Adsorptive removal of cadmium from aqueous solutions using NiFe2O4/hydroxyapatite/graphene quantum dots as a novel nano-adsorbent

Abstract

In this study, NiFe 2 O 4 /hydroxyapatite/graphene quantum dots (NiFe 2 O 4 /HAP/GQDs) as nano-adsorbent to remove cadmium (Cd 2+) from aqueous solution were synthesized. This nano-adsorbent was depicted by some techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Adsorption studies were conducted to investigate the effect of contact time, pH, adsorbent dosage and initial cadmium ion concentration on removal efficiency. To determine the most fitting kinetic model, the suitability of pseudo-first-order and pseudo-second-order models was compared. The adsorption isotherm was described well by the Langmuir isotherm and maximum equilibrium uptake capacity (q e) was 344.83 mg g −1. Studies revealed that adsorption process is not a physical process and formation of complexes (bidentate and monodentate complexes) between-COO − and-OH functional groups on the surface of NiFe 2 O 4 /HAP/GQDs and Cd 2+ ions may occur. In addition, the adsorbent can simply be removed by an ordinary filtration process.

Efficient removal of Cu(ii) from aqueous systems using enhanced quantum yield nitrogen-doped carbon nanodots

“…48,49 With increasing pH until 7, the surface occupation declines and positively charged Cu(II) attach to the free active sites of the adsorbent. 1 As previously reported, metal ion adsorption is favorable at a suspension pH higher than the pH PZC values. 48 The x potential data (Fig.…”

“…Water pollution caused by toxic Cu(II) metal has become a worldwide issue owing to its severe threat to human health and the environment. 1,2 Toxic Cu(II) can easily enter the food chain via anthropogenic activities causing diverse diseases in humans. 3 Cu(II) is widely found in the environment, industries, and domestic functions.…”

NiFe2O4 coated sand as a nano-adsorbent for removal of Pb (II) from aqueous solutions

“…Such solutions result in more absorption through electromagnetic interactions between Pb(II) ions and adsorbent surface. In accordance to the surface chemistry theory, when NiFe2O4 coated sand is in contact with Pb(II) ions in solution, it is encircled by an electrical diffused double layer, the thickness of which is remarkably extended by the existence of electrolyte [36]. In this study, for examining the effect of ionic strength on adsorption process by NiFe2O4 coated sand, the capability of three different ionic strengths (0.1, 0.3, and 3 mol L -1 ) were chosen.…”

Sustainable Development of Enhanced Luminescence Polymer-Carbon Dots Composite Film for Rapid Cd2+ Removal from Wastewater

“…Water is the prime component of human survival. Nevertheless, environmental pollution caused by heavy metals owing to the inappropriate disposal of wastewater is becoming a worldwide concern [ 1 , 2 ]. Cd(II) metal is one of the most toxic substances that tend to accumulate in living organisms.…”