The Synthesis Of Fulvic Acid Based β-cyclodextrin Eher And Its Adsorption For Cu²⁺ And Cd(2+)

Heavy metals are a species of the most serious environmental pollution in industrial wastewater and have seriously harming human health. There are some means reported for removing heavy metals in wastewater, such as chemical precipitation, oxidation reduction, ion exchange, membrane filtration. However, these methods usually require special reagents and are not very convenient in operation. Over the last decade, many researchers of domestic and forgein explored some low-cost and highly efficient adsorbent, such as humic acid (HA). Except for the acid, hydrophilic, ion-exchangeable, HA have strong complexation, chelation and adsorption capacity. But it is inefficient using single kind of HA to deal with heavy metals. First, the deposition rate was slowly, and second the sediment was not easily separated from the water because of high water content. For overcoming these shortcomings, it is necessary of modifying the HA. Fulvic acid (FA), one part of water soluble in the humic acid, has a stronger physiological and pharmacological activity because of its lower molecular weight and gathered functional groups. In this thesis,β-cyclodextrin was grafted on FA and a new kind of multi-adsorbent, named FA-β-CD, was synthesized. The research content included the following aspects: Extraction of fulvic acid purification; the synthesis of FA-β-CD and the adsorption properties of FA-β-CD.The synthesis of FA-β-CD include two steps:First, the FA reacted with epichlorohydrin in alkaline condition to prepare FA-based epoxy-resin. The structure of FA-based epoxy-resin was analyzed by IR. The influence of various factors on this reaction was investigated, such as the ratio of FA and epichlorohydrin, the volume of NaOH (10% by weight), the time and the temperature of reaction. The optimization reaction conditions were obtained as following:the weight ratio of FA and epiehlorohydrin was 1:14, the volume of NaOH(10%,by weight) was 10 mL, and the optimal reaction time was 3h under 75℃.And then, FA-based epoxy-resin was reaction withβ-cyclodextrin in alkaline solution to synthesize the multifunctional water treatment, FA-P-CD. FA grafted β-cyclodextrin. The influence of various factors on this reaction were studied too, such as the quality of (3-cyclodextrin, the volume of NaOH(10%, by weight), the time and temperature of reaction. The results showed that the optimal synthetical conditions were that the weight ration betweenβ-cyclodextfin and FA-based epoxy-resin of 3:1, the NaOH volume of 30 mL(10%by weight) and the reaction time was 3 h under 50℃.Using prepared FA-β-CD, the adsorption capacity for heavy metal ions Cu2+and Cd2+ were investigated with static adsorption method. The results showed that the saturated adsorption (Q) for Cu2+and Cd2+were 52.36mg/g and 63.32mg/g respectively. For contrasting, the adsorption using single kind of HA was studied for the same metal ions. The results showed that the adsorption capacity of FA-β-CD was greatly increased compared with that of HA.