CN101941860A - Trace metal element Chelation fertilizer in lignin and application thereof - Google Patents

Abstract

The present invention provides a chelated fertilizer of trace metal elements in lignin and its application. The chelated fertilizer of trace metal elements in lignin is a mixture containing lignin salt and metal element chelate, showing the following physical and chemical properties: (1 ) Appearance: white powder; (2) chelate stability parameters: the average coordination number x is between 0.9 and 1.95, the stability constant lgK is between 0.6 and 2.10, (3) the metal chelation rate is between 10% and 13.55 %between. The described lignin salt-metal element chelated fertilizer is prepared by oxidative modification reaction with papermaking pulping waste liquor lignin salt and metal elements such as iron, zinc and copper, and through the combination of lignin ammonium-Fe and The determination of the stability of ammonium lignin-Zn chelate is used to quantitatively describe the chelating performance of ammonium lignin. Industrial lignin and metal elements form a "lignin-metal element" chelate, which can be formed into a solid product after drying, or compounded with other fertilizers after proper concentration to make a variety of compound fertilizers.

Description

Trace metal element chelate fertilizer in a kind of lignin and application thereof

technical field

The invention relates to preparation of lignin-medium trace element chelated fertilizer by modifying lignin salt of papermaking pulping waste liquid and application of the chelated fertilizer in compound fertilizer.

Background technique

Plant growth needs to absorb dozens of chemical elements from the soil as nutrients, including iron (Fe), copper (Cu), zinc (Zn), boron (B), chromium (Mo), manganese (Mn), magnesium (Mg) The demand of plants and other plants is very small, accounting for a few ten thousandths or even a few millionths of the weight of things. Trace elements play an important role in the growth and development of plants, they are indispensable and cannot replace each other.

Traditional inorganic salt metal micro-fertilizers tend to form precipitation in the soil after application, which is not conducive to the absorption and utilization of plants. In agricultural production, there is an urgent need for a new type of chelating agent that has a wide range of sources, low prices, and can effectively combine with the trace elements required for plant growth to prepare trace element chelated fertilizers. Although the effect of EDTA chelated fertilizer is better, it has the disadvantage of high cost.

The various active groups contained in lignin have strong chelating and colloidal properties, and can be complexed with some trace elements, such as Fe, Cu, Zn, etc., to form organic trace element fertilizers. The lignin-Fe chelated micro-fertilizer can supply soluble iron to plants and prevent iron deficiency in plants. At present, the preparation method of sulfonated lignin chelated fertilizer is to firstly modify lignin to obtain water-soluble lignin salt, and then chelate with metal inorganic salt under specific conditions to obtain chelated fertilizer. However, the lignin salt has a limited ability to chelate trace elements, and the chelated metal elements generally do not exceed 5%.

Contents of the invention

In order to overcome the above-mentioned defects of the prior art, the present invention provides a modified lignin salt-metal element chelated fertilizer, its preparation method and its application in compound fertilizer. The modified lignin salt-medium trace metal element chelating fertilizer has low cost and strong chelating ability, and can be compounded with various fertilizers to increase the content of trace elements in the fertilizer.

Technical scheme of the present invention is:

The present invention provides a chelated fertilizer of trace metal elements in lignin, which is a mixture containing lignin salts and metal element chelates. The metals include iron and zinc, showing the following physical and chemical properties:

(1) Appearance: white powder;

(2) Chelate stability parameters: the average coordination number x is between 0.9 and 1.95, and the stability constant lgK is between 0.6 and 2.10;

(3) The metal chelation rate is between 10% and 13.55%.

The present invention quantitatively describes the chelating performance of lignin salt by measuring the stability of lignin salt-Fe and lignin salt-Zn chelate, and the experimental results prove:

The average coordination number x of lignin salt and iron is between 1.03 and 1.42, and the stability constant lgK is between 1.04 and 2.10.

The average coordination number x of oxidized lignin salt and iron is between 1.39-1.42, the stability constant lgK is between 2.01-2.10, and the chelation rate of iron is 13.55%.

The average coordination number x of lignin salt and zinc is between 0.93 and 1.94, and the stability constant lgK is between 0.62 and 0.98.

The optimal result of oxidized lignin salt and zinc is that the average coordination number x is between 0.93 and 0.99, the stability constant lgK is between 0.62 and 0.72, and the chelation rate of zinc is 11.01%.

