Economical and Environmentally Friendly Track of Biowaste Recycling of Scallop Shells to Calcium Lactate

Abstract

The scallop shell waste ( Pectinidae , one of saltwater clams) was used as a raw material (precursor) to prepare calcium lactate (Ca(C 2 H 4 OHCOO) 2 ), and the physicochemical properties of scallop-derived calcium lactate were then investigated. The scallop waste was first ground to obtain calcium carbonate (CaCO 3 ) powder, and the calcium lactate compounds were successfully synthesized by the reactions between shell-derived CaCO 3 and lactic acid (C 2 H 4 OHCOOH). The short preparation time, high percentage yield, and low-cost production are the preferred manners, and, in this research, it was the reaction of 70 wt % lactic acid and scallop-derived CaCO 3 . The thermal decompositions of both CaCO 3 precursor and all prepared calcium lactates resulted in the formation of calcium oxide (CaO), which is widely used as a catalyst for biodiesel production. By comparing with the literature, the results obtained from the characterization instruments (infrared spectrophotometer, X-ray diffractometer, thermogravimetric analyzer, and scanning electron microscope) confirmed the formation and crystal structure of both CaCO 3 and its calcium lactate product. The morphologies of calcium lactate show different sizes depending on the acid concentration used in the reaction process. Consequently, this work reports an easy, uncomplicated, low-cost technique to change the cheap calcium compound product (scallop CaCO 3 ) derived from shellfish waste to the valuable compound (calcium lactate), which can be used in many industries.

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“…Moreover, the quantity of waste mollusk shells is abundant; therefore, the use of these waste mollusk shells as an alternative calcium source will reduce the risk of microbiological and toxic problems and reduce the impact on the natural reserves of limestone. Mollusk-derived CaCO 3 powders could be obtained by simple and low-cost preparations, including protein removal, washing, drying, and milling, respectively [15] . After that, CaCO 3 -based waste shell powders can be used as a renewable calcium source to prepare value-added calcium compounds such as calcium oxide [16] , calcium hydroxide [17] , calcium phosphate [18] , calcium citrate [19] , calcium acetate [20] , and calcium lactate [15] .…”

“…Mollusk-derived CaCO 3 powders could be obtained by simple and low-cost preparations, including protein removal, washing, drying, and milling, respectively [15] . After that, CaCO 3 -based waste shell powders can be used as a renewable calcium source to prepare value-added calcium compounds such as calcium oxide [16] , calcium hydroxide [17] , calcium phosphate [18] , calcium citrate [19] , calcium acetate [20] , and calcium lactate [15] . Phosphate rocks originated from fossilized animal bone deposits [21] , which can be used as a phosphorus source to produce phosphoric acid [22] and as fertilizer [23] .…”

“…Due to its complexity, TSP shows a low solubility property and contains low phosphorus content [21] . Compared to MCPM, TSP is a low-grade and ineffective fertilizer [15] . Therefore, to increase the soluble phosphorus content\souts and to improve the purity of TSP, the TSP, made from the reaction between H 3 PO 4 and calcium-based ores, was dissolved in water to remove the non-soluble fraction by filtration, thus recovering the soluble phosphorus fertilizer in the form of dissolved MCPM.…”

Recrystallization of triple superphosphate derived from waste mollusk shells to produce mono- and di- calcium phosphates in green and low-cost way

“…Moreover, the quantity of waste mollusk shells is abundant; therefore, the use of these waste mollusk shells as an alternative calcium source will reduce the risk of microbiological and toxic problems and reduce the impact on the natural reserves of limestone. Mollusk-derived CaCO 3 powders could be obtained by simple and low-cost preparations, including protein removal, washing, drying, and milling, respectively 15 . After that, CaCO 3 -based waste shell powders can be used as a renewable calcium source to prepare valueadded calcium compounds such as calcium oxide 16 , calcium hydroxide 17 , calcium phosphate 18 , calcium citrate 19 , calcium acetate 20 , and calcium lactate 15 .…”

“…Mollusk-derived CaCO 3 powders could be obtained by simple and low-cost preparations, including protein removal, washing, drying, and milling, respectively 15 . After that, CaCO 3 -based waste shell powders can be used as a renewable calcium source to prepare valueadded calcium compounds such as calcium oxide 16 , calcium hydroxide 17 , calcium phosphate 18 , calcium citrate 19 , calcium acetate 20 , and calcium lactate 15 .…”