Rehman Tanzil Ur, Shah Luqman Ali, Khan Mansoor, Irfan Muhammad, Khattak Noor Saeed
Polymer Laboratory, National Center of Excellence in Physical Chemistry, University of Peshawar Peshawar KPK 25120 Pakistan
RSC Adv. 2019 Jun 12;9(32):18565-18577. doi: 10.1039/c9ra02488c. eCollection 2019 Jun 10.
A novel zwitterionic superabsorbent polymer hydrogel [ZI-SAH] was synthesized by free radical polymerization and used for the removal of crystal violet (CV) and congo red (CR) from an aqueous medium. ZI-SAH was composed of pH-sensitive monomers poly(3-acrylamidopropyl) trimethylammoniumchloride (APTMACl) and 2-acrylamido-2-methylpropanesulphonic acid (AAMPSA). The hydrogel was characterized by SEM and FT-IR spectroscopy, while the visco-elastic behavior was studied using rheological tests. The hydrogel showed a point of zero charge (PZC) at pH 7.2 and high swelling abilities of 3715% at pH 9 and 3112% at pH 5. The cationic crystal violet (CV) and anionic congo red (CR) dyes were employed to investigate the removal ability of ZI-SAH using the batch adsorption method. The materials became more selective towards oppositely charged dyes at pH 5 and 9. The effects of parameters such as contact time, initial concentration of dyes, pH, ZI-SAH dosage and ionic strength on the removal performance were investigated. A kinetic study was carried out Lagergren pseudo first order and pseudo second order kinetics. The adsorption efficiencies of ZI-SAH were 13.6 mg g for CV and 9.07 mg g for CR with % removal values of 97 and 89, respectively. The thermodynamic parameters, namely, Δ°, Δ° and Δ° were determined, and the negative value of free energy showed that the process of adsorption was spontaneous. ZI-SAH was recycled and reused in five consecutive cycles with removal efficiency > 75%.
通过自由基聚合反应合成了一种新型两性离子超吸水性聚合物水凝胶[ZI-SAH]，并将其用于从水介质中去除结晶紫（CV）和刚果红（CR）。ZI-SAH由pH敏感单体聚（3-丙烯酰胺基丙基）三甲基氯化铵（APTMACl）和2-丙烯酰胺基-2-甲基丙烷磺酸（AAMPSA）组成。通过扫描电子显微镜（SEM）和傅里叶变换红外光谱（FT-IR）对水凝胶进行了表征，同时使用流变学测试研究了其粘弹性行为。该水凝胶在pH 7.2时显示出零电荷点（PZC），在pH 9时具有3715%的高溶胀能力，在pH 5时具有3112%的高溶胀能力。采用阳离子结晶紫（CV）和阴离子刚果红（CR）染料，通过分批吸附法研究了ZI-SAH的去除能力。在pH 5和9时，该材料对带相反电荷的染料具有更高的选择性。研究了接触时间、染料初始浓度、pH、ZI-SAH用量和离子强度等参数对去除性能的影响。进行了动力学研究，采用了 Lagergren 准一级和准二级动力学模型。ZI-SAH对CV的吸附效率为13.6 mg/g，对CR的吸附效率为9.07 mg/g，去除率分别为97%和89%。测定了热力学参数，即Δ°、Δ°和Δ°，自由能的负值表明吸附过程是自发的。ZI-SAH经过五个连续循环的回收再利用，去除效率>75%。
