Hydroxyapatite Composite Adsorbent for Mercury and Selenium Removal
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Solution Overview
Problem
Current adsorbents, such as hydroxyapatite, are ineffective in removing mercury and selenium from wastewater due to low affinity for anionic species and the need for a single solution that can handle both cationic and anionic contaminants, especially in complex industrial wastewater compositions.
Innovation Solution
A hydroxyapatite composite is developed by incorporating additives during synthesis to enhance adsorption affinity and capacity, increasing porosity and BET surface area, allowing for simultaneous trapping of various contaminants including mercury, selenium, and arsenic in both cationic and anionic forms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional hydroxyapatite is used as adsorbent, then it can remove cationic metals from wastewater, but it shows low affinity for anionic species such as mercury and selenium
Solution Approach 1:
The patent applies composite materials by combining hydroxyapatite with other adsorbent materials to create a composite adsorbent that can effectively remove both cationic and anionic contaminants. The composite structure allows the material to maintain its ability to adsorb cationic metals while gaining enhanced affinity for anionic species through the contributing components.
Solution Approach 2:
The patent applies local quality by modifying specific regions or surfaces of the hydroxyapatite structure to enhance its affinity for particular contaminant types. This involves creating different functional zones within the adsorbent material that are optimized for adsorbing cationic versus anionic species, allowing simultaneous effective removal of both contaminant types.
2Productivity
If additives are incorporated during hydroxyapatite synthesis to enhance adsorption capacity, then adsorption efficiency improves, but manufacturing complexity increases
Solution Approach 1:
The patent applies preliminary action by incorporating additives during the synthesis process itself rather than adding them separately afterward. This allows the additives to be integrated into the hydroxyapatite structure formation, pre-establishing the enhanced adsorption properties before the material is fully formed, thereby avoiding additional processing steps.
Solution Approach 2:
The patent applies parameter changes by modifying synthesis parameters such as pH, temperature, and additive concentration to optimize the formation of hydroxyapatite composite with enhanced adsorption capacity. By carefully controlling these parameters during synthesis, the material achieves improved performance without requiring overly complex manufacturing procedures.
3Adaptability or versatility
If the adsorbent is designed to treat complex industrial wastewater compositions, then it can handle multiple contaminants, but the stability in aqueous solutions may be compromised
Solution Approach 1:
The patent applies intermediary by introducing substances or structural elements that mediate between the adsorbent material and the aqueous environment. These intermediaries help maintain the structural integrity and stability of the hydroxyapatite composite in water while enabling it to effectively adsorb multiple types of contaminants from complex wastewater compositions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hydroxyapatite composite effectively immobilizes a wide range of contaminants, improving adsorption efficiency and stability, making it suitable for treating industrial effluents and natural waters contaminated with metals and non-metals, while maintaining stability in aqueous solutions.
Implementation Method 1
an adsorbent effective on effluents of industrial origin and also applicable to water purification in general to remove cationic as well as anionic species of contaminating elements
Data Source
AI summary
A composite comprising a hydroxyapatite and at least one additive which is present during hydroxyapatite synthesis. The additive may be embedded or incorporated into or coated onto the hydroxyapatite. The additive preferably increases the hydroxyapatite porosity, e.g., providing a higher pore volume and/or BET surface area than a hydroxyapatite material without additive. The additive preferably comprises an activated carbon, chitosan, hopcalite, clays, zeolites, sulfur, and/or a metal such as Al, Sn, Ti, Fe, Cu, Zn, Ni, Cu, Zr, La, Ce, in the form of metal, salt, oxide, oxyhydroxide, and/or hydroxide. The hydroxyapatite may be calcium-deficient. The composite is in the form of particles having a D50 of at least 20 μm, a BET surface area of at least 120 m2/g; and/or a total pore volume of at least 0.3 cm3/g. An adsorbent material comprising a composite or a blend of composite with a hydroxyapatite without additive, and its use for removal of contaminants such as Hg, Se, As, and/or B from an effluent.