Graphene quantum dots coated on quartz sand as efficient and low‐cost adsorbent for removal of Hg²⁺ and Pb²⁺ from aqueous solutions

Abstract

Herein, a novel, efficient and inexpensive adsorbent based on graphene quantum dots (GQDs) coated on quartz sand (GQDs|QS) for removal of Hg2+ and Pb2+ from aqueous solutions was reported. The GQDs|QS was characterized by scanning electron microscopy, energy‐dispersive X‐ray spectroscopy, Fourier transform infrared spectroscopy, and X‐ray powder diffraction techniques. To optimize operation parameters and study removal efficiency of the prepared adsorbent, a batch removal system followed by anodic stripping voltammetry technique was used during the experiments. The maximum adsorption capacity of GQDs|QS for Hg2+ and Pb2+ were calculated 24.65 and 24.92 mg g−1, respectively, which reveal more improved adsorption capacitance of the GQDs|QS in comparison with nontreated QS. According to experimental results, adsorption of Hg2+ and Pb2+ on the developed adsorbent follows pseudo‐second order kinetic model. In addition, equilibrium experimental data appropriately fit with the Langmuir isotherm (R2 > 0.99). It was found that the stability and removal performance of the GQDs|QS strongly depend to the particle size of GQDs. Due to low cost, stability and effectiveness of the GQDs|QS, it could be used as a suitable choice for water treatment in industrial scale. © 2018 American Institute of Chemical Engineers Environ Prog, 38: S24–S31, 2019

Effect of the adsorbent dose in Pb(II) removal by using sugar cane bagasse: Kinetics and isotherms

“…The parameters of the isothermal models were evaluated by non-linear regression and are shown in Table 4. From Figure 3 and the values of the parameters reported in Table 4, it is established that the model that best adjusts the lead adsorption balance is that of Langmuir, which suggests that the surface of the adsorbent is uniform, all sites of adsorption are equivalent, adsorbed molecules do not interact, adsorption occurs through the same mechanism and that in maximum adsorption only a monolayer is formed where adsorbate molecules are not deposited on others already adsorbed (Basu et al, 2017;Mohammad-Rezaei and Jaymand, 2019). The above can be attributed to the homogeneous distribution of the binding sites in the adsorbents (Tatah et al, 2017).…”

Synthesis, Applications, and Prospects of Graphene Quantum Dots: A Comprehensive Review

“…GQDs have been coated on the surface of different solids such as magnetic materials and quartz sands in order to facilitate the collection of absorbents from aqueous solutions after the heavy metal extraction process. An inexpensive and highly efficient heavy metal absorbent based on GQDs coated on quartz sand was developed by Mohammad‐Rezaei and Jaymand [ 38 ] for removal of Hg 2+ and Pb 2+ ions from aqueous solutions. The quartz sand has a favorable flack‐like and rugged fracture surface through which GQDs can easily land on its surface and make stable heavy metal scavengers.…”

“…[ 29 ] GQDs have also found many applications in the fields of biomedical engineering (e.g., bioimaging, [ 30 ] drug delivery, [ 31 ] anticancer therapy, [ 32 ] and treatment of chronic diseases [ 33 ] ), catalysis, [ 34 ] sensors, [ 35 ] nanofluids, [ 36 ] and environmental remediation. [ 37,38 ] The most remarkable properties and potential applications of GQDs are illustrated in Figure .…”

Bioresource-Based Graphene Quantum Dots and Their Applications: A Review

“…The maximum adsorption capability was 40.00 mg/g. A cheap adsorbent consisting of GQDs coated on quartz sand (QS) was produced to remove Hg 2+ and Pb 2+ from aqueous solutions . Extremely tiny GQDs as coating GQDs avoid adsorbents on solids, which has drawbacks. , After adsorption, it is challenging and time-consuming to collect extremely tiny GQDs .…”