Efficient Removal of Heavy Metal Ions with Biopolymer Template Synthesized Mesoporous Titania Beads of Hundreds of Micrometers Size

We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr­(VI), Cd­(II), Cr­(III), Cu­(II), and Co­(II) ions from simulated wastewater with a facile subsequent solid–liquid separation because of their large sizes. We chose Cr­(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr­(VI) from simulated wastewater containing 8.0 mg·L^–1 of Cr­(VI) at pH = 2.0. The Cr­(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr­(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr­(VI) ions in the form of negatively charged HCrO₄^– by positively charged TiO₂ beads, accompanying partial reduction of Cr­(VI) to Cr­(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L^–1 of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid–liquid separation property for heavy metal ions removal

Efficient Removal of Heavy Metal Ions with Biopolymer Template Synthesized Mesoporous Titania Beads of Hundreds of Micrometers Size

We demonstrated that mesoporous titania beads of uniform size (about 450 μm) and high surface area could be synthesized via an alginate biopolymer template method. These mesoporous titania beads could efficiently remove Cr­(VI), Cd­(II), Cr­(III), Cu­(II), and Co­(II) ions from simulated wastewater with a facile subsequent solid–liquid separation because of their large sizes. We chose Cr­(VI) removal as the case study and found that each gram of these titania beads could remove 6.7 mg of Cr­(VI) from simulated wastewater containing 8.0 mg·L^–1 of Cr­(VI) at pH = 2.0. The Cr­(VI) removal process was found to obey the Langmuir adsorption model and its kinetics followed pseudo-second-order rate equation. The Cr­(VI) removal mechanism of titania beads might be attributed to the electrostatic adsorption of Cr­(VI) ions in the form of negatively charged HCrO₄^– by positively charged TiO₂ beads, accompanying partial reduction of Cr­(VI) to Cr­(III) by the reductive surface hydroxyl groups on the titania beads. The used titania beads could be recovered with 0.1 mol·L^–1 of NaOH solution. This study provides a promising micro/nanostructured adsorbent with easy solid–liquid separation property for heavy metal ions removal

Comparison of the kinetic parameters for the α-KG reduction activity of the mutant IDHs.

<p>Comparison of the kinetic parameters for the α-KG reduction activity of the mutant IDHs.</p

Primers used in this study.

a<p>“-S” and “-As”: indicate the sense (-S) and antisense (-As) primers of the corresponding genes.</p><p>b “-f” and “-r”: indicate the forward (-f) and reverse (-r) primers used in the site-directed mutagenesis.</p><p>Underlined bases indicate the mutant sites.</p><p>Primers used in this study.</p

Structure-based protein sequence alignment of ScIDH1, YlIDH and HcIDH.

<p>The conserved amino acid residues are shaded. The secondary structure components, j.e, α-helices and β-sheets, of HcIDH and ScIDH1 are also shown. The conserved amino acid residues involved in substrate binding (★) and cofactor binding (▴) are indicated. This figure was generated using ESPript 2.2.</p

GC/TOF-MS identification of the products generated by YlIDH R141H and ScIDH1 R148H catalysis.

<p>(A) and (D) Gas chromatograms of the products generated by YlIDH R141Hand ScIDH1 R148H catalysis, respectively. (B) and (E) Mass spectrogram identifications of the 11.94-min peak in (A) and 11.91-minpeak in (D), respectively.(C) and (F) Mass spectrogram identifications of the 17.43-min peak in (A) and (D), respectively.</p

GC/TOF-MS identification of the 2-HG, ICT and α-KG standards.

<p>The retention times of the 2-HG, ICT and α-KG standards in the gas chromatogram were 11.94 min (A), 17.44 min (B) and 12.03 min (C), respectively. (D), (E) and (F) show the mass spectrogram identifications of 2-HG, ICT and α-KG, respectively.</p

Comparison of the kinetic parameters of the isocitrate oxidation activity of the wild-type and mutant IDH enzymes.

a<p>When calculating the <i>K</i>_m for isocitrate, the concentration of D-isocitrate was calculated as 50% of the total DL-isocitrate in this study. “na” indicates no measurable activity.</p><p>Comparison of the kinetic parameters of the isocitrate oxidation activity of the wild-type and mutant IDH enzymes.</p

Circular dichroism (CD) spectra analysis of intact and mutant YlIDH, ScIDH1 and HcIDH.

<p>The CD was measured, and the molar ellipticity was calculated as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0115025#s2" target="_blank">Materials and Methods</a>. (A) The molar ellipticities of HcIDH (▪), HcIDH R148H (•), HcIDH R132A (▴) and HcIDH R132E (▾) from 195 to 260 nm; (B) the molar ellipticities of ScIDH1 (▪), ScIDH1 R148H (•), ScIDH1 R148A (▴) and ScIDH1 R148E (▾) from 195 to 260 nm; (C) the molar ellipticities of YlIDH (▪), YlIDH R141H (•), YlIDH R141A (▴) and YlIDH R148E (▾) from 195 to 260 nm.</p