| The present work emphasized in treating the wastewater and recycling the material in the wastewater to reduce the pollution. Three kinds of novel modified bentonite (polymerized bentonite, surface ion-imprinted polymer, and Grafted bentonite) were synthesized. The samples were used as treating agents in different section of the water treatment process. The study offered ways and materials to develop a series of novel modified bentonite agents with the function of purifing the wastewater and recycling the waste materials. We have studied the relation between the performance of the agents and modifying process, such as, organic/inorganic and the treating temperature; researched the selective adsorption ability of the ion-imprinted polymer; and studied the way of treating the paper sludge and recycling it to the process of papermaking. The present work povided novel technicle process and theory for the realistic application of modified bentonite.The main innovations of the work are expressed as follows:(1) The bentonite was modified by AM through in situ polymerization, then the modified production was treated in high temperature. The polymer between the mineral layers was carbonized or removed leaving clay production with great specific surface area and absorbability. The ratio of organic/inorganic and treating temperature were key factors effected the adsorption ability of the modified bentonite. The adsorption process in the multiple ions solution was also researched, and the competitive behavior of different ions was studied. The adsorption process was fitted with the Langmuir model and expanded Langmuir model well, and agreed with the pseudo second-order adsorption kinetics.(2) A new type of ion-imprinted polymer was synthesised on the surface of bentonite using heavy metal ions as template, displaying high affinity and selectivity to template ions. The ion-imprinted bentonite has selective cavities for the target ions. More important the cavities were located on the surface of polymer, which made it easy for the ions to reach the cavities. The ion-imprinted polymer was a favorable adsorbent to Zn2+(0.22< RL< 0.59). The adsorption process agreed with pseudo second-order adsorption kinetics well, and the adsorption process was feasible and spontaneous. The decrease in the value of △Go with rising temperature indicated that the adsorption was more favorable at high temperatures. The ion-imprinted polymer can be reused with many cycles and without significant dropping in the adsorption capacity, so it could be used to collect the target heavy metal ion in the water and recycled the heavy metal.(3) Bentonite was modified by AM and CTAC, respectively. Then, the samples were used to treat the paper sludge and recycled to process of papermaking. AM-modified bentonite had better effects on treating the sludge than CTAC-modified bentonite. To a further step, paper containing AM-bentonite treated sludge showed the property (formation of 3.85 g/m2, tensile index of 30.75 N·m/g, ring crush resistance of 8.31 N·m/g and burst index of 1.54 KPa-m2/g) highly close to those of paper without recycled sludge, so recyclable for paper making. The optimum molecular mass of the AM was 400000. The maximum AM-bentonite dosage for modifying the sludge and the maximum amount of sludge that can be added to the pulp are 0.20 wt% and 3 wt%, respectively. By recycling the paper sludge, the raw material of papermaking was saved, and less pollutant was discharged to the environment. |
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