Poly(methacrylic acid)-graft-Ni3Si2O5(OH)4 multiwalled nanotubes as a novel nanosorbent for effective removal of copper(II) ions

Reactive membranes for groundwater remediation of chlorinated aliphatic hydrocarbons: competitive dechlorination and cost aspects

A nanocomposite membrane incorporating reactive Pd-Fe nanoparticles (NPs) was developed to remediate chlorinated aliphatic hydrocarbons (CAHs) from groundwater. Other than recapturing the produced Fen+ for in-situ regeneration, the functionalized polyanions prevented NPs agglomeration and resulting in a spherical Fe0 core (55 nm, O/Fe = 0.05) and an oxidized shell (4 nm, O/Fe = 1.38). The reactive membranes degraded 92% of target CAHs with a residence time of 1.7 seconds. After long-term treatment and regeneration, reusability was confirmed through recovered reactivity, recurrence of Fe0 in X-ray photoelectron spectroscopy, and >96% remaining of Fe and Pd. The total cost (adjusted present value for 20 years) was estimated to be 13.9% lower than the granular activated carbon system, following an EPA work breakdown structure-based cost model. However, non-target CAHs from groundwater can compete for active sites, leading to decreased surface-area normalized dechlorination rate ( k sa ) by 28.2-79.9%. A hybrid nanofiltration (NF)/reactive membrane was proposed to selectively intercept larger competitors, leading to 54% increased dechlorination efficiency and 1.3 to 1.9-fold enlarged k sa . Overall, the practical viability of the developed reactive membranes was demonstrated by the stability, reusability, and cost advantages, while the optional NF strategy could alleviate competitive degradation towards complex water chemistry.

Self-Assembled Serpentine Ni3Si2O5(OH)4 Hybrid Sheets with Ammonium Polyphosphate for Fire Safety Enhancement of Polylactide Composites

Biodegradable polylactide (PLA) has been widely utilized in people's daily lives. In order to improve the fire safety of PLA, ammonium polyphosphate (APP) was self-assembled onto the surface of serpentine Ni₃Si₂O₅(OH)₄ through the electrostatic method, followed by mixing with PLA by melt compounding. The APP-modified serpentine (serpentine@APP) dispersed uniformly in the PLA matrix. Compared with pure PLA, the PLA composite with 2 wt% serpentine@APP reduced the peak heat release rate (pHRR) and total heat release (THR) by 43.9% and 16.3%, respectively. The combination of APP and serpentine exhibited suitable synergistic flame-retardant effects on the fire safety enhancement of PLA. In addition, the dynamical rheological tests revealed that the presence of APP and serpentine could reduce the viscosity of PLA composites. The plasticizing effects of APP and serpentine benefited the processing of PLA. The mechanical properties of PLA/serpentine@APP maintained suitable performance as pure PLA. This study provided a feasible way to enhance the fire safety of PLA without sacrificing its mechanical properties.

PAMPS-graft-Ni3Si2O5(OH)4 multiwalled nanotubes as a novel nano-sorbent for the effective removal of Pb(ii) ions

The existence of Pb(ii) ions in water systems poses significant potential hazards to public health and the environment. In the present study, poly(2-acrylamido-2-methylpropanesulfonic acid) (PAMPS) brush-modified Ni₃Si₂O₅(OH)₄ nanotubes were prepared, and their adsorption efficiency against the Pb(ii) ions was investigated. The characterization results of FTIR spectroscopy, TGA, TEM, and XPS indicated the successful grafting of PAMPS on the surface of free Ni₃Si₂O₅(OH)₄ NTs, and the prepared PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs exhibited a 6–8 nm grafting layer, which could provide abundant binding sites for metal adsorption. During the Pb(ii) removal process, a pH-dependent adsorption behavior was observed, and the adsorption processes fitted well with the pseudo-second-order kinetic model and the Langmuir isotherm model. Compared with unmodified Ni₃Si₂O₅(OH)₄, the PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs exhibited obviously faster adsorption of Pb(ii) and higher equilibrium adsorption capacity for the removal of Pb(ii). The maximum adsorption capacity calculated via the Langmuir isotherm model was 0.653 mmol g⁻¹ (135.3 mg g⁻¹) at 298 K. In a metal coexisting system, the total adsorption capacity of the NTs was increased; this indicated the potential of the proposed NTs in the removal of Pb(ii) from metal coexisting wastewater. This study showed the significant potential of PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs in the effective removal of Pb(ii).

PAMPS-g-Ni₃Si₂O₅(OH)₄ NTs for the effective removal of Pb(ii).

Enhanced adsorption of Cu(ii) ions on chitosan microspheres functionalized with polyethylenimine-conjugated poly(glycidyl methacrylate) brushes

Crosslinked chitosan microspheres were tethered with branched polyethylenimine-conjugated poly(glycidyl methacrylate) brushes via surface-initiated ATRP and were further utilized as novel adsorbent to purify Cu(ii)-contaminated aqueous solution​.