CN102621258B

CN102621258B - A kind of heavy metal chromium form fractionation method

Info

Publication number: CN102621258B
Application number: CN201210103292.2A
Authority: CN
Inventors: 景传勇; 余思伍
Original assignee: Research Center for Eco Environmental Sciences of CAS
Current assignee: Research Center for Eco Environmental Sciences of CAS
Priority date: 2012-04-09
Filing date: 2012-04-09
Publication date: 2016-08-03
Anticipated expiration: 2032-04-09
Also published as: CN102621258A

Abstract

The present invention uses dolomite as adsorbing material first, and in natural water environment, Cr (VI) and Cr (III) separates.Being shown by series of experiments, dolomite (80 100 mesh) is more than 95% in natural water body centering to the adsorption rate of Cr (III), and the adsorption rate of Cr (VI) is less than 5%.Adsorbent used in this method is natural minerals, low price, draws materials conveniently, and the separation method simple and fast of employing, separating effect are notable.Therefore, this method can be used for Cr in water body (III) and the form fractionation of Cr (VI).

Description

A kind of heavy metal chromium form fractionation method

Technical field

The present invention relates to environmental analysis field, be specifically related to a kind of heavy metal chromium form fractionation method.

Technical background

Chromium (Cr) is primarily present trivalent Cr (III) and two kinds of forms of sexavalence Cr (VI) in the environment, both forms Cr all has obvious difference in chemical property, biological activity and toxicity level.Cr (VI) is main with anion CrO₄ ^2-And Cr₂O₇ ^2-Form exist, there is high chemism, highly dissoluble and high toxic, easily plant dynamic Thing and people produce harm, the carcinogen confirmed by World Health Organization (WHO).On the contrary, Cr (III) is saccharide and fat Necessary trace element in metabolic process, appropriate Cr (III) can reduce the blood sugar concentration in blood plasma, improves people The stress ability of body, human body lacks Cr (III) can make carbohydrate metabolism disturbance, causes impaired glucose tolerance and diabetes. There is notable difference in the impact caused environmental and human health impacts due to the Cr of different shape, therefore, and the shape of Cr State is analyzed the most significant at aspects such as Environmental Chemistry, life sciences and physiological medical sciences.

But, in current Cr Element detection instrument, only Inductively coupled plasma mass spectrometry (ICP-MS) Can directly detect the Cr (VI) in solution and Cr (III) concentration.But, the testing cost of ICP-MS is relative Higher, it is not suitable for the detection of a large amount of sample.In order to make other instruments (such as atomic absorption spectrum AAS) also can Cr (VI) and Cr (III) in detection solution, can only separate the Cr of both forms before detection, make molten Liquid only exists the Cr (i.e. Cr (III) or Cr (VI)) of a kind of form, then measures in each component after separating Cr concentration.Therefore, in the solution Cr (VI) and Cr (III) is separated into and quick and precisely detects its concentration Crucial.

Solid phase extraction techniques (SPE) is a kind of conventional Isolation and purification method, has extraction efficiency height, choosing The features such as selecting property is good, applied widely, simple to operate and saves time.Solid phase extraction has been widely used in In the form fractionation research of Cr, the material of the separation used has resin, fiber, metal-oxide, biology Adsorbing material and novel nano material etc..Although above material can meet the form fractionation to Cr, but Mostly there is raw material rareness, prepare the shortcomings such as complicated, expensive, be unfavorable for using in a large number.Therefore, seek Look for a kind of adsorbent natural, that separation method is simple, separating effect is excellent, for Cr (III) and Cr (VI) Separation Research in the urgent need to.Dolomite (CaMg (CO₃)₂) it is a kind of natural minerals, at nature In generally exist, low price, easily obtain.Dolomite is applied in Adsorption environmental sample Cu, the heavy metal ion such as Pb, As, and be the most also used for the absorption of Cr (VI).But, The absorption of Cr (III) is studied and be have not been reported by dolomite.

