Experimental study on performance and influencing factors of chitosan-based nonwoven on gaseous HCHO removal

Chitosan is considered as one of the eco-friendly absorbents for HCHO removal, and its fibrous material possesses great application value in the domain of indoor air treatment. Herein, chitosan nonwoven (CSNW) and prepared chitosan-coated polypropylene nonwoven (CS-PPNW) were used to investigate the performance on dynamic HCHO purification in a one-pass air duct system. The impacts of exterior environmental parameters containing relative humidity and initial concentration on purification efficiency were assessed by CSNW at dynamic condition, while the other two interior factors including raw material and acid-pretreatment pH were both at dynamic and static condition for validation. Results indicated that the snow crab chitosan outperformed red crab in HCHO purification due to the higher amino content in molecule. The protonation of amino groups was found the reason for the deterioration of adsorptive capacity at low pH situation. And the optimum pH value was approximately 6, where the purification efficiency reached to 89.6% in static adsorption while 34.8% at dynamic condition. As the relative humidity and HCHO concentration ascends, the one-pass purification efficiency exhibits a near quadratic and exponential increase, respectively. The prepared CS-PPNW was characterized by SEM and FTIR analysis, which ascertained the adhesion of chitosan on the PP substrate. Despite lower utilization of chitosan, CS-PPNW revealed prominent capacity of HCHO removal at a loading amount of 292 g/m(2) or higher. Additionally, the robust resistance properties of CSNW and CS-PPNW at filtration velocities ranging from 0.05 to 0.2 m/s also suggested the potential applicability of chitosan-based nonwoven in air purification applications.

Automated summary

Chitosan, especially from snow crabs, was found to be more effective in HCHO removal compared to chitosan from red crabs, due to the higher amino content in the molecule. The protonation of amino groups was identified as the reason for decreased adsorption capacity at low pH. The optimum pH for purification efficiency was around 6, with a static adsorption efficiency of 89.6% and 34.8% in dynamic conditions.