氨基酸修饰的高交联吸附树脂对Cu(Ⅱ)和磺胺嘧啶的吸附机制研究

The coremoval properties and mechanisms of Cu(II) and sulfadiazine onto a hyper-cross-linked polymeric adsorbent modified by amino acid

采用络氨酸修饰氯球树脂(PS-DVB)并进行后交联反应制备了氨基酸修饰的高交联吸附树脂(PSTY).研究了PSTY树脂对Cu(II)和磺胺嘧啶(SDZ)的协同吸附性能及交互影响机制.单组分体系中,树脂对Cu(II)的吸附随pH值的增加而增加,对SDZ的吸附随着pH值的增加先增后减;共存体系中,SDZ的共存微弱促进了树脂对Cu(II)吸附,Cu(II)的共存抑制了树脂对SDZ的吸附,且pH大于6后抑制更为明显.PSTY对Cu(II)和SDZ的吸附等温线可采用Langmuir和Freundlich方程进行拟合,共存低浓度的SDZ使Cu(II)的饱和吸附量略有增加,而高浓度的SDZ使其下降.Cu(II)的增强去除主要是阴离子SDZ^-与树脂的质子化基团的静电作用减弱了对Cu(II)的静电斥力,Cu(II)与SDZ分别与PSTY中的极性基团发生配位作用和氢键作用进行竞争吸附,但Cu(II)的配位结合力更强,虽然吸附到树脂上的Cu(II)还可以通过桥连作用吸附SDZ,但作用较弱,因此,共存的Cu(II)抑制了PSTY树脂对SDZ的吸附,Cu(II)浓度越大抑制程度越高.

In this research,tyrosine modified hyper-cross-linked polymeric adsorbent PSTY was prepared by complexation of low crosslinked PS-DVB copolymers and post-crosslinking reaction.The coremoval properties of copper and sulfadiazine onto PSTY resin were investigated.The results indicated that,with the increased of pH,the adsorption capacity of Cu (Ⅱ) was meager increased,but the adsorption value of sulfadiazine increased at the beginning and then decreased.In the binary systems,the presence of sulfadiazine markedly enhanced the adsorption of Cu(Ⅱ),while Sulfadiazine uptake was suppressed when Cu(Ⅱ) was present,especially after the pH more than six.The adsorption isotherms of PSTY for Cu(Ⅱ) and sulfadiazine can be fitted by Langmuir and Freundlich equations.The coexistence of low concentration of sulfadiazine increases the saturation adsorption of Cu (Ⅱ) slightly, while the high concentration of sulfadiazine decreases it.The enhanced removal of Cu (Ⅱ) can be attributed to the protonated functional groups adsorbed on sulfadiazine,which shielded the electrostatic attraction between Cu(Ⅱ) and functional groups.Surface functional groups participated in the adsorption of both Cu (Ⅱ) and sulfadiazine by coordination and hydrogen bonding interaction,respectively,which resulted to the selective recognition and direct competition,but Cu(Ⅱ) was preferred with a higher affinity.On the other hand,Cu(Ⅱ) adsorbed onto the resin can also adsorb sulfadiazine by bridging, which the effect is weak.Therefore,the co-existing Cu(Ⅱ) inhibited the adsorption of SDZ on PSTY resin,and the higher the concentration of Cu(Ⅱ), the higher the degree of inhibition.