CN110357240B

CN110357240B - Water treatment method for reducing nitrosodimethylamine in water by cooperation of green rust and zero-valent iron

Info

Publication number: CN110357240B
Application number: CN201910675912.1A
Authority: CN
Inventors: 韩莹; 黄俊恺; 刘宏远; 吴越; 张克敏; 吴召
Original assignee: Zhejiang University of Technology ZJUT
Current assignee: Zhejiang University of Technology ZJUT
Priority date: 2019-05-15
Filing date: 2019-07-25
Publication date: 2022-05-03
Anticipated expiration: 2039-07-25
Also published as: CN110357240A

Abstract

A water treatment method for reducing nitrosodimethylamine in water by cooperation of green rust and zero-valent iron, comprising the following steps: 1) preparing deionized oxygen-free water with set volume, wherein the initial pH value is 7.0; then 10 g.L of the mixture is added^‑1The iron powder is added with 2.5-15 g.L respectively^‑1Adding 100. mu.g.L of green rust^‑1NDMA, covering the bottle cap tightly, and putting the bottle cap into a rotary incubator to rotate in a dark place; 2) and (3) sampling at regular time, performing filter pressing separation on the unreacted iron powder and the green rust of the sampled product by using a needle cylinder through a filter membrane of 0.22-0.45 mu m so as to terminate the reaction, and using the obtained water sample for the analysis and test of the NDMA concentration. The invention improves the degradation rate of NDMA.

Description

Water treatment method for reducing nitrosodimethylamine in water by cooperation of green rust and zero-valent iron

Technical Field

The invention belongs to the field of feedwater treatment, and relates to a chemical method for metal synergistic reduction.

Background

Nitrosodimethylamine (NDMA) is a substance with a high carcinogenic risk, and NDMA is classified as a class 2A carcinogen in the list of carcinogens published by the international cancer research institute of the world health organization. NDMA is present in many industrial processes such as leather making, rubber and tire manufacturing, pesticide and dye production, detergent and surfactant manufacturing, fish processing, casting, etc. NDMA was detected in water sources and subsequently discovered to be a disinfection by-product in the disinfection process in drinking and sewage treatment plants. The widespread presence of NDMA in water has raised high interest in the field of water treatment, and it is therefore necessary to develop techniques for its effective control.

Because NDMA has high solubility, low volatility, small octanol/water partition coefficient, small molecules, and no charge, it cannot be effectively treated by common treatment means (e.g., natural volatilization, gas stripping, soil and activated carbon adsorption, reverse osmosis). The existing strengthening treatment technology mainly comprises a biological method, membrane interception, adsorption, ozone oxidation, ultraviolet photolysis and a zero-valent iron reduction method. The long half-life of biological methods limits their use. Reverse osmosis membranes and nanofiltration membranes have no complete rejection. Hydrophobic adsorption materials do not effectively adsorb NDMA. Ozone cannot react directly with NDMA and its reaction with hydroxyl radicals generated in combination with hydrogen peroxide or uv is limited by free radical inhibitors in water. UV photolysis can effectively degrade NDMA, but requires a 10-fold UV dose of the normal disinfection process, about 1000 mJ-cm^-2And the energy consumption is higher.

Disclosure of Invention

In order to overcome the defects of slow NDMA degradation speed and high energy consumption in the prior art, the invention provides a water treatment method for reducing nitrosodimethylamine in water by cooperation of patina (GR) and zero-valent iron, which can improve the NDMA degradation rate.

The technical scheme adopted by the invention for solving the technical problems is as follows:

a water treatment method for reducing nitrosodimethylamine in water by cooperation of green rust and zero-valent iron, comprising the following steps:

1) preparing deionized oxygen-free water with set volume, wherein the initial pH value is 7.0; then 10 g.L of the mixture is added^-1The iron powder is added with 2.5-15 g.L respectively^-1Adding 100. mu.g.L of green rust^-1NDMA, covering the bottle cap tightly, and putting the bottle cap into a rotary incubator to rotate in a dark place;

2) and (3) sampling at regular time, performing filter pressing separation on the unreacted iron powder and the green rust of the sampled product by using a needle cylinder through a filter membrane of 0.22-0.45 mu m so as to terminate the reaction, and using the obtained water sample for the analysis and test of the NDMA concentration.

Further, in the step 1), the culture medium is put into a rotary incubator QB-328 for 45 r.min^-1The rotating speed of the rotating shaft is rotated in a dark place.

