Abstract
Abstract The acidic wastewater produced by the wet production of activated clay contains valuable components such as iron and aluminum. The precipitation method was successfully introduced to separate iron and aluminum from the activated clay production wastewater step by step, which can not only recover the valuable components, but also avoid environmental pollution. In the separation process, gypsum, iron aluminum phosphate, alumina, and sodium sulfate were prepared, and the phase compositions of separation products were analyzed by XRD and IR. The main influencing factors in the separation of iron and aluminum components were studied by single factor experiment. The results show that at the optimized conditions, phosphorus/iron molar ratio 6.0, the system pH 3.0, the reaction temperature 343 K, and the reaction time 90 min, the iron(iii) ion in the system can form a sodium-containing aluminum iron phosphate double salt, and the filtrate after separating Fe3+ and part of Al3+ can meet the requirements for forming high-purity Al2O3. During the phosphate precipitation process, the hypothesis should be correct that Al3+ reacts with PO 4 3 − {\text{PO}}_{4}^{3-} to form an AlPO4 skeleton, Fe3+ isomorphically replaces Al3+ in the [AlO4] tetrahedron, and adsorption occurs simultaneously, with Na+ occupying the terminal acid sites, P(Al)–OH.
Highlights
Bentonite is a clay rock composed mainly of montmorillonite
This paper focuses on achieving the efficient separation of valuable components such as iron and aluminum and solving the worries about the difficulty of acid wastewater handling in the activated clay production process
The influencing factors of the iron and aluminum components separation process were studied by single factor experimental method
Summary
Bentonite is a clay rock composed mainly of montmorillonite. Montmorillonite is a 2:1 layered silicate mineral composed of [SiO4] tetrahedral sheet and [AlO6] octahedral sheet [1], its structural formula can be expressed as (Na,Ca)0.3–0.6{(Al, Mg)2Si4O10(OH)2}·nH2O [2,3]. A novel separation method of the valuable components for activated clay production wastewater 531 quickly produces metal-proton exchange reaction with the interlayer cations Na+, Ca2+ of montmorillonite [11]. The acidic wastewater produced by wet process activated clay contains a certain amount of valuable components such as aluminum, iron, and magnesium. Based on the characteristics of valuable components of acid wastewater generated in the activated clay production process and the needs of production and environmental protection, the separation of iron and aluminum in the wastewater after pre-neutralization treatment was accomplished using phosphate precipitation and alkali precipitation respectively. This paper focuses on achieving the efficient separation of valuable components such as iron and aluminum and solving the worries about the difficulty of acid wastewater handling in the activated clay production process
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