CN102974303A - Method for synthesizing hydrotalcite by utilizing electroplating wastewater - Google Patents

Abstract

The invention discloses a method for synthesizing hydrotalcite by utilizing electroplating wastewater. The method comprises the following steps of filtering electroplating wastewater to remove solid particles, analyzing ions in the wastewater to guarantee that the molar concentration of divalent ions is 2-4 times of trivalent ions; dripping 50-70 percent of KOH solution into the electroplating wastewater, continuously stirring at the speed of 200-300rpm, and stopping dripping the KOH solution and separating precipitates when no precipitate is generated; preparing turbid liquid from the separated precipitates, wherein the mass ratio of solid to liquid is 1:4-1:8, continuously dripping 50-70 percent of KOH solution until the pH value is 10-13, ageing the turbid liquid at the room temperature for 24-48 hours, separating the precipitates, and drying at the temperature of 70-90 DEG C. As the hydrotalcite with wide application range is prepared by utilizing metal ions in the electroplating wastewater, wastes are recycled, the heavy metals in the electroplating wastewater can be removed, and the hydrotalcite can serve as an adsorption material and is continuously used for environmental management.

Description

A kind of method of utilizing the electroplating wastewater synthetic hydrotalcite

Technical field

The present invention relates to the exploitation of environmental pollution control new material, relate in particular to a kind of method of utilizing the electroplating wastewater synthetic hydrotalcite.

Background technology

Layered di-hydroxyl composite metal oxidate (Layered Double Hydroxides is called for short LDH) claims again hydrotalcite, is the important inorganic functional material of a class.The adjustable sex change of the layer structure that it is unique and laminate element and interlayer anion gets more and more people's extensive concerning, introduce new object anion through ion-exchange to interlayer and can make layer structure and composition produce corresponding the variation, thereby can prepare the functional material that a large class has special nature.Hydrotalcite material belongs to anion type laminated compound.The compounds that lamellar compound refers to have layer structure, interlayer ion has interchangeability, utilize intercalation that the lamellar compound main body has and the interchangeability of interlayer ion under strong polar molecule effect, form layer-pillared compound thereby some functional guest species are introduced bedding voids and the laminate distance strutted.

The hydrotalcite chemical structure of general formula is: [M ²⁺ _1-xM ³⁺X (OH) ₂] ^X+[(A ^N-) _X/nMH ₂O], M wherein ²⁺Be Mg ²⁺, Ni ²⁺, Mn ²⁺, Zn ²⁺, Ca ²⁺, Fe ²⁺, Cu ²⁺Deng the divalent metal anion; M ³⁺Be Al ³⁺, Cr ³⁺, Fe ³⁺, Co ³⁺Deng the trivalent metal anion; A ^N-Be anion, such as CO ₃ ^2-, NO ₃ ^-, Cl ^-, OH ^-, SO ₄ ^2-, PO ₄ ^3-, C ₆H ₄(COO) ₂ ^2-Etc. inorganic and organic ion and complex ion, different when the interlayer inorganic anion, the interlamellar spacing of hydrotalcite is different, and after hydrotalcite adsorption fouling thing, interlamellar spacing also can increase, to hold more pollutant simultaneously.

At present, the synthetic method of hydrotalcite-like material mainly contains salt-alkaline process, salt-conventional ceramic technique and ion-exchange, also derives Hydrolyze method, hydro-thermal method, the again hydration method of heat treatment etc. of inducing.Wherein the most frequently used method is coprecipitation, namely with the metallic ion mixed liquor that consists of the hydrotalcite layer co-precipitation occurs under the effect of alkali at a certain temperature and prepares.The method is simple to operation, is the preparation method who commonly uses, and needs to utilize a certain amount of bivalent metal ion and trivalent metal ion in the method, has increased input from the angle of economy; From the synthetic process of the angle of administering environment, increased the generation of waste water, environmental improvement has been proposed new problem.

Electroplate waste water and waste liquid that factory (or workshop) discharges, such as plating piece washings, useless tank liquor, component cooling water and the flushing surface water etc., its water quality is different because of production technology, and often in general the oil-containing many kinds of metal ions, often contains Cr ⁶⁺, Cd ²⁺, Ni ²⁺, Cu ²⁺, Zn ²⁺, Fe ²⁺In heavy metal, these metal ions need to be recovered utilization.

