CN103331176A - Photocatalyst used for processing arsenic-containing waste water and preparation method thereof - Google Patents

Abstract

The invention discloses a photocatalyst used for high-efficiently catalyzing and removing arsenic contaminants in waste water and a preparation method thereof. The photocatalyst is capable of catalyzing and oxidizing trivalent arsenic into pentavalent arsenic by using sunlight, and adsorbing and removing pentavalent arsenic. The preparation method mainly relates to solvent thermal processes; raw materials are easily available; operation is relatively simple; the synthesized photocatalyst possesses high catalytic efficiency and relatively large specific surface area; particles of the photocatalyst are large in size, and are easy to separate; and the catalytic efficiency remains relatively high after recycling for a number of times. It is proved by experiments that: under the irradiation of sunlight, oxidation efficiency of the photocatalyst on trivalent arsenic can reach 95% or more, and removal efficiency of total arsenic (trivalent arsenic and pentavalent arsenic) can reach 90% or more.

Description

A kind of photochemical catalyst of handling arsenic-containing waste water and preparation method thereof

Technical field

The invention belongs to the water treatment field of purification, be specifically related to a kind of efficient catalytic and remove photochemical catalyst of arsenic contamination thing in the waste water and preparation method thereof.

Background technology

The compound of arsenic is a kind of plasm poisonous substance with metalloid characteristic, has biological effect comparatively widely, is defined as first kind carcinogenic substance by the Center for Disease Control and the international research institution that gives protection against cancer.In recent years, along with the fast development of industries such as mining, pottery, leather, agricultural chemicals, the arsenic contamination in the water environment is serious day by day.And China is subjected to one of the most serious country of arsenic poisoning harm.Therefore, China's concentration to arsenic in discharge of wastewater and drinking water standard has been made strict regulations, for example, the content of arsenic in the drinking water standard is down to 10 micrograms per litre by 50 micrograms per litre, this situation will be brought new challenge to traditional waste water dearsenification and Removal of Arsenic in Drinking Water technology.

At present, the method that arsenic contamination is handled is a lot, can be summarized as follows:

The precipitation method: main outer adding medicine or the energy of utilizing forms with arsenic contamination thing in the water body and to precipitate and separate.Precipitation method technology is simple, small investment, but a large amount of arsenic-containing waste residues that produce can't utilize, and easily cause secondary pollution.

Absorption method: utilize high-specific surface area, insoluble solid material to make adsorbent, by physics or chemisorbed, the arsenic contamination thing is fixed on self surface, reach the purpose of arsenic removal.This method is simple, but stronger suction-operated also often causes certain difficulty to recovery, the recycling of adsorbent between arsenic compound and the adsorbent.In addition, materials such as the phosphate that exists in the waste water, sulfate, silicate, fluoride are easy and arsenic competitive Adsorption site also, causes adsorption efficiency to reduce.

Oxidizing process: because arsenious toxicity is 60 times of pentavalent arsenic, and is difficult to be adsorbed than pentavalent arsenic and removes, therefore in the processing procedure of arsenic-containing waste water, often trivalent arsenic is oxidized to pentavalent arsenic, absorption is removed again.In recent years, photochemical catalytic oxidation becomes the focus of environmental area.Utilize TiO ₂Photochemical catalyst under UV-irradiation, can be oxidized to pentavalent arsenic with most trivalent arsenic.But TiO ₂Photochemical catalyst can only have been wasted a large amount of visible light energy by the ultraviolet excitation that accounts for solar energy 3-4%, and TiO ₂The common particle diameter of powder particle is less, is difficult to recycle.Therefore, research and development visible-light photocatalyst stable, efficient, that easily reclaim becomes the new way in the photocatalytic oxidation.

Ion-exchange: ion-exchange also is a kind of effective arsenic removing method, but this method treatment process is comparatively complicated, and cost is higher, and is can only concentration for the treatment of lower, form simple and have the waste water that higher reclamation is worth, and is difficult to commercial running.

