Removal Of Heavy Metals From Aqueous Solution By Immobilization Of Penicillium Purpureum And Carbon Based Materials

With the continuous improvement of living standards and the continuous development of the economy,a series of environmental pollution problems have followed.The treatment of heavy metal polluted wastewater is not only related to the safety of the ecological environment but also related to the development and utilization of water resources.Therefore,it is necessary to remove heavy metals from wastewater.The removal of heavy metals from wastewater with a low concentration of heavy metals is often ignored due to the high investment benefit ratio.The removal of heavy metals from wastewater with a low concentration of heavy metals by microorganism is promising because of its low cost and efficient.However,the biomass after adsorption is difficult to recover and the living biomass,which is not highly resistant to metals.Graphene-oxide and active carbon are two kinds of carbon-based materials with outstanding adsorption capacity.However,the cost of apply to these two materials in water is high and there are also difficulties in solid-liquid separation after adsorption.A strain of Penicillium janthinillum GXCR was reported in our laboratory,which was highly resistant to heavy metals and had highly metal adsorption capacity.The purpose of this study is to utilize the advantages of GXCR,graphene-oxide,and active carbon to improve the removal capacity of heavy metals by immobilization to study the mechanism of adsorption and removal of heavy metals.Sodium alginate and polyvinyl alcohol were used as carriers to prepare microsphere beads.The optimum embedding conditions were determined by orthogonal test and single factor test as follows:3%sodium alginate,2%polyvinyl alcohol,The solution contained 3.0×10~8 GXCR spores,0.5 mg/L active carbon,0.5 mg/L graphene oxide.Sodium alginate polyvinyl alcohol graphene oxide fungus microsphere beads(SGFBs)and sodium alginate polyvinyl alcohol active carbon fungal microsphere beads(SAFBs)were prepared.Sodium alginate polyvinyl alcohol microsphere beads(SBs),sodium alginate polyvinyl alcohol fungus microsphere beads(SFBs)Sodium alginate polyvinyl alcohol graphene oxide microsphere beads(SGBs)and sodium alginate polyvinyl alcohol active carbon microsphere beads(SABs)were prepared as the experimental control group.For single metal salt solution(Pb,Fe,Cu concentration is 100 mg/L),the removal of heavy metals from solution by microsphere beads under different initial concentrations,adsorption time,temperature,p H value,and other factors were studied.Under the conditions of the initial concentration of 100 mg/L,p H 5 and 32℃for 140 min,the removal rates of Pb by SGFBs and SAFBs were 99.0%and 98.75%.respectively,the removal rates of Cu by SGFBs and SAFBs were 98.38%and 97.99%.This date meets the maximal emission concentration stipulated in Wastewater Discharge Comprehensive in China(GB8978-1996).At the same time,SGFBs and SAFBs have high Fe adsorption and removal efficiency.The results showed that the metal removal rate of the carbon-based materials was significantly higher than that of the control,and the metal removal rate of the microsphere beads with GXCR conidia was significantly higher than that of the control microsphere beads.For SFBs,SGFBs,and SAFBs in the mixed metal salt solution(Pb,Fe,and Cu concentrations are each 100 mg/L),the removal rates of Pb are 91.81%,93.57%and 92.21%,respectively.The removal rates of Fe by SFBs,SGFBs and SAFBs were 90.03%,91.41%and 90.74%,respectively.The removal rates of Cu by SFBs,SGFBs,and SAFBs were 91.02%,93.57%,and 91.31%,respectively.After three cycles of adsorption-desorption-adsorption,the metal removal rate of the adsorbent can still reach more than 90%.The results show that the adsorption of heavy metals on the surface of the mycelium is related to the change of the surface microstructure of the mycelium after adding carbon-based materials.After adding two kinds of carbon-based materials,the mycelium surface appeared network structure and scale structure.The adsorbents embedded with carbon-based materials have a larger specific surface area and a more abundant mesoporous structure.At the same time,the functional groups of SFBs,SGFBs,and SAFBs involved in heavy metal adsorption are:-C-H,-COOH,-C=O,-C-O,-OH,-C-O-C,which are mostly oxygen-containing groups.Where-C=O,-C-H,-C-O-C,are the newly added functional groups after adding carbon-based materials.According to the effect of adsorption time on the adsorption kinetics of single metals(Pb,Fe,Cu),SBs conforms to the pseudo-one-stage adsorption kinetics model,indicating that the adsorption type of SBs to metals is physical adsorption;The adsorption of SFBs,SGBs and SABs,SGFBs and SAFBs to single metals(Pb,Fe,Cu)conforms to both the pseudo-first-order and pseudo-two-order adsorption kinetic models,but the pseudo-second-order model is the main one,which shows that its adsorption of heavy metal ions.It is mainly chemical adsorption and has a certain physical adsorption effect.A chemical bond is formed between the adsorbent and the adsorbate,and the chemical adsorption rate is the rate-limiting step of adsorption.According to the influence of the initial concentration on the adsorption isotherm model of single metals(Pb,Fe,Cu),the Langmuir model of all microsphere beads has a better fit,indicating that all microsphere beads are monolayer adsorption.This study provides a good theoretical basis for further study and use of immobilized GXCR,graphene oxide,and active carbon to remove heavy metals from the solution.