Summary of the invention

The objective of the invention is provides a kind of method of utilizing the electroplating wastewater synthetic hydrotalcite for overcoming the deficiency of preparation hydrotalcite in the prior art.

The technical solution used in the present invention is in turn include the following steps:

1) electroplating wastewater filter is removed solid particle, the ion according to analysis of Production Technology wherein exists adds suitable metal cation, or with multiple electroplating wastewater mixing, guarantees that bivalent ions molar concentration is 2 ~ 4 times of molar concentration of trivalent ion;

2) drip 50% ~ 70% KOH solution in electroplating wastewater, continue 200 ~ 300 rpm and stir, metal ion precipitates under the alkali effect, when without the precipitation regeneration, stops to drip KOH solution, sediment separate out;

3) sediment after will separating is made suspension, the solid-liquid mass ratio is 1:4 ~ 1:8, in this suspension, continue to drip 50% ~ 70% KOH solution, until till pH value to 10 ~ 13, under 300 ~ 400 rpm, stir during dropping, after being added dropwise to complete with suspension aging 24 ~ 48 h at room temperature, sediment separate out, 70 ~ 90 ℃ of lower oven dry, namely make hydrotalcite.

Advantage of the present invention is the metal ion that utilizes in the electroplating wastewater, the hydrotalcite that preparation has broad field of application, realize twice laid, and can remove heavy metal in the electroplating wastewater, although the synthetic hydrotalcite that obtains contains various metals, may not satisfy the needs of high-level (such as the medication chemistry aspect) from purity, but as there being the material of hydrotalcite structure to can be used as sorbing material, continue on for environmental improvement.

The specific embodiment

Electroplating wastewater is filtered the removal solid particle, the ion that wherein may exist according to analysis of Production Technology, add suitable metal cation, or with multiple electroplating wastewater mixing, guarantee that bivalent ions molar concentration is 2 ~ 4 times of molar concentration of trivalent ion, if only have divalent metal, then add a small amount of trivalent metal cation (such as comparatively cheap Al ³⁺, Fe ³⁺), if only have trivalent metal cation, then add a small amount of divalent metal (such as comparatively cheap Mg ²⁺, Fe ²⁺), if divalent metal and trivalent metal cation have been arranged, then investigate concentration, guarantee that the concentration ratio of the two meets above-mentioned scope, in this scope, then do not need to add any other metal ion.

Drip fast 50% ~ 70% KOH solution in the electroplating wastewater, continue 200 ~ 300 rpm and stir, metal ion precipitates under the alkali effect, when alkali lye without precipitating regeneration, stop to drip KOH solution, sediment separate out.Sediment after the separation need not oven dry, directly make suspension, the solid-liquid mass ratio is 1:4 ~ 1:8, continue in this suspension to drip 50% ~ 70% KOH solution, until till pH value to 10 ~ 13, during dropping under 300 ~ 400 rpm rapid stirring, be added dropwise to complete at room temperature aging 24 ~ 48 h of rear suspension, sediment separate out 70 ~ 90 ℃ of lower oven dry, namely is prepared into hydrotalcite.

3 embodiment of the present invention below further are provided:

Embodiment 1

Electroplating wastewater is filtered the removal solid particle, according to analysis of Production Technology, wherein contain Ni ²⁺And Cu ²⁺, add a small amount of Al ³⁺, making divalent ion concentration is 2 times (mol ratios) of trivalent ion concentration; Drip fast 70% KOH solution in the electroplating wastewater, continue 300 rpm and stir, metal ion precipitates under the alkali effect, when alkali lye without precipitating regeneration, stop to drip KOH solution, sediment separate out; Sediment after the separation need not oven dry, make suspension, solid-to-liquid ratio is the 1:8(mass ratio), continue in this suspension to drip 70% KOH solution, until till the pH value to 13, during dropping under 400 rpm rapid stirring, be added dropwise to complete at room temperature aging 48 h of rear suspension, sediment separate out 90 ℃ of lower oven dry, namely is prepared into hydrotalcite.

