Here, according to the type-based modulation technique, the authors develop a novel modulation scheme by utilising ion collision and reaction to mitigate inter-symbol interference (ISI) in diffusive molecular communication (MC) systems. Two types of ions are employed as messenger molecules that cause a chemical reaction in the medium. According to the residual molecules and chemical reaction, the proposed modulation scheme adaptively adjusts the number of emitted molecules, thereby guaranteeing that the number of molecules that arrived at the receiver remains at a stable level. The authors evaluate the performance of the proposed scheme by comparing it with the conventional binary molecule shift keying (BMoSK), BMoSK with power adjustment (BMoSK-PA), and ideal BMoSK (without ISI) modulation techniques via diffusion. Numerical results show that the bit error probability and channel capacity of the proposed modulation scheme are much closer to the ideal BMoSK modulation scheme compared to the conventional BMoSK and the BMoSK-PA modulation schemes.