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Thermal properties of porous sodium polyacrylate/silica nanocomposites

Korobeinyk Alina, Yurchenko Gabriella, Matkovsky Alexander, Tertykh Valentin

Polimery

2023

Vol. 68, nr 2

106--112

Porous sodium polyacrylate/silica (SPA/SiO2) nanocomposites were obtained in a single-stage sol-gel process involving the acidic hydrolysis of tetramethoxysilane (TMOS) in the presence of SPA. The TMOS/SPA molar ratio ranged from 2:1 to 8:1. The physical and thermal properties of the nanocomposites were characterized by FTIR, SEM, TGA and adsorption analysis (BET, BJH). The mechanical and chemical treatment of the composite after the synthesis increased its specific surface area without significantly changing thermal properties. The process enables pore size control.

Porowate nanokompozyty poliakrylan sodu/krzemionka (SPA/SiO2) otrzymano w jednoetapowym procesie zol-żel polegającym na kwaśnej hydrolizie tetrametoksysilanu (TMOS) w obecności SPA. Stosunek molowy TMOS/SPA wynosił od 2:1 do 8:1. Właściwości fizyczne i termiczne otrzymanych nanokompozytów scharakteryzowano za pomocą FTIR, SEM, TGA i analizy adsorpcyjnej (BET, BJH). Mechaniczna i chemiczna obróbka kompozytu po procesie syntezy zwiększyła jego powierzchnię właściwą bez znaczącej zmiany właściwości termicznych. Proces umożliwia kontrolę wielkości porów.

Flotation separation of scheelite from calcite using sodium polyacrylate as depressant

Zhang Y., Chen R., Li Y., Wang Y., Luo X.

Physicochemical Problems of Mineral Processing

2018

Vol. 54, iss. 2

505--516

The depressing properties of sodium polyacrylate (PA-Na) for calcite from scheelite were studied by microflotation experiments, zeta potentials, X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculation. Flotation results revealed that the selective depression effect of PA-Na was better than that of sodium silicate (Na2SiO3), and PA-Na can depress calcite more effectively than scheelite. The flotation recovery of scheelite and calcite kept at about 75% and 15% respectively at the pulp pH 9.3~9.6 and PA-Na concentration from 37.5 mg/dm3 to 50 mg/dm3. The zeta potentials of the minerals were significantly altered and the zeta potential of calcite became more negative than scheelite. XPS analysis deduced the occurrence of chemisorption between PA-Na and mineral surfaces, and the chemisorption of PA-Na on calcite was stronger than on scheelite. The results from DFT calculation demonstrated that the absolute value of the adsorption energy in the presence of PA-Na on the surface of calcite {104} was larger than on the surface of scheelite {111}. With the combination of the analysis, it could be concluded that calcite was more easily depressed than scheelite, and this finding remarkably matched with the microflotation experimental results. Furthermore, by using PA-Na as depressant, the flotation separation of scheelite from calcite can be achieved by controlling the flotation pH and PA-Na dosage.