Journal of Ecology and Rural Environment ›› 2021, Vol. 37 ›› Issue (2): 234-241.doi: 10.19741/j.issn.1673-4831.2020.0305

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A New Adsorbent for Phosphorus Removal From Bark of Hibiscus syriacus Modified by Lanthanum

NI Lin-jie1,2, QIU Huan1, LIU Xiao-ling3, LEI Yan4, ZHANG Ke1,5, LUO Hong-bing1,5, CHENG Lin1,5, FAN Liang-qian1,5, CHEN Wei1,5   

  1. 1. Department of Municipal Engineering, College of Civil Engineering, Sichuan Agricultural University, Dujiangyan 611830, China;
    2. College of Environmental Science and Engineering, Nankai University, Tianjin 300071, China;
    3. Department of Information Engineering, Sichuan Water Conservancy Vocational College, Chengdu 611231, China;
    4. Environmental Monitoring Station of Jintang County, Chengdu 610400, China;
    5. Sichuan Higher Education Engineering Research Center for Disaster Prevention and Mitigation of Village Construction, Sichuan Agricultural University, Chengdu 611830, China
  • Received:2020-04-26 Online:2021-02-25 Published:2021-02-25

Abstract: Based on the bark of Hibiscus syriacus, a new phosphorus adsorbent was modified by lanthanum chloride to remove phosphorus from wastewater. The mono-factor method was used to determine the optimal modification conditions of the adsorbent. The effects of pH, adsorbent amount, adsorption time and adsorption temperature were investigated. Results show that: (1) The optimal modification conditions of the bark of Hibiscus syriacus were the lanthanum chloride solution concentration of 7%, the calcination temperature of 300 ℃ and the roasting time of 2.5 hours. (2) When the initial concentration of phosphorus was 5 mg·L-1, the solution acidity was pH 7 and the optimum dosage was 0.35 g, the best adsorption phosphorus removal rate reached to 94.99%. (3) When the adsorption time was 130 min, the adsorption reaction was in equilibrium. The adsorption modes of bark of Hibiscus syriacus modified by lanthanum chloride were all determined to the pseudo-second-order kinetic equation at different temperatures. (4) The Langmuir equation was suitable to describe the adsorption reaction which belonged to single molecule layer adsorption. At temperatures of 288, 298 and 308 K, the maximum adsorption capacity of modified bark of Hibiscus syriacus was 1.54, 1.55 and 1.63 mg·g-1, respectively. (5) Adsorption thermodynamic analysis results show that the ΔGθ, ΔHθ and ΔSθ was <0, >0 and <0, respectively, which means that the adsorption reaction was promoted when the temperature rose. These results also indicate that adsorption reaction using bark of Hibiscus syriacus modified by lanthanum chloride was a spontaneous, entropy increasing and endothermic process and belonged to the chemical adsorption. This study provides a theoretical reference for treating phosphorous wastewater by using bark of Hibiscus syriacus modified by lanthanum chloride.

Key words: bark of Hibiscus syriacus, modified by lanthanum, adsorption, phosphorus removal

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