Study On Preparation And Performance Of The Coal/PEI Crosslinked Composite Chelating Adsorbent

Now,the one of the most serious pollution is heavy metal pollution,it causes enormous harm to aquatic life and human health. Adsorption has became a popular way to deal with heavy metal from water. In order to improve the stability and the strength, in this paper, a new crosslinked composite chelating adsorbent was prepared by grafting the polyethyleneimine（PEI） to the surface of coal and be crosslinked using epichlorohydrin. In this paper, as a raw material which low metamorphic lignite was selected, ultrafine coal came from low metamorphic lignite by high energy ball milling, a new crosslinked composite chelating adsorbent was prepared by grafting the polyethyleneimine（PEI） to the surface of ultrafine coal and be crosslinked using epichlorohydrin. The reaction was divided into two parts:grafting and crosslinking.In the grafting, method of grafting, kinds of coupling agent,reaction time and reaction temperature, were observed to ensure the best preparation process.And in the crosslinking, kinds and amount of linking agent,reaction time and temperature were observed to ensure the best preparation process. The best prepration plan determination by scheme single factor method. Adsorption performance of coal based chelating adsorbtent was discussed by the removel rate of heavy metal ion. Adsorption kinetics and thermodynamics was respectively studied for Pb²⁺、Cu²⁺、Cd²⁺.The results as follows: in the grafting part, ultrafine coal was syntheticed by mechano coulping, KH550: ultrafine coal is 3%（w:w）, ultrafine coal:PEI is 30:1（w:w）, the temperature was 40℃, the reaction time was 4h.In the crosslinking part, epichlorohydrin was seleted as crosslinking agent in alkaline condition, the reaction temperature was 40℃, the reaction time was 3h.The adsorption dosage of Cu²⁺、 Pb²⁺、Cd²⁺ is 59.88 mg·g-1,48.54mg·g-1,40.24mg·g-1,respectively. Asorption kinetic data were found to follow the pseudo second-order model and the equilibrium data fitted very well with the Langmuir equation.Physicochemical structures and reaction mechanism of ultrafine coal, Grafted product, Crosslinked product and chelating agent were respectively characterized by FT-IR, SEM and N₂ absorbed.The main infrared speaks of ultrafine coal: the 2920cm-1,1457cm-1,803cm-1 is the stretch vibration absorption peak of –CH2.the 1035cm-1 is the symmetric stretching vibration shifting of Si-O,the 1618cm-1 is the weak vibration absorption peak of C-N-H.Compared with infrared speaks of grifted ultrafine coal, the result is the stretch vibration absorption peak of C-N-H enganced.It observed that PEI was grafted on the surface of ultrafine coal. The main infrared speaks of end-product: the 2870cm-1, 1475cm-1 is the stretching vibration shifting of C-H, 3100cm-1 is a broad infrared speaks which is composed –COOH and C-H, 1250cm-1 is infrared speaks of C-H from Aromatic,1650cm-1 is strong stretching vibration shifting of C=O. The main infrared speaks of the end-product adsorped metal ions: the 3417cm-1 is the stretching vibration shifting of N-H, the 1629cm-1 is the bending vibration shifting of N-H, the 1400cm-1is the strong shifting of C-N extension amide. Based on the infrared speaks of appeared and disappeared,the vibration of strong and weak,it can be observed that the adsorbed has a good performance for metal ions frm the Coal/PEI Crosslinked Composite Chelating Adsorbent,also the prepration and adsorbtion rection mechanism can be inferred.The surface structure characterized by SEM,the pore volume, aperture and foramen area characterized by N₂ Absorbed, from ultrafine coal and the end-product.