Modified Peanut Shells On The Adsorption Characteristics Of Heavy Metal Ions In Water And Dyes

Modified peanut shell by using peanut shells as raw material with citric acid and formaldehyde as modifiers.The study went on its impact on Pb²⁺,Cr(Ⅵ),methylene blue's adsorptive properties and adsorptive mechanism.The results showed that 10g of peanut shell flour is added to 250mL 0.6mol·L^-1 citric acid solution,heated at 70℃refluxed 4h.After leached,washed,dried,citric acid modified peanut shell was prepared.The best conditions of using this modified peanut shell absorbing Pb²⁺ are as follows:treat 50 mg·L^-1 of the Pb²⁺ solution of 50 mL,using 1.0g of modified peanut shell at 4.5 pH.after stirring absorbing 60min,the adsorptive rate reaches 96.8%,after absorption,peanut shell was eluted with 0.5mol·L^-1 solution of HCl,absorptive actions are consistent with the Langmuir adsorption isotherm equation,the theoretical saturated adsorption amount is 5.42 mg·g^-1,the adsorption process agrees with the proposed kinetic modelⅡ,absorption takes place mainly in ion exchange and complexation reactions.10g peanut shell flours is added to 50mL formaldehyde solution and 200mL 0.1mol·L^-1 solution of H₂SO₄,heated 60℃,and refluxed 4h,after leached,dried and washed formaldehyde modified peanut shell was prepared,the best conditions of using this modified peanut shells adsorbing Cr(Ⅵ) are as follows:treat 30 mg·L^-1 of Cr(Ⅵ) solution of 50 m L,using 1.0g of modified peanut shell,at 2.0 pH, oscillating absorption 100min,the adsorptive rate is up to 98.4%,after the absorption, peanut shell was eluted with 0.1mol·L^-1 solution of NaOH;absorptive actions are consistent with the Freundlich adsorption isotherm equation,the theoretical saturated adsorptive amount is 4.46 mg·g^-1,the adsorptive process is consistent with the two power study model,the adsorption happens mainly in electrostatic gravitational.The best conditions of formaldehyde modified peanut shell absorbing methylene blue are as follows:treat 50 mg·L^-1 solution of methylene blue of 50 mL,using 1.0g of modified peanut shell,at 4.18～10.0 pH,oscillating absorption 100min,the adsorptive rate gets up to 96.8～97.7%,after the absorbing peanut shell is eluted with 3mol·L^-1 solution of H₂SO₄;absorptive behavior are in line with the Langmuir and Freundlich adsorption isotherm equation,the theoretical saturated adsorptive amount is 7.18 mg·g^-1,the adsorptive process is in line with the proposed kinetic modelⅡ, the role of a static gravitational absorption lies in ion exchange-based.Through the modification,peanut shell's active ingredients are not only remained,to stop the dissolution of non-ferrous material,but also the physical structure of peanut shells and chemical stability for use are improved in wastewater treatment,which can significantly reduce treatment costs. Besides,people can improve the comprehensive utilization of the value of peanuts,there are broad prospects for development.