蛭石与人造沸石氨氮等温吸附理论式与判别式

Theoretical Equation and Criterion Formula for Describing Sorption of NH_4^+-N by Vermiculite and Synthetic Zeolite Minerals

为比较在高起始氨氮浓度C_0点和介质用量W_0点上,吸附理论通式Q_(?)=W_0q_mC_0/[q_mKw+W_0(q_m—q_r)+C_0]与其简化方程Q_(?)=W_0q_mC_0/[q_m(K_w+W_0)+C_0]的适用性,测定了给定pH值和温度条件下反应平衡时NH_4Cl溶液中蛭石和人造沸石的氨氮吸附量(Q_(?)),在该试验条件下确定的蛭石单位介质吸附容量q_m和介质系数K_w值分别为22mg/g和15.5g/L,人造沸石的q_m和K_w的值分别为45mg/g和8g/L,在整个试验氨氮浓度C_0和介质用量W_0范围内,用该通式描述两介质对氨氮的等温吸附过程具有很高的精确度,而简化方程仅在有限范围内即C_0相对小或W_0相对大时才适用,若给定预测相对误差(RD),则C_0/q_m(K_w+W_0)≤RD可作为简化方程应用的判别式。

Tests were conducted to measure the quantity of NH4^＋-N sorption at equilibrium （Qr） by vermiculite and synthetic zeolite minerals in NH4Cl solution under given pH and temperature eonditions with the objective to comparing the fitness of the general sorption equation Q=W0qmC0/[qm（Kw＋W0）＋C0] with that of the simplified form Q=W0qmC0/[qm（Kw＋W0）＋C0] at high initial NH4^＋-N concentration （C0） and sorbent quantity （W0） levels. The maximum sorption quantity per unit sorbent qm and the medium coefficient Kw. were found to be respectively 22 mg/g and 15.5 g/L for vermiculite, and 45 mg/g and 8 g/L for .synthetic zeolite. The general form gave high levels of accuracy in describing the thermal sorption processes for both media within the whole tested C0 and W0 range while the simplified form fitted only in a limited area of either relatively low C0 or high W0 levels. Given required relative deviation （RD） for prediction, C0/qm（Kw＋W0）≤RD was presented as criterion formula for use of the simplified equation.