Synthesis of magnetic core-shell amino adsorbent by using uniform design and response surface analysis (RSM) and its application for the removal of Cu2+, Zn2+, and Pb2

• Published in: Environmental science and pollution research international 2021-07, Vol.28 (27), p.36399-36414
• Main Authors: Alam, Easar, Feng, Qiyan, Yang, Hong, Fan, Jiaxi, Mumtaz, Sameena
• Format: Article
• Language: English
• Subjects: Adsorbents; Adsorption; Aminopropyltriethoxysilane; Ammonium; Ammonium hydroxide; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Coating effects; Copper; Earth and Environmental Science; Ecotoxicology; Environment; Environmental Chemistry; Environmental Health; Environmental science; Ethanol; Iron oxides; Lead; Magnetic cores; Optimization; Reaction time; Research Article; Response surface methodology; Silicon dioxide; Sol-gel processes; Surface analysis (chemical); Surface chemistry; Synthesis; Tetraethyl orthosilicate; Tetramethyl ammonium hydroxide; Waste Water Technology; Water Management; Water Pollution Control; Zinc
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-11840-7

The magnetic Fe 3 O 4 was synthesized by using a one-step solvothermal method. Then, anhydrous ethanol as a solvent, tetramethyl ammonium hydroxide (TMAOH) as an auxiliary agent, tetraethyl orthosilicate (TEOS) as a silicon source, and (3-aminopropyl) triethoxysilane (APTES) as amino source were used to prepare Fe 3 O 4 @mSiO 2 -NH 2 by using the sol-gel method. Uniform design U14*(14 5 ) and the response surface method (RSM) were used to optimize the synthesis ratio. According to the results of TEM, SEM, N 2 adsorption–desorption test, VSM, and XRD, it found that the best coating effect obtained when the relative molar ratio of TMAOH:TEOS:APTES:Fe 3 O 4 was 5:4:6:0.45. The results of EDS and elemental analysis confirmed the success of amino group coating; VSM magnetization after surface modification was 32 emu/g; BET results show that specific surface area is 236 m 2 /g, size 5 nm, and the pore volume is 0.126 cm 3 /g. The removal of Cu 2+ , Zn 2+ , and Pb 2+ by Fe 3 O 4 @mSiO 2 -NH 2 was studied at the optimal initial pH value 6 of the adsorption test system. The isothermal adsorption results show that the Langmuir model and Redlich–Peterson model are more suitable than the Freundlich model to describe the adsorption behavior, and Cu 2+ , Zn 2+ , and Pb 2+ adsorption is mainly single molecular layer. The maximum adsorption capacity qm of the Langmuir model for Cu 2+ , Zn 2+ , and Pb 2+ removal was 48.04 mg/g, 41.31 mg/g, and 62.17 mg/g, respectively. The adsorption kinetic rates of Cu 2+ , Zn 2+ , and Pb 2+ on Fe 3 O 4 @mSiO 2 -NH 2 relatively more suitable for pseudo-second-order kinetic model, i.e., R 2 , were ranged between 0.995 and 0.999, and the suitable reaction time was 60 min. These results proved that Fe 3 O 4 @m-SiO 2 -NH 2 prepared by using this method is easy to synthesize, has easy recovery, is ecofriendly, and can be potential adsorbent for Cu 2+ , Zn 2+ , and Pb 2+ removal.