ZSM-5 Molecular Sieve Prepared From Biomass Power Plant Ash And Its Adsorption Ionic Dye Properties

Biomass resources have been arising in recent years after large-scale application of fossil fuels for few centuries,i.e.coal,oil and nature gas.Meanwhile,it is one of the most potential ways to be considered for biomass power generation in the power industry after coal-fired power.However,thousands of biomass was consumed annually,and it was bound to produce large quantities of waste ash.Whether burned ash were used with low-value applications,nor abandoned.Learning from resource utilization methods for coal fly ash in the coal-fired power plants,this study will focus on the recycle and utilization of biomass power plant ashes.The ashes will be used to synthesize ZSM-5 zeolites for simulated textile wastewater treatment,which could achieve the target for series of researches on recycling and emission,resource transformation,and valued uses.Detailed investigations and results are as follow:(1)Chemical compositions of multi-biomass power plant ash(MBPA)and simulated rice husk power plant ash(SRPA)were identified.The chemical structure of SiO₂ was characterized via FTIR,²⁹Si MAS NMR and XPS.Response surface methodology(RSM)was used to study on the interaction between experiment conditions and calcination activation.The results show that the SiO₂ in MBPA is composed of the chemical structure of Q²[(OH)₂Si(OSi)₂],and which is Q⁴[Si(OSi)₄]in SRPA.SRPA is more suitable to be as Si sources in the process of zeolite synthesis.Simultaneously,MBPA ash is not only Si sources,but also can provide Al sources.(2)ZSM-5 zeolites were synthesized from MBPA and SRPA by hydrothermal template method.Crystallography and morphology of synthesized ZSM-5 zeolites were investigated via XRD,FE-SEM and TEM technologies.In particular,microporous properties were obtained from t-plot and Horvath-Kawazone(H-K)methods,and refer to the special phenomenon of N₂ adsorption and desorption curve to clarify the formation of ZSM-5 zeolites.At the same time,the adsorbent for next stage study was selected according to the microporous properties.The results show that ZSM-5 zeolites can be successfully synthesized at 120 ^oC for 48 h,150 ^oC for 36 h,180 ^oC for 24 h,and 210 ^oC for 6 h,whereas the 10-membered rings of ZSM-5 zeolites were crossed due to the presence of Si—OH in MBPA.(3)Obtained ZSM-5 zeolites were used to adsorb the cationic dye of methylene blue(MB)and anionic dye of Conge red(CR)in the simulated textile wastewater,respectively.Firstly,adsorption traits were analyzed by the equilibrium isotherm models of Langmuir,Freundlich,Temkin,Sips,Redlich-Peterson,etc.Besides,the adsorption behaviors were described via pseudo-first order,pseudo-second order and intraparticle diffusion models.Finally,thermodynamic parameters were calculated from Van't Hoff and Arrhenius equations,and make clear of adsorption mechanism and performance.Meanwhile,the change of dye adsorption quantity from zeolites after recovery and regeneration time and again was investigated.The results show that the adsorption process of MB on the zeolites was more homogeneous than that of CR on the zeolites.Additionally,the adsorbing diffusion of CR dye was hindered resulted from the large molecular weight.In a certain range of adsorption temperature,the adsorption of MB dye is more efficient at high temperature and low concentration,and vice versa for CR dye in terms of the influence of electrostatic interaction.Moreover,obtained ZSM-5 zeolites have a good performance of recovery,regeneration and reutilization for adsorption and removal of dyes.All in all,this work aims at the recovery and utilization of biomass power plant ash,and gives out the feasibility strategy to realize the target of waste controlled by waste!...