热处理富钙凹凸棒黏土吸附磷的影响因素

以800℃热处理富钙凹凸棒黏土（记为NCAP800）为研究对象，通过批处理试验和动态试验研究了不同因素（pH、竞争离子、柠檬酸）对NCAP800吸附磷的能力的影响.结果表明:酸性条件对磷的吸附能力无影响，碱性条件（pH>9）对NCAP800的磷吸附具有一定的抑制作用，pH对NCAP800磷吸附能力的影响主要通过改变黏土矿物中可交换钙、镁含量与矿物表面Zeta电位.阴离子中HCO₃-对磷的抑制作用较为显著，尤其当ρ（HCO₃-）为5~20 mg/L时抑制作用最为显著，其次是SO₄2-，NO₃-和Cl-对磷的吸附无抑制作用.HCO₃-和SO₄2-抢夺钙的结合位点，从而降低了NCAP800对磷的吸附能力.低浓度（c为0~5 mmol/L）的柠檬酸对磷的吸附抑制作用较弱，高浓度（c为5~50 mmol/L）的柠檬酸对磷的抑制作用较为显著，柠檬酸对磷的抑制机制同样是通过竞争NCAP800表面的磷吸附位点.研究显示，NCAP800在碱性条件下对磷具有较好的吸附作用，HCO₃-和SO₄2-及高浓度柠檬酸均会抑制NCAP800对磷的吸附. 

Factors Influencing the Phosphorus Adsorption Capacity of Thermally Modified Calcium-Rich Attapulgite

The influencing factors(e.g.pH, competing anions and citric acid) of phosphorus adsorption capacity of 800℃-heated calcium-rich attapulgite were studied.The results showed that pH had no influence on phosphorus adsorption capacity in acidic conditions, while in alkaline conditions, pH had a certain effect on the phosphorus adsorption when it was in the range of 8-10.The effect of pH on phosphorus adsorption capacity was mainly via changing the amount of exchangeable metals(Mg and Ca) and the Zeta potential.It was noted that HCO₃- inhibited phosphorus adsorption of NCAP800 mostly when the concentration of HCO₃- was 5-20 mg/L, followed by SO₄2-, NO₃- and Cl-, which had no effect on phosphorus adsorption.The inhibiting effect was mainly through competing adsorption sites, which reduced phosphorus adsorption capacity of NCAP800.The low citric acid concentration(0-5 mmol/L) had a slightly lower effect on phosphorus adsorption than that of high citric acid concentrations(5-50 mmol/L), resulting from the inhibition mechanism of competing adsorption sites on the NCAP800 surface.