颗粒13X分子筛复合材料去除水中Cu^(2+)的机理及共存Pb^(2+)、Cd^(2+)、Zn^(2+)的影响研究

Mechanism for Cu^(2+) removal from aqueous solution by particle 13X molecular sieve composite and the effect of coexisting Pb^(2+), Cd^(2+) and Zn^(2+)

制备了颗粒13X分子筛复合材料,将其装填为固定床,探究复合材料去除水中Cu^(2+)的机理及共存重金属离子Pb^(2+)、Cd^(2+)和Zn^(2+)对复合材料固定床去除Cu^(2+)性能的影响。结果表明,在进水流速为150 mL·min^(-1)、Cu^(2+)浓度为100 mg·L^(-1)的条件下,固定床运行23.5 h后,Cu^(2+)达到穿透点,复合材料对Cu^(2+)的饱和富集量为1.58 mmol·g^(-1)(铜含量达10.03%)。颗粒13X分子筛复合材料去除Cu^(2+)的机理主要包括离子交换吸附和表面沉淀。Cu^(2+)-Pb^(2+)、Cu^(2+)-Cd^(2+)和Cu^(2+)-Zn^(2+)二元体系的运行结果表明,Pb^(2+)、Cd^(2+)和Zn^(2+)的共存分别使Cu^(2+)的穿透时间提前了34.0%、40.4%和53.6%,进出水中Cu^(2+)浓度相等时复合材料对Cu^(2+)的富集量分别降低到0.28 mmol·g^(-1)、1.08 mmol·g^(-1)和1.55 mmol·g^(-1),影响强弱顺序为Pb^(2+)>Cd^(2+)>Zn^(2+)。水合离子直径和水合能越小、电负性越大的共存重金属离子,对复合材料去除Cu^(2+)产生的不利影响越强。

A column fixed bed filled with particle 13X molecular sieve composite was adopted to enrich Cu^(2+)from wastewater. The mechanism of Cu^(2+)removal by 13X molecular sieve composite material and the effect of coexisting heavy metal ions(Pb^(2+), Cd^(2+), Zn^(2+)) on the removal efficiency were investigated. The results showed that the fixed bed reached its breakthrough point after 23.5 h under the operational conditions(influent flow rate = 150 mL·min^(-1)and Cu^(2+)concentration = 100 mg·L^(-1)). The saturated enrichment of Cu^(2+)by the particle 13X molecular sieve composite was 1.58 mmol·g^(-1)(the copper content reached 10.03%). Furthermore, the results revealed that ion exchange and surface precipitation were the main mechanisms of Cu^(2+)removal by 13X molecular sieve composite. The operating results of Cu^(2+)-Pb^(2+), Cu^(2+)-Cd^(2+)and Cu^(2+)-Zn^(2+)binary systems showed that the coexistence of Pb^(2+), Cd^(2+)and Zn^(2+)increased the penetration time of Cu^(2+)by 34.0%, 40.4% and 53.6% respectively. In addition, the balance point enrichment was reduced to 0.28 mmol·g^(-1), 1.08 mmol·g^(-1)and 1.55 mmol·g^(-1), respectively. Moreover, the order of the influence of the three coexisting ions on the adsorption of Cu^(2+)by the molecular sieve composite was identified to be Pb^(2+)>Cd^(2+)>Zn^(2+). The smaller the diameter and hydration energy of the hydrate, the greater the electronegativity of the coexisting heavy metal ions and the stronger the ability to compete for adsorption sites. These eventually result in strong adverse effect on Cu^(2+)removal by the molecular sieve composite.