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

Abstract

Triple superphosphates [TSPs, Ca(H 2 PO 4 ) 2 ·H 2 O] 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, P 2 O 5 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. From the successful results, the method for TSP production can be applied in the fertilizer industry based on starting waste materials of oyster shells that can replace the use of unsustainable phosphate or calcium minerals obtained from nonliving things.

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

“…From these obtained results, it can be concluded that some specific concentrations of acetic acid can leach more oxide impurities, and the suitable concentration of acetic acid was observed to be 10 mol L −1 . Similar results were reported by Seesanong et al [ 53 ] in the preparation of triple superphosphate (TSP, Ca(H 2 PO 4 ) 2 ·H 2 O) compound synthesized from the exothermic reactions between oyster-shell derived CaCO 3 powder and phosphoric acid (H 3 PO 4 ). The influence of the H 3 PO 4 concentrations (10−70 wt%, increment: 10 wt%) on the chemical composition of Ca(H 2 PO 4 ) 2 ·H 2 O products was also investigated.…”

Synthesis of novel green phosphate pigments with phosphophyllite composition

“…Figure 3 shows the FT-IR spectra of samples prepared with Zn/Fe/P = 2/1/2 for 1 h. The peaks at 500 and 1000/cm were absorptions seen in phosphate, and the peak at 800/cm and the doublets at 1320 and 1360/cm were those seen in iron oxalate. 19,20 These results indicate that the samples contain phosphate and oxalate, which is consistent with the XRD pattern results. Figure 4 shows the photographs of samples prepared under various conditions (1 h).…”

Selective formation of neodymium phosphate from iron-neodymium magnet waste

“…2 shows IR spectra of samples prepared with various concentrations of hydrochloric acid and then heated at 700 ºC for 1 h. All samples had a similar spectrum with NdPO 4 [20,21]. The peaks due to the bending of O-P-O and the P-O stretching were observed in the region of 630-520 and 1100-960 cm -1 , respectively [22]. From these results, the main composition of the obtained thermal products was neodymium phosphate.…”