This hydrotalcite powder is added to the water, and the weight ratio of powder and water is 1:2, makes suspension; Add again the neopelex that quality is hydrotalcite quality 1/20, stirred 1 hour, precipitation, oven dry, grind, make organic hydrotalcite, with the organic wastewater of this organic hydrotalcite for the treatment of the p-nitrophenyl that contains 15mg/L, the handled wastewater volume that every gram hydrotalcite is corresponding is about 1 L, rapid stirring 60 minutes; Product stopped 30 minutes at sedimentation basin, Separation of Solid and Liquid, and ultraviolet-uisible spectrophotometer is measured supernatant concentration, and pollutants removal rate is 97.6%.

Embodiment 2

Electroplating wastewater is filtered the removal solid particle, according to analysis of Production Technology, wherein contain Fe ³⁺And Al ³⁺, add a small amount of Mg ²⁺, making divalent ion concentration is 4 times (mol ratios) of trivalent ion concentration; Drip fast 50% KOH solution in the electroplating wastewater, continue 200 rpm and stir, metal ion precipitates under the alkali effect, when alkali lye without precipitating regeneration, stop to drip KOH solution, sediment separate out; Sediment after the separation need not oven dry, make suspension, solid-to-liquid ratio is the 1:4(mass ratio), continue in this suspension to drip 50% KOH solution, until till the pH value to 10, during dropping under 300 rpm rapid stirring, be added dropwise to complete at room temperature aging 24 h of rear suspension, sediment separate out 70 ℃ of lower oven dry, namely is prepared into hydrotalcite.

This hydrotalcite powder is added to the water, and the weight ratio of powder and water is 1:2, makes suspension; Add again the neopelex that quality is hydrotalcite quality 1/20, stirred 1 hour, precipitation, oven dry, grind, make organic hydrotalcite, with the organic wastewater of this organic hydrotalcite for the treatment of the p-nitrophenyl that contains 15 mg/L, the handled wastewater volume that every gram hydrotalcite is corresponding is about 1 L, rapid stirring 60 minutes; Product stopped 30 minutes at sedimentation basin, Separation of Solid and Liquid, and ultraviolet-uisible spectrophotometer is measured supernatant concentration, and pollutants removal rate is 96.2%.

Embodiment 3

Multiple electroplating wastewater is mixed, remove solid particle, wherein have Ni according to analysis of Production Technology ²⁺, Cu ², Fe ³⁺And Al ³⁺, and divalent ion concentration is 3 times (mol ratios) of trivalent ion concentration, drips fast 60% KOH solution in electroplating wastewater, continue 300 rpm and stir, metal ion precipitates under the alkali effect, when alkali lye without precipitating regeneration, stop to drip KOH solution, sediment separate out; Sediment after the separation need not oven dry, make suspension, solid-to-liquid ratio is the 1:6(mass ratio), continue in this suspension to drip 60% KOH solution, until till the pH value to 12, during dropping under 350 rpm rapid stirring, be added dropwise to complete at room temperature aging 36 h of rear suspension, sediment separate out 80 ℃ of lower oven dry, namely is prepared into hydrotalcite.

This hydrotalcite powder adding is contained in the waste water from dyestuff of 20 mg/L acid scarlets, and the handled wastewater volume that every gram hydrotalcite is corresponding is about 1 L, rapid stirring 60 minutes; Product stopped 30 minutes at sedimentation basin, Separation of Solid and Liquid, and ultraviolet-uisible spectrophotometer is measured supernatant concentration, and pollutants removal rate is 98.4%.

Claims (1)

1. method of utilizing the electroplating wastewater synthetic hydrotalcite is characterized in that in turn including the following steps:

1) electroplating wastewater filter is removed solid particle, the ion according to analysis of Production Technology wherein exists adds suitable metal cation, or with multiple electroplating wastewater mixing, guarantees that bivalent ions molar concentration is 2 ~ 4 times of molar concentration of trivalent ion;

2) drip 50% ~ 70% KOH solution in electroplating wastewater, continue 200 ~ 300 rpm and stir, metal ion precipitates under the alkali effect, when without the precipitation regeneration, stops to drip KOH solution, sediment separate out;

3) sediment after will separating is made suspension, the solid-liquid mass ratio is 1:4 ~ 1:8, in this suspension, continue to drip 50% ~ 70% KOH solution, until till pH value to 10 ~ 13, under 300 ~ 400 rpm, stir during dropping, after being added dropwise to complete with suspension aging 24 ~ 48 h at room temperature, sediment separate out, 70 ~ 90 ℃ of lower oven dry, namely make hydrotalcite.