Evonik offers innovative products and solutions for the Pulp and Paper industry to reach excellence in its production processes, with lower environmental impact and better life quality. Decades of investment in research and development were required to attain this goal. Hydrogen Peroxide is one of Evonik’s most important products. It can be used in different applications in pulp and paper production.
The manufacturing unit in the country is located in Barra do Riacho – Aracruz (ES) and its annual production capacity is 70.000 tons. This plant was one of the first in the segment to be granted the environmental management system certificate according to the Brazilian standard NBR ISO 14001.
Chemical pulp bleaching
Hydrogen Peroxide can be applied at different steps along the bleaching sequence. The application of the product offers the following advantages:
- It can lower the demand for other bleaching chemicals, such as chlorine dioxide.
- It can minimize the overall bleaching cost.
- It allows to boost the final brightness.
- It helps to overcome a shortage of on-site produced bleaching compounds.
- It can help to push the capacity of a bleach plant.
- It will decrease the effluent color.
- It minimizes brightness reversion thus improving pulp stability.
Application in mechanical pulp bleaching
The mechanical defiberization of wood yields fibers rich in lignin can be bleached only with mild bleaching agents. Hydrogen Peroxide is capable to oxidize dominantly the chromophores of the lignin. Reductive bleaching with sodium dithionite (hydrosulfite) similarly keeps the yield high. However, reductive bleaching only has a limited brightening effect.
Peroxide bleaching of mechanical fibers typically requires high consistency conditions (consistency higher than 20%) and buffered conditions in order to avoid wide pH swings. The typical reaction conditions are at temperature between 70°C and 85°C, a retention time of at least 2 hours and up to 5 hours. The buffering of the process typically is achieved with the addition of sodium silicate solutions.
Application of Hydrogen Peroxide in paper recycling
Repulping of waste paper with the target of ink removal typically is conducted under mild alkaline conditions. In order to avoid alkaline yellowing and achieve a bleaching effect, small amounts of Hydrogen Peroxide are added to the pulper.
If higher brightness increases are required, Hydrogen Peroxide can also be applied in a post bleaching stage for example under the high consistency conditions of the disperser. In order to fully developed brightness a retention time of about one hour is required, temperature of 85°C, and Hydrogen Peroxide amount of approximately 1.5%.
Additives and Raw Materials for Paper Coating - AEROSIL®, AEROXIDE®, AERODISP®, Dynasylan®, SIPERNAT®
Used as additives or raw materials, Evonik’s additives – a benchmark in the paper industry – create paper with different surfaces rendering them the desired quality for a number of printing purposes: from a document to an ultra-high definition photograph.