Low‐Spin‐State Hematite with Superior Adsorption of Anionic Contaminations for Water Purification

Abstract

Hematite attracts intensive interest as an adsorbent for water purification, but the oversized dimension and inherent high‐spin Fe(III) restrict its adsorption capability and kinetics. Herein a spatial‐confinement strategy is reported that synthesizes ultrafine α‐Fe2O3 benefiting from nanogrids constructed by predeposition of TiO2 nanodots in the MCM‐41 channel, and that tunes the spin‐state of Fe(III) from high‐spin to low‐spin induced by the strong guest–host interaction between the ultrafine Fe2O3 with SiO2 (MCM‐41). The low‐spin Fe(III) endorses strong bonding with anionic adsorbates, and significantly facilitates the electrons transfer from Fe2O3 to SiO2 to form a highly positive charged surface, and thereby shows superior electrostatic multilayer adsorption performance to different kinds of anionic contaminations. Specifically, the maximum uptake, adsorption rate, and distribution coefficient (Kd) for Rose Bengal dye reach as high as 1810 mg g−1, 1644 g (g min)−1, and 2.2 × 106 L kg−1, which are more than 8, 230, and 3700 times higher than those of commercial activated carbon, respectively. It also shows outstanding purification performance for real field water. It is demonstrated that a strong guest–host interaction can alter the spin‐state of transition metal oxides, which may pave a new way to improve their performance in adsorption and other applications like catalysis.

Application of Pineapple Leaves as Adsorbents for Removal of Rose Bengal from Wastewater: Process Optimization Operating Face-Centered Central Composite Design (FCCCD)

“…Nonetheless, RB has shown serious impacts on human health, especially when it gets in contact with skin and eyes causing discomfort, irritation, redness and blistering [ 14 , 15 , 16 , 17 , 18 ]. Removal of RB from wastewater has been done implementing various methods such as photo-degradation, nanofiltration and adsorption [ 19 , 20 , 21 , 22 ].…”

Facile fabrication of highly flexible and floatable Cu2O/rGO on Vietnamese traditional paper toward high-performance solar-light-driven photocatalytic degradation of ciprofloxacin antibiotic

“…This isotherm model presented concordantly the adsorption processes that occur as multilayers on the heterogeneous surfaces. 33 The value of parameter n in the Freundlich model is 1.63 (in the range from 1 to 10), indicating that the adsorption of CIP onto Cu 2 O/rGO/VTP is a favorable process. The maximum adsorption capacity q m of CIP onto Cu 2 O/rGO/VTP calculated from the Langmuir equation is 24.50 mg g À1 .…”

Photocatalytic Synthesis of High-Energy-Density Fuel: Catalysts, Mechanisms, and Challenges

“…MCM-41 features well-defined hexagonal mesopores with a large internal surface area and, thus, exhibits great potential as supporting material for TiO 2 [46]. Incorporating Ti ions into the MCM-41 framework or loading on the walls of the latter has been reported to generate unique photocatalytic activity.…”