Synthesis of Nano Calcium Oxide from a Gastropod Shell and the Performance Evaluation for Cr (VI) Removal from Aqua System

Abstract

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.

Synthesis of clamshell derived Ca(OH)2 nano-particles via simple surfactant-hydration treatment

“…Some researchers showed that CaO catalyst in nano-dimension will render amazing level of performance in terms of product selectivity and catalytic reactivity. This includes the transesterification reaction of triglyceride with methanol [13,14], and reacted as chemisorbents for toxic gases, chlorinated or phosphorus-containing compounds and pollutant in water [15,16]. CaO is capable of providing high surface area-to volume ratio in nano-crystalline structure, which is five times more in the number of active sites per unit area [17], thus offering higher basicity of catalyst which shall have positive effects on various reactions.…”

“…Different studies were discussed on the preparation methods for Ca(OH) 2 nanoparticles including sonochemical technique [4,21], hydrogen plasma-metal reaction [5], sol-gel method [22][23][24], hydrothermal method [25], homogeneous and heterogeneous phase syntheses [26][27][28][29] and precipitation method [30,31]. However, these techniques come with its own limitations which are high cost of organic solvents and chemical reagents that required as CaO starting precursor.…”

Polypyrrole-coated halloysite nanotube clay nanocomposite: Synthesis, characterization and Cr(VI) adsorption behaviour

“…Amongst these, adsorption has been proven to be one of the best alternative techniques due to its simplicity, low cost and robustness (Atia, 2008;Sarkar et al, 2010). Numerous adsorbents like metal oxide, chitosan, industrial waste material, biomaterials, activated carbon and clays have been assessed for the removal of Cr(VI) from water and wastewater by different researchers (Hu et al, 2003;Lee et al, 2005;Bhattacharyya and Sen Gupta, 2006;Liu et al, 2006;Oladoja et al, 2012;Shroff and Vaidya, 2012). In most of the studies, these materials were found to have low adsorption capacity and slow kinetics.…”

The Utilization of Catfish Bone Waste as Microcalcium by Different Preparation Methods

“…Several studies related to calcium sources [2][3][4] used raw material mussel shells, fish scales, and gastropod shells respectively. Sol-gel method using HCl and NaOH produced calcium from catfish bone by 19.87% [5].…”