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Preparation and application of carbon-coated iron oxide of high-mediation oxalic acid reduced chromium

An iron oxide, carbon coating technology, applied in catalyst activation/preparation, metal/metal oxide/metal hydroxide catalyst, chemical/physical process, etc., can solve problems such as iron ion leaching, achieve low cost, Simple preparation method and wide-ranging effects

Pending Publication Date: 2022-04-12
CENT SOUTH UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] Carbon-based materials are usually doped with some transition metals, such as iron, to improve their conductivity and electron transfer, but surface modification inevitably leads to the leaching of a large number of iron ions.

Method used

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  • Preparation and application of carbon-coated iron oxide of high-mediation oxalic acid reduced chromium
  • Preparation and application of carbon-coated iron oxide of high-mediation oxalic acid reduced chromium
  • Preparation and application of carbon-coated iron oxide of high-mediation oxalic acid reduced chromium

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] This example is used to illustrate the morphology characterization of carbon-coated iron oxides.

[0030] The method comprises the following steps: (1) adding a certain amount of Acidithiobacillus ferrooxidans cell suspension to 200 mL of deionized water with a pH of 2.00 containing 15 g of ferrous sulfate heptahydrate and 0, 1, 1.5, and 2.0 g of polyvinyl alcohol;

[0031] (2) After culturing in a constant temperature shaking shaker at 200 rpm and 30°C for 72 hours, simply filter, dry and grind to obtain different PVA-doped and modified Shi formula minerals;

[0032] (3) The Shi-type minerals obtained with different PVA doping modifications were calcined in a tube furnace for 2 hours, taken out at room temperature, and sealed with nitrogen gas for storage.

[0033] Further, the different PVA-doped and modified Shi-type minerals obtained in step (3) were calcined in a tube furnace at 500, 700, and 900°C for 2 hours, the calcining conditions were argon atmosphere, and th...

Embodiment 2

[0036] This example is used to illustrate the structural characterization of carbon-coated iron oxides.

[0037] Such as figure 2 (a), PVA-modified Shi minerals retain their original phase composition and crystal structure. Such as figure 2 (b), the functional groups of the calcined Sch and modified Sch are significantly reduced. Including -OH characteristic band becomes weaker, SO 4 2- The characteristic bands disappear due to the evaporation of elemental sulfur. Calcined Sch-PVA has obvious Fe 2+ -O 2- group, with the increase of calcination temperature, Fe 2+ -O 2-The group bands gradually disappear. This can be attributed to the enhanced reduction of iron in PVA-modified Shi-type minerals at higher calcination temperatures.

[0038] Such as image 3 As shown in (c), the specific surface areas of C-Sch, C-1.0-Sch-PVA, C-1.5-Sch-PVA and C-2.0-Sch-PVA are 7.768, 13.890, 16.067 and 36.962m respectively 2 g -1 . The specific surface area of ​​PVA modified sampl...

Embodiment 3

[0040] This example is used to illustrate the effect of carbon-coated iron oxides modified by pyrolysis with different PVA contents and different temperatures on mediating the reduction of Cr(VI) with oxalic acid.

[0041] Such as image 3 As shown, the modified Shi-type minerals with different PVA content after calcination will produce obvious differences when mediating OA to remove Cr(VI). Individual OA, C-Sch, C-1.0-Sch-PVA, C-1.5 -Sch-PVA, C-2.0-Sch-PVA within 90min, mediated oxalic acid removal efficiency of Cr(VI) was 1.0%, 0.4%, 29.3%, 60.2% and 84.9%. Those modified with high PVA content will retain more carbonaceous framework after calcination. The presence of aromatic structures in carbon-coated iron oxides produced at a calcination temperature of 700 °C facilitates electron transfer, and more oxygen-containing groups are beneficial to drive redox reactions in Cr(VI) and OA systems. The high specific surface area of ​​C-2.0-Sch-PVA provided more functional sites fo...

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Abstract

The invention relates to preparation and application of carbon-coated iron oxide of high-mediation oxalic acid reduced chromium, and belongs to the technical field of environmental materials. The material is prepared by adding polyvinyl alcohol (PVA) for modification on the basis of synthesizing iron-based secondary minerals through iron-oxidizing bacteria, culturing for a period of time, filtering, drying, grinding into powder, finally calcining for 2 hours in an inert gas atmosphere of 700 DEG C, cooling to room temperature, taking out, and introducing nitrogen for sealing. The carbon-coated iron oxide can efficiently mediate oxalic acid (4mM) to realize nearly 100% removal of hexavalent chromium (Cr (VI), 40mg / L) within 90 minutes under the dosage of 0.75 g / L, and shows an excellent Cr (VI) removal effect in a relatively wide pH range, different salt ion concentrations and different water bodies. The carbon-coated iron oxide is wide in raw material source, simple to synthesize, low in cost and capable of being industrially prepared on a large scale, and has the main characteristic that the removal of Cr (VI) can be realized by efficiently mediating oxalic acid within a short time. Therefore, the carbon-coated iron oxide material has a wide application prospect in removal of heavy metal polluted water.

Description

technical field [0001] The invention belongs to the field of environmental functional materials, and relates to the preparation and application of a carbon-coated iron oxide that highly mediates the reduction of chromium with oxalic acid. [0002] technical background [0003] Chromium is used extensively in various modern industries such as electroplating, leather tanning and paint making. However, hexavalent chromium (Cr(VI)), as a dissociative anion with carcinogenic, mutagenic and teratogenic properties, has been included in the 20 priority hazardous substances of the Superfund National Priority List. Traditional remediation methods for Cr(VI) pollution include biological reduction, chemical precipitation, and photocatalytic reduction, all of which convert Cr(VI) into less toxic and less mobile Cr(III). However, these methods are accompanied by various disadvantages, such as long reduction period, secondary pollution, and extra energy consumption, which limit the large-s...

Claims

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Application Information

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IPC IPC(8): B01J23/745B01J37/08B01J37/36C02F1/70C02F101/22
Inventor 甘敏蔡渺顾春尧朱建裕刘梦飞何鹏熊瑶唐宾林周熠豪
Owner CENT SOUTH UNIV
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