| Biomass-based nanoporous carbons has caused great concern in the field of purification for printing and dyeing wastewater due to high specific surface area, high porosity, good thermal stability and renewable etc. However, the reports are still scarce for similar structures and properties of the dye molecules in the competitive adsorption onto nanoporous carbon surface. The contents of this thesis were as follows:1. We used the four kinds of peels as raw materials from rutaceae, the peels of orange-I, finger citron, pomelo and orange-â…¡, potassium hydroxide as activator by the chemical method and prepared four biomass-based porous carbons under the same preparation condition. The result of nitrogen adsorption showed that the specific surface area of four kinds of porous carbons were 1866,2289,1359 and 1105 m2/g, respectively. At meantime, we studied the adsorption equilibrium isotherms and adsorption kinetics properties for the two anionic dye molecules with similar structure but different molecular weights, orange â…¡ (Oâ…¡) and acid chrome blue K (ACBK) on four porous carbons. The results showed that the order of adsorption capacities for the two anionic dyes was orange-â… (Oâ…¡:930 mg/g, ACBK:592 mg/g)> finger citron carbon (Oâ…¡:835 mg/g, ACBK:555 mg/g)> pomelo carbon (Oâ…¡:645 mg/g, ACBK: 446 mg/g)> orange-â…¡ carbon (Oâ…¡:547 mg/g, ACBK:315 mg/g). The adsorption capacity of orange â…¡ with smaller molecular weight than the acid chrome blue K were up to 36.3%,33.5%,30.9% and 42.4% of the finger, orange-1, pomelo and orange-2, on four kinds of carbon material surface. Langmuir isotherm equation could better describe adsorption isotherms for four kinds of carbons and adsorption kinetics be in fit with the pseudo-second order kinetic model.2. We used the magnolia leaves (ML) as the raw material to prepare the super magnolia leaf-based porous carbons by KOH activation method. Magnolia leaves and the corresponding carbon materials were characterized. At the same time, we studied the static adsorption behavior of magnolia leaf-based porous carbons in the two-component system for two kinds of anionic dyes, methyl orange (MO) and orange â…¡ (Oâ…¡), including adsorbent dosage, initial dye concentration, adsorption time, pH value, etc. The results showed that the surface area of magnolia leaf-based porous carbons could reach 2834 m2/g and the average pore size and pore volume were 2.23 nm and 1.58 cm3/g, which is a microporous material. For the single component system, the equilibrium adsorption capacities of magnolia leaf-based porous carbons for MO and Oâ…¡ were 868 mg/g and 1487 mg/g, respectively. For the two-component system, the adsorption capacity were decreased to 447 (MO) and 951 mg/g (Oâ…¡) and decreased to 48.5% and 36.0% due to the competitive adsorption between the two dye molecules. Langmuir adsorption isotherm model was better described the two systems and the pseudo-second order kinetic model could better describe the adsorption process.3. To further achieve the adsorption capacity and selectivity, we used the nickel-metal cation to modify the surface of magnolia leaf-based porous carbons by impregnation technique. The porous carbons were characterized by nitrogen adsorption, SEM, TEM, EDS and XPS techniques. respectively. Batch tests were used to investigate the adsorption performance of anionic dye congo red. The results showed that the surface area of the as-prepared carbon decreased from 2834 m2/g to 2367 m2/g and the pore volume and average pore size increased from 1.58 cm3/g,2.23 nm to 1.91 cm3/g and 3.32 nm before and after modification. TEM, EDS and XPS were further proved that the nickel ions were doped in the pore of porous carbon. Because of the chemistry adsorption between nickel ions with anionic dyes, the adsorption capacity was greatly improved and the maximum equilibrium adsorption capacity was 1780 mg/g.This work shown that the structure of carbon materials and adsorption properties of the dyes were quite different even using the similar biomass plant subject as the material and the preparation under the same conditions. Weight of dye moleculars,Ï€-Ï€-conjugated, the surface properties of carbon materials and the other factors were the key factors for the adsorption capacity and selectivity. Modification by metal cations into the pore structure could remarkable improve the adsorption capacity of anionic dye onto porous carbons. |
