Bio synthesis of carbon quantum dots from lemon juice and study of its applications

Abstract

Carbon quantum dots (CQDs) are the latest generation of carbon nano materials in applications with several attractive properties. In this study, is used lemon as a natural source is the third Citrus species most widely cultivated world wide. Lemon fruits' health benefits are undeniable and scientifically established to help prevent cancer, cardiovascular disease, high blood glucose , cholesterol levels, obesity and has been related these benefits its high amount content of bioactive elements such as dietary fibers, polyphenols, micronutrients, vitamins, acids, mineral salts, essential oils, ascorbic acid, antioxidants substances, and antimicrobials for preparing the introduced carbon quantum dots powder (CQDs) using the one-pot simple hydrothermal method, because this method is considered safe, fast, and inexpensive when compared to chemical and physical methods, which are polluting for the environment, have high costs, and require a lot of energy to complete. Transmission electron microscopy (TEM),Scanning electron microscope (SEM), X-ray diffraction XRD, Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis), were utilized to explore the morphology, chemical content, and spectroscopy properties for carbon quantum dots (CQDs). Where transmission electron microscopy analysis showed that the CQDs are approximately spherical and have nearly uniform dispersion with a diameter of (2-8) nm, the images of the scanning electron microscope display nanoparticles with the average daimeter (5 - 12) nm .The UV-Visibie spectra showed bands around 288 nm for CQDs, and the infrared absorption spectrum showed various peaks ranging from (400 - 4000) IX cm -1 used to identify the functional groups responsible for reducing and capping of CQDs. The applied of carbon quantum dots are investigated The antibacterial effectiveness of CQDs was investigated against Gram positive bacteria such as Staphylococcus lentus, Enterococcus faecalis, Kokerococcus Kristina, and Staphylococcus aureus, as well as Gram negative bacteria such as Escherichia.coli stander, Escherichia coli, and Pseudomonas. The results showed that CQDs exhibited better antibacterial efficiency against Kokerococcus Kristina (with inhibition zone was 35mm) comparing to other bacterial. The sensitivity parameter , reaction time and recovery time of the manufactured CQDs gas sensor detector, is determined using NO2 and NH3 gases with different temperatures (200,250,300) o C .The sensitivity factor (S %) at various temperatures calculated which was found to be around 79 % (200 o C) and 22 % (300 o C) for NO2 and NH3, respectively. The detection time were equal to 23.35 s for NO2 gas and 33 s for NH3 gas. the recovery time for NO2 was calculated as 11.93 s and the response time was 14.7s at 200 C. while the response time for NH3 gas was 11.21 s and the recovery time was 6.11 s at 250 o C. These temperatures were chosen due to the fact that the CQD sensors was optimal at these degrees. Hydrophilic & Hydrophobic of carbon quantum dots were measured by contact angle system. The contact angle for CQDs is 9.534o reffering that CQDs have the possess high water solubility