| Recycling paper has become one of the most important raw materials in the papermaking industry.However,stickies present in recovered paper would affect both the quality of products and the process efficiency.Most macrostickies could be removed by mature methods,microstickies hasn't established satisfactory methods to control it.In recent years,enzymatic approaches as an effective and exclusive biotechnology have been pursued by many industries.However there are still lack of appropriate detecting methods to study the behavioral characteristics of microstickies in papermaking whitewater treated by enzyme.This study investigated the behaviors characteristics of the microstickies in papermaking whitewater treated by cellulase,esterase,laccase and lipase alone and mixtures of different compositions from mixed office paper(MOP)by using a modified flow cytometer,and investigating the purification methods and mechanisms of the microstickies treated by enzyme.Meanwhile,this study also utilized this purification method to purify microstickies in the factory.The results are as follows:The microstickies particles with 40 U/L cellulase dosages treated aggregated with the time went on and the weak action of shearing;when samples treated by 80 U/L dosage of cellulase are instable.Moreover,the agglomeration of these smaller microstickies particles(>10 ?m)and dispersion of bigger particles(<10 ?m)happened with the increase of the temperature.Esterase could cleave ester linkages in the microstickies and disperse these particles into smaller particles,and the effects of different dosages of esterase were similar.These new microstickies particles were not stable with the time went on,higher temperature and stronger shearing action.Meanwhile,these cleaved smaller particles agglomerated with the higher temperature and lower stirring rate.The microstickies particles treated by laccase occurred to disperse/agglomerate on the same time,and influenced by the dosage of enzyme.Those treated microstickies with 10 U/L laccase dosages accumulated obviously with the time went on,and these particles were applied 30 U/L laccase also tend to agglomerate when the action shearing was stronger.Lipase works on the triglyceride ester bond and promote the dispersion of microstickies.After treated by lipase,microstickies has different variations in various dosages.Microstickies treated by 1 U/L tend to disperse with the stirring speed increased;particles treated by 4 U/L lipase began to agglomerate in higer stirring rate.With different ratios of esterase and cellulase,the smaller microstickies particles tend to aggregate due to their own viscosity when the time went on.However,when the samples with 1:1 ratio,the effect of dispersion of bigger particles is stronger,and it also promotes small particles to disperse and aggregate more intensely at this rato.Microstickies treated by mixtures of different compositions are less affected by the temperature and the shearing action.The purification efficiency of microstickies treated by cellulase,esterase,lipase,laccase and without enzyme treated are 35.99%,27.20%,18.87%,18.55% and 11.45% separately.The purification efficiency of microstickies treated by enzyme improved obviously.And the probably mechanism was that the surface energies of these new particles were higher than the primary particles,so these microstickies treated by enzyme could adhere to materials more easily than those without enzyme treated.However,some particles adhered in the adhesion materials would peel off because of the function of the external force,resulting to the purification efficiency decreased with the adhesion time went on.Using the same method to purify the microstickies in the whitewater in the factory,the purification efficiency of those microstickies treated by laccase,lipase,esterase and without enzyme treated was 19.50%,1.14%,2.46% and 0.91%,respectively.The purification efficiency improved obviously compared with those microstickies without enzyme treated. |
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