Synthesis of highly fluorescent carbon quantum dots from rubber seed shells for the adsorption and photocatalytic degradation of dyes

Abstract

The potentials of biomass-based carbon quantum dot (CQD) as an adsorbent for batch adsorption of dyes and its photocatalytic degradation capacity for dyes which are congo red (CR) and methylene blue (MB) have been conducted in this study. The CQDs properties, performance, behaviour, and photoluminescence characteristics were assessed using batch adsorption experiments which were carried out under operating conditions including, temperature, pH and dosage. The morphological analysis revealed that CQDs are highly porous, uniform, closely aligned and multi-layered. The presence of hydroxyl, carboxyl and carbonyl functional groups indicated the significance of the oxygenated functional groups. Spectral analysis of photoluminescence for CQDs confirmed their photoluminescent quality by exhibiting high excitation intensity and possessing greenish-blue fluorescence under UV radiation. The removal percentage of the dyes adsorbed for both CR and MB dyes was 77% and 75%. Langmuir isotherm and pseudo-second-order models closely fitted the adsorption results. Thermodynamics analysis indicated that the adsorption process was exothermic and spontaneous, with excellent reusability and stability. The degradation efficiency of CQDs on both dyes was more than 90% under sunlight irradiation and obeyed the first-order kinetic model. These results demonstrated CQDs to be an excellent adsorbent and outstanding photocatalyst for organic dye degradation.

Degradation Efficiency of Organic Dyes on CQDs As Photocatalysts: A Review

“…Production of CQDs from sugar cane bagasse, having an amine group on the surface, and then using it for dye removal and degradation. Having these amines modified CQDs paired up with tungsten dioxide to make a composite, but quite recently in 2023, Nizam et al produced CQDs using rubber seed which is considered to be biomass waste and used it for CR and MB removal and photodegradation …”

“…These Oxygen groups attracted the N-functionalities on the dyes, making it an efficient material for dye removal and photocatalysis. A complete discoloration of CR in the sample, in 90 min, indicates the strong capability of CQDs as a photocatalyst and a sorbent . The mechanism pathway for CR degradation is diagrammatically shown in Figure , and Table reports various types of CQDs produced over the years to degrade CR.…”

“…Having these amines modified CQDs paired up with tungsten dioxide to make a composite, but quite recently in 2023, Nizam et al produced CQDs using rubber seed which is considered to be biomass waste and used it for CR and MB removal and photodegradation. 71 …”

“…A complete discoloration of CR in the sample, in 90 min, indicates the strong capability of CQDs as a photocatalyst and a sorbent. 71 The mechanism pathway for CR degradation is diagrammatically shown in Figure 11 , and Table 3 reports various types of CQDs produced over the years to degrade CR. CR degradation can also be observed in Figure 12 .…”

“… Degradation mechanism pathway of Congo Red (CR) using CQDs. Reprinted with permission from ref ( 71 ). Available under a Creative Commons CC BY license.…”