Preparation of coal kaolinite composites and study of adsorption properties

Pb(Ⅱ) in industrial wastewater and coal-based solid waste can cause great damage to the ecological environment, and it is of great significance to study the efficient removal technology of Pb(Ⅱ) and the high-value utilization of coal-based solid waste. In this paper, we propose to use modified coal-based kaolinite grafted with chitosan novel composite material CK-CTAC/CTS as the adsorbent to realize the removal of Pb(Ⅱ) from wastewater by adsorption method. Coal kaolinite (RK) was used as raw material, dimethyl sulfoxide (DMSO), methanol (MeOH) and cetyltrimethylammonium chloride (CTAC) were used as the intercalating agents, and modified kaolinite (CK-CTAC) was obtained by three times intercalation, and CK-CTAC/CTS composite was prepared by grafting chitosan (CTS) through the copolymerization reaction, and the batch experimental method was used to study the Pb(II) XRD, SEM and BET analyses showed that the intercalation rates of CK-D, CK-M and CK-CTAC reached 93.8%, 75.1% and 66.5%, respectively, and the morphology did not change significantly before and after the intercalation of CK-D and CK-M, while the large molecular structure of CTAC and the energy input of ultrasonic instrument changed the interlayer morphology of kaolinite into tubular, with an increase in pore space and a 4-fold increase in surface area compared with that of the CK-CTAC. XPS and FTIR results showed that CK-CTAC/CTS has rich functional groups, which can effectively adsorb Pb(II), and the adsorption equilibrium was approached after 100 min at a solution pH of 6 at 25 ℃. The excellent spatial structure and exposed functional groups of modified kaolinite provided more active sites for adsorption, and the abundant amino and hydroxyl groups of chitosan could chelate and adsorb Pb(II), which synergistically promoted the adsorption performance of the composites higher than that of chitosan or kaolinite alone. The adsorption kinetics and thermodynamics showed that the adsorption of Pb(II) ions by the composites conformed to the quasi-secondary kinetic model and Langmuir isotherm model, and it was a monomolecular-layer, chemisorption-dominated, heat-absorbing and spontaneous process with a maximum equilibrium adsorption capacity of 195.37 mg/g. The adsorption experiments confirmed the applicability of the CK-CTAC/CTS to the removal of Pb(Ⅱ) in wastewater for the industrial removal of Pb(II) provides an efficient and feasible method.