Intercalation of Gastropod Shell Derived Calcium Oxide in Clay and Application in Phosphate Removal from Aqua Medium

Abstract

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

Sequestration of naturally abundant seawater calcium and magnesium to enhance the adsorption capacity of bentonite toward environmental phosphate

“…By the intercalation of CaO into gastropod shell clays, high phosphate adsorption capacity of modied gastropod shell clay could be achieved. 12 Similarly, through the slow pyrolysis of Mg-enriched tomato tissues in an oxygen-decient environment, engineered biochar embedded with nanoscale Mg(OH) 2 and MgO is found to have a high phosphate adsorption capacity because these nanoparticles serve as the main adsorption sites for phosphate accommodation. 13 These interesting results clearly indicate that the appropriate acquisition of naturally abundant alkaline earth elements would be an environmentally friendly route to prepare high-performance adsorbents for the removal of phosphate.…”

Enhancement of Kaolin Adsorption Affinity Toward Phosphate by Sequestrating Naturally Abundant Ca/Mg From Seawater

“…This result was also found for the adsorption of phosphate by BS600, Ca-Mg-loaded biochar, and CaO-modified clay, respectively. [10,18,26] Consequently, the strong interaction between phosphate and CaO/MgO played a key role in the enhancement of phosphate adsorption.…”

“…Bentonite modified with Mg(OH) 2 has a significant effect on the removal efficiency of phosphate, resulting in a maximum adsorption density of 14.33 mg m −2 . Similarly, the intercalation of CaO in a gastropod shell clay framework can enhance the phosphate adsorption capacity from the perspective of low cost and waste recycling . Previous study has also shown that the negatively charged bentonite (Na‐type MX‐80) surface can be well modified by the incorporation of seawater Ca/Mg via ion exchange, resulting in effective removal of phosphate .…”

“…[17] Similarly, the intercalation of CaO in a gastropod shell clay framework can enhance the phosphate adsorption capacity from the perspective of low cost and waste recycling. [18] Previous study has also shown that the negatively charged bentonite (Na-type MX-80) surface can be well modified by the incorporation of seawater Ca/Mg via ion exchange, resulting in effective removal of phosphate. [10] The kaolin clay reserves in China are vast and much larger than those of other clays such as sepiolite, illite, and chlorite, which should allow for cheap extraction.…”

Copper (11) Ions Biosorption from Aqueous Solution Using Modified Moringa Oleiferal Leaves (MMOL)

“…This is a pointer to the fact that the sorption of the CU(II) ions moieties on MMOL occurred via chemisorptions. If the sorbate uptake is chemically rate controlled, then the pseudo second order constants will be independent of particle diameter and flow rate will depend on concentration of the ions in solution [20]. A review of the results, presented in Tables 3, showed that the pseudo second order parameters obtained from the uptake of CU(II) ions onto MMOL (qe and k 2 values) varied with the initial CU (II) concentration.…”