Another technical scheme of the present invention is: provide a kind of compound fertilizer of lignin metal element chelate fertilizer, add the described lignin metal element chelate fertilizer of effective dose in other fertilizers and carry out compounding, just can obtain various Chelated compound fertilizer of metal elements.

The method for preparing trace metal element chelated fertilizer in lignin provided by the invention, the method comprises the following steps carried out in order:

(1) Industrial lignin salt is configured into an aqueous solution of a certain concentration in the dissolving tank;

(2) Transfer the configured industrial lignin aqueous solution to the reaction vessel, and use a pH regulator to adjust the pH of the solution;

(3) Add oxidizing agent and initiator, start the stirring device of reaction vessel, add the inorganic salt containing medium and trace metal elements after fully mixing;

(4) React for 10-150 minutes after heating to 40-80 degrees.

In the step (1) the solution prepared by industrial lignin salt has a concentration of 10% to 50%. For the selection of the reaction concentration, the production cost and the possibility of actual operation should be considered. A higher or lower concentration is theoretically feasible, but too low or too high a concentration will introduce an increase in production cost or inconvenience in operation.

The dissolution tank is a resin-lined steel structure tank or a reinforced concrete structure tank or a stainless steel tank.

The reaction vessel in the step (2) is a normal-pressure acid-resistant reaction kettle with a stirring device.

The pH value of the solution ranges from 1 to 7. In theory, most inorganic acids or organic acids can be used to adjust the pH value of the reaction system. The pH value regulator can be industrial waste sulfuric acid or other reliable and low-cost sources. inorganic or organic acids.

The oxidizing agent in the step (3) is hydrogen peroxide, and its added amount is 1%-20% of the lignin.

The initiator is an inorganic salt containing ferrous ions, such as FeSO ₄ , FeCl ₂ and the like.

The inorganic salt containing trace metal elements depends on the trace metal elements required by the product.

The reaction temperature of the step (4) is 40-80°C.

The reaction time is 10-150 minutes, which varies according to the addition of different trace elements.

Beneficial effects of the present invention: first: the chelated fertilizer of trace metal elements in lignin provided by the present invention has strong metal chelating ability, good fertilizer effect, and low raw material price, thereby reducing the price of chelated fertilizer.

Second: the chelate fertilizer provided by the invention can be compounded with other fertilizers to form a variety of compound fertilizers, which are suitable for different crops.

Description of drawings

Fig. 1 is the relationship between lignin salt-Fe chelate lg (λ0/λ-1) and lg[lignin salt]

Fig. 2 is the relationship between oxidized lignin salt-Fe chelate lg (λ0/λ-1) and lg[oxygen lignin salt]

Fig. 3 is the relationship between lignin salt-Zn chelate lg (λ0/λ-1) and lg[lignin salt]

Fig. 4 is the relationship between oxidized lignin salt-Zn chelate lg (λ0/λ-1) and lg[oxygen lignin salt]

Figure 5 is the distribution map of the experimental plot

Detailed ways

In order to quantitatively describe the chelating effect of industrial lignin and oxidized industrial lignin on Fe ²⁺ and Zn ²⁺ , and clarify the mechanism of action of industrial lignin and oxidized industrial lignin in chelating trace element organic fertilizers, this part studies the application of ion The stability of lignin salt and H ₂ O ₂ oxidized lignin salt-Fe(Zn) chelate was analyzed by exchange equilibrium method. By calculating the chelation average coordination number x and the chelation equilibrium constant lgK of the chelate, we can understand the size of the chelation ability of lignin and oxidized lignin to Fe and Zn, and the chelation at a certain temperature and pH value. The strength of chelation stability provides a theoretical basis for the chelation reaction of industrial lignin.

1 Experimental principle

The complexation equilibrium reaction of mononuclear complexes can be represented by the following formula:

In the formula:

M-metal ion;

A-complexing agent;

The coordination number of the x-complex, that is, the amount of the substance of the complexing agent combined with 1 mole of metal ions.

The complex stability constant K is:

$\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ]</span>}{{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; x</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>$

In the formula:

[M]-the activity of free metal ions in the solution at equilibrium;

[A]-the activity of the free complexing agent in the solution during equilibrium;

[MA _x ]-complex activity;

x has the same meaning as before.

When the ionic strength of the solution is constant at equilibrium, the molar concentration of the substance can be used instead of the activity.

