Brushite-Metakaolin Composite Geopolymer Material as an Effective Adsorbent for Lead Removal from Aqueous Solutions

Abstract

Newly designed mesoporous brushite-metakaolin-based geopolymer materials were examined with an idea for using this material as a potential adsorbent for Pb(II) removal from aqueous solutions. As a starting component for geopolymer synthesis, a natural raw kaolinite clay with the addition of 2 wt.%, 4 wt.%, 6 wt.%, 8 wt.%, and 10 wt.% of pure brushite was used. Phase, structural, morphological, and adsorption properties of newly synthesized mesoporous brushite-metakaolin geopolymer materials were examined in detail by the means of XRPD, FTIR, SEM-EDS, BET/BJH, and ICP-OES methods. The ICP-OES results showed that the synthesized material samples with 2 wt.%, 4 wt.%, and 6 wt.% of brushite possess significant adsorption properties and the mechanisms of the adsorption process can be attributed to chemisorption. The most notable result is that brushite-metakaolin-geopolymer with 2 wt.% of brushite have the best efficiency removal, more than 85% of Pb(II).

Design of PEI and Amine Modified Metakaolin-Brushite Hybrid Polymeric Composite Materials for CO2 Capturing

“…The highest amounts of N are in the samples BGM10 and GM10, which is in accordance with the synthesis procedure since 1,000,000 of PEI is attached in these samples. Additionally, the Ca:P ratio in the samples with brushite is approximately 1:1, which is in accordance with the literature data and also the synthesis of brushite [ 7 , 33 ].…”

“…The key role of the organic-inorganic hybrids is in developing advanced functional materials because their chemical and physical properties are unique and stem from the synergistic interaction of organic and inorganic phases [ 6 ]. The inorganic component of the hybrid material (inorganic polymer) would be of aluminosilicate and calcium phosphate origin and would be based on local potential raw materials, such as kaolin clay, with materials from the calcium phosphate group [ 7 ]. Calcium phosphate materials and clay minerals are typical and fragile cement-based materials that can be modified by incorporating organic polymer to enhance the workability, flexural and tensile strength, and water resistance [ 8 ].…”

“…Additionally, due to their excellent structural characteristics, these materials can be used as adsorbents in various applications for organic and inorganic pollutants [ 13 ]. There is the possibility to use different type’s aluminosilicate materials as raw materials with phosphate types of cement for producing new inorganic polymer materials for specific applications [ 7 ]. Inorganic polymers based on natural aluminosilicate precursors with calcium phosphate are a relatively new class of materials [ 14 , 15 ], adding organic components to improve their materials’ mechanical properties, durability, and thermal stability.…”

Synthesis and adsorption performance of fly ash/steel slag‐based geopolymer for removal of Cu (II) and methylene blue

“…In addition, the equilibrium adsorption capacities calculated from the pseudo‐second‐order (34.025 mg/g for MB, 22.624 mg/g for Cu 2+ ) were closer to the experimental values (33.30 mg/g for MB and 24.15 mg/g for Cu 2+ ). Thus, the adsorption of MB and Cu 2+ onto the G20 sample was dominated by chemisorption 38 . Furthermore, according to the fitting results based on the intraparticle diffusion model, the fitted straight line did not pass through the zero point, indicating that intraparticle diffusion was not the only rate‐controlling step, and the adsorption process of G20 on MB and Cu 2+ contained multiple mechanisms and was a complicated process 39 …”

“…Thus, the adsorption of MB and Cu 2+ onto the G20 sample was dominated by chemisorption. 38 Furthermore, according to the fitting results based on the intraparticle diffusion model, the fitted straight line did not pass through the zero point, indicating that intraparticle diffusion was not the only rate-controlling step, and the adsorption process of G20 on MB and Cu 2+ contained multiple mechanisms and was a complicated process. 39 Besides, fitting the adsorption data of various concentrations to the Langmuir and Freundlich isotherm models were presented in Figure 9 and Table 4.…”