Highly Efficient Lead(II) Sequestration Using Size-Controllable Polydopamine Microspheres with Superior Application Capability and Rapid Capture

In this work, we successfully prepared the mussel inspired polydopamine microspheres (PDA-Ms) with controllable sizes, through a facile self-oxidative polymerization method. The prepared PDA-M biomaterial with environmentally benign properties exhibits efficient lead(II) sequestration against high salts of competitive Ca(II), Mg(II), or Na(I) ions. It reveals 30 times greater than the commercial ion-exchanger 001x7 by selectivity evaluation. Kinetic results show that an exceedingly rapid lead(II) uptake can be achieved below 1 min. More attractively, the prepared PDA-Ms further exhibit the distinguished application ability with superior treated capacity of similar to 42000 kg contaminated water/kg sorbent, and the effluents can be reduced from 1000 mu g/L to below 10 mu g/L, reaching the drinking water standard (WHO), which is equal to 200 times greater than commercial ion exchanger resin (similar to 210 kg) and granular activated carbon (similar to 120 kg). In addition, the exhaust PDA-M material can be well regenerated and repeated use using binary 1% HCl + 5% Ca(NO3)(2) solution. X-ray photoelectron spectroscopy (XPS), zeta potential, and FT-IR analysis prove that such satisfactory performances can be ascribed to the following aspects (1) the well-dispersed nanoscale morphology and highly charged property will achieve the rapid adsorption and sufficient sorbent utilization. That is, the negatively-charged PDA sphere can exert the famous Donnan membrane effects for target lead(II) enrichment and diffusion enhancement; (2) the strong amine and carbonyl/hydroxyl group within the matrix can offer sorption selectivity for powerful lead(II) capture. Effective performances as well as environmentally friendly features suggest PDA-M material is a promising lead(II)-removing candidate for water remediation.