Preparation And Adsorption Properties Of Cellulose Based Heavy Metal Ion Adsorbents

Cellulose is the most abundant renewable resource in the nature. Bagasse, wheat straw, saw dust and other slashes of agriculture and forestry are rich in cellulose.With the development of industry, a lot of different kinds of heavy metal ions are used in our lives. The survival environment of human being and other creatures have been threatened by heavy metal ions pollution which has become the most serious problem in our lives. we need to Find a good and cheap adsorbent, which are both environmental friendly and can adsorb heavy metal ions effectively. Cellulose adsorbent which is parpared by using slashes of agriculture and forestry will not only save the resource but also reduce the pollution with petroleum based adsorbent. In this paper, different monomers with anionic, cationic or nonionic hydrophilic groups were grafted onto various slashes of agriculture and forestry.Three kinds of novel cellulose based adsorbent were prepared by grafting acrylic acid(AA),acrylamide(AM) and [2-(methylacryloyloxy)ethyl]trimethylammonium chloride (MAETAC) onto bagasse pulp fiber,bagasse and poplar wood powder. The factors affecting absorbency of the adsorbents, such as actived time,cellulose mass composition,monomers dosage,neutralization degree of AA,initiator content,reaction temperature and reaction time were investigated in detail. The optimum synthesis conditions of various adsorbents were abtained.The adsorption properties of three kinds of adsorbent for heavy metal ions, including adsorption dynamics,isothermal adsorption,regeneration adsorption and factors that affect the adsorption,were determined. The experimental results showed that: The saturated adsorption capacities of bagasse pulp cellulose adsorbent for Pb²⁺,Ag⁺,Cu²⁺ and Mn²⁺ were 106.48,75.60,26.71 and 22.53 mg/g ,which were 8～16 times larger than that of bagasse pulp fiber. The adsorption capacities of bagasse adsorbent for Pb²⁺,Ag⁺,Cu²⁺ and Mn²⁺ were 185.64,150.92,58.53 and 42.88 mg/g , which were 7～30 times larger than that of bagasse.The adsorption capacities of poplar wood powder adsorbent for Pb²⁺,Ag⁺,Cu²⁺,Mn²⁺ were 89.46,73.92,22.25 and 21.08 mg/g, which were 4～10 times larger than that of poplar wood powder. From the datas of adsorption dynamics, it showed that the adsorption speed of three adsorbents was fast. The study of isothermal adsorption showed that adsorption process could be described by the Langmuir or Freundlich equation within the the range of experimental concentrations. The optimum pH value for adsorption of metal ions was obtained. What's more, three kinds of adsorbent had also high adsorption capacities after being regenerated.