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| Adsorption Characteristics of Pb2+ and Cd2+ by Modified Paulownia Leaf Powder from Aqueous Solution |
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| KeyWord:paulownia leaves; modification; Pb2+;Cd2+; adsorption kinetics; Fourier transform infrared spectroscopy（FTIR） |
| Author Name | Affiliation | | LIU Wen-xia | Department of Environmental Sciences, College of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | LI Jia-xin | Department of Environmental Sciences, College of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | WANG Jun-li | Department of Environmental Sciences, College of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | CHEN Xue-bin | Department of Environmental Sciences, College of Forestry, Henan Agricultural University, Zhengzhou 450002, China | | MENG Xiang-yuan | Department of Environmental Sciences, College of Forestry, Henan Agricultural University, Zhengzhou 450002, China |
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| Abstract: |
| Tree leaves are waste litter and can be used as an adsorbent to remove heavy metals from water. In this study, paulownia leaf powder was modified with three chemicals, sulfuric acid, sodium hydroxide and thioglycolic acid, and was then examined its adsorption of Pb2+ and Cd2+ from aqueous solution. The surface and structure of modified paulownia leaf powder were characterized using Fourier transform infrared spectroscopy（FTIR） and scanning electron microscope（SEM）. Adsorption of Pb2+ and Cd2+ by three modified paulownia leaf powder was fast and reached an equilibrium within 4 h. At pH5, temperature of 25 ℃ and adsorbent dose of 3 g·L-1 in solution, adsorption kinetics of Pb2+ and Cd2+ could be expressed by pseudo-second-order kinetics model. Compared with unmodified paulownia leaf powder（UMPPA）, adsorption ability of NaOH-ethanol modified paulownia leaf powder（MPPA No.1） was improved significantly, and the equilibrium adsorption capacity of Pb2+ and Cd2+ was 15.38 mg·g-1 and 14.71 mg·g-1, respectively. In addition, the adsorption speed was faster for Cd2+ than for Pb2+. UMPPA revealed flat and smooth surface, while MPPA No.1 exhibited rough and honeycomb-patterned surface. The specific surface area of MPPA No.1 was 3.124 m2·g-1, 50% greater than that of UMPPA. Paulownia leaves contain active functional groups such as hydroxyl, carboxyl and amides, facilitating adsorption of Pb2+ and Cd2+. In conclusion, NaOH-ethanol modified paulownia leaves exhibited excellent adsorption for Pb2+ and Cd2+ in wastewater. |
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