CN101561390A - Method for determining retention rate of fluorescent whitening agent in pulp fiber system - Google Patents

Abstract

The invention discloses a method for determining the retention rate of a fluorescent whitening agent in a pulp fiber system by utilizing an ultraviolet spectrophotometer, namely the amount of the fluorescent whitening agent in a filtrate is quantified through the ultraviolet spectrophotometer, and the retention rate of the fluorescent whitening agent in the fiber system is calculated based on a mass conservation principle. The determination method comprises the following steps of production of a standard curve, collection of the filtrate, pretreatment on the filtrate, determination of the ultraviolet spectrophotometer, determination of a blank sample, and calculation, and a determined result has smaller deviation and good reproducibility. The invention is the method with simplicity, easy operation and good reproducibility for determining the retention rate of the fluorescent whitening agent on the surface of pulp fiber.

Description

Measure the method for fluorescer at paper pulp fiber system retention

Technical field

The present invention relates to the retention of fluorescer, relate in particular to a kind of method of measuring fluorescer at paper pulp fiber system retention in the paper pulp fiber system.

Background technology

Fluorescer is also referred to as optical whitening agent, it is a kind of almost colourless fluorescence organic compound, it has the characteristic that sightless ultraviolet light is changed into visible light, therefore processed paper pulp fiber is under the irradiation of light, will send and have Lan Se or purple light, thereby can offset yellow or canescence in the fiber, play the complementary color effect, and presented pure white.Because whiteness or colourity are to estimate an important quality index of paper pulp or paper, therefore, fluorescer is often used in all kinds of paper products, is used for improving the whiteness and the visual quality that improves paper product of paper pulp.The whitening effect of fluorescer depends primarily on fluorescer keeping and its functioning efficiency in the paper fibre network.Usually, the functioning efficiency of fluorescer in network of fibers is all than higher; And its influence of keeping because of the surrounding environment factor in network of fibers alters a great deal.Therefore, fluorescer is to estimate the important indicator of its whitening effect in the result of calculation of paper pulp fiber system retention.

The method of the traditional measurement fluorescer amount of keeping mainly contains two kinds: extraction method and the direct fluorescence intensity method of measuring.All there is serious defective in these two kinds of methods.First kind of assay method need damage measured object, and measuring process is very loaded down with trivial details; It is not high that second method is measured degree of accuracy because of fluorescence intensity is made greatly by surrounding environment influence.

In the last few years, the method for the measurement fluorescer amount of keeping openly introduced of external scientific and technical literature was as follows:

1, Yoshimura, people such as Y. are published in 1996 the 52nd volumes of " Sen ' i Gakkaishi " magazine, 1 phase 32-36 page or leaf " the Convenient photometric quantitative analysis offluorescent brightening agent adsorbed on fabrics and films " literary composition and have mainly studied a kind of method of measuring fluorescer adsorbance on fabric by the fluorescent reagent method.This method is to carry out quantitative test at the fluorescer that has adsorbed, the concentration of the fluorescer of keeping in the searching sample and ultraviolet light diffuse reflection that it causes and the linear relationship between the transmission.In fact this continued to use the first method in the traditional measurement, and this method not only needs to damage measured object, and the reappearance of the data of measuring is bad.

2, people such as Veleva S. and Valcheva E. are published in to have studied in " React ion Kinetics andCatalysis Letters " magazine calendar year 2001 the 72nd volume 2 phase 355-364 pages or leaves " Applicationof an exponential kinetic equation to the interaction of opticalbrighteners with pulp " literary composition under different condition and fluorescer are used for softwood kraft pulp, by adopting indicial equation to describe absorption chemical action mechanism between whitening agent and the paper pulp, and attempt to study relation between the whiteness of the concentration of whitening agent and slurry.The method of this mensuration fluorescer retention is only applicable to bleach chemical pulp, is not suitable for using in high yield pulp (mechanical pulp and chemi-mechanical pulp).Therefore, this method does not have ubiquity.

3, Stana, K.K. wait the people to be published in " Colloid and Polymer Science " magazine nineteen ninety-five the 273rd volume 12 phase 1174-1178 pages or leaves " Adsorption of whitening agents oncellulose fibres-monitored by streaming potential measurements, calorimetry and fluorescence " literary grace and study the concentration of fiber surface fluorescer and the relation between the absorption by the variation of measuring streams current potential, heat and Zeta potential with physical and chemical principle.The measuring process of this method is complicated, needs high theoretical basis and exact instrument incompatible the finishing that match.Therefore, the poor operability of this method, general Study personnel are not easy to grasp.

