| As a very important raw material for pulp and paper fiber,waste paper has many advantages in its recycling and utilization.However,the problem of stickies is inevitably encountered in the process of recycling waste paper.Because of the wide range of stickies and their complex components,it is difficult to detect their composition and properties by ordinary methods.Most of the existing methods for measuring micro-stickies such as extraction method,deposition method,density method,screening method,and adsorption method waiting time is generally too long and the operation process is complicated,so it can not adapt to the actual production well.In recent years,flow cytometry has been gradually applied to the field of stickies detection as a fast and efficient detection method.Based on the existing research results,this paper explores the selective adsorption of the staining agent used in the detection of stickies in waste paper by flow cytometry and its adsorption mechanism,and puts forward some precautions and solutions for the actual situation;The cytometer was used to establish the particle size distribution of micro-stickies in waste water and white water,and the formula was explored to calculate the quality of micro-stickies in white water.The accuracy of the formula was verified by combining the actual stickies control methods.First,Nile Red was used to dye waste pulp white water,tap water(simulating water for papermaking),white water after phenol extraction and bleached pulp,and white water after enzyme treatment,followed by flow cytometry to analyze Nile The selective adsorption of Red dye was studied by conductance titration and particle charge meter.The results show that Nile Red has a dyeing effect on other substances besides stickies.Nile Red's dyeing mechanism is that because the Nile Red structure contains diethylamine groups,the N atom of diethylamine groups contains a pair of lone pairs of electrons,and H+ionized by water forms a positively charged state,which can be negatively charged.Material combination.The carbonyl group in the ester bond of the stickies is an electron-withdrawing group,exhibiting a large electronegativity,so the two can be dyed by electrostatic attraction between positive and negative charges.Due to the presence of negative ions such as sulfate and nitrate in tap water,it can also adsorb and stain with Nile Red due to electrostatic attraction.Fibers can form negative charges on the surface due to ionization of their carboxyl groups on the surface,and they can also adsorb and dye with Nile Red due to electrostatic attraction.The correction coefficient of the result of the laboratory measurement of the concentration of micro-stickies particles is 85%.Second,by using standard microspheres to determine the relationship between particle size and FSC light intensity in a flow cytometer,a standard curve and particle size distribution of particle size and light intensity were obtained.The formula was calculated to calculate the mass of fine glue in white water.The results show that the standard curve of particle size and FSC light intensity is y=0.0013x+2.2132,and R2 is 0.9922.The mass of stickies in white water(the default stickies is spherical)is M=m*n=4/3?pR3n.The content of micro-stickies in white water of OCC and ONP prepared by the laboratory was calculated to be 0.350 g/L and 0.264 g/L.Finally,the accuracy of the micro-stickies control effect detected by flow cytometry was verified by the stickies control methods commonly used in factories now.The results showed that the detection by flow cytometry was consistent with the detection results of CD value,turbidity and particle size.Three dispersants were tested to control micro-stickies,and Dispersant No.3 had the best effect. |
PDF Full Text Request