| Cr(?)has attracted much attention because of its high toxicity,non-biodegradability and durability.Therefore,the discharge of highly toxic chromium in industrial wastewater is one of the major problems in the field of environmental governance.Polypyrrole(PPy)has high thermal stability,low cost,non-toxic and other characteristics.It contains a large number of imino groups in the molecule,and has a certain degree of oxidation and reduction.It has a good removal capacity on Cr(?)and has a wide range of applications in the field of environmental governance.However,due to the strong?-?bond between the molecular chains of polypyrrole,the single polypyrrole particle is easy to agglomerate,resulting in the decrease of the specific surface area and adsorption active sites,and the limited surface functional groups.There are limitations in the removal capacity and application scope of Cr(?).Molybdenum disulfide(Mo S2)is a typical binary transition metal inorganic material with a special“sandwich”chemical structure.Due to its stable chemical properties and low cost,it has great application prospects in the field of adsorption.Therefore,it is an effective way to load PPy on Mo S2 to improve its dispersibility,and to use the synergy of Mo S2 to enhance the ability of PPy to remove Cr(?).In this study,polypyrrole was used as the main body and molybdenum disulfide as the carrier.The polypyrrole supported molybdenum disulfide organic-inorganic hybrid material(PPy/Mo S2)were prepared by a simple in-situ oxidative polymerization.It was used as a novel absorbent to remove Cr(?).The adsorption of Cr(?)was intensively p H dependent,which the optimal removal efficiency was achieved at p H 2.Meanwhile,the sorption of Cr(?)on PPy and PPy/Mo S2 followed pseudo-second-order kinetic model and Langmuir isotherm model.Compared with PPy,PPy/Mo S2 exhibited better removal capacity for Cr(?)because of its well-dispersion and abundant surface active sites.The maximum adsorption ablity of Cr(?)by PPy/Mo S2 was 257.73 mg/g at 298 K,which was obviously higher than that of PPy(151.29 mg/g).The coexisting ions like K+,Na+,Ca2+,Mg2+,NO3-,Cl-and SO42-had no remarkable influence for Cr(?)removal,whereas H2PO4-was main competitors.Mechanism investigation indicated that the mechanism of Cr(?)removal by PPy/Mo S2 included the ion exchange,electrostatic interactions,chemical reduction and surface chelation.Moreover,the PPy/Mo S2 could be used for three continuous cycles without significantly reducing the adsorption capacity of Cr(?).This research showed that PPy/Mo S2 composites were a promising absorbent for efficient treatment Cr(?)in contaminated water. |
PDF Full Text Request