The cation exchange equilibrium method is mainly based on the fact that the amount (MR) of a certain metal ion adsorbed by a certain amount of cationic resin (R) is proportional to the concentration [M] of the metal ion in the solution within a considerable concentration range during equilibrium, namely:

${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; MR</span>}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; =</span>\frac{{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}\mathrm{<span\; class="notranslate">\; v</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; a</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; b</span>}<span\; class="notranslate">\; )</span>$

In the formula:

λ ₀ - partition coefficient of metal ions without complexing agent;

The amount of material of the metal ion adsorbed by the unit weight of the cation exchange resin during MR-balance;

a ₀ - the metal ion combined with the resin accounts for the percentage of the total metal ion amount;

100-a ₀ - the metal ion remaining in the solution accounts for the percentage of total metal ion amount;

v - the volume of the equilibrium solution, mL;

g-mass of cationic resin, g.

The distribution coefficient λ when there is a complexing agent is:

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; MR</span>}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; MA</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ]</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; av</span>}}{<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 100</span>}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; a</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; g</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; c</span>}<span\; class="notranslate">\; )</span>$

In the formula:

[M]+[MA _x ]-the total concentration of metal ions in the equilibrium solution when there is a complexing agent, mol/L;

a ₀ - when there is complexing agent, the metal ion combined with resin accounts for the percentage of total metal ion amount;

100-a ₀ - when there is a complexing agent, the metal ions remaining in the solution account for the percentage of the total metal ions;

MR, v, g have the same meaning as before.

From formula (b) and formula (c), we can get:

$<span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; MA</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; MR</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; MR</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; MR</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>$

Substituting formula (d) and formula (b) into formula (a), we get:

$\mathrm{<span\; class="notranslate">\; K</span>}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; MR</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span>{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; x</span>}}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; MR</span>}<span\; class="notranslate">\; (</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; -</span>\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}<span\; class="notranslate">\; )</span>}{\frac{\mathrm{<span\; class="notranslate">\; MR</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; x</span>}}}<span\; class="notranslate">\; =</span>\frac{\frac{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}}{{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ]</span>}^{\mathrm{<span\; class="notranslate">\; x</span>}}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; e</span>}<span\; class="notranslate">\; )</span>$

Taking the logarithm of the above formula, we get:

$\mathrm{<span\; class="notranslate">\; lg</span>}<span\; class="notranslate">\; (</span>\frac{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}}{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}<span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; lm\; w</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; xlg</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; A</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; f</span>}<span\; class="notranslate">\; )</span>$

为纵坐标，以lg[A]为横坐标作图，即可根据截矩求得lgK，根据斜率求出络合物的配位数x。Under the condition of constant pH value, ionic strength, temperature, cation exchange resin weight _, etc., _the corresponding _distribution coefficient (λ ₁ , λ ₂ , λ ₃ ,...). If the concentration of complexing agent is much greater than the concentration of metal ions, the concentration of free complexing agent in the solution at equilibrium can be regarded as equal to its initial concentration. in this way

is the ordinate, and lg[A] is used as the abscissa to draw a graph, then the lgK can be obtained according to the intercept, and the coordination number x of the complex can be obtained according to the slope.

2. Experimental raw materials

1. Pretreatment of 732 cationic resin

Take the commercially available 732 cationic resin and rinse it repeatedly with tap water to remove pigment, dust, water-soluble impurities, small particle size and dehydrated resin floating on the water surface. Then soak with 95% ethanol for 24 hours, and pour out the ethanol to remove alcohol-soluble impurities. Then wash it repeatedly with tap water until the washing liquid is colorless and has no ethanol smell.

Soak the resin after the above preliminary treatment with 2mol/L HCl (chemically pure) for 2-3 hours, and stir frequently, then pour off the HCl, and wash repeatedly with distilled water until the pH of the eluate is 6-7. Then soak in 2mol/L NaOH (chemically pure) for 2-3 hours (stir frequently during soaking), pour off the NaOH, and wash repeatedly with distilled water until the pH of the eluate is 7-8. Repeat the treatment with 2mol/L HCl and 2mol/L NaOH for 2-3 times according to the above method. Soak in 2mol/L HCl (analytical pure) solution for the last time overnight, then wash repeatedly with deionized water until there is no Cl- in the washing solution, and dry it in a 40°C incubator for later use.

