Novel Functional Biocomposite And Semiconductor Photocatalytic Materials In The Application Of Chromium(?)-containing Wastewater Treatment

Disordered discharge of industrial wastewater has caused serious damage to the ecological environment,in which heavy metal water pollution is particularly serious and harmful,in order to effectively remove heavy metal ions in water,has developed a number of excellent performance of composite nano-materials to achieve rapid enrich the purpose of rapid degradation of Cr???.Microbial degradation of heavy metals because of its environmental pollution without secondary pollution in recent years has attracted wide attention.In which the combination of microorganisms with functionalized silica materials has shown excellent performance in handling contaminants.Microbes have congenital defects at the same time,the longer the degradation period of pollutants and thus limit their promotion.In order to solve this problem,microbial modification is the trend.At the same time with the visible light response of the semiconductor nano-materials because of its rapid degradation of heavy metal ions can be applied to the treatment of heavy metal wastewater,and by more and more pro-Lai.?1?Biotreatment of hexavalent chromium has attracted widespread interest due to its cost effective and environmental friendliness.However,the difficult separation of biomass from aqueous solution and the slow hexavalent chromium bioreduction rate are bottlenecks for biotechnology application.In this approach,a core-shell structured functional polymer coated magnetic nanocomposite was prepared for enriching the hexavalent chromium.Then the nanocomposite was connected to the bacteria via amines on bacterial?Bacillus subtilis ATCC-6633?surface.Under optimal conditions,a series of experiments were launched to degrade hexavalent chromium from the aqueous solution using the as-prepared bionanocomposite.Results showed that B.subtilis@Fe₃O₄@mSiO₂@MANHE?BFSM?can degrade hexavalent chromium from the water more effectively?a respectable degradation efficiency of about 94%?when compared with pristine B.subtilis and Fe₃O₄@mSiO₂@MANHE?FSM?.Moreover,the BFSM could be separated from the wastewater by magnetic separation technology conveniently due to the Fe₃O₄ core of FSM.These results indicate that the application of BFSM is a promising strategy for effective treating wastewater containing hexavalent chromium.?2?We report an efficient method for fabricating flexible membranes of electrospun carbon nanofiber/tin?IV?sulfide?CNF@SnS₂?core/sheath fibers.CNF@SnS₂ is a new photocatalytic material which can be used to treat wastewater containing high concentrations of hexavalent chromium?Cr????.The hierarchical CNF@SnS₂ core/sheath membranes have a three-dimensional macroporous architecture.This provides continuous channels for the rapid diffusion of photoelectrons generated by SnS₂ nanoparticles,under visible light irradiation.The visible light??>400 nm?driven photocatalytic properties of CNF@SnS₂ are evaluated by the reduction of water-soluble Cr???.CNF@SnS₂ exhibits high visible light-driven photocatalytic activity,because of its low band gap of 2.34 eV.Moreover,CNF@SnS₂ exhibits good photocatalytic stability and excellent cycling stability.Under visible light irradiation,the optimized CNF@SnS₂ membranes exhibit a high rate of degradation of 250 mg/L aqueous Cr???,and can completely degrade the Cr???within90 min.?3?The core-like nanomaterials C@MoS₂/SnS₂ with core-shell structure were prepared by hydrothermal one-pot method for the photocatalytic reduction of low concentration Cr???in water.The nanocatalyst accelerates the photoelectron flow rate by using the heterojunction between MoS₂/SnS₂ to improve the reduction rate of Cr???.The effect of heterojunction can significantly reduce the band gap of the catalyst.Therefore,C@MoS₂/SnS₂ shows a better photocatalytic reduction effect on Cr???.The solution of Cr???solution with 50 mg/L and below can be completely reduced within 40 min,which solves the problem that many materials can not be low concentration Cr???to achieve the removal of the problem.