Study On The Preparation Of Palygorskite-based Composite Materials And Their Adsorption Properties

Freshwater is the basic requirement for the survival of humans and wildlife on earth.Supplying of clean drinking water is a top priority in maintaining a healthy life.Due to intensive industrialization and urbanization,inorganic and organic pollutants have led to the pollution of natural water resources.How to effectively deal with the effects of excessive amounts of heavy metals and organic substances has become a widespread concern.So far,treatment methods for removing different pollutants mainly include precipitation,ion exchange,electrochemistry,membrane filtration technology,adsorbent and so on.In view of the simple operation and strong practicality of the adsorption method,this paper has been designed and synthesized several kinds of inorganic polymer composites with palygorskite of the high specific surface area,low cost,non-toxic and environmental compatibility.A series of composites was mainly used to treat dyes and heavy metal ions in wastewater.The paper mainly did the following work:1.The activated carbon composite materials were carbonized at different ratios of high temperature by using palygorskite and mangosteen shell as raw materials.The morphologies and structures of the materials were characterized by FT-IR,SEM,X-ray powder diffraction?XRD?,and N₂ adsorption-desorption.With five kinds of organic solutions?methylene blue,methyl orange and malachite green,p-nitrophenol?and three kinds of heavy metal ion(Cu²⁺,Pb²⁺and Ni²⁺)as the objects,the composite material adsorption properties were investigated.The comprehensive comparison of the adsorption performance of the composite adsorbent PGS/2MS was optimal.2.The adsorption of methyl orange,p-nitrophenol,Cu²⁺,Pb²⁺and Ni²⁺by PGS/2MS was studied.The effects of pH value,adsorbent dosage,adsorption time,initial concentration and temperature on the adsorption quality were investigated in detail,and the optimal conditions for adsorption were determined.The experimental results showed that the maximum adsorption capacity of the initial concentration of50 mg/L pH 3.0,methyl orange and pH 5.0,p-nitrophenol were 26.4 mg/g and 33.5mg/g under 60 min for 10 mg PGS/2MS at 293 K;The adsorption kinetics indicated that the pseudo-second-order kinetic equation was more suitable to describe the adsorption process of methyl orange and p-nitrophenol and the Freundlich isothermal adsorption equation equation were better simulated.293 K,under the condition of pH5.0 Cu²⁺,Pb²⁺,and Ni²⁺solution with an initial concentration of 50 mg/L,oscillation60 min,10 mg PGS/2MS,the maximum adsorption capacity was 50 mg/g,27.7 mg/g,and 16.2 mg/g,respectively.Kinetic studies had shown that the adsorption of Cu²⁺,Pb²⁺and Ni²⁺were in accordance with the pseudo-second-order kinetic equation by PGS/2MS and the adsorption process of metal ions were mainly chemical adsorption.The results of isothermal experiments show that the adsorption of Cu²⁺and Ni²⁺can be simulated by the Langmuir model,and the adsorption processes were single layer adsorption.3.A series of palygorskite/magnesium oxide composite materials were obtained and calcined in the muffle furnace after mixing the different quality of the palygorskite clay with the precursor solution of MgO.The morphologies and structures of the materials were characterized by Fourier transform infrared spectroscopy?FT-IR?,X-ray powder diffraction?XRD?,scanning electron microscopy?SEM?,EDS and N₂-adsorption desorption.Scanning electron microscopy showed that Rod-shaped palygorskite was loaded on the flower-shaped MgO surface.The specific surface area of the composite was 111.31 m²/g,which is 44.11 m²/g more than that of the palygorskite,and the average pore diameter was 27.34 nm.The larger specific surface area composites have higher adsorption capacities for methyl orange,p-nitrophenol,Cu²⁺,Pb²⁺,and Ni²⁺than that of palygorskite.4.The effects of pH value,adsorbent dosage,adsorption time,initial concentration and temperature were investigated in detail on the adsorption of methyl orange,p-nitrophenol,Cu²⁺,Pb²⁺and Ni²⁺ions on PGS/MgO?mass ratio=9:1?.The optimum adsorption conditions were selected respectively.The experimental results show:293 K,under the condition of pH 4.0,oscillation 60 min,10 mg 10%MgO/PGS,the maximal adsorption of methyl orange and p-nitrophenol solutions at the initial concentration of 50 mg/L was 38.4 mg/g,41.8 mg/g respectively.The adsorption process of methyl orange and p-nitrophenol were suitable for the pseudo-second-order kinetic equation,and the isothermal adsorption model can be simulated with the Freundlich isothermal adsorption equation.In addition,the adsorption of Cu²⁺,Pb²⁺,and Ni²⁺solutions with pH 5.0 initial concentration of 50mg/L for 20 min were 49.7 mg/g,50 mg/g,and 50 mg/g,respectively.The kinetic data of the three ions were all in accordance with the model of pseudo-second-order kinetic.Isothermal adsorption experiments show the Freundlich isothermal model were more suitable for describing the adsorption process of by Cu²⁺,Pb²⁺,and Ni²⁺10%MgO/PGS.