Copper(II)-mediated thermolysis of alginates: a model kinetic study on the influence of metal ions in the

thermochemical processing of macroalgae

by J. S. Rowbotham, P. W. Dyer, H. C. Greenwell, D. Selby, and M. K. Theodorou

Interface FocusVolume 3(1):20120046

February 6, 2013

©2013 by The Royal Society

Schematic of the mode of uptake of various mono- and di-valent metallic ions found in seawater by α-l-guluronic acid and β-d-mannuronic acid, which polymerize to form alginic acid (and the

corresponding alginate salts) in large quantities in brown macroalga...

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

The affinity of alginic acid in L. digitata for various divalent cations [47].

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

The ‘egg box’ model of divalent cation bonding in alginic acid [46].

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

L. digitata collection site: Marsden Bay, South Shields, UK.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

The (a) DTG, (b) TGA and (c) degree of conversion profiles for the thermolysis of H-Alg, Na-Alg and Cu-Alg over the temperature range 25–1000°C obtained with a heating rate (β) of 10°C min−1

under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

Comparison of TGA (dashed line) and DSC (solid line) curves for (a) H-Alg, (b) Na-Alg, and (c) Cu-Alg over the temperature range 50–400°C obtained with a heating rate (β) of 10°C min−1

under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

The (a) DTG and (b) TGA profiles for the thermolysis of Na2CO3, CuCO3 and CaCO3 over the temperature range 25–1000°C obtained with a heating rate (β) of 10°C min−1 under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

Plot of ln(β/T2) versus 1/T (with T in kelvin) at the points of maximum volatilization of H-Alg, Cu-Alg and Na-Alg, pyrolysed at β = 5, 10, 20, 30 and 40°C min−1.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

The DTG profiles for the main pyrolysis region of (a) H-Alg, (b) Cu-Alg and (c) Na-Alg at heating rates (β) of 5, 10, 20, 30 and 40°C min−1 under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

TGA-FTIR profile for the thermolysis of (a) Na-Alg, (b) Cu-Alg and (c) H-Alg over the temperature range 25–1000°C obtained with a heating rate (β) of 10°C min−1 under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

(a) Plot of absorbance at 2360 cm−1 versus temperature for the thermolysis of Na-Alg, Cu-Alg and H-Alg over the temperature range 150–300°C obtained with a heating rate (β) of 10°C min−1

under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

The (a) DTG and (b) TGA profiles for the thermolysis of raw L. digitata and L. digitata treated in a solution of Cu2+ ions in the range 25–800°C with a heating rate (β) of 10°C min−1 under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society

(a) Comparison of DSC curves for copper(II) alginate (solid line) and copper(II)-doped L. digitata (dotted line) over the temperature range 50–400°C obtained with a heating rate (β) of 10°C min−1

under N2.

J. S. Rowbotham et al. Interface Focus 2013;3:20120046

©2013 by The Royal Society