| Abstract [eng] |
In this Master‘s Final work adsorption capacity of heavy metals (Zn2+, Co2+, Cu2+, Fe3+) and F– ions by synthetic hydroxyapatite and monetite was investigated. In order to obtain calcium phosphates, two different mixtures were prepared: 1) blue mussel shells with phosphoric acid; 2) blue mussel shells with diammonium hydrogen phosphate. The molar ratio of primary composition corresponded to Ca/P = 1,67. The prepared mixtures have been put in 40 ml PTFE vessels and mixed with water to obtain water to solid ratio equal to 10. Later on, vessels were places in the autoclave and treated under hydrothermal conditions at temperatures of 100 °C, 140 °C, 180 °C, and 200 °C for 0 h, 4 h, 6 h, and 8 h. It was examined that optimal synthesis conditions of hydroxyapatite are: 1) mixture is made of blue mussel shells and diammonium hydrogen phosphate; 2) synthesis temperature – 180 °C; 3) the duration of isothermal treatment – 2 h. Meanwhile optimal hydrothermal synthesis conditions of monetite are: 1) mixture is made of blue mussel shells and phosphoric acid; 2) synthesis temperature – 100 °C; 3) the duration of isothermal treatment – 0 h. The samples obtained under these synthesis conditions were analysed using main instrumental analysis methods for powder samples: X-ray diffraction analysis, simultaneous thermal analysis, scanning and transmission electron microscopies, Fourier transformation – infrared spectroscopy, adsorption of nitrogen gas at 77 K temperature. It was determined that calcium phosphates have the best adsorption capacity for iron ions and the worst adsorption capacity for fluorine ions. It was determined that the increment of liquid temperature has a positive effect on the adsorption process because at a higher temperature the amount of interfering ions into hydroxyapatite and monetite was rather bigger. X-ray diffraction analysis results showed that hydroxyapatite remains stable under all adsorption conditions, meanwhile, monetite partially crystallise to the familiar compound – brushite in copper and cobalt solutions. It was determined that monetite reacts with F– ions presented in the solution thus fluorapatite was formed after the adsorption process. Based on obtained results the technological recommendations of production of calcium phosphates and their application for adsorption were proposed. |
