Preparation And Characterization Of Modified Cellulose And Its Application For Adsorbing Of Heavy Metal Ions From Aqueous Solution

Series of functional celluloses were prepared for adsorbing metal ions. Celluloses from solid waste common paper and cotton fiber reacted with succinic anhydride (SA) and poryglutamic acid (PGA) to offer esterified celluloses PC-SA, CC-SA, PC-PGA, CC-PGA. These esterified celluloses were characterized by modern instrument analysis means. Adsorption activity of the modified celluloses to heavy metal ions such as Cu(Ⅱ), Pb(Ⅱ), Cd(Ⅱ) in aqueous solutions were investigated under varied environmental parameters, including ionic concentration, solution pH value, and adsorption time. The adsorption kinetics, isotherm adsorption, resolution and regeneration were studied. Conclusions from the investigations were showed following:(1) Paper and cotton were treated with alkaline solution (NaOH15%(w/v), H2O210%) for30minutes at room temperature to give celluloses in82.4%and92.6%for PC, CC respectively. Their structure and morphology were determined according to the analysis results of FIR, SEM compared to micro crystalline cellulose.(2) The modified celluloses PC-SA, CC-SA, PC-PGA, CC-PGA from actions of celluloses and SA and PGA, were characterized by three means, FT-IR、XRD and SEM. As a result, the modified sample celluloses were introduced carboxyl group.(3) The effects on the removal of heavy metal ions by modified celluloses PC-SA, CC-SA, PC-PGA, CC-PGA were studied. As a result, Under the optimization adsorption conditions, at pH value of5.5-6.0,5.5-5.7,6.3-6.6for Cu, Pb, Cd, the corresponding initial concentration were410-512mg·L-500-510mg·L-1,420-500mg·L-1, after adsorption reaction45-70min, at room temperature. These four modified adsorbents showed a maximum adsorption capacity of230mg·g-1,148mg·g-1,185mmg·g-1;172mg·g-1,136mg·g-1,150mg·g-1;205mg·g-1,129mg·g-1,156mg·g-1;177mg·g-1,105mg·g-1,140mg·g-1, on Cu2+, Pb2+, Cd2+, respectively. And the removal rate reached78-92%,41-60%,56-88%. Compared with unmodified PC and CC, the modified celluloses showed a better and more enhanced adsorption capacity.(4) Adsorption dynamics research results showed that the adsorption of PC-SA, CC-SA, PC-PGA, CC-PGA to heavy metal ions such as Cu2+, Pb2+Cd2+was a fast and stable process. With secondary adsorption rate equation for fitting, it turned out that the adsorption obeyed pseudo-second-order sorption kinetics, and the order of corresponding adsorption capacity was PC-SA> PC-PGA> CC-SA> CC-PGA.(5)0.5Mol·L-1HCL solution was used as desorption agent. Desorption of Cu2+, Pb2+, Cd2+from PC-SA, CC-SA, PC-PGA, CC-PGA resulted in analytic rate between85-95%, indicating that these adsorbents could be recycling used, to get economic benefits. (6) The adsorbent regeneration was examined with NaOH5%solution. Regenerated PC-SA, CC-SA, PC-PGA, CC-PGA showed secondary adsorption capacity of Cu2+、Pb2+、Cd2+in98-140mg·g-1,71-93mg·g-1, and90-108mg·g-1, respectively.