2. Determination of Chelation Stability

The present invention adopts ion exchange method to measure lignin chelate stability, and concrete method is: preparation lignin salt solution concentration is 5g/L, draws the lignin salt solution 0,1,2,4,8 and 16mL of above concentration, Place them in 100mL tall beakers, add deionized water to a total volume of about 25mL, then add 5mL of 1mol/L NaCl (analytical pure) solution and 2mL of 0.125g/L divalent metal ion salt (the amount of metal ion after constant volume The concentration is about 5~6mg/L). At this point, the total volume of the solution should be about 35 mL. Adjust the pH to 7.0 with 0.01-0.1 mol/L NaOH and HCl (analytical pure) solutions. The volume of the solution after pH adjustment was about 45 mL. Transfer all of this solution to a stoppered 50mL colorimetric tube, and add deionized water to the mark. Then add 1.00g of 732-type cation exchange resin to each colorimetric tube, place in a constant temperature shaking incubator at 25°C for 1h, and then balance for 24h.

After equilibration, filter the solution in the colorimetric tube with a G3 glass sand funnel. Take 25mL of the filtrate and place it in the original 100mL tall beaker, and evaporate it to dryness on the electric stove (during the evaporation period, especially when it is drying quickly, care must be taken to prevent the precipitate from splashing out). After cooling, add 3mL concentrated HNO3 (excellent grade) and 2mL concentrated HClO4 (excellent grade), cover with a watch glass, and reflux digestion at 150°C to 180°C. After the solution is clear, suspend digestion, cool to room temperature, wash the watch glass with deionized water, then remove the watch glass, and continue digestion until the precipitate in the cup turns white. If the precipitate is yellow or brown after digestion, add 1-2mL concentrated HClO4 to digest until the precipitate in the cup is white (if the raw material contains more elements such as Fe and Cu, the precipitate will have some color after digestion is complete). After cooling, add 1-2mL 0.25mol/L HCl (excellent grade) to dissolve the precipitate, filter it with fast filter paper while it is hot, wash the precipitate repeatedly with deionized water, collect the filtrate and washing liquid in a volumetric flask, and dilute to 25mL. Finally, the concentration of metal ions in the solution was measured by an inductively coupled plasma emission spectrometer.

Wash the resin several times with deionized water to fully wash the lignin solution between the resins. Then replace it with another clean volumetric flask to accept the metal ion washing solution complexed with the resin. The resin was first washed twice with 1-2mL 2mol/L HCl (premium grade), and then washed several times with 2-3mL 0.1mol/L HCl (premium grade). The volume of the washing solution was adjusted to 25 mL, and the content of the adsorbed metal ions was measured on an inductively coupled plasma emission spectrometer.

3. Calculation of Chelation Stability

λ0 and λ can be obtained according to formulas (b) and (c) respectively. For the convenience of calculation, it can be simplified as:

${\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}_{\mathrm{<span\; class="notranslate">\; 0</span>}}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; (</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; V</span>}}{<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; g</span>}}$

$\mathrm{<span\; class="notranslate">\; \&lambda;</span>}<span\; class="notranslate">\; =</span>\frac{<span\; class="notranslate">\; \{</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; m</span>}}_{\mathrm{<span\; class="notranslate">\; f</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; [</span>{\mathrm{<span\; class="notranslate">\; MA</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; )</span><span\; class="notranslate">\; \}</span>\mathrm{<span\; class="notranslate">\; V</span>}}{<span\; class="notranslate">\; (</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; +</span><span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; m</span>}{\mathrm{<span\; class="notranslate">\; A</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ]</span><span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; g</span>}}$

In the formula:

[Mf]-metal ion initial concentration ppm;

The meanings of V, g, [M] and ([M]+[MAx]) are the same as before.

Embodiment one:

Chelation Stability of Lignin Salts and Fe Elements

In this study, the chelation average coordination number x and the chelation equilibrium constant lgK of the lignin salt-Fe chelate were measured respectively by the ion exchange equilibrium method, and the results are listed in Table 1. The lg(λ ₀ /λ-1) and lg [lignin salt] is shown in Figure 1.

Chelation stability determination of table 1 lignin salt and FeSO

Note: α is [M], β is [M]+[MAx], γ is [Mf]-[M], δ is [Mf]-([M]+[MAx])

It can be seen from Figure 1 that the coordination number x of lignin salt and Fe in FeSO ₄ is 1.03, and its stability constant lgK is equal to 1.04.

