Pretreatment method for rapidly decreasing concentration of hexavalent chromium in waste water

A hexavalent chromium and pretreatment technology, applied in water/sewage treatment, neutralized water/sewage treatment, water/sewage multi-stage treatment, etc., can solve the problem of separation and recovery of hexavalent chromium and magnetic particles, and the consumption of chemical agents Large volume, secondary pollution and other problems, to achieve the effect of reducing comprehensive treatment costs, good removal effect, and pressure relief

Inactive Publication Date: 2016-10-26
SHANDONG UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This method has strong practicability and can realize the recovery of chromium-containing magnetic particles. The disadvantage is that the consumption of chemical agents is large, the energy consumption is high, and the separation and recovery of hexavalent chromium and magnetic particles are relatively difficult, which is easy to cause secondary pollution.

Method used

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  • Pretreatment method for rapidly decreasing concentration of hexavalent chromium in waste water

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] Take the concentration of hexavalent chromium as 300mg·L -1 1000mL of waste water, add 0.85gCa(OH) 2 and 0.93gAlCl 3 ·6H 2 O(Ca(OH) 2 and AlCl 3 ·6H 2 The molar ratio of O is 3:1, and the total mass is 1 times the stoichiometric amount required to generate chromate-type ettringite), the pH value of the solution is adjusted to 12.80 using NaOH, and then the reaction is stirred at 20°C for 4h, followed by vacuum The water pump is filtered to obtain chromium-containing sediment and clear liquid. Take the clear liquid to detect the concentration of hexavalent chromium, and the concentration is 115.35mg L -1 , the method reduces the concentration of hexavalent chromium in wastewater by 61.55% in a relatively short period of time, and better realizes the pretreatment process of wastewater.

[0032] The XRD pattern of this embodiment gained chromium-containing sediment is as follows figure 1 shown. It can be seen from the figure that the main phase of the sediment obt...

Embodiment 2

[0034] Take the concentration of hexavalent chromium as 300mg·L -1 1000mL of waste water, add 1.28gCa(OH) 2 and 1.39gAlCl 3 ·6H 2 O(Ca(OH) 2 and AlCl 3 ·6H 2 The molar ratio of O is 3:1, and the total mass is 1.5 times the stoichiometric amount required to generate chromate-type ettringite), the pH value of the solution is adjusted to 12.80 using NaOH, and then the reaction is stirred at 20°C for 4h, followed by vacuum The water pump is filtered to obtain chromium-containing sediment and clear liquid. Take the clear liquid to detect the concentration of hexavalent chromium, and the concentration is 80.13mg L -1 , the method reduces the concentration of hexavalent chromium in wastewater by 73.29% in a short period of time, realizes the pretreatment of chromium-containing wastewater well, and reduces the treatment cost.

Embodiment 3

[0036] Take the concentration of hexavalent chromium as 300mg·L -1 1000mL of waste water, add 1.28gCa(OH) 2 and 1.39gAlCl 3 ·6H 2 O(Ca(OH) 2 and AlCl 3 ·6H 2 The molar ratio of O is 3:1, and the total mass is 1.5 times the stoichiometric amount required to generate chromate-type ettringite), the pH value of the solution is adjusted to 12.80 using NaOH, and then the reaction is stirred at 20°C for 24h, followed by vacuum The water pump is filtered to obtain chromium-containing sediment and clear liquid. Take the clear liquid to detect the concentration of hexavalent chromium, and the concentration is 55.26mg L -1 , this method reduces the concentration of hexavalent chromium in wastewater by 81.58% in a short period of time, indicating that prolonging the reaction time is conducive to improving the removal rate of hexavalent chromium in wastewater, but it will reduce the efficiency of wastewater treatment.

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Abstract

The invention discloses a pretreatment method for quickly reducing the concentration of hexavalent chromium in wastewater, comprising the following steps: a. 2 :AlCl 3 ·6H 2 O molar ratio is that the ratio of 3: 1 is mixed with medicament; B joins medicament in the waste water that contains hexavalent chromium, and the quality of added medicament is 1~5 times of the required stoichiometric amount of generating chromic acid type ettringite, then Add NaOH, adjust the pH value of the wastewater to 11.7-13.1, control the temperature of the wastewater to 5-40°C, and react under stirring conditions for 0.5-24 hours to obtain a suspension; c. Suction filter the suspension obtained in step b, A filtrate and a chromium-containing sediment are obtained. The present invention will Ca(OH) 2 and AlCl 3 ·6H 2 The agent formulated with O can form chromate-type ettringite with hexavalent chromium in wastewater in a short period of time, stabilize hexavalent chromium ions in its molecular structure and precipitate them out, and quickly reduce the concentration of hexavalent chromium in wastewater Concentration, realize the pretreatment process of wastewater containing hexavalent chromium, and reduce the pressure for the subsequent wastewater treatment to meet the standard.

Description

technical field [0001] The invention relates to a pretreatment method for rapidly reducing the concentration of hexavalent chromium in waste water, belonging to the field of waste water treatment. Background technique [0002] At present, industries such as electroplating, metal surface pretreatment, and leather processing involve the use of a large amount of raw materials such as chromic anhydride and potassium dichromate. The hexavalent chromium contained in them is not only easy to accumulate in the body, but also has strong carcinogenicity. , are more likely to cause genetic defects, and have continuous harm to the environment and human body. [0003] As the governments of various countries attach importance to environmental protection, the application of hexavalent chromium in many fields has been strictly restricted. For example, the European Union's RoHS directive has strictly limited the content of hexavalent chromium in electronic and electrical equipment products ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C02F9/04C02F101/22
CPCC02F9/00C02F1/001C02F1/5236C02F1/66C02F2101/22
Inventor 王俊祥吕宪俊吴蓬王周全吴雷陈亚男
Owner SHANDONG UNIV OF SCI & TECH
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