Method for preparing efficient heavy metalion adsorbent carbon hydroxy apatite

Abstract

The invention discloses a method for preparing a novel high-efficiency heavy metal ion sorbent-carbonic hydroxyl apatite: washing egg shells, drying, and crushing them into below 30 meshes, adding egg shell powder into phosphoric acid in the molar ratio of 1 to 1, calculated by CaCO3, controlling pH value at 1-3, controlling temperature at 30-40 deg.C, and reacting for 2-3 hours, where reaction equation: CaCO3+H3PO4=CaHPO4+CO2+H2O, filtering out nonsoluble matters, adding in urea and Ca(OH)2 powder in the molar ratio of 1 to 1, regulating the pH value to 9-12 with 1mol/L NaOH solution, preserving heat at 50-60 deg.C for 24 h, where chemical reaction formula: CaHPO4+(NH2)2CO+Ca(OH)2-Ca10{(PO4)6-x,(CO3 OH)x}(OH)2, cooling reaction product, and then washing with 1% NH4Cl solution to neutral, drying at 60 degrees centigrade, crushing and obtaining carbonic hydroxyl apatite powder.

Description

technical field [0001] The invention relates to the preparation of an adsorbent for heavy metal ions in sewage, and belongs to the technical field of sewage treatment in environmental protection. Background technique [0002] With the continuous development of industry, metallurgical and mining industries produce a large amount of wastewater containing heavy metal ions such as mercury, cadmium, zinc, lead, copper, chromium, nickel, etc. Due to the non-biodegradability and bioaccumulation of heavy metal ions, heavy metals The harm to people, animals and plants is very serious. [0003] Heavy metal poisons have the following characteristics: ①It cannot be degraded by microorganisms, but can only be transformed and dispersed among various forms. For example, inorganic mercury can be transformed into more toxic methylmercury under the action of microorganisms; ②Its toxicity exists in an ion state Metal ions are easily absorbed by negatively charged colloids in water, and the co...

AI Technical Summary

Problems solved by technology

However, these methods have some disadvantages, for example, precipitation results in a large amount of sludge containing high concentrations of heavy metal ions, which must be treated before being discharged into the environment

Ion exchange and membrane separation methods are too expensive and sometimes difficult to translate from laboratory scale to full-scale large-scale industrial application

Although the cost of the biological method is low, it causes a large amount of heavy metal ions to remain in the excess sludge, so that the excess sludge must be treated before it can be used (composting), which increases the cost of treatment

The disadvantages of the above methods are: (1) cannot remove heavy metals completely; (2) require expensive reagents or energy; (3) lack the selectivity of removing special heavy metal ions; (4) the removal process is relatively slow; ( 5) Low removal capacity

As the main part of the adsorption method, the cost and adsorption performance of the adsorbent become the bottleneck of the application of the adsorption method