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Method for degrading hexavalent chromium in wastewater by photocatalytic reduction method

A technology of hexavalent chromium and reduction method is applied in the field of environmental pollution treatment, and can solve the problems of inability to fundamentally solve the problem of hexavalent chromium pollution, time-consuming, and hexavalent chromium precipitate pollution.

Pending Publication Date: 2022-06-03
NANJING UNIV OF INFORMATION SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The treatment method of hexavalent chromium is mainly divided into biological method, physical adsorption method, photocatalytic reduction method, wherein biological method and physical adsorption method cannot fundamentally solve the problem of hexavalent chromium pollution; Chinese patent document CN112079462A discloses the use of The method of adsorption of hexavalent chromium in wastewater, but the adsorption cannot solve the fundamental problem, and the pollution of hexavalent chromium still exists
Chinese patent document CN112159025A discloses a method for precipitating hexavalent chromium in waste water and then separating it by precipitation method, but its operation is complicated, and the pollution of hexavalent chromium precipitate still exists
Photocatalytic reduction has become the preferred choice for the treatment of hexavalent chromium wastewater pollution. However, the existing reports on the photoreduction of hexavalent chromium have shortcomings such as low conversion efficiency and long time consumption.

Method used

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  • Method for degrading hexavalent chromium in wastewater by photocatalytic reduction method
  • Method for degrading hexavalent chromium in wastewater by photocatalytic reduction method
  • Method for degrading hexavalent chromium in wastewater by photocatalytic reduction method

Examples

Experimental program
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Effect test

Embodiment 1

[0012] Example 1: Preparation of photocatalyst as Bi 4 O 5 Br 2 .

[0013] At room temperature, 1.5 mmol of bismuth nitrate hexahydrate was added to beaker 1 containing 5 mL of ethylene glycol, and stirred evenly; 15 mL of ethylene glycol was added to beaker 2, and under stirring conditions, 3 mmol of potassium bromide was added, and stirred evenly; Mix the solutions in beaker 1 and beaker 2, stir for half an hour, transfer to a polytetrafluoroethylene liner, and conduct hydrothermal reaction at a constant temperature of 180 °C for 6 hours; wash, centrifuge, and dry, and the product is Bi 4 O 5 Br 2 catalyst of light.

[0014] The product was detected by X-ray diffraction and scanning electron microscope. The X-ray diffraction pattern and scanning electron microscope of the product are shown in the attached figure 1 and attached figure 2 .

[0015] Depend on figure 1 It can be seen that the product prepared in this example is the same as Bi 4 O 5 Br 2 The standard...

Embodiment 2

The method for degrading hexavalent chromium in wastewater by the photocatalytic reduction method of the present invention specifically comprises the following steps:

Step 1. Add an alcohol-promoted photocatalyst to the wastewater containing hexavalent chromium (Preparation of Bi 4 O 5 Br 2 photocatalyst), and stirring for 1 hour in the dark to make the air reach the adsorption / desorption equilibrium on the surface of the photocatalyst. The photocatalyst is Bi 4 O 5 Br 2 , the alcohol used is methanol, and the dosage ratio of photocatalyst and methanol is 1 g photocatalyst: 200 mL methanol.

[0018] Step 2, irradiating the wastewater containing hexavalent chromium that has undergone the light-shielding reaction in step 1, and performing a photocatalytic reaction to reduce the hexavalent chromium in the wastewater, until the hexavalent chromium content is lower than the discharge standard.

Embodiment 3

The photocatalytic reduction method of the present invention degrades hexavalent chromium in wastewater, and the alcohol-promoted photocatalyst adopts Example 1 to prepare Bi 4 O 5 Br 2 The photocatalyst specifically includes the following steps:

Step 1. Add an alcohol-promoted photocatalyst to the wastewater containing hexavalent chromium, and stir in the dark for 0.5 hours to make the air reach adsorption / desorption equilibrium on the surface of the photocatalyst. The photocatalyst is Bi 4 O 5 Br 2 , when the alcohol used is isopropanol, the dosage ratio of photocatalyst and isopropanol is 1 g photocatalyst: 150 mL isopropanol.

[0020] Step 2, irradiating the wastewater containing hexavalent chromium that has undergone the light-shielding reaction in step 1, and performing a photocatalytic reaction to reduce the hexavalent chromium in the wastewater, until the hexavalent chromium content is lower than the discharge standard.

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Abstract

The invention discloses a method for degrading hexavalent chromium in wastewater by a photocatalytic reduction method, which comprises the following steps: adding a photocatalyst promoted by mixed alcohol into the wastewater containing hexavalent chromium, stirring in a dark place, enabling air to reach adsorption / desorption balance on the surface of the catalyst, and carrying out photocatalytic reaction under the irradiation of visible light, the mixed alcohol is methanol or isopropanol or a mixed solution of methanol and isopropanol. The method disclosed by the invention is simple, environment-friendly and efficient; the operation is convenient, and the hexavalent chromium can be efficiently degraded without other excessive treatment. The invention provides a new thought and method for reducing hexavalent chromium.

Description

technical field [0001] The invention relates to the technical field of environmental pollution treatment, in particular to a method for degrading hexavalent chromium in wastewater by a photocatalytic reduction method. Background technique [0002] Hexavalent chromium wastewater pollution from industries such as industrial pigments, tanning, rubber, ceramics, and metal chrome plating is a lasting danger to the environment and seriously endangers human health. Hexavalent chromium is an ingested poison. Skin contact may cause allergies, and it is more likely to cause genetic defects and cancer. These toxicity are the characteristics of hexavalent chromium, and chromium metal, trivalent or tetravalent chromium does not have. Therefore, the reduction and conversion of hexavalent chromium to low-toxicity or non-toxic low-valent chromium is an effective strategy to reduce chromium pollution. The treatment methods of hexavalent chromium are mainly divided into biological methods, p...

Claims

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Application Information

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IPC IPC(8): C02F1/30C02F1/70C02F101/22
CPCC02F1/30C02F1/70C02F2101/22C02F2305/10Y02W10/37
Inventor 滕飞袁晨阮万生刘喆
Owner NANJING UNIV OF INFORMATION SCI & TECH
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