The present invention uses dolomite as adsorbing material, the Cr (VI) being applied in actual water body and Cr (III) first Separation.By series of experiments, and combine graphite furnace atomic absorption spectrometry (GFAAS) as detection side Method, it was demonstrated that natural dolomite has good adsorption effect to Cr (III), and to Cr (VI) almost without absorption. It is contemplated that provide for the morphological analysis of Cr, one is the easiest, economical, method efficiently.

Summary of the invention

Main contents and the inventive feature of the present invention is illustrated by explained below.

The present invention relates to a kind of heavy metal chromium form fractionation method.The adsorption material that the method with natural dolomite is Material, is experimentally confirmed this adsorbent obvious to Cr (III) adsorption effect, to Cr (VI) almost without absorption.Cause This can be used for Cr in water body (VI) and Cr (III) and separates.The adsorbent wide material sources that the present invention uses, price is low Honest and clean, the separation method of use is simple and easy to operate, can overcome the defect of existing Cr form fractionation method.

The particular content of the present invention is as follows:

(1) first oarse-grained dolomite is pulverized and sieved, select particle diameter granule between 80-100 mesh to use In experiment.

(2) at the SPE little column bottom pad last layer filter paper of 15mL, and one is connect at the outlet of pillar 200 μ L liquid-transfering gun rifle heads；Weigh dolomite particles in 4g (1), be filled in pillar, and spread on upper strata Upper a small amount of silk floss prevents granule from floating.

(3) with deionized water and CrCl₃·6H₂The storing solution of O preparation Cr (III), with deionized water and K₂CrO₄ The storing solution of preparation Cr (VI), concentration is 1000mg/L, and ionic strength is 0.05mol/L NaClO₄, and Add 0.1% (v/v) HNO₃, cryopreservation is stand-by.Working solution is diluted above-mentioned deposit by deionized water Liquid is prepared.Use HClO₄Required pH value is regulated with NaOH.

(4) prepared appropriate Cr (III) and Cr (VI) working solution by deionized water dilution storing solution, and regulate it PH=7.0 ± 0.5, takes 12mL treatment fluid flow dolomite SPE post (natural flow velocity=0.7mL/ through preparing Min), collect effluent and measure pH value.

(5) choose electroplating wastewater and two kinds of actual chromate waste waters of chromium slag extract, and regulate its pH=7.0 ± 0.5, Take the 12mL treatment fluid flow dolomite SPE post (natural flow velocity=0.7mL/min) through preparing, collect stream Go out liquid and measure pH value.

(6) detect before and after absorption in solution respectively by atomic absorption spectrography (AAS) (AAS) and spectrophotometer The concentration of total Cr and Cr (VI).In solution, Total Cr with Cr (VI) concentration difference is i.e. adsorbed by dolomite The amount of Cr (III).

Accompanying drawing explanation

Accompanying drawing 1 is the photoelectron spectroscopy figure (EDX) of adsorbent dolomite, be can be seen that used by spectrogram Dolomite mainly contains the elements such as calcium, magnesium, carbon, oxygen, with its chemical formula CaMg (CO₃)₂It is consistent.

Accompanying drawing 2 is pH value impact of adsorption rate on dolomite on Cr (VI) and Cr (III).It can be seen that PH be 4-10 interval in, dolomite is all higher than 95% to the adsorption rate of Cr (III), and the absorption to Cr (VI) Rate is less than 5%, illustrates that this adsorbent may be used for separating the Cr (VI) in water body and Cr (III).

Accompanying drawing 3 is the Common materials impact on adsorption effect in water body.As seen from the figure, Mg²⁺, Ca²⁺And HA (humic acid) on adsorption effect all without impact；Carbonate (CO₃ ^2-) and acetic acid HAc not shadow when low concentration Ring adsorption effect, when concentration is more than 0.05mol L^-1Rear just adsorption effect can be impacted.At natural water body In, there's almost no acetic acid and (investigate at this and be because in following actual sample chromium slag extracting solution containing vinegar Acid), the background value of carbonic acid is also below 0.05mol/L.Therefore, test result indicate that material pair main in water Adsorption effect there is no significantly impact.

