Study Of Sr²⁺、Co²⁺ Adsorption On Organo-montmorillonites

That developing a new, efficiency and low-cost adsorption materials is one of theimportant research heats now. And montmorillonite, as one of the2:1clay, with a variety ofadvantages such as large surface area, excellent adsorption property and high content, iswidely applied to the remediation of polluted environment. As one of silicon surfactant, silaneowes more advantages than other organic surfactants. With special group in molecule, itscoupling function would lead to well remediation in heavy metal. Thus, alkyl surfactants（SDS,HDTMAB） and silicon surfactants are used to prepare different organo-Mts. XRD, XRF,FTIR,BET and SEM are used to charac terize the as-products. These materials are applied todeal with wastewater with Sr（Ⅱ） and Co²⁺.The prepared materials include SDS-Mt, HDTMAB-Mt and APTES-Mts. The results ofcharacterization showed that the organic items have been intercalated into the interlayer ofCa-Mt, and the d001of APTES-Mt increases with more APTES. The decrease of surface areaof these organo-Mts and the increase of pore diameter stated that the organic modifiers existedmostly on the surface of Ca-Mt. After modification, the pHZPCof APTES-Mt was apparent,and that of HDTMAB-Mt appeared in small pH condition, which stated that more APTESexisting on Ca-Mt.The adsorption results of Sr（Ⅱ） by organo-Mts showed that APTES-Mt and SDS-Mtadsorbed more than the original Ca-Mt, while the opposite for HDTMAB-M t.Pseudo-second-order would fit well with adsorption items on all materials （R²>0.99, exceptHDTMAB-Mt）. Isotherm studies demonstrated that Langmuir and DKR model fitted theadsorption on SDS-Mt well, while Freundlich fitted well with that of Ca-Mt and APTES-Mt.The adsorption capacity increased with increase of pH, temperature and quantity of modifier.The impact of the existing ions followed with the order: H₂PO₄^->CH₃COO^-≈NO₃^->Cl^->SO₄^2-.The desorption experiments indicated that APTES-Mt, with low desorption capacity, wouldhave good application value. Charac terization and adsorption results demonstrated that ionexchange was the major adsorption mechanism for Sr（Ⅱ） adsorption on Ca-Mt, ion exchangeand surface adsorption for that on SDS-Mt and HDTMAB-Mt, while ligand adsorption onAPTES-Mt. Well adsorption of Co²⁺on APTES-Mt was observed. The adsorption fitted well todifferent kinetic studies on materials with different capacity of APTES, while that would befitted well with Freundlich model. pH and modifier dosage would impact the adsorption, andthe adsorption mechanisms were the same with that of Sr（Ⅱ） adsorption.