Construction Of Montmorillonite-Based Adsorption Materials And Study On Their Adsorption Kinetics And Thermodynamics

Montmorillonite,natural clay mineral,has excellent properties,abundant reserves and low price,so it’s often applied as an adsorbent material for water environment repairment.However,the untreated natural montmorillonite has very poor affinity for organic and anionic pollutants,so it needs to be modified.In this paper,three montmorillonite-based adsorption materials have been developed for removing lead,potassium dihydrogen phosphate,benzothiazole（BTH）,and 2-hydroxylbenzothiazole（2-OH-BTH）contaminants in water.The details are as follows:1.A series of protonated graphite-phase carbonitride/montmorillonite composites（g-C₃N₄/Mt）were successfully prepared by utilizing acid-activated montmorillonite（Na-AMt）as carrier and XRD,FT-IR,TG,BET,XPS and SEM were used to characterize its structure and the adsorption effects of the materials on Pb（II）and phosphate were studied.The results showed that:（1）After composited,its basic skeleton was not damaged and its surface structure became more loose and rough,and the surface active groups increased,which created favorable conditions for adsorption;（2）g-C₃N₄/Mt had a greater improvement in the adsorption performance of Pb（II）and phosphate than single material.Adsorption equilibrium can be reached in about 30 minutes,and the adsorption process conformed well to the Langumir isothermal adsorption and pseudo-second-order kinetic model.At the same time,the adsorption process was an endothermic reaction;（3）The main adsorption mechanism of g-C₃N₄/Mt for Pb（II）was cation exchange and charge attraction;the main adsorption mechanism for phosphate was charge attraction.2.A series of organic modified montmorillonite materials（CPMMt）were successfully prepared by inserting amphoteric surfactant cationic panthenol（CP）into the interlayer of Na-AMt using ion exchange and its structure was characterized by XRD,FT-IR,TG,BET,etc;at the same time,the adsorption effects of CPMMt on BTH and 2-OH-BTH were investigated.The results showed that:（1）After organically modified,its basic skeleton was not damaged and its surface structure became more rough,and the surface positive charge and hydrophobicity increased,which created favorable conditions for adsorption;（2）CPMMt had greater adsorption performance for BTH and 2-OH-BTH than Na-AMt.Adsorption process can reach equilibrium in about 60 min,and the adsorption process conformed to Langumir isotherm adsorption and pseudo-second-orderkinetic model,while the adsorption process was spontaneous and exothermic reaction;（3）The main adsorption mechanism of CPMMt for BTH and 2-OH-BTH was charge attraction and hydrophobic interaction.3.In order to further increase the adsorption capacity of Na-AMt for BTH and2-OH-BTH,a series of inorganic-organic modified montmorillonite（Fe-CPMMt）were synthesized with hydroxyl iron,CP,and Na-AMt by hydrothermal method,and its structure was characterized by XRD,FT-IR,FT-IR,TG and BET.The results showed that:（1）After inorganic-organic modification,the basic skeleton of montmorillonite was not damaged,the surface structure became more rough,the surface positive charge and hydrophobicity increased,the specific surface area and thermal stability of the material than CPMMt also improved,which created favorable conditions for adsorption;（2）Fe-CPMMt was more favorable than Na-AMt and CPMMt to adsorb BTH,was less favorable than CPMMt to adsorb 2-OH-BTH.The adsorption process can reach equilibrium in about 60minutes.Adsorption process conformed to Langumir isotherm adsorption and pseudo-second-orderkinetic model,while the adsorption process was spontaneous and exothermic reaction;（3）The main adsorption mechanism of Fe-CPMMt for BTH was charge attraction and hydrophobic interaction;the main adsorption mechanism for 2-OH-BTH was hydrophobic interaction.