Chelation stability of H ₂ O ₂ oxidized lignin salts and Fe elements

The reaction conditions for the preparation of oxidized lignin salt are H ₂ O ₂ addition 2.5%; FeSO ₄ : _{H 2} O ₂ =1:20 (mol ratio), reaction temperature 40° C., and reaction time 30 minutes. The chelation average coordination number x and chelation equilibrium constant lgK of the H ₂ O ₂ oxidized lignin salt-Fe chelate were determined by ion exchange equilibrium method, and the results are listed in Table 2. The relationship between H ₂ O ₂ oxidized lignin salt-Fe chelate lg (λ ₀ /λ-1) and lg [oxidized lignin salt] is shown in Fig. 2 .

Chelation stability determination of table 2 oxidized lignin salt and FeSO

Note: α is [M], β is [M]+[MAx], γ is [Mf]-[M], δ is [Mf]-([M]+[MAx])

It can be seen from Figure 2 that the average coordination number x of oxidized lignin salt and Fe ³⁺ in FeSO ₄ is 1.42, and its stability constant lgK is equal to 2.10. Its chelation stability is slightly higher than that of dilute nitric acid oxidation of lignin and metal.

Comparing lignin salts and oxidized lignin salts, it can be seen that the average coordination number and stability constant lgK of oxidized lignin salts and iron are larger than those of lignin salts and iron. The possible reasons are: first, due to the oxidation of lignin The salt contains more carboxyl and carbonyl groups, so it has a strong charge, and the ferrous center ion has a higher degree of chelation and chelation stability with oxidized lignin salt. Second, when the lignin salt is oxidized by H ₂ O ₂ , its molecular weight decreases, so that the steric hindrance is weakened, so that Fe ²⁺ and Fe ³⁺ can be closer to the lignin salt ligand, thereby increasing the average coordination ratio. number and chelation stability. In general, as the degree of chelation increases, the stability of the complex increases.

Chelation stability determination of table 3 lignin salt and ZnSO

Note: α is [M], β is [M]+[MAx], γ is [Mf]-[M], δ is [Mf]-([M]+[MAx])

Embodiment two:

Chelation Stability of Lignin Salt and Zn

Measure the chelation average coordination number x of lignin salt-Zn chelate and the chelation equilibrium constant lgk respectively with ion exchange equilibrium method equally, the result is listed in table 3, lignin salt-Zn ²⁺ chelate 1g (λ ₀ /λ-1) and lg [lignin salt] is shown in Figure 3:

It can be seen from Figure 3 that the average coordination number of the lignin salt-Zn chelate is 1.94, and the chelation stability constant is 0.98. Its coordination number is higher than lignin salt-Fe chelate, but its stability constant is lower.

Chelation Stability of H2O2 Oxidized Lignin Salt and Zn

The reaction conditions for the preparation of H ₂ O ₂ oxidized lignin salts are: the addition of H ₂ O ₂ is 2.5%, the addition of FeSO ₄ is determined according to FeSO ₄ : _{H 2} O ₂ =1:20 (mol ratio), and the reaction temperature is 40°C. The reaction time is 30min. The chelation average coordination number x and chelation equilibrium constant lgK of the H ₂ O ₂ oxidized lignin salt-Zn chelate were measured by ion exchange equilibrium method, and the experimental results are listed in Table 4. The relationship between H ₂ O ₂ oxidized lignin salt-Fe ²⁺ chelate lg (λ ₀ /λ-1) and lg [oxidized lignin salt] is shown in Figure 4.

Table 4 Oxygenated lignin salt and ZnSO Chelation stability determination

Note: α is [M], β is [M]+[MAx], γ is [Mf]-[M], δ is [Mf]-([M]+[MAx])

It can be seen from Fig. 4 that the chelation average coordination number of the oxidized lignin salt-Zn chelate is 0.93, which is smaller than the chelation average coordination number of the unoxidized lignin salt. The chelation stability constant of oxidized lignin-Zn chelate is 0.62, which is also smaller than that of unoxidized lignin. The reason for this situation may be that Zn ²⁺ is more likely to accept nitrogen and sulfur as coordination atoms, so Zn ²⁺ is easier to chelate with -SO ₃ ^- on the lignin salt, and when the lignin salt is absorbed by H ₂ After _O2 oxidation, due to the increase in the content of carboxyl groups, according to the hard and soft acid-base theory, the coordination stability of Zn ²⁺ with oxygen in carboxyl groups is relatively low, so the average coordination number of chelation of oxidized lignin salt-Zn chelates And chelation stability constants are less than lignin salt-Zn chelate.

