Reduction of Cr⁶⁺ from Wastewater Using a Novel in Situ-Synthesized PANI/MnO₂/TiO₂ Nanocomposite: Renewable, Selective, Stable, and Synergistic Catalysis

Abstract

An in situ synthesis of a new nanocomposite, polyaniline/manganese dioxide/ titanium dioxide (PANI/MnO 2 /TiO 2 ), via a one-pot oxidative polymerization method at room temperature is described in this article. The characterization was done on the synthesized nanocomposite using UV−vis, FT-IR, XRD, TGA, SEM, and TEM analysis. A superior catalytic activity is exhibited by the synergistic PANI/MnO 2 /TiO 2 nanocomposite in the conversion of toxic Cr 6+ to benign Cr 3+ in comparison with PANI, MnO 2 , TiO 2 , PANI/MnO 2 , PANI/TiO 2 , MnO 2 /TiO 2 , and other nanocomposite materials reported. The reduction rate is dependent on the concentration of substrate (Cr 6+ ), oxidant (HCOOH), and catalyst, pH, temperature, and foreign ions. The PANI/MnO 2 /TiO 2 reveals an excellent conversion (99.9%), rate constant (15.97 × 10 −2 min −1 ), and turnover frequency (0.3333 mmol/mg/min) in the reduction of Cr 6+ . The results obtained from this study illustrate that the prepared nanocomposite, PANI/MnO 2 /TiO 2 , can be very well used as an effective and economically viable catalyst for the reduction of toxic contaminant Cr 6+ from wastewater.

Facile development of photochromic cellulose acetate transparent nanocomposite film immobilized with lanthanide‐doped pigment: ultraviolet blocking, superhydrophobic, and antimicrobial activity

“…[ 20–23 ] They have been utilized in various applications, such as antireflective coatings, [ 24 ] air/water filters, [ 25 ] drug delivery, [ 26 ] light‐emitting diodes, [ 27 ] electronic recording devices, [ 28 ] solar cells [ 29 ] and food packaging. [ 30–33 ] Nanocomposite films immobilized with nanomaterials have received great consideration due to their desirable properties, such as optical, [ 34 ] catalytic, [ 35 ] sensory, [ 36,37 ] water‐repellent, [ 38,39 ] antimicrobial, [ 40 ] UV protection, [ 41 ] and electrical conductivity [ 42 ] that make them suitable for various advanced technical applications.…”

Two-Dimensional Titanium Carbides (Ti3C2Tx) Functionalized by Poly(m-phenylenediamine) for Efficient Adsorption and Reduction of Hexavalent Chromium

“…At present, adsorption remains an effective method for Cr(VI) remediation [6], which involves the conversion from toxic Cr(VI) to mild Cr(III) in the adsorption process [7,8]. Various adsorbents have been developed, such as biochar [9,10], the metal-organic framework [11,12], nanoscale zero-valent iron [13,14], graphene oxide [15,16], and organic polymer [17,18]. Unfortunately, current adsorbents generally suffer from unsatisfactory removal capacity, a low adsorption rate, and weak reduction capacity.…”

Engineering a Rapid Charge Transfer Pathway for Enhanced Photocatalytic Removal Efficiency of Hexavalent Chromium over C3N4/NH2–UIO‐66 Compounds

“…It is well accepted that the positiveness of the catalyst is benefited for the adsorption performance of Cr(VI) by electrostatic interaction, due to Cr(VI) mainly existing in the form of dichromate in aqueous solution. [ 47–49 ] As shown in Figure a, the pure CN showed poor adsorption performance toward Cr(VI) due to it is electronegativity; the adsorption rate of hexavalent chromium was less than 10% within 30 min. However, with increasing of NU content on the surface of the CN nanosheet, the surface of CNU underwent a negative‐to‐positive charge transition (Figure S6, Supporting Information), and the adsorption capacities of Cr(VI) increased accordingly, due to the electron‐rich amino groups on MOF tending to protonate and form NH 4+ in acid solution, which provided a positive surface and an advantage for the adsorption of hexavalent chromium.…”