Low-Cost and Eco-Friendly Calcium Oxide Prepared via Thermal Decompositions of Calcium Carbonate and Calcium Acetate Precursors Derived from Waste Oyster Shells.

Waste oyster shells were utilized to produce calcium carbonate (CaCO) by grinding. This CaCO was then reacted with acetic acid to yield calcium acetate monohydrate (Ca(CHCOO)·HO). Both CaCO and Ca(CHCOO)·HO were used as precursors for synthesizing calcium oxide (CaO) through thermal decomposition at 900 °C and 750 °C, respectively.

Green Ca-source of cockle shells converted to calcium acetate for environmental sustainability.

This work aimed to synthesize and characterize the calcium acetate monohydrate (Ca(CHCOO)·HO) from the exothermic reaction between CaCO powder derived from cockle shells with three different acetic acids (8, 10, and 12 mol L) concentrations by the rapid and easy process without pH and temperature control to lead to cheap chemical production. The physicochemical characteristics of all synthesized Ca(CHCOO)·HO samples are investigated based on the chemical compositions, crystal structures, vibrational characteristics, morphologies, and thermal behavior to confirm the target compound. A suitable concentration of 10 mol L CHCOOH was chosen to produce Ca(CHCOO)·HO with the highest yield (96.

Efficient, Green, and Low-Cost Conversion of Bivalve-Shell Wastes to Value-Added Calcium Lactate.

This work presents the efficient, green, and low-cost preparation of calcium lactate by using bivalve-shell wastes (cockle, mussel, and oyster shells) as raw materials. Three bivalve shells, a cockle, mussel, and oyster, were used separately as an alternative calcium-source material for the preparation of calcium lactate. The bivalve-shell waste was cleaned and milled, obtaining calcium carbonate (CaCO) powder, which reacted to the lactic acid, forming calcium lactate.

Composition and Properties of Triple Superphosphate Obtained from Oyster Shells and Various Concentrations of Phosphoric Acid.

Triple superphosphates [TSPs, Ca(HPO)·HO] were produced by exothermic reactions of oyster shells and different concentrations of phosphoric acid (10, 20, 30, 40, 50, 60, and 70% w/w) in a molar ratio of 1:2. The percentage yields, PO and CaO contents, metal impurities, and thermal behaviors of all the as-prepared products are dependent on the concentrations of phosphoric acid added during the production processes, which confirm to get the best optimum of 60% w/w phosphoric acid. All the as-prepared products were characterized by several characterization methods [X-ray fluorescence, thermal gravimetric/derivative thermal gravimetric analysis, powder X-ray diffraction, Fourier-transform infrared spectroscopy, and scanning electron microscopy], verifying that all the obtained compounds are TSP that can be used as fertilizers without metal toxic contaminants.