Ting Wu,Xiang Cai,Shaozao Tan,Hongye Li,Jiesheng Liu,Weidong Yang
In order to explore the potential of graphene (G) in removal of hazardous chemicals in waste water, chemically reduced graphene oxide was employed as the adsorbent and the adsorption characteristics of graphene toward acrylonitrile (AN), p-toluenesulfonic acid (p-TA), 1-naphthalenesulfonic acid (1-NA) and methyl blue (MB) were evaluated under laboratory conditions. The results showed that the organic chemicals with larger molecule size and more benzene rings possessed a higher adsorption speed and a higher maximum adsorption capacity on G. The maximum adsorption capacities of p-TA, 1-NA and MB on G are ∼1.43 g/g G, ∼1.46 g/g G and ∼1.52 g/g G at 30 °C, respectively, which are the highest values of p-TA, 1-NA or MB adsorption on different kinds of today's nanomaterials. Under the maximum adsorption capacity, the absorption quantity of MB on G was dependent on the initial concentration of MB, and higher temperature could facilitate the adsorption process. The G efficiency remains almost constant during the first five cycles of the adsorption–desorption process. In addition, the fluorescence spectra implied that the adsorption of MB on G was a π–π stacking adsorption process. In conclusion, the G could serve as a promising adsorbent for the removal of chemicals containing benzene rings in waste water.
Ping Zhang,Ling Li,Yun Zhao,Zeyun Tian,Yumei Qin,Jun Lu
The fluorescent dye 8-anilino-1-naphthalenesulfonate (ANS) is a widely used fluorescent probe molecule for biochemistry analysis. This paper reported the fabrication of ANS/layered double hydroxide nanosheets (ANS/LDH)n ultrathin films (UTFs) via the layer-by-layer small anion assembly technique based on electrostatic interaction and two possible weak interactions: hydrogen-bond and induced electrostatic interactions between ANS and positive-charged LDH nanosheets. The obtained UTFs show a long-range-ordered periodic layered stacking structure and weak fluorescence in dry air or water, but it split into three narrow strong peaks in a weak polarity environment induced by the two-dimensional (2D) confinement effect of the LDH laminate; the fluorescence intensity increases with decreasing the solvent polarity, concomitant with the blue shift of the emission peaks, which show good sensoring reversibility. Meanwhile, the UTFs exhibit selective fluorescence enhancement to the bovine serum albumin (BSA)-like protein biomolecules, and the rate of fluorescence enhancement with the protein concentration is significantly different with the different protein aggregate states. The (ANS/LDH)n UTF has the potential to be a novel type of biological flourescence sensor material.
Jinshui Liu,Meijiao Xu,Bin Wang,Zihan Zhou,Lizhen Wang
An easy-to-use fluorescent probe for detecting protamines was developed. Protamines are detected using the probe because of competitive interactions of polyacrylic acid modified with sodium 4-amino-1-naphthalenesulfonate (ANS-PAA) with protamines and aminated graphene oxide (GO-NH2). The ANS-PAA fluorescence was effectively quenched by the GO-NH2, the high quenching efficiency being caused by the ANS-PAA becoming non-covalently bound to the GO-NH2 surface through electrostatic interactions, forming a ANS-PAA/GO-NH2 complex. Adding protamines recovered the fluorescence of the ANS-PAA/GO-NH2 complex. This recovery was due to the positively charged protamines removing ANS-PAA from the GO-NH2 surfaces and forming ANS-PAA/protamine complexes. Displacement of GO-NH2 by protamines gave a high fluorescence recovery efficiency. Under optimal conditions, the fluorescence intensity when protamines were added was proportional to the protamine concentration over the range 0 to 6.0 μg mL−1. The detection limit was 0.4 μg mL−1. This approach offers a new quantitative method for determining protamines.
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