Abstract
Influence of variables [soda, (0.5 to 3.0%), hydrogen peroxide (1.0 to 10.0%) and time (1 to 5 h)] in the bleaching of soda pulp of Hesperaloe funifera, on the properties of bleached pulps, was studied. Polynomial and neural fuzzy models had reproduced the results of Kappa number, brightness and viscosity of the pulps with errors less than 10 and 15%, respectively. By simulating the bleaching process of pulp H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables. Thus, by application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g. Key words: Pulp bleaching, Hesperaloe funifera, hydrogen peroxide, neural fuzzy model, polynomial model.
Highlights
In the industry of cellulosic pulp and paper two main problems today are the reduction of environmental pollution and shortage of raw materials
By simulating the bleaching process of pulp H. funifera, with the polynomial and neural fuzzy models, the optimal values of operating variables can be found, so that the properties of bleached pulps differ little from their best values and instead will save chemical reagents, energy and plant size, operating with lower values of operating variables
By application of polynomial models, it was found that operating with a soda concentration of 0.5%, a hydrogen peroxide concentration of 5.5% and for a processing time of 3 h, it was possible to get a pulp with a brightness of 65.9% and a viscosity of 587 ml/g
Summary
In the industry of cellulosic pulp and paper two main problems today are the reduction of environmental pollution and shortage of raw materials. The pulp bleaching plants are the most contaminating section in the pulp and paper manufacturing process, so you have to take numerous changes intended to alleviate its adverse impact. The need to reduce or eliminate the formation of organochlorinated compounds of high toxicity, during the bleaching processes has led to the emergence of new products in the market, such as elemental chlorine free (ECF) and totally chlorine free (TCF) pulps (Ramos et al, 2008). TCF pulping processes avoid the formation of highly toxic organochlorine compounds adsorbable organic halogen (AOX) during bleaching. Enzyme stages involving xylanases or the laccase-mediator system have so far provided very promising results in pulp bleaching sequences (Valls et al, 2009) TCF sequences include oxygen, hydrogen peroxide and ozone based stages (Freire et al, 2006; López et al, 2003; Pedrola et al, 2004; Shatalov and Pereira, 2005; Villaverde et al, 2009).
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