Preparation And Adsorption Capability Of 3D Printing PLA/Chlorella Composites-based Water Treatment Reactor

Dried chlorella is a biomass powder with excellent adsorption property for both organic and heavy metal contaminant in water.However,the subsequent treatment is complicated after adsorption process due to the difficulty separating the biomass powder from water.In this paper,the biodegradable polylactic acid（PLA）and polyadipate-butyleneterephthalate（PBAT）were used as printing substrates to immobilize chlorella,and PLA/PBAT/chlorella water treatment reactor（PIBC）was prepared via the fused deposition modeling（FDM）technology.The adsorption capability of dye and heavy metal ions from water onto the resultant water treatment reactor was investigated.The details are given as follows.Firstly,PBAT was used to improve the inherent brittleness of PLA and solve the problems of broken wire,product cracking and inaccurate size during fused deposition modeling.The scanning electron microscopy,rotary rheometer,differential calorimeter and electronic universal testing machine were used to explore the effect of different contents of PBAT on the properties of PLA/PBAT composite.The characteristics of 3D printed PLA/PBAT products were also investigated.The results show,the introduction of PBAT into PLA can increase the storage modulus,loss modulus and complex viscosity of the material obviously.The impact strength of the FDM 3D printed sample reaches to7.15 kJ/m²at the PBAT concentration of 20 wt%.The value increases by 146.56%with a comparison of that of PLA.The 3D printing production of PLA/PBAT（80/20）shows high precision without broken wire in the preparation process,suggesting that the formula has a good property for FDM process.However,further increasing the PBAT content is founded to reult in gradually increasing the average particle size of dispersed phase particles but decreasing the homogeneity of the blending system,suggesting that PBAT is partially compatible with PLA.When the content of PBAT reaches 30 wt%,the two phases in the system The compatibility is poor,and the average particle size of the PBAT particles in the blend system reaches 1.06 um,which affected the effect of FDM products.Secondly,PLA/PBAT（80/20）was blended with chlorella,and PLA/PBAT/Chlorella productions were fabricated via（FDM）technology.The PLA/PBAT/chlorella materials and their 3D printing productions were investigated by scanning electron microscope,rotary rheometer,differential calorimeter and electronic universal.The results show that,increase the content of chlorella leads to decrease and then increase of the storage modulus,loss modulus and complex viscosity,and decrease of the tensile strength and impact strength.The impact strength is still higher than 38.96%of pure PLA,indicating good properties in FDM process.Furthermore,PLA/PBAT/Chlorella reactor shows high effect for methylene blue and heavy metal（Pb）adsorption,High chlorella content in the PLA/PBAT/Chlorella FDM 3D printing adsorbent causes to high methylene blue and lead removal capability.The methylene blue and lead removal rate can still reach 72%and50%after 6 cycles of adsorption and desorption respectively,suggesting excellent adsorption-desorption cycle property.Thirdly,the behaviors of PLA/PBAT/Chlorella reactor on the adsorption of methylene blue was evaluated.The results show that,increase the solution pH results in increase the removal rate of methylene blue.The removal rate of methylene blue increases to 96.14%with increase pH to 10.It also clears that,the presence of inorganic ions causes to decrease in methylene blue removal rate.The removal rate decreases to16.83%（reduced by 81.84%）by increasing he concentration of sodium chloride from 0to 1 mol/L,The adsorption of methylene blue onto the reactor is mainly chemical adsorption.The Langmuir model can better describe the material of methylene blue compared with the Freundlich model.The adsorption of methylene blue on materials is more inclined to homogenous monolayer adsorption.?G is negative at temperatures of298,308and 318 K,indicating that the adsorption of methylene blue on the material is a thermodynamic spontaneous reaction process.When the concentration of methylene blue solution is 100mg/L,the positive value of?H indicates that the adsorption reaction is an endothermic reaction.At last,FITR indicate that hydroxyl,carboxyl and amino groups provide adsorption sites for methylene blue during the adsorption process,which promotes the completion of adsorption.Finally,Adsorption of Pb²⁺by PLA/PBAT/Chlorella（80/20/30）reactor was performed.The results show that,when the pH of 100mg/L Pb²⁺solution increases from2 to 6,the removal rate of Pb²⁺by PLA/PBAT/Chlorella reactor increases.When the pH value increases to 6,the removal rate increases to 95.33%.Moreover,when the concentration of sodium chloride increases from 0 to 1 mol/L,the removal rate of Pb²⁺by PLA/PBAT/Chlorella reactor decreases,and the adsorption amount decreases to48.94%,which is reduced by 46.76%.It is also founded that,the second-order kinetic model better describes the adsorption of Pb²⁺by PLA/PBAT/Chlorella reactor,and concludes that there is strong chemical force between Pb²⁺and the surface functional group of the material.Compared with the Freundlich model,the Langmuir model can better describe the Pb²⁺adsorption characteristics of the material and the Pb²⁺adsorption of the material is more inclined to the homogeneous monolayer adsorption.The?G is negative at 298,308 and 318 K,indicating that the adsorption of Pb²⁺on the material is a thermodynamic spontaneous reaction.In the process,when the concentration of Pb²⁺solution is 100 mg/L,a positive value of?H indicates that the adsorption reaction is an endothermic reaction.At last,FITR and XPS analysis indicate that Pb²⁺can be combined with O during the adsorption of Pb²⁺by PLA/PBAT/Chlorella.It forms a coordination bond with N,and combines with the hydroxyl,carboxyl and amino groups of the donor group of O and N in the chlorella cells to promote efficient adsorption.