Accompanying drawing 4 is the adsorption capacity of dolomite Cr (III).It can be seen that Cr (III) concentration 10mg/L with Time lower, almost can be adsorbed completely by dolomite, maximum adsorption capacity is 0.03mg/kg.

Accompanying drawing 5 is the dolomite adsorption penetration amount to Cr (III) solution in continuous flow process.At (a diameter 1.1cm, long 21cm) pillar loads 16g dolomite.With pump under the flow velocity of 0.7mL/min the most open close Enter to prepare Cr (III) solution of 500 μ g/L with tap water and (add 0.05mol/L NaClO₄), then by timing Cr (III) concentration after sampling detection absorption.From above-described embodiment it can be seen that be higher than country at outflow concentration Before drinking water chromium standard 100 μ g/L, it is 500 μ g/L that the dolomite of 16g at least can adsorb 25L concentration Cr (III) solution.Show the Cr (III) in this method energy effectively catching solution.

Detailed description of the invention

The present invention is illustrated further below by embodiment.

Embodiment 1 adds 30 μ g/L Cr (III) and 20 μ g/L in tap water, well water, river respectively Cr (VI), only adds 1000 μ g/L Cr (III) in electroplating wastewater and chromium slag extracting solution.Utilize dolomite upper State and actual water sample separates Cr (III) and Cr (VI): take 12mL water sample respectively, white through 4g in SPE pillar Marble adsorbs, and flow velocity is 0.7mL/min.Before surveying absorption with GFAAS (GFAAS) Cr (III) concentration after the concentration (i.e. Total Cr contains Cr (III) and the concentration of Cr (VI)) of total Cr and absorption. The concentration of the Cr (VI) after detecting absorption with spectrophotometer especially at 540nm wavelength again.Experimental result is Measure Cr (III) after absorption the most again, and the amount of the Cr measured (VI) and absorption are front consistent (table 1).Therefore, This example demonstrates the effect that Cr (III) and Cr (VI) separates by the present invention notable.

Table 1. dolomite separates Cr (III) and Cr (VI) in actual water sample.

^aRepresent and do not measure；

^bExpression is not added with.

Claims

1. a heavy metal chromium form fractionation method, it is characterised in that step is as follows:

(1) particle diameter natural dolomite between 80-100 mesh is first selected；

(2) at the SPE little column bottom pad last layer filter paper of 15mL, and one 200 is connect at the outlet of pillar μ L liquid-transfering gun rifle head；Weigh dolomite particles in 4g step (1), be filled in pillar, and Spreading a small amount of silk floss on upper strata prevents granule from floating；

(3) with deionized water and CrCl₃·6H₂The storing solution of O preparation Cr (III), with deionized water and K₂CrO₄ The storing solution of preparation Cr (VI), concentration is 1000mg/L, and ionic strength is 0.05mol/L NaClO₄, and Add 0.1% (v/v) HNO₃, cryopreservation is stand-by；

(4) prepared appropriate Cr (III) and Cr (VI) working solution by deionized water dilution storing solution, and regulate it PH=7.0 ± 0.5, takes the 12mL treatment fluid flow dolomite SPE post through preparing, natural flow velocity=0.7mL/ Min, collects effluent and measures pH value, uses HClO₄Required pH value is regulated with NaOH；

(5) choose electroplating wastewater and two kinds of actual chromate waste waters of chromium slag extract, and regulate its pH=7.0 ± 0.5, Take the actual chromate waste water of 12mL and flow through the dolomite SPE post prepared, natural flow velocity=0.7mL/min, receive Collection effluent also measures pH value；

(6) total Cr of detecting respectively before and after absorption in solution with atomic absorption spectrography (AAS) and spectrophotometer and The concentration of Cr (VI)；Achieve trivalent chromium and chromic separation in water body.