Khurshid Sumaira, Gul Zarnab, Khatoon Jaweria, Shah Muhammad Raza, Hamid Irum, Khan Iffat Abdul Tawab, Aslam Fariha
Department of Chemistry, University of Karachi Karachi-75270 Pakistan
Department of Chemistry, Federal Urdu University of Arts, Science and Technology, Gulshan-e-Iqbal Campus Karachi-75300 Pakistan.
RSC Adv. 2020 Jan 3;10(2):1021-1041. doi: 10.1039/c9ra07686g. eCollection 2020 Jan 2.
The current study is aimed at synthesizing and characterizing magnetic cobalt-iron oxide nanoparticles (CoFeNPs) functionalized with two different amino reagents, hydrazine and dodecylamine, resulting in CoFeNPs1 and CoFeNPs2, respectively. Both types of cobalt-ferrite nanoparticles were investigated for the removal of six different negatively charged azoic dyes (Amaranth, Acid Orange 7, Naphthol Blue Black, Reactive Orange 16, Acid Orange 52 and Reactive Red-P2B) from water, and their removal efficiency was compared as a function of different factors such as time, type of anchored amine, size of CoFeNPs and structure of the dye. CoFeNPs were successfully characterized by FT-IR spectra, AFM, SEM-EDS, surface charge (ζ-potential) and thermal analysis. CoFeNPs1 revealed 44.5-82.1% dye removal at equilibrium (attained within 28-115 min) with an adsorptive capacity ( ) of 5.4-13.5 mg g observed under unoptimized conditions (temp. 30 °C, adsorbent dose 0.67 g L, pH 6, dye concentration 20 μmol L). Use of CoFeNPs2 significantly enhanced the removal of each dye (percent dye removal 68.0-98.9%, 6.6-23.5 mg g) compared to CoFeNPs1 under similar conditions. From a comparative structural study, a larger size, more complex structure, hydrophobic character and greater number of phenyl SO groups among the tested dyes facilitated their removal by CoFeNPs2, while all of these structural factors were negatively related to dye removal by CoFeNPs1. CoFeNPs2 showed some dye aggregation along with adsorption, while in the case of CoFeNPs1, only adsorption was observed as confirmed by FT-IR and UV-visible spectral studies. Dye removal data in all cases was in best compliance with pseudo-second order kinetics in comparison to pseudo-first order or the Elovich model, where film diffusion was a dominant phenomenon compared to intra-particle diffusion. Adsorption isotherms, thermodynamics and reusability of the CoFeNPs were studied selecting Reactive Orange 16. Adsorption equilibrium was best fitted to the Langmuir isotherm. Δ° and Δ° indicated spontaneous and exothermic adsorption. Amine-functionalized CoFeNPs are recommended as potential cost-effective adsorbents with excellent reusability that could be applied efficiently for rapid and selective dye removal from textile effluents considering the size, structure, charge and number of S atoms in the target azo dyes.
本研究旨在合成并表征用两种不同氨基试剂（肼和十二烷基胺）功能化的磁性钴铁氧化物纳米颗粒（CoFeNPs），分别得到CoFeNPs1和CoFeNPs2。研究了这两种钴铁氧体纳米颗粒对水中六种不同带负电荷的偶氮染料（苋菜红、酸性橙7、萘酚蓝黑、活性橙16、酸性橙52和活性红-P2B）的去除效果，并比较了它们在不同因素（如时间、锚定胺类型、CoFeNPs尺寸和染料结构）作用下的去除效率。通过傅里叶变换红外光谱（FT-IR）、原子力显微镜（AFM）、扫描电子显微镜-能谱仪（SEM-EDS）、表面电荷（ζ电位）和热分析对CoFeNPs进行了成功表征。在未优化条件下（温度30℃、吸附剂剂量0.67 g/L、pH值6、染料浓度20 μmol/L），CoFeNPs1在平衡时（28 - 115分钟内达到）显示出44.5 - 82.1%的染料去除率，吸附容量为5.4 - 13.5 mg/g。在相似条件下，与CoFeNPs1相比，使用CoFeNPs2显著提高了每种染料的去除率（染料去除率为68.0 - 98.9%，吸附容量为6.6 - 23.5 mg/g）。通过比较结构研究发现，在所测试的染料中，较大的尺寸结构、更复杂的结构、疏水特性以及更多的苯基-SO基团有利于CoFeNPs2对其的去除，而所有这些结构因素与CoFeNPs1对染料的去除呈负相关。FT-IR和紫外-可见光谱研究证实，CoFeNPs2在吸附时显示出一些染料聚集现象，而对于CoFeNPs1，仅观察到吸附现象。与伪一级动力学或埃洛维奇模型相比，所有情况下的染料去除数据与伪二级动力学最相符，其中膜扩散比颗粒内扩散更占主导地位。以活性橙16为对象研究了CoFeNPs的吸附等温线、热力学和可重复使用性。吸附平衡最符合朗缪尔等温线。Δ°和Δ°表明吸附是自发的且为放热过程。考虑到目标偶氮染料的尺寸、结构、电荷和S原子数量，氨基功能化的CoFeNPs被推荐为具有潜在成本效益且可高效重复使用的吸附剂，可有效用于从纺织废水中快速选择性去除染料。
