3种表面修饰活性炭对水体中磷的吸附

Adsorption of phosphate from water to three kinds of surface modified activated carbons

为克服活性炭磷吸附能力有限的问题,使用ZnCl_2、十六烷基三甲基氯化铵(CTAC)和Fe/Al(氢)氧化物纳米颗粒分别研究了物理结构法、表面活性剂法和载体法3种表面修饰方法对活性炭磷吸附能力的影响。实验发现,载体法为3种方法中最好的修饰方法。对载体法制备吸附剂的材料用量的比较发现,在Fe(Ⅲ)和Al(Ⅲ)摩尔比为9:1的条件下,把1.5 g活性炭加入到总浓度为1 mol·L^(-1)的200 m L Fe(Ⅲ)和Al(Ⅲ)混合溶液中,形成的纳米Fe/Al(氢)氧化物能够较好地利用活性炭表面,该复合材料1.5AC-Fe/Al在磷平衡浓度约为50 mg·L^(-1)时吸附量达到29.3 mg·g^(-1)。该材料表征结果表明,纳米Fe/Al(氢)氧化物颗粒被成功负载在活性炭表面。在酸性条件下,复合材料表面的—H^+和—OH_2^+所引起的静电吸附和配位交换是促进吸附带负电磷酸根离子的原因。

In order to improve the phosphate adsorption ability of activated carbon（AC）, AC was modified by activator method, surfactant method and carrier method through treating with activator（ZnCl2）, hexadecyl trimethyl ammonium chloride（CTAC） and Fe/Al（hydr）oxide nanoparticles, respectively. The results showed that carrier method was the best one among the tested methods. Through the comparison of different material ratios in the adsorbent preparation of carrier method, it was found that when the molar ratio of Fe（Ⅲ） and Al（Ⅲ） was 9：1, and when 1.5 g activated carbon was added into 200 m L of 1 mol·L^（-1） Fe（Ⅲ） and Al（Ⅲ） solution, Fe/Al（hydr）oxide nano particles could make good use of AC surface. The adsorption amount could reach 29.3 mg·g^（-1） for 1.5 AC-Fe/Al when the equilibrium concentration of phosphate was around 50 mg·L^（-1）. The results of SEM and XRD demonstrated that Fe/Al（hydr）oxide nanoparticles were loaded successfully on the surface of AC. Under acidic condition, electrostatic adsorption and ligand exchange caused by the existence of —H^＋ and —OH2^＋ on the surface of the composite material were responsible for the enhanced adsorption of negative charged phosphate.