Therefore, the pulping and paper-making industry is demanded developing a kind of easy grasp urgently and is had the method for the mensuration fluorescer of well reproduced at paper pulp fiber system retention at present.

Summary of the invention

The mensuration fluorescer of a kind of simple, easy to operate, the favorable reproducibility that the objective of the invention is the defective that exists at above-mentioned prior art and design is in the method for pulp fiber surface retention.

For realizing purpose of the present invention, the technical scheme that is adopted:

A kind of method of measuring fluorescer at paper pulp fiber system retention, it is characterized in that: measuring principle is based on the principle of mass conservation, keep the amount that total amount that the amount of the fluorescer on fiber should equal to add deducts fluorescer in the filtrate, the amount of fluorescer can be come quantitatively by ultraviolet spectrophotometer in the filtrate.Utilizing ultraviolet spectrophotometer to measure fluorescer may further comprise the steps at the assay method of paper pulp fiber system retention:

1), the making of typical curve

Prepare the solution of a series of known fluorescent brightening agent concentrations, adopt the ultraviolet light spectrophotometer under ultraviolet wavelength 280nm, a series of concentration known optical brightener solutions to be measured, make the typical curve between the fluorescent brightening agent concentration and UV Absorption accurately;

2), the collection of filtrate

In the slurry system of concentration known, add a certain amount of fluorescer m _Total, in carrying out slurry handsheet experimentation, collect whole filtrate off the net, and recording volume V ₁

3), filtrate is carried out pre-service

Adopt the filtering membrane of 0.1 μ m that collected filtrate is filtered, remove molecule, influence the absorption of ultraviolet light to avoid them;

4), ultraviolet spectrophotometer is measured

Utilize ultraviolet spectrophotometer that the filtrate of handling is measured, the concentration of fluorescer is determined its concentration according to the typical curve of being set up in the filtrate, is labeled as C ₁

5), the mensuration of blank sample

Adopt same slurry, do not add fluorescer, repeating step (2)-(4) obtain C ₀

6), result of calculation

(C ₁-C ₀)×V ₁＝m _filtrate

m _fiber＝m _total-m _filtrate

Rt(％)＝m _fiber÷m _total×100％

In the formula: m _Fiber=keep the quality (g) of the fluorescer on fiber

m _Total=add the gross mass (g) of fluorescer in the slurry to

m _FiltrateThe quality of fluorescer (g) in=filtrate

The retention (%) of Rt (%)=fluorescer on paper pulp fiber.

Advantage of the present invention:

1), measuring principle is easy-to-understand, easily grasp.

2), measuring process is simple, workable.

3), measuring method do not need to damage testing sample, only needs the waste water in the process of taking to detect.

4), measuring method has ubiquity, data reappearance is good.

Description of drawings

Fig. 1 is an assay method step synoptic diagram of the present invention;

Fig. 2 is the typical curve of fluorescer of the present invention (model is Tinopal ABP-A) solution.

Embodiment

In order further to understand content of the present invention, characteristics, with specific embodiment the present invention is described below.

Embodiment

A kind of method of measuring fluorescer at the pulp fiber surface retention, selected one), experimental raw, medicine, filter membrane material and experimental facilities and two), concrete experimentation is described below respectively:

One), experimental raw

Paper pulp

Needlebush (dragon spruce) bleached kraft pulp (whiteness 87.2%ISO, freedom 470ml CSF) and leaf wood (Eucalyptus) bleached kraft pulp (whiteness 88.4%ISO, freedom 490ml CSF) are provided by Canadian Tembec Inc.;

Medicine

Fluorescer (Tinopal ABP-A) is provided by Switzerland's vapour crust chemical company;

Filter membrane material:

0.1 the filtering membrane of μ m (material is a nylon) is provided by U.S. MAGNA company;

Experimental facilities

Ultraviolet spectrophotometer (model Spectronic 1001Plus) U.S. Miton Roy company produces;

Standard fibers fluffer Sweden L﹠amp; W company produces;

The red Bell Co. of standard sheet forming apparatus Canada produces.

