Wu et al. 2023 - Hybrid membrane adsorption of Pb2+ and Cu2+

Wu, Zheng, and Han synthesized negatively charged PEG/Si-O-Si organic-inorganic hybrid membranes and tested their adsorption of Cu2+ and Pb2+ under varied pH, temperature, initial concentration, and contact time. This is primary remediation-method evidence, not occurrence evidence: the source reports laboratory adsorption capacities and condition optimization for prepared metal-ion solutions rather than concentrations in food, ingredients, drinking water, or field wastewater.

Key numbers

Membrane formulations

Table 1 defines four membrane formulations by the molar ratio of WD-60 to PEG-6000:

FTIR confirmed PEG/Si-O-Si covalent bonding and carboxyl groups; TGA/DSC indicated improved thermal stability after hybridization, with heat resistance above 300 C.

Cu2+ adsorption

The paper reports a maximum Cu2+ adsorption capacity of 0.331 mmol/g for the negatively charged siloxane hybrid membrane, compared with 0.075 mmol/g in the zwitterionic hybrid-copolymer comparator cited by the authors. Cu2+ adsorption increased slightly as WD-60 increased across samples A-D.

Cu2+ optimization details reported in the main text:

Pb2+ adsorption

The 6:1 membrane material (sample D) had the highest Pb2+ adsorption capacity, 5.012 mmol/g. Table 2 compares this with 0.244 mmol/g for a zwitterionic hybrid copolymer, 0.506 mmol/g for silica-based hybrid adsorbents, and 6.379 mmol/g for pyromellitic-acid-dianhydride hybrid adsorbents.

Pb2+ optimization details reported in the main text:

The intraparticle-diffusion plots were non-linear and involved three stages: rapid interface diffusion from 0 to 3 hours, slower intraparticle diffusion, and approach to equilibrium. The authors conclude that Cu2+ and Pb2+ adsorption on samples A-D was not governed solely by intraparticle diffusion.

Methods (brief)

The membrane materials were prepared in DMF from PEG-6000, maleic anhydride, and the silane coupler WD-60 via epoxy ring-opening and sol-gel reactions. Reaction mixtures were heated at 80 C for 8 hours, coated on Teflon, dried at room temperature for 2-3 days, and then oven-dried with stepwise temperature increases to 50 C. Membranes were characterized by SEM, FTIR, and TGA/DSC.

Cu2+ and Pb2+ adsorption experiments used aqueous nitrate solutions as the adsorption medium. The main paper reports condition sweeps for pH, temperature, initial metal-ion concentration, and contact time; detailed capacity-determination procedures are in supplementary Files S1 and S2.

Implications

Certification: Do not use this source in any product, ingredient, drinking-water, or food occurrence pool. It is a laboratory membrane-adsorbent study using prepared Cu2+ and Pb2+ nitrate solutions.

App: Context for water-treatment and remediation notes. The main signal is that the 6:1 WD-60:PEG formulation had the highest Pb2+ capacity and that Pb2+ capacity was much higher than Cu2+ capacity under the reported optimized conditions.

Courses: Useful for teaching condition optimization, membrane adsorbent design, and the difference between mmol/g adsorbent capacity and metal concentration in a sampled matrix.

Wiki pages this source may touch

• remediation-evidence
• lead
• copper
• index

Verification notes

This page was built from the full PDF, including Table 1 membrane recipes, SEM/FTIR/TGA characterization, Table 2 capacity comparison, Cu2+ and Pb2+ condition-optimization sections, Tables 3 and 4 time-fraction summaries, intraparticle-diffusion discussion, conclusion, and supplementary-materials note. The source reports Cu2+ and Pb2+ adsorption capacities in prepared aqueous systems only. Products and ingredients are intentionally empty because no food, ingredient, drinking-water field sample, or consumer-product matrix was sampled.

Page history

The five most recent substantive edits to this page. The full version history lives in git; when DOI minting comes online (see schema docs), each entry below will also link to a version-pinned DataCite DOI.