Summary of the invention

The objective of the invention is to overcome the above-mentioned deficiency of prior art, photochemical catalyst of arsenic contamination thing in a kind of efficient catalytic removal waste water and preparation method thereof is provided.Raw material of the present invention is easy to get, and operates comparatively simple and easyly, and the catalyst efficient height that synthesizes have than bigger serface, and particle size is bigger, is easy to separate, and after repeatedly recycling, catalytic efficiency is still higher.Experiment showed, that under solar light irradiation this catalyst can reach more than 95% arsenious oxidation efficiency, total arsenic (trivalent and pentavalent arsenic) is removed efficient and can be reached more than 90%.

For achieving the above object, the present invention adopts following technical scheme:

A kind of photochemical catalyst BiOI that handles arsenic-containing waste water has PbFCl type crystal structure, i.e. [Bi ₂O ₂] ²⁺With I ^-Staggered stack forms layer structure, and this layer structure exists electrostatic field to be conducive to the separation of photo-generated carrier owing to inner.

The BiOI photochemical catalyst utilizes the glycerine solvent thermal method synthetic, utilize the bigger viscosity of glycerine, make the BiOI laminated structure of being synthesized have thinner thickness, carrier separation efficient is higher, the BiOI laminated structure of being synthesized can self assembly under experiment condition forms the spheroidal aggravation of classification, granular size is about the 10-50 micron through scanning electron microscopic observation, and has bigger specific area.The preparation method may further comprise the steps:

(1) processing of predecessor: five water bismuth nitrates and the KI of the amount of same substance are dissolved in respectively in the glycerine, mix, stir and make predecessor;

(2) predecessor is placed the polytetrafluoroethylene (PTFE) reactor, in 130-180 ℃ of insulation 6-12 hour, be cooled to room temperature subsequently naturally, gained precipitation is after distilled water washing for several times, and 60-80 ℃ of vacuum or air were dried 12-24 hour, namely got the BiOI photochemical catalyst.

The BiOI photochemical catalyst utilizes sunshine, and the efficiently catalyzing and oxidizing trivalent arsenic is pentavalent arsenic, and pentavalent arsenic absorption is removed.Concrete experiment content and detection method are: a certain amount of catalyst is joined in the trivalent arsenic simulating pollution waste water of different content, under magnetic agitation, adopt sunshine or simulated solar light source irradiation certain hour, after centrifugal, get supernatant liquor, adopt atomic fluorescence spectrophotometer to measure trivalent arsenic and total arsenic concentration.

Remarkable advantage of the present invention is:

(1) adopt solvent thermal method to prepare catalyst, raw material is easy to get, and step is less, and is simple to operate, is applicable to suitability for industrialized production.

(2) catalyst that is synthesized has the arsenious activity of higher photochemical catalytic oxidation, and the pentavalent arsenic that generates is also had than excellent adsorption performance, the removal efficient height of total arsenic under sunshine or the irradiation of simulated solar light source.

(3) catalyst stability that is synthesized is better, still have greater activity after repeatedly recycling, and catalyst particle size is bigger, is easy to recycle.

Description of drawings

Fig. 1 is the X-ray diffractogram of the synthetic catalyst of embodiment 1.

Fig. 2 is the field emission scanning electron microscope figure of the synthetic catalyst of embodiment 1.

Fig. 3 is that the synthetic catalyst of embodiment 1 is through the photo of 15 minutes natural subsidence.

The specific embodiment

Enumerate embodiment below and further specify the present invention.

Embodiment 1

Take by weighing 2.425 gram five water bismuth nitrates and 0.83 gram KI, and be dissolved in respectively in 40 milliliters of glycerine, both are mixed, and stirred 30 minutes, obtain predecessor, subsequently predecessor is placed 100 milliliters of polytetrafluoroethylene (PTFE) reactors, reactor is put in the steel bushing, and placed baking oven, insulation is 12 hours under 160 ° of C, naturally be cooled to room temperature subsequently, after the gained precipitate with deionized water washing 6 times, 60 ° of C baking oven hollow air dry 12 hours.

