Preparation And Performance Of Non-woven Basalt Fiber-based Organic-inorganic Composite Boron Absorbent Material

Nonwoven basalt fibers(NBF)with excellent mechanical properties,water resistance,acid and alkali resistance,environment friendly and low price was selected as the matrix.Polyhydroxy N-Methyl-D-glucamine(NMDG)is an adsorption functional group of boron.In the present work,the pretreatment method(NBF→NBF+the coupling agent→NBF+the coupling agent+NMDG)and precursor method(NMDG+the coupling agent→the precursor→the precursor on NBF)were developed to prepare the organic-inorganic composite boron adsorbent material by loading NMDG on nonwoven basalt fiber.FESEM,EA,EDS,FTIR and H NMR were employed to characterize the properties and structure of the composite boron adsorbents.The preparation of composite boron adsorption materials by pretreatment method show that the best effect of coupling effect of the coupling agents,y-glycidoxypropyltrimethoxysilane(GPTMS)and y-chloropropyltrimethoxy-silane(CPTMS),is on the NBF acid-etched 12 h.The NMDG is.evenly loaded onto the coupling agent/NBF surface.As a result,the boron adsorption performance of NBF-GPTMS-NMDG is better than that of NBF-CPTMS-NMDG.In precursor method,the composite boron adsorption material NMDG-GPTMS-NBF was obtained by loading the NMDG-GPTMS precursor on the surface of acid-etched NFB.In NMDG-GPTMS-NBF composite boron adsorption material,the precursor layer is uniform and without any cracking and falling off,and the distribution of NMDG is well-proportioned.Besides,NMDG-GPTMS-NBF prepared by the precursor method has excellent mechanical properties and the boron adsorption performance,which is superior to that of the NBF-GPTMS-NMDG prepared by the pretreatment method.In order to improve the loading of NMDG-GPTMS,NMDG-GPTMS was catalyzed by HCl-C2H5OH and the active SiO2 film was coated on NBF surface,respectively.The results showed that the NMDG loading of NMDG-GPTMS-NBF after catalysis increased significantly,and the boron adsorption capacity of the material was further improved.After the addition of the SiO2 intermediate layer,a large number of inhomogeneous precursor loading occurs on the surface of the fibers,and the connection between the filaments of the fibers occurred.Furthermore,the amount of the NMDG loading and boron adsorbed in the composite material are greatly increased,but the stability of the material was deteriorated.The result of the performance of NMDG-GPTMS-NBF indicate that the boron adsorption capacity increases with the increase of the solution pH value,reaches the maximum when the pH value is 9,and then gradually decreases.Na+ and Li+promoted the boron adsorption at a low concentration and inhibited it at a high concentration.The promotion of Mg2+ on the boron adsorption was positively correlated with its concentration.When the pH,temperature and initial boron concentration is 7,35℃ and 0.18 mol/L,respectively,the maximum boron adsorption capacity reaches,1.64 mmol/g.Meanwhile,it has a good recycling ability.The boron adsorption process consistent with Freundlich isothermal adsorption model,the adsorption process is non-unifonn.The adsorption equilibrium time was 40 min,showing a good adsorption efficiency.The boron adsorption process conforms to the second-order kinetic model,that is,it is chemical adsorption.