Chitosan–Zinc(II) Complexes as a Bio-Sorbent for the Adsorptive Abatement of Phosphate: Mechanism of Complexation and Assessment of Adsorption Performance

Abstract

This study examines zinc(II)–chitosan complexes as a bio-sorbent for phosphate removal from aqueous solutions. The bio-sorbent is prepared and is characterized via Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), and Point of Zero Charge (pHPZC)–drift method. The adsorption capacity of zinc(II)–chitosan bio-sorbent is compared with those of chitosan and ZnO–chitosan and nano-ZnO–chitosan composites. The effect of operational parameters including pH, temperature, and competing ions are explored via adsorption batch mode. A rapid phosphate uptake is observed within the first three hours of contact time. Phosphate removal by zinc(II)–chitosan is favored when the surface charge of bio-sorbent is positive/or neutral e.g., within the pH range inferior or around its pHPZC, 7. Phosphate abatement is enhanced with decreasing temperature. The study of background ions indicates a minor effect of chloride, whereas nitrate and sulfate show competing effect with phosphate for the adsorptive sites. The adsorption kinetics is best described with the pseudo-second-order model. Sips (R2 > 0.96) and Freundlich (R2 ≥ 0.95) models suit the adsorption isotherm. The phosphate reaction with zinc(II)–chitosan is exothermic, favorable and spontaneous. The complexation of zinc(II) and chitosan along with the corresponding mechanisms of phosphate removal are presented. This study indicates the introduction of zinc(II) ions into chitosan improves its performance towards phosphate uptake from 1.45 to 6.55 mg/g and provides fundamental information for developing bio-based materials for water remediation.

Characterization of a chitosan‐based sustained release nanofertilizer formulation used as a soil conditioner while simultaneously improving biomass production of Zea mays L.

“…It has been demonstrated that nanoparticles can be taken up by plants and are transported through phloem tissues (Abdel‐Aziz, Hasaneen, & Omer, 2016) and it is conjectured that higher dosages might cause interferences. The mechanism of such inhibition brought about by relatively higher concentration of nanoparticles has been stated to be still unexplored (Siddiqi & Husen, 2016) but plausible explanations have been attributed to film formation and coating (Badawy & Rabea, 2011; Beenken et al, 2015), gelling properties of chitosan that may form protein–chitosan conjugates (da Silva et al, 2014; Kumar, Smith, & Payne, 1999), and ion‐chelating potential (Gritsch, Lovell, Goldmann, & Boccaccini, 2018; Yazdani, Virolainen, Conley, & Vahala, 2017). Reduced root growth brought about by CS‐PMAA‐fertilizer nanoparticles was also reported by Khalifa and Hasaneen (2018).…”

Sorption of Hg(II) and Pb(II) Ions on Chitosan-Iron(III) from Aqueous Solutions: Single and Binary Systems

“…Samples with mass of 6 mg were degraded between 30 and 800 °C at a heating rate of 10 °C·min −1 in N 2 atmosphere. The pH pzc was evaluated according to the methodology of Yazdani et al [ 18 ] with a Bante 901 Benchtop pH meter instruments (Bante, Shanghai, China). The morphological observations, and energy dispersive X-ray (EDX) probe analysis of composite beads was done before and after metal sorption, using a Phenom XL SEM-EDX (PhenomWorld, Rotterdam, The Netherlands).…”

Synthesis of polyaminophosphonic acid-functionalized poly(glycidyl methacrylate) for the efficient sorption of La(III) and Y(III)

“…The equilibrium pH (pH eq ) was recorded. The pH PZC is the pH value corresponding to pH i = pH eq [33,34].…”