A 50Hz glow discharge He/CH4
plasma was generated and applied for the glass surface modification to reduce the powder
adhesion on wall of spray dryer. The hydrophobicity of the samples determined by the water droplet contact angle and
adhesion weight on glass, dependent on the CH4 flow rate and plasma exposure time. The presence of CH3
groups and
higher surface roughness of the plasma treated glass were the factors for its hydrophobicity development. Response
surface methodology (RSM) results using central composite rotatable design (CCRD) showed that optimal responses
were obtained by the combination of parameters, CH4
gas flow rate = 3 sccm and exposure time = 10 min. In optimum
conditions, the contact angle increased by 47% and the weight of the adhesion reduced by 38% (w/w). The plasma
treatment could enhance the value of the contact angle and thus reduced the adhesion on the spray dryer glass surface.