Adsorption Dye Using Montmorillonite Modified By Peptide Surfactant Prepared From Waste Leather

With the development of Chinese economy and the improvement of citizen's living standards,the pollution of dye wastewater has become an increasingly serious problem.Montmorillonite,as an adsorbent with good adsorption capacity,is widely used in the treatment of dyes.However,The hydrophilic nature of the surface of montmorillonite makes the dye adsorption of natural montmorillonite relatively low.It is necessary to change hydrophilic properties through a certain modification method.Peptide-based surfactants synthesized by peptide can not only improve the hydrophilicity of montmorillonite,but also provide a large number of active functional groups such as-NH₃ and-COOH for dye treatment.In this paper,peptide peptide hydrolysate?CH?prepared from chrome-containing waste leather shavings is used as raw material to prepare three different types of peptide surfactants,namely peptide acyl surfactant,peptide silicon-based surfactant and peptide surfactant compound solution.Montmorillonite was modified by the best surface-active peptide surfactant,and further exploring the structure of the composite.cationic methylene blue?MB?is adsorbed by modify montmorillonite.The main research contents and results are as follows:?1?According to the Schotten-Baumann reaction,peptide acyl surfactants were synthesized by acid chloride and CH.Based on the conversion rate of free amino,peptide acyl surfactants was optimized the conditions such as pH value,amount of ethyl acetate,reaction temperature and different carbon chain lengths.Characterization such as surface tension,foamability and foam stability were carried out.The results showed that the optimal conditions for the synthesis of peptide acyl surfactant:pH value 9.0,ethyl acetate to lauroyl chloride volume ratio of 2:1,reaction temperature of 60?,acyl chloride carbon chain length of 12 lauroyl conversion.The highest conversion rate of free amino is 77.9%,the surface tension is 40.3 mN/m,and the foam loss rate is12.5%.?2?According to the reaction of free amino groups and epoxy silicon groups,peptide silicon-based surfactants are synthesized by KH560 and CH.Based on the conversion rate of free amino groups,peptide silicon-based surfactants was optimize the conditions such as pH,reaction time,the amount of KH560,the amount of acetone,and the reaction temperature.Characterization such as surface tension,foamability and foam stability were carried out.The results show that the optimal conditions for the synthesis of peptide-based silicon-based surfactants:pH value 9.0,the ratio of the amount of free amino groups to KH560 is 1:1.4,the volume ratio of KH560 to acetone is 3:1,and the reaction temperature is 40?,the reaction time is 6 h.Under this condition,The highest conversion rate of free amino is 56.10%,the surface tension is 52.2 mN/m,and the foam loss rate is 33.1%.?3?Peptide surfactant compound solution was obtained by combining CH with anionic surfactant?sodium dodecyl sulfate,SDS?,cationic surfactant?cetyltrimethylammonium bromide,CTAB?and non-ionic surfactant?polyethylenedioxide alcohol octyl phenyl ether,Triton X-100?.Based on the surface tension,foamability,foam stability and foam morphology of the compounding solution.It was optimized by the optimal ratio of CH to different ionic surfactants.Based on the surface tension and foam loss rate,by comparing the peptide acyl surfactant,peptide silicon-based surfactant and peptide surfactant compound solution,it was obtained the best peptide surfactant.The results show that the optimal surface activity of CH/CTAB,CH/SDS,and CH/Triton X-100 are the amount of CH added is 30%,30%,and 50%,respectively.The surface tension of the CH/SDS compounding solution is 36.5 mN/m,and the foam loss rate is 3.7%,which is the best surface-active peptide surfactant.?4?It was obtained that peptide modified montmorillonite?peptide/dodecyl sulfate-sodium-octadecyltrimethylammonium bromide-montmorillonite,CH/SDS-STAB-MMT?composite material by blending sodium octadecyltrimethylammonium bromide modified montmorillonite?STAB-MMT?with CH/SDS compound solution.The surface properties of CH/SDS-STAB-MMT were characterized by X-ray diffraction analysis?XRD?,scanning electron microscope?SEM?,Fourier transform infrared spectroscopy?FTIR?and specific surface area analysis?BET?.MB initial concentration,temperature and time were explored to optimize the conditions for adsorbing MB.The adsorption kinetics,adsorption isotherms and adsorption thermodynamics are studied,and the mechanism of MB adsorption by CH/SDS-STAB-MMT is further explained.When the initial concentration was 500 mg/L,the adsorption time was 60 min,and the temperature was 30?,the adsorption amount of CH/SDS-STAB-MMT to methylene blue was 160.82 mg/g.The adsorption kinetics and isotherm models follow pseudo-secondary and Langmuir models,respectively.Thermodynamic studies indicate that the adsorption of MB by CH/SDS-STAB-MMT is an endothermic,spontaneous physical adsorption process.The adsorption mechanism of CH/SDS-STAB-MMT to methylene blue includes hydrophobic interaction,hydrogen bonding,electrostatic force,van der Waals force,and ion exchange force.