AMPLITUDE CONTROL OF CHEMICAL WAVES IN CATALYTIC MEMBRANES - ASYMMETRIC WAVE-PROPAGATION BETWEEN ZONES LOADED WITH DIFFERENT CATALYST CONCENTRATIONS

Chemical waves of the Belousov-Zhabotinsky type are studied applying b athoferroin catalyst fixed on a polysulfone membrane. A new method is developed to create contacting high- (H) and low-amplitude (L) regions for chemical waves. The amplitude is high in zones (H) loaded with hi gh catalyst concentrations, and it is low in zones (L) loaded with low catalyst concentrations. An asymmetric wave propagation is found: wav es coming from region H can initiate waves in region L across the HL b oundary with a higher frequency than vice versa. The ratio of the cros s-recovery times R(L --> H) and R(H --> L) is 1.7 in the experiments r eported here. To measure this ratio, rotating chemical waves were appl ied. The waves propagate in two concentric annular zones-the inner zon e with low and the outer with high catalyst concentration-and the HL. boundary forms a circle. It was found that in such a reactor complex w ave patterns (so-called chemical pinwheels) can rotate nearly independ ently in the H and L zones, interacting only weakly across the HL boun dary.