多孔陶瓷膜用于碳量子点的分离与纯化

Carbon quantum dots with uniform size distribution have broad application prospects in the fields of optoelectronic devices, ion detection, nano-sensors, biological imaging and catalyst's due to their good optoelectronic properties. An "ultrafiltration-nanofiltration" bi-membrane method was proposed for the separation and purification of carbon quantum dots (CQDs). The molecular weight cutoff (MWCO) of ceramic ultrafiltration (UF) and nanofiltration (NF) membranes was 2000 and 800 andthe corresponding Stocks-Einstein sizes were 2.3 nm and 1.4 nm, respectively. The pure waterflux of UF and NF membranes were 140 and70L•(m²•h)^-1, respectively. The effects of pH on the fluorescence intensity and particle size distribution of CQDswere studied. At pH =3, the carbon quantum dots were well dispersed and the fluorescence intensity is high. The ceramic UF membrane could effectively reject the large grained impurities. The average size of the CQDsinthe permeate was about 2 nm with good dispersion and no agglomeration. Ceramic NF membrane played a great role in retention properties to CQDs. Small molecular impurities could be further removed in the concentration and washing process by using NF membrane. After bi-membrane treatment, the emission spectrum changed from multimodal to monomodal distribution, and the peak width narrowed. The luminouspurity of CQDswas significantly improved.