Efficient adsorption removal and adsorption mechanism of basic fuchsin by recyclable Fe_(3)O_(4)@CD magnetic microspheres

Excessive discharge of dye wastewater has brought serious harm to human health and the environment.In this paper,a magnetic absorbent,ferroferric oxide@β-cyclodextrin(Fe_(3)O_(4)@CD),was prepared for the efficient adsorption removal of basic fuchsin(BF)from dye wastewater,based on the special amphiphilicity ofβ-CD and the strong magnetism of Fe_(3)O_(4).A series of influence factors including the initial dye concentration,adsorbent dosage,temperature and pH were investigated,as well as the adsorption mechanism.The results show that Fe_(3)O_(4)@CD has the best adsorption and removal effect on BF dye at room temperature and neutral pH,when the initial concentration of dye is 25 mg/L and the adsorbent dosage is 100 mg.The adsorption behavior conforms to the pseudo-second-order kinetics and the Langmuir adsorption isotherm,and the adsorption process is spontaneously endothermic.Fe_(3)O_(4)@CD adsorbed with BF dye can be rapidly separated under an external magnetic field and then easily regenerated by HCl treatment.After 5 times of recycling,the removal rate of the prepared magnetic composite on BF dye is kept above 75%.This work will provide an economic and eco-friendly technology for the treatment of the actual dye wastewater.

Spectroscopic and Electrochemical Studies of the Interaction Between Fuchsin Basic and DNA

Visible spectroscopic and electrochemical methods were used to study the interactions between DNA and fuchsin basic（FB）. FB has an irreversible electro-oxidation peak in 5 mmol/L Tris-HCl buffer solution at pH = 7.4 on a glassy carbon electrode（GCE）. After adding certain concentration of dsDNA, the oxidation peak current of FB decreases, but the peak potential hardly changes. The visible absorption spectroscopic study shows that the binding mode of FB to dsDNA is intercalative binding and electrostatic binding when the ratio of the concentration of dsDNA to FB is smaller than 0. 2, and anew substance, which produces a new absorption peak, is obtained via a covalent binding between dsDNA and FB apart from intercalative binding and electrostatic binding when the ratio of the concentration of dsDNA to FB is larger than 0. 2. The visible absorption spectra varies no longer when the ratio of the concentration of dsDNA＇to FB is larger than 1.5. A mean binding ratio of dsDNA to FB was determined to be 1.4： 1, suggesting that two complexes FB-dsDNA and FB-2dsDNA be formed. The interaction between FB and ssDNA was only electrostatic binding. The more powerful interaction of FB with dsDNA than with ssDNA may be applied for the recognition of dsDNA and ssDNA, and in DNA biosensor as hybridization indicator.

S-doped graphene quantum dots as nanophotocatalyst for visible light degradation

Graphene quantum dots （GODs） recently emerge as the new and appealing nanophotocatalyst because of their low-cost, environmental compatibility and the ability to facilitate the charge migration and prolong the charge lifetimes. In this work, a visible photocatalyst of S-doped graphene quantum dots （S-GQDs） was prepared by a facile hydrothermal synthesis using 1,3,6-trinitropyrene and Na2S as precursors. The well crystallization and monodispersity as well as the chemical environment of S-GQDs were characterized by transmission electron microscopy, atom force microscopy and X-ray photoelectron spectrum. A superior photocatalytic performance of S-GQDs was demonstrated for degradation of basic fuchsin under visible light irradiation. Furthermore, the possible photocatalytic mechanism was proposed based on the trapping experiments of active species.