A spongy, porous nano calcium oxide (NC) with point zero charge of 11.80 was synthesized using the shell of a Gastropod (Achatina achatina) via the sol–gel technique. The ability of the NC to adsorb Cr (VI) from aqueous solution was assessed systematically in a batch process via isothermal, kinetic, and variable process optimization procedure. The sorption data had the best fitting for the Langmuir isotherm model and the monolayer sorption capacity (q
m, mg/g) value of 125 mg/g was obtained. The initial solution pH had no palpable effect on the monolayer sorption capacity. The amount of sorbed Cr (VI) increased with contact time and initial Cr (VI) concentration and attained equilibrium within 120 min. The fitting of the different kinetic models to the sorption data, by error analysis, using the linear coefficient determinations (r
2) and the Chi-square statistical analysis (χ2), showed that the mechanism of the sorption process is better described by the pseudo second order kinetic model. Thermodynamic evaluation showed that the sorption process was spontaneous (ΔG
o: −15.27; −14.87 and −14.45 kJ/mol at 303, 313, and 333 °C, respectively), exothermic (ΔH
0 = −22.568 kJ/mol) and increased disorder (ΔS
0 = 0.0244) appeared on the NC–solution interface during the adsorption process.
One-pot synthesis of Co3O4 nanocrystals on reduced graphene oxide (rGO) was carried out by reacting cobalt nitrate, L-arginine, extract of Laportae aestuans as oxidant, fuel and reducing agent, respectively, in a domestic microwave. Morphologies of Co3O4–rGo (RGCO) composite was elucidated using UV-Vis, FT-IR, TEM, SEM, EDX, XRD and photoluminescence spectroscopies. The synthesized RGCO composite was applied as heterogeneous photocatalyst in the activation of Na2SO3 (sulfite) as sacrificial agent to degrade cationic dyes: rhodamine B (RhB) and methylene blue (MB), under visible light, at neutral pH 7.0. Photocatalytic performance of as-prepared RGCO was significantly enhanced in the presence of Na2SO3. Enhanced photocatalytic activity of RGCO was attributed to the synergistic effects between sulfite radicals generated in situ, and reduced graphene oxide, in which rGO served as electron sink to suppress recombination of photogenerated charge carriers. Plausible mechanistic pathways responsible for the activation of sulfite anions in situ are presented in this paper.
The phosphate sorption potential of the layered framework of naturally occurring clay, which acts as a host in the sorption process, was boosted via intercalation of CaO derived from a Gastropod shell (GS). GS was used as precursor for the synthesis of the CaO in the perspective of waste recycling and cost minimization in environmental remediation. The phosphate sorption potential, PZC, and the surface area of raw clay sample were substantially enhanced by the intercalation process. The value of the Langmuir monolayer sorption capacity (q m mg/g) increased from 49.02 to 71.43, PZC values increased from 4.70 to 7.20, and the surface area (m 2 /g) value increased from 23 to 103 after the intercalation process. The modification caused no change in the clay surficial microstructure but increased the lattice spacing of the clay framework. Increase in phosphate solution pH triggered monotonical reduction in the magnitude of phosphate sorbed while increase in phosphate solution ionic strength and concentration of anionic interferences caused an increase in the amount of phosphate sorbed per gram of sorbent. Phosphate sorption caused no change in the surficial microstructure of either sorbents but the crystallinity of the sorbent was considerably impacted, especially in the raw sample
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.