In this work, functionalized CQDs have been synthesized from rice husks through hydrothermal process by varying the amount of Ethylenediamine (EDA) and ascorbic acid as sources of amine group and carboxyl group, respectively. HRTEM images show the formation of functionalized CQDs with sizes less than 10 nm. XRD analysis shows that CQDs have graphitic structure of (002) plane while their thermal stabilities were analyzed using TGA. FTIR analysis of functionalized CQDs reveals the presence of oxygen containing groups which indicates their higher affinity towards cationic binding. UV Visible spectra show highest peak at around 240 nm which corresponds to electronic transition of CC bond. In addition, XPS analysis shows that atomic percentages of carbon and nitrogen increase when using higher amount of ascorbic acid and EDA. Photoluminescence (PL) properties of CQDs indicate that increasing amount of functionalization agent can tune the intensity, with emission in green region wavelength (495−570 nm). Meanwhile, quenching of PL intensity and reduction in AAS absorbance show that carboxyl and amino functionalized CQDs have the potential in detection of cadmium and more than 70 % removal of cadmium from aqueous solution. The cadmium removal fits the pseudo-second order kinetic model and Freundlich isotherm with kinetic rate of 0.0000243 gmg⁻¹ min⁻¹ and maximum adsorption capacity of 332.72 mg/g, respectively.

在这项工作中，通过分别改变作为胺基和羧基来源的乙二胺（EDA）和抗坏血酸的量，通过水热过程从稻壳中合成了功能化的CQD。HRTEM图像显示尺寸小于10 nm的功能化CQD的形成。XRD分析表明，CQD具有（002）面的石墨结构，同时使用TGA分析了它们的热稳定性。FTIR对官能化CQD的分析表明存在含氧基团，这表明它们对阳离子结合的亲和力更高。紫外可见光谱在240 nm附近显示出最高峰，对应于C的电子跃迁C键。此外，XPS分析表明，当使用更高量的抗坏血酸和EDA时，碳和氮的原子百分比会增加。CQD的光致发光（PL）特性表明，随着绿色区域波长（495-570 nm）的发射，功能化剂数量的增加可以调节强度。同时，PL强度的猝灭和AAS吸光度的降低表明，羧基和氨基官能化的CQD具有检测镉的潜力，并且可以从水溶液中去除70％以上的镉。去除镉符合拟二级动力学模型和Freundlich等温线，动力学速率分别为0.0000243 gmg ^-1 min ^-1和最大吸附容量为332.72 mg / g。