A method of removing nitrates from water by utilization of a zero-valent iron/oxidizing agent/zeolite synergetic system

A technology of zero-valent iron and oxidant, which is applied in the field of water treatment, can solve the problems of high preparation cost of nano-scale zero-valent iron, abnormal use of water body, and reduced reaction rate, etc., and achieve good application prospects, high nitrate removal rate, low energy consumption effect

Active Publication Date: 2015-02-11
BEIJING NORMAL UNIVERSITY
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Problems solved by technology

Choea et al. (2004) obtained a nitrate removal rate of 81% under the condition of maintaining the pH of the water body at 3.0, but such a low pH value has made the water body unusable. At the same time, in order to maintain the low pH value of the water body, the reaction process It needs to be adjusted with strong acid or weak acid buffer, which in turn leads to the pollution of other anions in the water body, and the acidity adjustment process will significantly increase the treatment cost
The passivation phenomenon of zero-valent iron is the biggest shortcoming that restricts zero-valent iron technology. During the reaction process of zero-valent iron and nitrate, a passivation layer will gradually be formed on the surface, which will greatly reduce its reaction rate (Huang et al, 2005; Westerhoff et al, 2003), the passivation phenomenon seriously restricts the efficiency of zero-valent iron to reduce and convert nitrate, and to solve the passivation phenomenon requires additional physical and...

Method used

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  • A method of removing nitrates from water by utilization of a zero-valent iron/oxidizing agent/zeolite synergetic system
  • A method of removing nitrates from water by utilization of a zero-valent iron/oxidizing agent/zeolite synergetic system
  • A method of removing nitrates from water by utilization of a zero-valent iron/oxidizing agent/zeolite synergetic system

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Experimental program
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Effect test

Embodiment 1

[0019] Nitrate (NO 3 - ) was removed in a 250ml three-neck flask. NO in the experiment 3 - The initial concentration of -N is 1mmol / L, the solution volume is 200ml, and the mass of iron powder is 1.00g. Use 0.1mol / L HCl and NaOH solutions to adjust the pH of the solution to keep it stable at 7.0. Add KMnO when the reaction reaches 120 minutes 4 , the dosage is such that the initial concentration in the solution is 1mmol / L, the reaction is continued for 240 minutes, and samples are taken and analyzed at regular intervals. After 240 minutes, transfer the remaining reaction solution (150mL) to a new 250ml three-neck flask, add 1.00g zeolite (20-80 mesh in particle size), stir (200rpm) at room temperature for 1 hour, and periodically take samples for analysis . Reductive removal of nitrate and its products vary with time as figure 1 shown. The adsorption and removal amount of ammonia nitrogen is shown in Table 1.

[0020] Experiments show that if no oxidant KMnO is added ...

Embodiment 2

[0024] Nitrate (NO 3 - ) was removed in a 250ml three-neck flask. NO in the experiment 3 - The initial concentration of -N is 1mmol / L, the solution volume is 200ml, and the mass of iron powder is 1.00g. Use 0.1mol / L HCl and NaOH solutions to adjust the pH of the solution to keep it stable at 7.0. Add H when the reaction reaches 120 minutes 2 o 2 , the dosage is such that the initial concentration in the solution is 1mmol / L, the reaction is continued for 240 minutes, and samples are taken and analyzed at regular intervals. After 240 minutes, the reaction residue (150mL) was transferred to a new 250ml three-neck flask, 1.00g of zeolite (20-80 mesh in particle size) was added, and stirred (200rpm) at room temperature for 1 hour, during which time sampling and analysis were performed. Reductive removal of nitrate and its products vary with time as figure 2 shown. The adsorption and removal amount of ammonia nitrogen is shown in Table 2.

[0025] Experiments show that if ...

Embodiment 3

[0029] Nitrate removal was carried out in a 250ml three-neck flask. NO in the experiment 3 - The initial concentration of -N is 1mmol / L (14mg / L), the volume of the solution is 200ml, the mass of iron powder added is 2.00g, and H 2 o 2 , the dosage is such that the initial concentration in the solution is 1 mmol / L, and the pH of the solution is adjusted with 0.1 mol / L HCl and NaOH solutions to keep it stably at 7.0. Stir (200rpm) at room temperature and react for 3 hours, during which periodical sampling and analysis are carried out. After the reaction, the waste liquid is discarded, but the residual iron powder is kept, and 200ml of nitrate solution (1mmol / L) is added again, and H 2 o 2 , the dosage still makes its initial concentration 1mmol / L. Repeat this 4 times. The results of reduction and removal of nitrate are as follows image 3 shown. The experimental results show that in the continuous treatment of five batches of nitrate solution, the removal rate of each ba...

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Abstract

A method of removing nitrates from water by utilization of a zero-valent iron/oxidizing agent/zeolite synergetic system is provided. The zero-valent iron is common iron powder. The oxidizing agent is a common oxidizing agent used in water treatment. The zeolite is natural zeolite or artificial zeolite. The method is characterized in that: the oxidizing agent in the system oxidizes and strips a passivation layer formed on the surface of the zero-valent iron to allow electrons in the zero-valent iron to be transferred continuously to the outside, so that the zero-valent iron maintains high reduction activity to reduce the nitrates into ammonia nitrogen. Then efficient selective absorption of the zeolite to the ammonia nitrogen is utilized to remove the ammonia nitrogen in the water body. The method is environmental friendly, simple, feasible, low in cost, and capable of being efficiently used for treatment of waste water containing nitrates of industrial enterprises and nitrate restoration and removal for underground water.

Description

technical field [0001] The invention belongs to the technical field of water treatment, in particular to a method for removing nitrate in water by utilizing a zero-valent iron / oxidant / zeolite synergistic system. Background technique [0002] With the rapid development of economy, the pollution of my country's water environment is becoming more and more serious. Among them, nitrate nitrogen pollution in groundwater has become a very important environmental problem, directly affecting people's production and life (Chen Jianyao et al., 2006). Nitrate in groundwater will not only damage the water quality (Kang Haiyan, 2007), but after nitrate enters the human body, it will be converted into nitrite through the action of nitrate reductase, which is extremely harmful and will cause infantile methemoglobinemia (Kostraba et al , 1992) and have carcinogenic, teratogenic and mutagenic effects on humans (Jennifer et al, 1998; Grahan et al, 1999; Janos, 2001). Therefore, how to econom...

Claims

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Application Information

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IPC IPC(8): C02F9/04C02F101/16
CPCC02F1/281C02F1/705C02F9/00C02F2101/16
Inventor 郭学军杨喆金心
Owner BEIJING NORMAL UNIVERSITY
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