Easily modified barium phosphate composites for effective removal of methyl blue from solution

• Published in: Journal of environmental chemical engineering Vol. 9; no. 4; p. 105423
• Main Authors: Zhaozhao, Wu, Rongjuan, Li, Luyao, Pei, Yang, Yang, Xiaoguang, Li, Juncen, Jiang, Fan, Zhang
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01-08-2021
• Subjects: Barium phosphate; Isothermal; Kinetics; Lewis acid base interaction; Solution pH; Barium phosphate; Lewis acid base interaction; Isothermal; Kinetics; Solution pH
• ISSN: 2213-3437; 2213-3437
• DOI: 10.1016/j.jece.2021.105423

In this work, barium phosphate composites were easily modified by changing the reactants and surfactants to be barium sodium phosphate (NaBaPO4), barium phosphate (Ba3(PO4)2), barium hydroxyl phosphate (Ba5(PO4)3OH), and barium hydrogen phosphate (BaHPO4) (denoted NBP, BP, BPO, and BHP, respectively) using a one-step hydrothermal method. Positively charged cetyl trimethyl ammonium bromide (CTAB) on phosphate composites can slightly increase their removal capacities for methyl blue (MB) though it had no obvious effects on the composition and crystal type of materials. Dye removal experiments were carried out in a batch system to optimize operation variables such as solution pH, temperature, adsorbent dosage, contact time, and initial dye concentration. The kinetic behavior of all the materials agreed well with the pseudo-second-order model. The isothermal data of NBP and BPO fitted to the Langmuir model while Freundlich model was better to describe the isothermal data of BP and BHP. The removal capability for MB solution followed an order of NBP (249.6 ± 6.0 mg/g) > BP (226.0 ± 6.0 mg/g) > BPO (162.5 ± 5.0 mg/g) > BHP (85.84 ± 4.0 mg/g). NBP is most suitable for MB removal because of its high alkalinity: (1) The obvious increase of pH from 6.03 ± 0.10 to 12.26 ± 0.20 after adding NBP in solution can lead to improved decolorization of MB solution. (2) Strong Lewis acid base interaction between cations (Ba2+/Na+) in NBP and –SO3- in MB as well as the hydrogen bonding between PO43- in NBP and N–H or C–H in MB contributed to the high removal capacity of NBP.
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•Barium phosphate composites were easily modified by changing the reactants.•Cationic surfactants on these phosphate are helpful for removing methyl blue anions.•Increased pH of solution after adding basic phosphate improved dye decolorization.•Lewis acid base interaction and hydrogen bonding lead to high removal ability of NBP.•NBP with high alkalinity is suitable for MB removal.