Absorption of calcium ions on oxidized graphene sheets and study its dynamic behavior by kinetic and isothermal models

Abstract

Sorption of calcium ion from the hard underground water using novel oxidized graphene (GO) sheets was studied in this paper. Physicochemical properties and microstructure of graphene sheets were investigated using Raman spectrometer, thermogravimetry analyzer, transmission electron microscope, scanning electron microscope. The kinetics adsorption of calcium on graphene oxide sheets was examined using Lagergren first and second orders. The results show that the Lagergren secondorder was the best-fit model that suggests the conception process of calcium ion adsorption on the Go sheets. For isothermal studies, the Langmuir and Freundlich isotherm models were used at temperatures ranging between 283 and 313 K. Thermodynamic parameters resolved at 283, 298 and 313 K indicating that the GO adsorption was exothermic spontaneous process. Finally, the graphene sheets show high partiality toward calcium particles and it will be useful in softening and treatment of hard water.

A novel approach for the removal of lead (II) ion from wastewater using Kaolinite/Smectite natural composite adsorbent

“…Environmental pollution became one of the common important subjects that attract the attention of many scientists at the present time (Fathy et al 2016a). Toxic metals have a dangerous impact on human health, and these substances may go into human body either directly in drinking water or indirectly via food, plant, fish, and meat.…”

Cement-Induced Coagulation of Aqueous Graphene Oxide with Ultrahigh Capacity and High Rate Behavior

“…By measuring the concentration difference before and after the addition of CaCl 2 , Ca 2+ -induced coagulation capacity was calculated to be 3940.7 mg/g, which accounted for more than 50% in the maximum GO coagulation capacity of cement. This confirmed that Ca 2+ decreased the stability of GO and displayed an aggressive ability in GO aggregation [ 45 ] because of the binding capacity of Ca 2+ ions with hydroxyl and carboxyl functional groups of GO [ 46 ]. Therefore, we believe that one of the mechanisms of GO removal by cement was Ca 2+ -induced coagulation.…”

Adsorption Analysis of Fluoride Removal Using Graphene Oxide/Eggshell Adsorbent

“…According to pseudo-second-order theory, the adsorption of fluoride onto GO/ES adsorbent is a chemisorption process which involves sharing or exchange of electrons between the adsorbent and F - [13]. There is a possibility that Fmay diffuse across a liquid phase prior to GO/ES's active sites through intraparticle diffusion and indirectly reacts with available active sites, such Ca 2+ to produce CaF [17][18][19][20].…”

“…The values of ΔG° in between 0 and to 20 kJ/mol indicate a physic-sorption process, while the values in between -80 to -400 kJ/mol correspond to the chemisorption process [15]. The increment in values of ΔG° with an increase in temperature suggests that higher temperature makes the adsorption of Funfavorable, while the negative value of ΔS° indicates that the process is enthalpy driven and the negative value of ΔH° implies that the adsorption phenomenon is exothermic [12][13]19]. This explains that the adsorption of Fby using GO/ES adsorbent is not suitable to be conducted at high temperature.…”