The Preparation And Application Of MHCF (LDHs)/carbon Fibers Composite

2D-structured polyglycidyl methacrylate precursor film was grafted at surface of carbon fibers（CFs）by electrochemically mediated atom transfer radical method（eATRP）,and L-aspartic acid was modified in situ to form 3D structure of chelating carbon fiber composites（CCFs）;Ni-Al layered double hydroxides（Ni/Al-LDHs）and nickel hexacyanoferrates（NiHCF）were sequentially deposited in situ with the formation of NiHCF/NiAl-LDHs/CCFs,which was used to recover Cs⁺in aqueous solution.NiHCF/NiAl-LDHs/CCFs were characterized by FT-IR,XRD,SEM and electrochemical techniques.The CCFs displayed 3D structure,the Ni/Al-LDHs showed porous flower-like structures,and the NiHCF are embedded in the layer of the Ni/Al-LDHs.The uptake of NiHCF/NiAl-LDHs/CCFs towards Cs⁺in aqueous solution was investigated by static adsorption method.Under the optimal conditions（pH 6,45°C,12 h）,the maximum adsorption capacity was 42.69 mg/g.The recovery mechanism of NiHCF/NiAl-LDHs/CCFs towards Cs⁺in aqueous solution was studied during two-step membrane-free electrochemically switched ion exchange processes（ESIX）.In the adsorption process,under the optimal conditions（pH 6,-0.4 V,4 h）,the maximum adsorption capacity was 41.87 mg/g,the adsorption time was shortened 2/3 compared to that of static adsorption method with a significant efficiency.In the desorption process,under the optimal conditions（pH 7,-0.1¹.2 V,120 cycles）,85%of Cs⁺could be desorbed from the NiHCF/NiAl-LDHs/CCFs-Cs⁺by XPS analysis,the electrodes could be regenerated conveniently.Under the optimal conditions,NiHCF/NiAl-LDHs/CCFs could be used to the recovery of Cs⁺from salt lake brine.Bismuth hexacyanoferrate-modified graphene coated carbon fibers composite（BiHCF/GN/CFs）was prepared simultaneously as a multifunctional air diffusion electrode and heterogeneous photo-electro-Fenton catalyst,in which the BiHCF was used as the source of Fe²⁺and photo catalyst instead of a solution iron salt in classical Fenton.The formation of BiHCF/GN/CFs was characterized by SEM,XRD,FT-IR and electrochemical methods.The photo-electro catalysis of BiHCF/GN/CFs towards hydroxyl radical（?OH）was investigated during photo-electro-Fenton process with methyl orange（MO）as a model pollutant.Because of the excellent heterogeneous photo-electro-catalyst,the photo-electro-Fenton process was used for the efficient degradation of MO,where?OH could be vigorously photo-electro-generated from O₂ reduction at BiHCF/GN/CFs in a potential range of-0.5^-0.9 V under visible light.Benefited from the high?OH generating rate（4.88¹0.34 mM/h）at BiHCF/GN/CFs,MO（200 mg/L）could be rapidly degraded with first-order kinetic constants of 5.538⁶.29 h^-1 at pH 4,0.1 M Na₂SO₄,and the removal of MO was achieved to 95%within 35 min.