Further, in the step 2), the reaction time is 168-180 h.

The technical conception of the invention is as follows: in order to be applied to actual water treatment, a new simple and feasible treatment method capable of effectively removing the NDMA in the water needs to be established. The zero-valent iron reduction technology has wide raw material sources, low price and easy material obtaining, is applied to removing NDMA, but has longer reaction time and low removal rate when the NDMA is reduced by the zero-valent iron, and can become a novel simple and easy water treatment technology if a substance can be found to promote the reduction of the zero-valent iron so as to effectively degrade the NDMA. The patina is an oxidation product of iron, the structure of the patina has ferrous iron, the patina has certain reducing capability, but the reducing capability of the patina is lower than that of zero-valent iron, and the patina and the zero-valent iron are combined to form a potential difference, so that the rate of giving electrons out by the zero-valent iron is accelerated, and the degradation rate of the patina on NDMA is improved.

The invention has the following beneficial effects: the zero-valent iron powder can effectively remove NDMA existing in water under the cooperation of the green rust.

Drawings

FIG. 1 is a graph showing the comparison of the potency of Rust in combination with the reduction of NDMA [ NDMA]＝100μg·L^-1pH 7.0 and rotation speed 45r min^-1T20 ℃, wherein (a) represents Fe 10g/L and GR 2.5 g/L; (b) represents Fe is 10g/L, GR is 5 g/L; (c) represents Fe is 10g/L, GR is 10 g/L; (d) the formula is 10g/L for Fe and 15g/L for GR.

Detailed Description

The invention is further described below with reference to the accompanying drawings.

Referring to fig. 1, a water treatment method for reducing nitrosodimethylamine in water by cooperation of green rust and zero-valent iron comprises the following steps:

1) 8mL (set volume of 8mL) of deionized, oxygen-free water was added to an 8mL extraction flask at an initial pH of 7.0, followed by 10 g.L^-1Respectively adding 2.5 g.L of the iron powder^-1，5g·L^-1，10g·L^-1，15g·L^-1Adding 100. mu.g.L of green rust^-1NDMA, cover the bottle tightly, put into a rotary incubator QB-328 (manufactured by Nippon Linbel instruments Co., Ltd., Haimen) at 45 r.min^-1The rotating speed of the rotating shaft is rotated in a dark place.

2) And (3) sampling at regular time, performing filter pressing separation on the unreacted iron powder and the green rust of the sampled product by using a needle cylinder through a filter membrane of 0.22-0.45 mu m so as to terminate the reaction, and using the obtained water sample for the analysis and test of the NDMA concentration. The reaction time is 168-180 h, and the removal rate of NDMA (ferric sulfate) by the cooperation of the green rust and the zero-valent iron cannot be obviously improved by continuously prolonging the reaction time.

FIG. 1 shows the respective ratios of 10 g.L^-1Zero-valent iron powder of (2), 10 g.L^-1Zero-valent iron powder and 2.5 g.L^-1Mixture of patina, 10 g.L^-1Zero-valent iron powder and 5 g.L^-1Mixture of patina, 10 g.L^-1Zero-valent iron powder and 10 g.L^-1Mixture of patina, 10 g.L^-1Zero-valent iron powder and 15 g.L^-1The reduction initial concentration of the mixture of patina was 100. mu.g.L^-1NDMA of (2).

As shown in FIGS. 1(a), (b), (c) and (d), the reaction is carried out for 168h, the removal rate of NDMA by zero-valent iron is 42%, while the removal rate of NDMA by green rust and zero-valent iron can reach 70% -90%, the reduction efficiency of the combination system to NDMA is improved along with the increase of the dosage of green rust, and after the reaction is carried out for 168h, 10 g.L^-1Zero-valent iron powder and 15 g.L^-1The removal rate of the mixed system of the patina to the NDMA can reach 89 percent, so that the patina can cooperate with the zero-valent iron to effectively reduce and degrade the NDMA compared with the zero-valent iron.

Claims

1. A water treatment method for reducing nitrosodimethylamine in water by cooperation of green rust and zero-valent iron is characterized by comprising the following steps:

2. The method of claim 1, wherein the step 1) comprises placing the culture medium in a rotary incubator QB-328 for 45 r-min^-1The rotating speed of the rotating shaft is rotated in a dark place.

3. The method for treating water by reducing nitrosodimethylamine in water by using patina in combination with zero-valent iron according to claim 1 or 2, wherein the reaction time in the step 2) is 168-180 h.