Research On The Efficient Adsorption Of Hexavalent Chromium In Water And Regeneration Of Two Kinds Modified Materials

In the course of human development,environmental problems are a major problem that must be faced.The water pollution which has always been a problem to be solved and perfected.In recent years,the harm of heavy metal pollution in water has attracted more and more attention.Among many methods of treatment,adsorption is widely applied to remove heavy metal pollutants in water.Therefore,the study of adsorbent is particularly important.Two kinds of adsorbent materials which are choosed in this paper are formaldehyde modified reed and flour modified porous ceramics,respectively.They are adopted to remove heavy metal chromium from wastewater.In the preparation of formaldehyde modified reed straw,the influence of the size and temperature of the reeds on the preparation conditions was investigated.The results show that the particle size of 60 mesh,modification temperature is 80?,the modified reeds had excellent adsorption efficient of Cr(?).In the investigation of adsorption conditions,the effects of adsorbent dosage,pH value,and initial concentration of Cr(?)wastewater,adsorption time,adsorption temperature and other factors on adsorption performance were investigated.The results showed that formaldehyde modified reed adsorbent of hexavalent chromium ion removal rate,increased with an increase in the amount of adsorbent,and decreased with the increase of pH value,with the increase of initial concentration increased before they are reduced.The adsorption time and temperature are influential to adsorbent adsorption hexavalent chromium.And the higher the temperature,the faster the adsorption speed,the longer the time,the more complete the adsorption.In conditions of 15 mg/L Cr(?),an pH of 2.0,30 g/L of modified reeds,60?,and a contact time of 60 min,the removal rate of Cr(?)by modified reeds could be up to 99.38%.In the research of modified porous ceramics,the influences of particle size,sulphuric acid concentration,flour quality and modification temperature on the modified porous ceramics during preparation are mainly studied.The size of particle is 5 mesh,and the concentration of sulphuric acid is 2.5 mol/L.The flour quality is 15 g and the modified temperature is 90?.The modified porous ceramic adsorbent has good adsorption performance.In the investigation of adsorption conditions,the effects of adsorbent dosage,pH value,and initial concentration of Cr(?)wastewater,adsorption time,adsorption temperature and other factors on adsorption performance were investigated.The results show that the flour modified adsorbent porous ceramics of hexavalent chromium ion removal rate,increased with an increase in the amount of adsorbent,and decreased with the increase of pH value,and decreased with the increase of initial concentration.In conditions of Cr(?)in the initial concentration of 10 mg/L,pH 2.0,1 g of modified porous ceramic and a contact time of 100 min,the removal rate of Cr(?)by modified porous ceramics could be up to 99.73%.The reusability and reproducibility of the modified porous ceramics are studied,and the results show that the porous ceramics can be restored to the original shape after calcining,thus the new adsorption can be made.In this research,the modified adsorption materials were characterized by infrared spectroscopy(FTIR)and scanning electron microscopy(SEM).The results reveal that the surface texture of the reeds has been optimized.Meanwhile,the modified adsorption materials have a larger porosity and the adsorption site increased.In this manner,the ability of ion exchange and complexation of the modified materials are improved and provide possible solutions for engineering applications about n heavy metal water treatment.