Oxidized Fiber from Dissolved Air Flotation Rejects and its Influences on Paper Properties

Abstract

Fibers obtained from dissolved air flotation rejects were oxidized using a TEMPO oxidation system to prepare oxidized recovered fibers. The effects of oxidization time on carboxyl content, water retention value, and physical properties of handsheets were evaluated. The effects of pH, amount of oxidized recovered fibers, and aluminum sulfate on paper properties were also considered. The results showed that carboxyl content and water retention values increased with the increasing of oxidized time. FTIR analysis indicated that carboxyl groups were connected to the surface of fibers. SEM micrographs showed that fibers were integrated more closely in the paper sheet, benefiting from the addition of the oxidized recovered fibers. Tensile index, burst index, and folding endurance were respectively increased by 71.7%, 38.5%, and 600% when 3% of oxidized recovered fibers was added to the pulp at pH 5, with 0.5% aluminum sulfate addition, based on the original pulp. Tensile index and folding endurance were increased by 40.2% and 433.3%, respectively, when 1% oxidized recovered fibers (the oxidized time was 60 min) were added into pulp for recycled pulp. This finding may lay the foundation for greater re-use of fiber obtained from dissolved air flotation rejects.