Preparation And Application Of Bentonite Composites Modified By Nitrogen-containing Compounds And Complexes

The resource of Water is very scarce in China.In recent years,it is polluted seriously with the development of industry and agriculture.Dye wastewater have strong chroma and is difficult to decompose.And it reduces the light transmittance of water so that can affect aquatic organisms to survive.So the pollution of dye is the most outstanding question.This is an urgent need to find some economic and efficient water treatment method.Bentonite is a kind of natural non-toxic mineral materials,and it is abundant reserves and low cost advantage.It can be used as adsorbent for sewage treatment.In this paper,we prepared bentonite composites with excellent properties through the different modifier and modified method.We also explore decoloration efficiency and adsorption-desorption mechanism that the composite materials use for dealing with cationic or anionic dyes.The research contents and results are as follows:(1)By ion exchange,coordination synthesis and complex directly intercalatin method,the imidazole metal complex had been encapsulated in bentonite([M(?)-MZ/BNT ](M= Cu,Zn,Ni,MZ = imidazole)for short),(2E)-2-[4-(Diethylamino)-2-hydroxybenzylidene]hydrazinecarbothioamide(DSD,for short)and 4-hydroxy-3-methoxybenzaldehyde thiosemicarbazone(DVN,for short)lanthanum complex had been encapsulated in bentonite([La(?)-DSD/BNT] and[La(?)-DVN/BNT] for short).Trihydrazine triazine had been encapsulated in bentonite([TDT/BNT] for short).In addition,we prepared the cation-nonionic surfactants modified bentonite composites([DSD/CTMAB/BNT] and([NOD/CTMAB/BNT](NOD= Nonanedihydrazide)for short)by composite modification approach.Which is rarely reported in the literature.(2)The composite materials were characterized by XRD,FT-IR and TGA-DTA analysis.The layer spacing of [Zn(?)-MZ/BNT] composite material is 1.78 nm,increased by 0.51 nm.The layer spacing of [La(?)-DSD-BNT],[La(?)-DVN/BNT],[DSD/CTMAB/BNT],[NOD/CTMAB/BNT] and [TDT-BNT] composites increased by 0.63 nm,0.36 nm,1.4 nm,1.19 nm and 0.59 nm,respectively.By FT-IR analysis,the spectra of the composite material has characteristic spectral bands in the corresponding organic compounds.TGA spectra showed that there is an obvious exothermic peak in composite materials.In TGA-DTA analysis,modifier successfully is encapsulated into the interlayer of bentonite.(3)We emphatically discussed the four kinds of composite materials for dye adsorption.The results showed that: the removal efficiency of [Zn(?)-MZ/BNT] to100 mg·L-1 Congo red is more than 92%;the removal efficiency of[La(?)-DVN/BNT] to 100 mg·L-1 methylene blue is more than 95%;the removal efficiency of [DSD/CTMAB/BNT] to 150 mg·L-1 methylene blue is more than 95%;the removal efficiency of [TDT/BNT] to 50 mg·L-1 rhodamine B is more than 85%.(4)We used adsorption isotherm and adsorption kinetics fitting,the results showed that the [Zn(?)-MZ/BNT] to Congo red,[La(?)-DVN/BNT] and[DSD/CTMAB/BNT] to methylene blue,[TDT/BNT] composite material to rhodamine B can better conform to the Langmuir isotherm adsorption model.Adsorption behavior accord with pseudo-second-order model.Thermodynamic parameters indicated that Congo red on Zn(?)-MZ/BNT],methylene blue on La(?)-DVN/BNT,rhodamine B on TDT/BNT is a spontaneous and endothermic process.The chaotic degree of system increase in the process.