High Adsorption MOFs Loaded On PVA-co-PE Nanofiber

As we know,different kinds of dyes are widely used in textile,paper and other industries.Large amount of dyes wastewater will damage the environment and even threaten the human health if the wastewater is discharged directly without any treatment.Therefore,developing an effective,selective and environmental friendly adsorbent is urgent.Because of the high surface area and porosity,multifunctional MOFs is prospected used in many fields.In this paper,MOFs loaded on PVA-co-PE nanofiber hydrogel was prepared as an efficient and highly selectively adsorbent.HKUST-1 crystals was prepared with 1,3,5-Benzenetricarboxylic acid(H3BTC)and copper nitrate trihydrate(Cu(NO3)2·3H2O)by solvent thermal synthesis method.The influences of synthesis condition on the crystal's physical properties including morphology and porous structure characterized by SEM,XRD and ATR were studied.Then,the effects of pH value,concentration of methylene blue(MB)solution and the adsorption time on the adsorption property of HKUST-1were investigated systematically.The adsorption isotherm models and adsorption kinetics equation were detemined further to explore the adsorption mechanism of the HKUST-1 crytals and to investigate the adsorption ability of different types of dyes.The PVA-co-PE nanofibers,Poly(vinyl alcohol),and HKUST-1 crystals were used as raw materials to prepare nanofiber hydrogels and nanofiber/HKUST-1 composite hydrogels in this paper.The optimum mass ratio of nanofiber to PVA was studied according to the removal ability of MB solution.The adsorption characteristics of nanofiber/HKUST-1 hydrogels were investigated by changing the pH values of MB dye solution,adsorption time and the initial concentrations.The adsorption isotherm models and adsorption kinetics equation were also researched.What's more,the adsorption ability of different types of dyes was studied.Firstly,the synthesis condition of MOFs(HKUST-1 crystals)was investigated.Theexperimental results showed that the HKUST-1 crystals with regular octahedron could be prepared in the condition of n(Cu2+/H3BTC)=1.5:1,and 120? reacted for 24 h.Then,the removal properties of MB by HKUST-1 crystals were studied.The results indicated that,the maximum adsorption of MB was 486.78 mg/g at the pH value of 2 and the initial concentration of 600 mg/L with 0.02 g adsorbent.HKUST-1 crystals adsorption isotherm fitted in Langmuir model,and the adsorption process followed the pseudo-second order kinetic model.Secondly,the preparation conditions of the nanofiber hydrogels for the removal of MB were studied.The experimental results showed that with solution weight ratios of PVA-co-PE nanofiber to PVA 1:8,the adsorption properties of nanofiber hydrogels reached the best.Compared to unloaded nanofiber hydrogels,0.02 g HKUST-1 loaded nanofiber hydrogels had good adsorption capability and removal rate.Then the removal properties of MB using nanofiber/ HKUST-1hydrogels were studied.The results showed that the maximum adsorption of MB was 107.93 mg/g at the p H value of 2 and the initial concentration of 600 mg/L.Experiment data showed that the nanofiber/HKUST-1 hydrogels corresponded well with the Langmuir isotherm and the pseudo-second order kinetic model.Finally,the adsorb abilities of different types of dyes were studied.The results indicated that HKUST-1 crystals and nanofiber/HKUST-1 hydrogels had highly selective adsorption towards rhodamine B,methyl violet cationic dyes and there were poor adsorption of reactive yellow,reactive red and argacid blue N-2G anionic dyes.