Convenient pH-responsive removal of Acid Black 1 by green l-histidine/iron oxide magnetic nanoadsorbent from water: performance and mechanistic studies

Abstract

Effective and eco-friendly separation of Acid Black 1 dye from water by electrostatic adsorption onto reusable Histidine-Fe3O4 nanoparticles, credited to their pH-responsiveness.

Anionic azo dyes removal from water using amine-functionalized cobalt–iron oxide nanoparticles: a comparative time-dependent study and structural optimization towards the removal mechanism

“…The first step of weight loss up to 150 °C is assigned to libration of water molecules from the CoFeNPs surface, where an initial mass loss of about 6% up to 100 °C is attributed to physisorbed water, while further loss in weight (7–10%) up to 150 °C corresponds to chemisorbed water. 15 …”

“…Such enhanced adsorption in successive runs was also observed in previous reusability studies of a histidinemagnetite NPs adsorbent with Acid Black 1 dye. 15 The NaOH concentration (1 M or 2 M) did not signicantly affect the percent desorption from CoFeNPs1. MeOH, HCl (1 M) and MeOH/CH 3 COOH mixture (9 : 1) gave no desorption from CoFeNPs1; instead, HCl and the MeOH/CH 3 COOH mixture caused slow dissolution of CoFeNPs1 aer a day.…”

“…The rst step of weight loss up to 150 C is assigned to libration of water molecules from the CoFeNPs surface, where an initial mass loss of about 6% up to 100 C is attributed to physisorbed water, while further loss in weight (7-10%) up to 150 C corresponds to chemisorbed water. 15 An apparent unexpected mass increase of about 3% from 150 to 200 C observed for CoFeNPs1 could be due to the adsorption of oxygen on the nanoparticle surface, which may penetrate into the core of the nanoparticles under aerobic conditions. The subsequent 5.8% mass loss up to 300 C for CoFeNPs1 is probably due to the release of gases (N 2 , NH 3 , H 2, etc.)…”

“…The fraction of dye adsorbed onto CoFeNPs at time t (i.e., F in the expression of B t ) can be calculated by the ratio q t /q e . 15 The Boyd plots for adsorption of six different anionic azoic dyes onto CoFeNPs1 and CoFeNPs2 are illustrated in Fig. 15, and the related R 2 values (correlation coefficients) are reported in Tables 4 and 5.…”

“…This application of magnetic NPs is associated with their dominant features of reduced size (high surface area), low cost, easy and quick magnetic separation, fast reactivity, high environmental stability and adsorption capacity, easy surface functionalization and low biotoxicity. 2,15 Magnetic nanoparticles of the ferrite group are of current research interest due to their wide range of industrial, biomedical and environmental applications. 3,16,17 Cobalt-ferrite is an efficient member of the ferrite family with dominant properties such as chemical stability, high mechanical stability, wear resistance, high anisotropy and medium saturation magnetization.…”