TY - JOUR
T1 - Pre-treatment of the paper pulp in the bleaching process using biodegradable chelating agents
AU - Pinto, I. S. S.
AU - Ascenso, O. S.
AU - Barros, Maria Teresa
AU - Soares, H. M. V. M.
N1 - SCOPUSID:84922530193
WOS:000349382100018
PY - 2015/3
Y1 - 2015/3
N2 - The aim of this work was to study the application of two biodegradable chelating agents, pyridine-2,6- dicarboxylic acid (PDA) and methylglycinediacetic acid (MGDA), in the treatment of the pulp, prior to hydrogen peroxide bleaching. Such compounds must remove transition metals (Mn, Fe and Cu) from pulp, that catalyze the degradation of hydrogen peroxide, and Ca, which is also problematic due to the formation of precipitates that accumulate in the equipment. Computer simulations were first performed to study the best conditions for metal complexation, and optimum pH was defined as 5–5.5 for PDA and 6.5–7 for MGDA. Metals removal from the pulp, as well as the subsequent bleaching process (Q-P1-Paa-P2), were tested experimentally, and performances were compared to ethylenediaminetetracetic acid (EDTA). PDA removed both Mn and Ca efficiently, leaving most Mg in the pulp after first chelation stage, while MGDA had a lower Ca removal, even using a higher pH and concentration. Residual hydrogen peroxide and kappa number after peroxide stages showed a similar bleaching efficiency between the studied compounds and EDTA.
AB - The aim of this work was to study the application of two biodegradable chelating agents, pyridine-2,6- dicarboxylic acid (PDA) and methylglycinediacetic acid (MGDA), in the treatment of the pulp, prior to hydrogen peroxide bleaching. Such compounds must remove transition metals (Mn, Fe and Cu) from pulp, that catalyze the degradation of hydrogen peroxide, and Ca, which is also problematic due to the formation of precipitates that accumulate in the equipment. Computer simulations were first performed to study the best conditions for metal complexation, and optimum pH was defined as 5–5.5 for PDA and 6.5–7 for MGDA. Metals removal from the pulp, as well as the subsequent bleaching process (Q-P1-Paa-P2), were tested experimentally, and performances were compared to ethylenediaminetetracetic acid (EDTA). PDA removed both Mn and Ca efficiently, leaving most Mg in the pulp after first chelation stage, while MGDA had a lower Ca removal, even using a higher pH and concentration. Residual hydrogen peroxide and kappa number after peroxide stages showed a similar bleaching efficiency between the studied compounds and EDTA.
KW - Bleaching
KW - Chelating agents
KW - Methylglycinediacetic acid
KW - Paper pulp
KW - Pyridine-2,6-dicarboxylic acid (dipicolinic acid)
U2 - 10.1007/s13762-013-0480-0
DO - 10.1007/s13762-013-0480-0
M3 - Article
SN - 1735-1472
VL - 12
SP - 975
EP - 982
JO - International Journal of Environmental Science and Technology
JF - International Journal of Environmental Science and Technology
IS - 3
ER -