Embodiment three:

This study mainly investigated the effects of the amount of H ₂ O ₂ , reaction temperature and reaction time on the chelation of ammonium lignin and Fe in the presence of excess FeSO ₄ . FeSO in the reaction system The mass ratio of ammonium lignin is ₂ : 3, H _{2 O} Consumption (based on ammonium lignin) is 0%, 2.5%, 5% and 10% respectively, and the reaction times are respectively 10min, 30min and 120min; the reaction temperatures were 20°C, 40°C and 60°C, respectively. By comparing the chelation rate of Fe element in the product under different reaction conditions, the technological conditions of the chelation reaction between lignin ammonium salt and FeSO ₄ were determined. Table 5 shows the chelation _rate of iron in the chelated product under different _H2O2 dosages, different reaction temperatures and different reaction times.

The chelation rate of Fe ²⁺ under the different process conditions of table 5, %

Effect of H ₂ O ₂ Dosage on the Chelation Reaction of Lignin Ammonium Salt and FeSO ₄

Under different reaction time and reaction temperature, the iron content in lignin ammonium salt-Fe chelate increases with the increase of H ₂ O ₂ addition, and reaches the maximum when the H ₂ O ₂ addition is 10% , as shown in Table 5. It may be because the more H ₂ O ₂ is added in the process, the free radical reaction of H ₂ O ₂ can generate more hydroxyl radicals to oxidize the branched chain and benzene ring structure of lignin ammonium salt, making the carboxyl content increases, therefore, the chelation rate is significantly improved. The effect of time on the chelation reaction of lignin ammonium salt with FeSO ₄

Under the conditions of different temperatures and different H ₂ O ₂ dosages, the iron content in lignin ammonium salt-Fe chelates generally increased firstly with the increase of reaction time, and then tended to be stable. When the reaction time reaches 30 minutes, the iron chelation rate can reach the maximum value.

And when the reaction temperature is 60℃, with the increase of time, the chelation rate of iron with different H ₂ O ₂ dosage tends to be similar. It may be due to the chelation of lignin ammonium salt with iron and the condensation reaction of lignin ammonium salt itself at high temperature as time goes on.

Effect of temperature on chelation reaction of lignin ammonium salt with FeSO ₄

The chelation rate of iron sometimes reaches the maximum when the reaction initial temperature is 40°C, and the chelation rate of iron is small when the temperature is too low or too high. The possible reasons are: (1) The reaction between Fe ²⁺ and H ₂ O ₂ is an exothermic reaction, so if the initial reaction temperature is too high, the oxidation of H ₂ O ₂ will be hindered, thereby affecting the chelation rate. The chelation rate decreased rapidly at 60°C, and at lower temperature, the reactivity of lignin was low, which was not conducive to the oxidation of lignin structure by H ₂ O ₂ , so the chelation rate was also low; (2) when When the temperature is too high, the hydroxyl free radicals produced by H ₂ O ₂ disappear rapidly without fully oxidizing lignin, so that the chelation rate becomes smaller; (3) the sulfonic acid group on the side chain of lignin ammonium salt at high temperature It may be oxidized by H ₂ O ₂ to cause desulfonation reaction, so that the carbocations of the side chains of the lignin structural units that have removed the sulfonic acid groups undergo polycondensation reactions with the aromatic rings of other lignin units, affecting the sulfonic acid groups and iron of chelation.

Determination of the best process for chelating lignin ammonium salt with FeSO ₄

By comparing the temperature, time and the amount of H ₂ O ₂ , it can be concluded that the temperature and the amount of H ₂ O ₂ have the greatest impact on the chelation rate in the reaction. When the reaction temperature is 40°C, the reaction time is 30min, and the amount of H ₂ O ₂ is 10%, the chelation rate of lignin ammonium salt and FeSO ₄ is the highest at 13.55%. However, considering the energy consumption and production cost, the optimal process conditions for the preparation of lignin ammonium salt-Fe ²⁺ trace element fertilizer were chosen as reaction temperature 40℃, reaction time 30min, H ₂ O ₂ dosage 5%. At this time, the chelation rate of iron was 12.06%, which was not much different from 13.55%.

Embodiment four:

The present invention describes the preparation method of lignin salt-metal element chelate fertilizer and the equipment used by taking lignin salt as an example;

Preparation of lignin ammonium salt-Zn element chelate

Lignin ammonium salt reacts with ZnSO ₄ under acidic conditions to prepare lignin ammonium salt-zinc element chelate. During the reaction, an excessive amount of ZnSO ₄ (the amount of ZnSO ₄ added is 50% of the lignin ammonium salt) is added to the lignin ammonium salt solution, and then a small amount of FeSO ₄ is added to initiate the reaction. React at a certain temperature for a specified time, add NaOH solution to adjust the pH to 12, at this time the excess Zn ²⁺ reacts with NaOH to form a Zn(OH) ₂ precipitate, centrifuge to remove the precipitate, and the liquid part is lignin ammonium salt-zinc Chelates, where the zinc content is zinc chelated with ammonium lignin. By measuring the content of zinc chelated with lignin ammonium salt, the chelation rate of ligninsulfonic acid per unit mass and zinc can be calculated, so as to determine the best process plan for preparing zinc lignin ammonium salt-Zn element chelate organic fertilizer.

In the chelation reaction of lignin ammonium salt and ZnSO ₄ , a certain amount of Fe ²⁺ needs to be added to start the reaction, and the amount of H ₂ O ₂ is directly related to the amount of FeSO ₄ . In this study, an orthogonal experimental reaction with four factors and four levels of interaction was used to determine the optimal process conditions, in which the amount of H ₂ O ₂ and the amount of FeSO ₄ were the two factors with interaction. Orthogonal experiment table is shown in Table 6, variance analysis table and interaction table are shown in Table 7 and 8 respectively.

From the variance analysis of the chelation reaction between lignin ammonium salt and ZnSO ₄ , it can be seen that for the zinc chelation rate, comparing the range of each factor, the range R _A > R _B > R _D > R _{A × B} > R _C , it can be seen that the primary and secondary order of the chelation reaction conditions between lignin ammonium salt and ZnSO is: H ₂ O ₂ dosage, FeSO ₄ dosage, interaction between H ₂ O ₂ dosage and FeSO ₄ dosage, reaction time and reaction _temperature , That is, the amount of H ₂ O ₂ is the decisive factor for improving the zinc chelation rate in the reaction.

Table 6 Orthogonal experiment table L ₁₆ (4 ⁵ ) for the chelation reaction of lignin ammonium salt and ZnSO ₄

Table 7 Lignin ammonium salt and ZnSO _chelation reaction variance analysis table

Note: I, II, III, and IV represent the mean value of each factor, and R represents the range, the same below.

Comparing the average value of each factor, it can be seen that the amount of H ₂ O ₂ : A _IV >A _II ＞A _III ＞A _I ; the amount of FeSO ₄ : B _II ＞B _I ＞B _III ＞B _IV ; the reaction time: C _I ＞ C _IV >C _III >C _II ; reaction temperature: D _IV >D _I >D _III >D _II . It can be concluded that when the interaction between the amount of H ₂ O ₂ and FeSO ₄ is not considered, the optimal reaction conditions are H ₂ O ₂ 10%, FeSO ₄ 0.834g, reaction time 10min, reaction temperature 80℃.

Table 8 Chelation interaction table of lignin ammonium salt and ZnSO ₄

Comparing the interaction between the amount of H ₂ O ₂ and the amount of FeSO ₄ , it can be seen from the interaction table 8 that for zinc, the value of A ₄ B ₂ is the largest, which is 11.01%, so A ₄ B ₂ is selected as the best combination condition, Same as when no interaction is considered.

Comprehensive analysis of variance and interaction analysis, the optimal process conditions are H ₂ O ₂ dosage 10%, FeSO4 dosage 0.834g, reaction time 10min, reaction temperature 80℃. Under these conditions, the chelation rate of zinc is 11.01%, and the total chelation rate of zinc and iron is 11.60%, which is 3% to 4% higher than that of traditional dilute nitric acid oxidation chelation products.

Embodiment five:

Fertilizer Efficiency Evaluation of Lignin Chelate Fertilizer

There are 6 treatments in this experiment, each treatment has 3 repetitions, and there are 18 plots in total. The distribution of each plot is shown in Figure 5.1. There are two controls in this experiment, CK1 does not apply any fertilizer, CK2 is treated with fertilization and other nutrients without additives, 1# is applied oxidized wheatgrass lignin iron zinc fertilizer, 2# is applied oxidized wheatgrass alkali lignin iron zinc Fertilizer, 3# apply wheatgrass alkali lignin iron-zinc fertilizer, 4# apply wheatgrass lignin iron-zinc fertilizer. The area of each plot is 3m2. Due to the low soil fertility in the test area, the amount of fertilizer applied is 60kg/mu. Fertilize and transplant Chinese cabbage on January 28, 2007, slow seedlings on January 31, each treatment except fertilization is different, watering, weeding, spraying are all consistent, harvested and weighed on February 23.

Soil Fertility

The fertility status of the red loam used in the test base is shown in Table 9. The pH of the red loam used in this study is strongly acidic; the soil organic matter is at a low level; the soil available nitrogen is at a low level, the available phosphorus is at a high level, and the soil available potassium is at a low level.

Table 9 Soil Fertility Status

Yield Increase Effect of Lignin-Fe/Zn Chelate Fertilizer

Through this field test, it is clearly shown that, as shown in Table 10, the application of 1# fertilizer can greatly increase the crop yield by 23.2%, while the application of 3# fertilizer does not increase the biomass of crops significantly.

Table 10 harvesting results (unit: kg)

Field experiments show that the promotion effect of industrial lignin chelated fertilizers on crops is obvious, and the application of iron/zinc chelated fertilizers with oxidized industrial lignin has a better effect on crop growth than the application of iron/zinc chelated fertilizers without oxidized industrial lignin. Good promotion effect, the yield increase reaches 23.2%. At the same time, industrial lignin chelated fertilizer is a kind of non-toxic and harmless environment-friendly fertilizer, which is beneficial to the production of pollution-free vegetables.

Claims (10)

1. xylogen-middle micro-metals chelating fertilizer is the mixture that contains lignin salt and metallic element inner complex, and described metal comprises iron and zinc, demonstrates following physicochemical characteristic:

(1) outward appearance: white powder:

(2) inner complex stability parameter: average coordination number x is between 0.9～1.95, and stability constant lgK is between 0.6～2.10;

(3) the metal-chelating rate is between 10%～13.55%.

2. xylogen according to claim 1-middle micro-metals chelating fertilizer, it is characterized in that: the average coordination number x of lignin salt and iron is between 1.03～1.42, and stability constant lgK is between 1.04～2.10.

3. xylogen according to claim 2-middle micro-metals chelating fertilizer is characterized in that: the average coordination number x of oxidative lignin's salt and iron is between 1.39～1.42, and stability constant lgK is between 2.01～2.10, and the chelation percent of iron is 13.55%.

4. xylogen according to claim 1-middle micro-metals chelating fertilizer, it is characterized in that: the average coordination number x of lignin salt and zinc is between 0.93～1.94, and stability constant lgK is between 0.62～0.98.

5. xylogen according to claim 4-middle micro-metals chelating fertilizer, it is characterized in that: the average coordination number x of oxidative lignin's salt and zinc is between 0.93～0.99, and stability constant lgK is between 0.62～0.72, and the chelation percent of zinc is 11.01%.

6. one kind is utilized the composite fertilizer that the described xylogen of claim 1-middle micro-metals chelating fertilizer is made, in other fertilizer, add the described xylogen metallic element of significant quantity chelating fertilizer and carry out compositely, just can obtain the multiple chelate compound fertilizer material that contains middle micro-metals.

7. manufacture method as claim 1-5 xylogen-middle micro-metals chelating fertilizer, this method comprises the step that following order carries out:

(1) industrial lignin salt is configured to the certain density aqueous solution in dissolving tank;

(2) the industrial lignin aqueous solution that configures is transferred in the reaction vessel, adopts pH value conditioning agent regulator solution pH value;

(3) add oxygenant and initiator, start the whipping appts of reaction vessel, the inorganic salt of micro-metals during thorough mixing even back adding contains;

(4) be heated to 40～80 degree afterreactions 10～150 minutes.

8. the manufacture method of xylogen metallic element chelating fertilizer according to claim 7, its feature is being: the described certain density aqueous solution, its concentration are 10%～50%.

9. the manufacture method of xylogen metallic element chelating fertilizer according to claim 7 is characterized in that: the pH value scope of described regulator solution is 1～7, and described employing pH value conditioning agent is industrial waste sulfuric acid or other mineral acid or organic acid.

10. the manufacture method of xylogen metallic element chelating fertilizer according to claim 7 is characterized in that: described oxygenant is a hydrogen peroxide, and its add-on is 1%～20% of an xylogen, and described initiator is the inorganic salt that contain ferrous ion.

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