Two), concrete experimentation

1), the preparation a series of variable concentrations optical brightener solutions, utilize ultraviolet spectrophotometer to measure its ultraviolet absorption value under ultraviolet wavelength 280nm.The typical curve of fluorescer under ultraviolet wavelength 280nm, as shown in Figure 2.The absorptivity of optical brightener solutions under ultraviolet wavelength 280nm is 1870L/g/cm.Drawing computing formula is:

y＝1.87×x

In the formula: y is a ultraviolet absorption value;

X is fluorescent brightening agent concentration (mg/L or ppm).

2), with softwood kraft pulp and broad-leaved wood sulphate pulp in 30% and 70% ratio, in the standard fibers fluffer, adopt 1.5% slurry concentration to discongest 15000 and change, be mixed with 1% pulp suspension, standby.(area is 0.02m at the standard sheet forming apparatus according to U.S. pulping and paper-making association (Tappi) standard (T205 sp-95) ²) on to copy the formulation amount be 150g/m ²Handsheet.1# slurry sample does not add any chemicals, and 2# slurry sample adds 0.5% fluorescer.In the process of carrying out handsheet, collecting whole machine waters is 4 liters.

3) get an amount of 1# and 2# plain boiled water, respectively, utilize filtering membrane respectively it to be filtered, respectively 1# and 2# filtrate are measured by ultraviolet spectrophotometer, draw its ultraviolet absorption value and be: 1# is 0.044, and parallel sample 1# ' is 0.046; 2# is 0.417, and parallel sample 2# ' is 0.420.Gained 1# average out to 0.045,2# average out to 0.419.

4), calculate

Add total fluorescer quality: 150g/m ²* 0.02m ²* 0.5%=0.015g by the concentration that ultraviolet absorption value and fluorescent brightening agent concentration formula draw fluorescer in the filtrate is:

(0.419-0.045)÷1.87＝0.2ppm＝2×10 ^-7g/ml

The quality of fluorescer is in the filtrate: 2 * 10 ^-7G/ml * 4000ml=8 * 10 ^-4g

The retention of fluorescer is:

$\frac{0.015-8\×{10}^{-4}}{0.015}\×100\%=94.67\%$

The standard deviation of institute's measurement result data:

1#(0.046-0.045)÷0.045×100％＝2.22％；

2#(0.419-0.417)÷0.419×100％＝0.48％；

Show that from above-mentioned 2# measurement result data the measured result error of the inventive method is less, favorable reproducibility.

Claims (1)

1, a kind of method of measuring fluorescer at paper pulp fiber system retention, it is characterized in that: measuring principle is based on the principle of mass conservation, keep the amount that total amount that the amount of the fluorescer on fiber should equal to add deducts fluorescer in the filtrate, the amount of fluorescer can be come quantitatively by ultraviolet spectrophotometer in the filtrate, utilizes ultraviolet spectrophotometer to measure fluorescer and may further comprise the steps in the method for paper pulp fiber system retention:

1), the making of typical curve

Dispose a series of concentration known optical brightener solutions, adopt the ultraviolet light spectrophotometer under ultraviolet wavelength 280nm, a series of concentration known optical brightener solutions to be measured, make the typical curve between the fluorescent brightening agent concentration and UV Absorption accurately;

2), the collection of filtrate

In the slurry system of concentration known, add a certain amount of fluorescer m _Total, in carrying out slurry handsheet experimentation, collect whole filtrate off the net, and recording volume V ₁

3), filtrate is carried out pre-service

Adopt the filtering membrane of 0.1 μ m that collected filtrate is filtered, remove molecule, influence the absorption of ultraviolet light to avoid them;

4), ultraviolet spectrophotometer is measured

Utilize ultraviolet spectrophotometer that the filtrate of handling is measured, the concentration of fluorescer is determined its concentration according to the typical curve of being set up in the filtrate, is labeled as C ₁

5), the mensuration of blank sample

Adopt same slurry, do not add fluorescer, repeating step (2)-(4) obtain C ₀

6), result of calculation

(C ₁-C ₀)×V ₁＝m _filtrate

m _fiber＝m _total-m _filtrate

Rt(％)＝m _fiber÷m _total×100％

In the formula: m _Fiber=keep the quality (g) of the fluorescer on fiber

m _Total=add the gross mass (g) of fluorescer in the slurry to

m _FiltrateThe quality of fluorescer (g) in=filtrate

The retention (%) of Rt (%)=fluorescer on paper pulp fiber.

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