The potential of tourmaline as a natural adsorbent for toxic metals, such as Pb(II), from acidic water was investigated. Batch experiments were conducted to study the effects of pH, temperature, particle size, and dose of absorbents. Results indicated that the adsorption of Pb(II) depended significantly on all the above-mentioned parameters except pH: no significant differences in adsorption mass were noted between pH 4.0 and pH 5.0. This independence from pH was in contrast to heavy metal adsorption by the conventional materials in acidic conditions. Furthermore, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) analyses elucidated the adsorption mechanisms of tourmaline of different particle sizes for Pb(II). FTIR analyses revealed that the bands originating from tourmaline particles of the spectra of 0.5–50 μm differed from those of 60–180 μm before and after interaction with aqueous Pb(II). SEM showed the evidence that Pb(II) aggregates were formed on tourmaline surfaces of 0.5–50 μm size particles. These results indicated differences in Pb(II) adsorption between 0.5–50 and 60–180 μm particle sizes, which were attributed to their differing extent of adjusting the pH of the solution. Hence, Pb(II) adsorption on the 0.5–50 μm tourmaline particles at 25 °C was the result of electropolar adsorption and chemisorption processes. Langmuir, Freundlich, and Langmuir–Freundlich isotherms all indicated good fits to the experimental data. The maximum mass of Pb(II) adsorbed (q m), as evaluated by a Langmuir–Freundlich isotherm, was 108 mg/g on tourmaline of 0.5–50 μm at an initial pH 5.0, which was much greater than that obtained for previously reported materials. Thus, this study shows that tourmaline may be explored as a new material for removing pollutants from the environment.

There is a lack in clinically-suitable vascular grafts. Biotubes, prepared using in vivo tissue engineering, show potential for vascular regeneration. However, their mechanical strength is typically poor. Inspired by architectural design of steel fiber reinforcement of concrete for tunnel construction, poly(ε-caprolactone) (PCL) fiber skeletons (PSs) were fabricated by melt-spinning and heat treatment. The PSs were subcutaneously embedded to induce the assembly of host cells and extracellular matrix to obtain PS-reinforced biotubes (PBs). Heat-treated medium-fiber-angle PB (hMPB) demonstrated superior performance when evaluated by in vitro mechanical testing and following implantation in rat abdominal artery replacement models. hMPBs were further evaluated in canine peripheral arterial replacement and sheep arteriovenous graft models. Overall, hMPB demonstrated appropriate mechanics, puncture resistance, rapid hemostasis, vascular regeneration, and long-term patency, without incidence of luminal expansion or intimal hyperplasia. These optimized hMPB properties show promise as an alternatives to autologous vessels in clinical applications.

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