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Biomass Chemical Engineering ›› 2021, Vol. 55 ›› Issue (1): 63-69.doi: 10.3969/j.issn.1673-5854.2021.01.009

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Preparation of Walnut Shell Carbon and Its Adsorption of Ammonia-nitrogen Wastewater

Ke JIN, Qian LU, Laijiu MA, Huijuan LI(), Zhengjun SHI   

  1. Key Laboratory of National Forestry and Grassland Administration on Highly-Efficient Utilization of Forestry Biomass Resources in Southwest China(Southwest Forestry University), Kunming 650224, China
  • Received:2019-12-09 Online:2021-01-30 Published:2021-01-25
  • Contact: Huijuan LI E-mail:muzilihuijuan@163.com


Aiming at the problem of ammonia-nitrogen wastewater pollution, walnut shell carbon was used as adsorbent, and the NH4+ was used as model adsorption molecules. The effects of pretreatment conditions of walnut shell, roasting temperature, roasting time and initial concentration of ammonium ion on the adsorption of ammonia-nitrogen wastewater were investigated. The results showed that walnut shell carbon modified by H3PO4 (700℃, 2 h) had excellent adsorption capacity for low concentration NH4+. When the initial concentration of NH4+ was 0.8 mg/L, the amount of walnut shell carbon was 2 g/L and the adsorption time was 240 min, the adsorption rate was 93.41%. Adsorption of ammonium ion by walnut shell charcoal accorded with pseudo-second-order kinetics model. The specific surface area of the walnut shell carbon obtained by H3PO4 pretreatment was 269.18 m2/g, the total pore volume was 0.173 6 cm3/g, the micropore volume was 0.125 0 cm3/g and the average pore size was 5-46 nm. Phase characterization of walnut shell charcoal was carried out by infrared (IR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that walnut shell carbon modified by H3PO4 (700℃, 2 h) was graphite-carbon crystalline phase with graphite lamellar structure on its surface which resulted in good adsorption.

Key words: walnut shell carbon, ammonia-nitrogen ion, adsorption, wastewater

CLC Number: