Bio-green synthesis of calcium acetate from oyster shell waste at low cost and reducing the emission of greenhouse gases

Abstract

Biological wastes obtained from food, oyster shells, were recycled to calcium carbonate and then used as bio-green raw material to replace limestone/carbonate stone for calcium acetate (Ca(CH3COO)2·H2O) production. The conditions (ambient temperature occurred in an exothermic reaction, drying time, yield, and solubility) of the reaction between the bio-green CaCO3 and three different acetic (CH3COOH) concentrations (8, 10, and 12 M) were investigated. The product's maximum yield (93%) with a shorter drying time (18 h) was obtained from the reaction between the bio-green CaCO3 with 12 M acetic acid revealing a lower cost. The chemical compositions without any toxic metal impurity revealed by the X-ray fluorescence technique would be useful to suggest use in the specific application. The X-ray diffraction, Fourier Transform Infrared, and Thermogravimetric analysis data of Ca(CH3COO)2·H2O prepared by the bio-green CaCO3 obtained from oyster shell wastes in this work and those in previous works used other calcium sources were consistent. The morphologies with different sizes of the obtained Ca(CH3COO)2·H2O depend on the CH3COOH concentrations reported in this work and were different from those reported in previous works because of different calcium sources. According to the observation, it can be concluded that the low-cost and bio-green technique without the environmental effects was successfully applied to produce cheap Ca(CH3COO)2·H2O and reduce greenhouse gas emissions, which can be used in the specific industry.

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

“…The XRF results show that CAM8, CAM10, and CAM12 mostly consisted of CaO of around 95.1, 96.2, and 94.6 wt%, respectively. This data confirms the % purity of the synthesized Ca(CH 3 COO) 2 ·H 2 O samples, which are lower than those of Ca(CH 3 COO) 2 ·H 2 O (95–98 % purity) produced by scallop shells and oyster shells with acetic acid reported in the previous work [ 43 , 45 ]. The reason could be explained by the %purity of calcium carbonate from the difference in sources and kinds (cockle and scallop shells).…”

“…All vibrational characteristics obtained in this experimental work confirmed the formation of cockle shell derived Ca(CH 3 COO) 2 ·H 2 O compound. The vibrational characteristics of all synthesized Ca(CH 3 COO) 2 ·H 2 O compounds are in good agreement to the results reported by Thongkam et al [ 43 ], Seesanong et al [ 45 ], Musumeci et al [ 54 ] and Koleva [ 57 ].…”

“…On the other hand, the lowest percentage yield (91.88 %) was observed from CAM8 due to the highest amount of reaction medium (water), which might cause the low amount of the starting reagent (acetic acid) for Ca(CH 3 COO) 2 ·H 2 O production. The drying time of the Ca(CH 3 COO) 2 ·H 2 O from cockle shells that mainly contain CaCO 3 in aragonite form in this work is lower than the preparation of Ca(CH 3 COO) 2 ·H 2 O using oyster shells and scallop shells that mainly contain CaCO 3 in calcite form in the previous work [ 43 , 45 ]. However, all percentage yields observed in this work (cockle shells as raw agent) are higher than those reported in the previous work (89–93 % yield) [ 43 , 45 ] which results in cheaper production costs.…”

“…The drying time of the Ca(CH 3 COO) 2 ·H 2 O from cockle shells that mainly contain CaCO 3 in aragonite form in this work is lower than the preparation of Ca(CH 3 COO) 2 ·H 2 O using oyster shells and scallop shells that mainly contain CaCO 3 in calcite form in the previous work [ 43 , 45 ]. However, all percentage yields observed in this work (cockle shells as raw agent) are higher than those reported in the previous work (89–93 % yield) [ 43 , 45 ] which results in cheaper production costs. The results obtained are consistent with previous research, showing that using cockle shells (aragonite) (91–95 %) instead of oyster shells (89–93 %) or scallop shells (calcite) (85–87 %) leads to increased percentage yields during the preparation of calcium acetate.…”

“…This work focuses on acetic acid concentrations in the range 8–12 mol L −1 based on the results of the physical and chemical properties of calcium acetate obtained from other shells, reported in previous work [ 43 , 45 ] as a guideline. To prepare the target calcium acetate compound according to Eq.…”