So far many theories have been developed for the adsorption-desorption of polyelectrolytes. Unfortunately none of them can well explain phenomena of the adsorption-desorption of polyelectrolytes. However, authors noted that The Jack-in-The-Box Effect which the authors investigated could explain the phenomena. Polyelectrolytes can develop charges within the macromolecules when subjected to pH. changes in their environments. Therefore, the maximum adsorption to adsorbent will. take place at the smallest size of macromolecules. If a sudden increase in the dimensions of the adsorbed polyelectrolytes occurs as the pH of their environment changes, some of the macromolecules within the adsorbents will become greater in size than their containing pore. Thus, they will be trapped within pore. For example, the adsorbent, impregnated with an aqueous solution of protein gave maximum adsorption of the polymer at its isoelectric point because the protein macromolecule was in its smallest form at this pH. On the other hand, lower adsorption was observed at the other pH region, as a result of the expansion of the macromolecules. A general theory for the physical entrapment of polyelectrolytes onto porous materials can be formulated as follows. R=K0Dx0 (1/ [η] ad.-1/ [η] w) R : amount of adsorption K0 constant Dxo : distribution of accumulated pore volume for a pore diameter X0 corresponding to the polymer diameter at the adsorption pH. [η] ad., [η] w : intrinsic viscosities of polymer at pH's of adsorption and wash X0, X : Pore diameter and corresponding polymer diameter during adsorption and elution.
Lignosulfonate alone worked as coagulant of polluted water with clay, if its molecular weight was sufficiently high. It was difficult to obtain the high molecular weight of lignosulfonate which was commercially available, by condensing with formaldehyde. Moreover, the building up molecular weight of lignosulfonate is not economical. Thus, the complexes of lignosulfonate with polyethylenimin or protein were employed for abatement of polluted water with clay. Incorporation of PEI or protein of four percent with lignosulfonate reduced remarkably floc sedimentation time. Also, the coagulation properties of the complexes were better than those of PEI and protein alone.