The Characterization Of Modified Pyrolytic Carbon And By HNO₃ And DETA And The Adsorption Of Typical Pollutants From The Aqueous Solution

In this paper, pyrolytic char(Py C) from pine sawdust was modified by nitric acid oxidation and diethylenetriamine(DETA) grafting with epichlorohydrin and carbon MC1 and MC2 were obtained, respectively. The characterization of the Py C before and after modification was characterized with various methods, such as isoelectric point set, the determination of functional groups, elemental analysis, FTIR, scanning electron microscope(SEM) and the determination of specific surface area and so on. The results showed that the nitric acid oxidation had changed the number of acidic functional groups of Py C and DETA was also grafted onto the surface of the Py C successfully. Methylene blue(MB), congo red(CR), lead ions, 2,4-dichlorophenoxyacetic acid(2,4-D) were selected to evaluate the property of adsrobents.The adsorption process for MC1-MB, MC1-Pb2+, MC2-CR and MC2-(2,4-D) was operated in two ways(single and binary system) to study the static adsorption behavior. The influence of several factors on the adsorption process was examined, mainly including the adsorption time, adsorbent dose, initial p H and co-existing ions, initial concentration of solution and temperature. Meanwhile, absorbent effect of ASC-CR and the competitive adsorption between MB and Pb2+ were also studied. When the value of p H was 8.00 and 6.00, the adsorption quantity attains its maximum for MC1-MB and MC1-Pb2+, respectively; the optimal value of p H for MC2-CR and MC2-(2,4-D) is 2.00. For the four single-component systems, the equilibrium adsorption time was 480 min, 100 min, 400 min, 180 min, respectively. With the temperature increasing, the adsorption quantity increases gradually for MC1-MB and MC2-CR while a little change for MC1-Pb2+ and MC2-(2,4-D). The soluble salt existing in the solution has certain influence on the adsorption in different degrees. In the mixed system, the competitive adsorption between MB and Pb2+ exists and affect the adsorption quantity each other. For ASC-CR system, it is better for adsorption in alkaline conditions and soluble salt is in favor of the adsorption.Thermodynamic parameters of each system indicated that the adsorption reaction can occur spontaneously. For isothermal adsorption model, Koble- Corrigan model and Redich-Peterson model can describe each system; Temkin model is fit for MC1-MB, MC1-Pb2+, MC2-2,4-D; Langmuir model can describe the system of MC1-Pb2+ and MC2-CR, and then Freundlich model is better to describe the system MC2-(2,4-D). For dynamic adsorption model, pseudo-second-order model, Elovich model and double constant model can be suitable to describe the three systems of MC1-MB,MC2-CR,MC2-(2,4-D) and the dynamics data for MC1-Pb2+ is fitted well to Elovich model.