MODIFICATION OF ABSORPTION ABILITY OF SOME LIGNOCELLULOSIC MATERIALS BY MILD ALKALINE TREATMENT

Several kinds of lignocellulosic materials such as leaves, needles, ba rks, cones and remains of fruits were subjected to mild alkaline treat ment to determine the variation of cation exchange capacity (c.e.c.) a nd that of absorption of heavy metal ions (copper). Comparisons were m ade between the two figures and with the increase obtained by N. Saito et al.(4) on some leaves treated with formaldehyde. Alkaline treatmen t caused an almost General increase of c.e.c. of materials due to the occurrence of carboxyl ester groups in their polyoses: larger increase s were exhibited by barks and cones; minor ones by leaves and needles. Adsorption of copper appears larger than the c.e.c. of sodium because of complex formation by polyphenols; the same treatment however solub ilizes part of them to provoke a decrease in leaves and needles. From the comparison with Saito's data alkaline treatment on leaves and need les is found to he less effective with respect to formaldehyde; it how ever exhibits its superiority for other lignocellulosic materials as i t raises their adsorption ability in an exceptional manner.