesis, characterization, photoluminescent properties of carbon quantum dots and its applications in wastewater treatment

“…Meanwhile, it was discovered that sunlight was absorbed in the visible and ultraviolet spectrums. The optical absorption peak of QDs at 250 nm may be related to the transition of C=C bonds from aromatic and sp 2 carbon bonds [10,[23][24][25]. When carbonbased quantum dots were oxidised, the transitions of the C=O and CO-H groups, which correspond to an analogous peak at about 340 nm, showed the presence of oxygen-functionalized groups.…”

“…The creation processes and physical/chemical characteristics of these luminous QDs will be discussed first in this paper. Following that, the methods used to fabricate carbon quantum dots from biomass waste including typical methods used to fabricate QDs, the characterization of the QDs fabricated and the use of QDs in wastewater treatment, such as membrane filtering [2], electrochemical reduction ion-exchange [7], photocatalytic degradation [8] and adsorption [1,9,10], particularly the benefits they could provide to these features.…”

Contemporary, Multidisciplinary Roles of Mesoporous Silica Nanohybrids/Nanocomposites

“…[158] In this regard, Teymoorian et al developed a hybrid with nitrogen and sulfur doped CDs inside hexagonal MS (N, S-CQDs/HMS) for efficacious removal of MB. [159] They have also investigated the effect of variables; adsorbent dosage, pH, contact time, and initial MB dye concentration on adsorption and a maximum adsorption capacity of 370.4 mg/g and removal of 97 % of MB was achieved under optimum conditions at 303 K. The selective removal of MB was investigated with a mixture of MB, RhB and Reactive Black 5 dyes and the results showed that the hybrid has a higher selectivity towards MB. Porous characters, reduction in the band gap, surface area, charge properties, and quantum yield of the N, S-CQDs/HMS were found to be the essential factors affecting the dye adsorption.…”

Optical absorption investigations for efficient crystal violet dye removal from wastewater via carbon nanotubes:Montmorillonite‐based nanocomposite

“…Teymoorian et al doped carbon quantum dots with nitrogen and sulfur and loaded them inside hexagonal mesoporous silica to remove methylene blue dye from aqueous solution. [ 34 ] Wei and Kamali reported efficient removal of methyl orange and methylene blue dyes from their aqueous solutions using mesoporous carbon nanostructure embedded with magnetic nanoparticles. [ 35 ] Among the carbon nanomaterials, carbon nanotubes possess unique physico‐chemical properties including very high surface area, nano‐scale tubular hollow structures and accessible adsorption sites.…”