Preparation Of Lignin Based Porous Carbon And Study On Their Adsorption Performance Of Tetracycline In Water

Tetracycline as a broad-spectrum antibiotic have long been widely used as feed additive in aquaculture and animal husbandry, resulting in that the content of tetracycline in water overweight seriously. What is worse is that tetracycline enter into the human body through the ecological food chain system, endangerring the public health and promoting the spread of bacterial resistance, thus effectively separating tetracycline antibiotic residues from the water environment is a urgent problem. Due to that adsorption is lower cost, simple and will not cause secondary pollution, it has become the most common method of removing tetracycline antibiotic residues from water environment. However, the most commonly used adsorbents with low adsorption capacity and slow adsorption rate can not meet the actual demand. The porous carbon material because of its high specific surface area, tunable pore structure,rich surface functional groups and high chemical stability, etc. is considered to have great application prospect in the adsorptive separation of tetracyclines, but the high cost of porous carbon material preparation limits its use. Therefore, the development of an economical and environmentally friendly technology which is used to prepare porous carbon material with excellent performance from renewable energy is very important.In this paper, lignin sulfonate(SLS), the paper industry by-products with low cost,was used as a carbon source to prepare a series of porous carbon material by different methods. Different characterization methods were conducted to reveal the physical and chemical properties. And the adsorption processes for TC were researched via adsorption isotherms, adsorption kinetics and reuse adsorption. The detailed work was as follows:(1) In this work, we reported the successful conversion of the industrial SLS originated from black liquor to low-cost porous carbon with tunable microstructure and ultrahigh adsorption performance of tetracycline(TC) from water for the first time, via pre-carbonation and KOH activation. The optimum porous carbon was synthesized at 850 oC with the weight ratio of 4. LCA-850-4 with a very high specificsurface area(2805.8 m~2/g) and pore volume(1.45 cm3/g) showed a maximum adsorption of 1172.7 mg/g at 298 K, which was far higher than other reported adsorbents. LCA-850-4 exhibited excellent adsorption over a broad pH range.Kinetics and isotherm data was well fitted to the Pseudo-second-order rate and Langmuir model, respectively. Thermodynamic parameters indicated a spontaneous and endothermic adsorption. The mechanism of strong TC adsorption onto LCA-850-4 was mainly Van der waals force, π-π EDA and electrostatic interaction.LCA-850-4 with fast kinetics and excellent reusability possessed the huge potentials in practical antibiotic wastewater treatment. The current research suggested that the black liquor could be efficiently transformed to an ultrahigh-performance sustainable carbon material for antibiotic removal from water environments, with the integration use of renewable biomass.(2) A facile approach was developed for the preparation of hierarchically porous carbons(named lignin-based templated carbon after activation, LCTA) through combing hard template carbonation route(natural halloysite nanotubes, HNTs, as sacrificial template) and KOH activation, using an industrial by-product sodium lignin sulfonate(SLS) as biomass carbon precursor, which was renewable, enormous and commercially available. The LTCA showed high specific surface area of 2320 m~2/g and total pore volume of 1.342 mL/g. The LTCA exhibited the maximum monolayer adsorption capacities was 1297.0 mg/g for tetracycline at 298 K, which were far higher than that of other previous adsorbents. The Pseudo-second-order model described the adsorption kinetics data well. Intra-particle diffusion was not the only rate-controlling step. Thermodynamics analysis implied that adsorption processes were spontaneous and exothermic. Additionally, good regeneration ability make this novel HPCs as promising materials for wastewater treatment but also for energy storage and conversion as well as catalysis applications.(3) The inorganic salts, sodium chloride which was low cost and easy to remove and SLS was used as hard template and carbon source, respectively, by hard template method and KOH activation method to successfully prepare carbon nano-sheets(LTCA-NaCl) containing a large amount of microporous structure. LTCA-NaCl, withsuper high specific surface area(3504.8 m~2/g) and total pore volume(1.997 mL/g),demonstrated extraordinary adsorption of TC, specifically in the high equilibrium adsorption capacity, fast adsorption kinetics and good regeneration performance.Static adsorption results showed that the equilibrium adsorption amount of LTCA-NaCl up to TC was 1613.63 mg/g at 298 K and the Langmuir isotherm model and Pseudo-second-order kinetic model could well describe the adsorption behavior.The thermodynamic study results suggested that the adsorption process was endothermic and spontaneous. Compared with other adsorbents, LTCA-NaCl exhibited much more excellent adsorption performance to TC.