Embodiment 2

Press the synthetic catalyst of method of embodiment 1, after X-ray diffractometer scanning, see Fig. 1, be defined as the BiOI crystal.

Embodiment 3

Press the synthetic catalyst of method of embodiment 1, observe through field emission scanning electron microscope, the catalyst granules that is synthesized is formed by the self assembly of nano-sheet structure, and its sheet thickness is about 10 nanometers, about granular size 10-50 micron, sees Fig. 2.

Embodiment 4

Take by weighing the catalyst that 40 milligrams of embodiment 1 synthesize, join in the sodium arsenite solution of 80 milliliter of 5 mg/litre, change under the magnetic agitation 1000, adopt xenon lamp simulated solar light source, shine 60 minutes after, centrifugal, filter, get supernatant and detect by atomic fluorescence spectrophotometer (PF6, Beijing Puxi General Instrument Co., Ltd), arsenious clearance has reached 97%, and the clearance of total arsenic reaches 92%.

Embodiment 5

Take by weighing the catalyst that 20 milligrams of embodiment 1 synthesize, join in the sodium arsenite solution of 80 milliliter of 1 mg/litre, change under the magnetic agitation 1000, irradiation is after 3 hours under sunshine, centrifugal, filter, get supernatant and detect by atomic fluorescence spectrophotometer, arsenious concentration is 0.9 micrograms per litre, clearance is 99.9%, the concentration of total arsenic is 6.9 micrograms per litre, and clearance is 99.3%, and arsenic content has reached national drinking water standard.

Embodiment 6

Process according to embodiment 4, after used catalyst recovery oven dry, continue to take by weighing in 40 milligrams of sodium arsenite solution that join 80 milliliter of 5 mg/litre, carry out the 2nd test, reaction after finishing is dried catalyst recovery, carry out the 3rd test, circulate so repeatedly after 5 times, after testing, clearance such as the table 1 of trivalent arsenic and total arsenic (trivalent arsenic and pentavalent arsenic).

The trivalent arsenic of the catalyst that table 1 embodiment 1 synthesizes and the clearance of total arsenic (trivalent arsenic and pentavalent arsenic)

Embodiment 7

Take by weighing 40 milligrams of catalyst, join in the sodium arsenite solution of 80 milliliter of 5 mg/litre, leave standstill, through observing, sedimentation is complete substantially in 15 minutes, sees Fig. 3.

The above only is preferred embodiment of the present invention, and all equalizations of doing according to the present patent application claim change and modify, and all should belong to covering scope of the present invention.

Claims (4)

1. photochemical catalyst of handling arsenic-containing waste water, it is characterized in that: described photochemical catalyst is BiOI.

2. method for preparing the photochemical catalyst of processing arsenic-containing waste water as claimed in claim 1 is characterized in that: described BiOI photochemical catalyst utilizes the glycerine solvent thermal method synthetic.

3. the preparation method of the photochemical catalyst of processing arsenic-containing waste water according to claim 2 is characterized in that: may further comprise the steps:

(1) processing of predecessor: five water bismuth nitrates and the KI of the amount of same substance are dissolved in respectively in the glycerine, mix, stir and make predecessor;

(2) predecessor is placed the polytetrafluoroethylene (PTFE) reactor, in 130-180 ℃ of insulation 6-12 hour, be cooled to room temperature subsequently naturally, gained precipitation is after distilled water washing for several times, and 60-80 ℃ of vacuum or air were dried 12-24 hour, namely got the BiOI photochemical catalyst.

4. the application of the photochemical catalyst of a processing arsenic-containing waste water as claimed in claim 1 is characterized in that: the BiOI photochemical catalyst utilizes sunshine, and the efficiently catalyzing and oxidizing trivalent arsenic is pentavalent arsenic, and pentavalent arsenic absorption is removed.

Images