The Shaping Of Magnesium Oxide Based Adsorption Materials And It’s Properties

Four kinds of Magnesium Oxide based adsorption materials (magnesium silicate,sepiolite, palygorskite, layered double hydroxides(LDHs)’) have been investigated inthe shaping and their adsorption performance on water pollutants such as methyleneblue, cobalt ion, fluorinion and free fatty acids in biodiesel, which can solve thedefects of powder adsorbent such as high dispersibility, cannot be recycled and tend tobecome clogged.The physicochemistry properties of the obtained samples were characterizedwith FT-IR spectrometers, Scanning electron microscope, thermogravimetry andatomic force microscope. Their adsorption properties of water contaminants and freefatty acid were determined, moreover, the principle of kinetics in the adsorptionprocess was also studied, and the adsorption mechanism was discussed. The mainresearch contents and results are as follows:1. Prepared activated Magnesium Oxide based adsorption material by calcination,determined the suitable calcinate temperature after the investigation of adsorptionproperties, the physicochemistry properties of the obtained samples werecharacterized with modern analysis instruments, the results show that with theincrease of calcination temperature, the material surface changed, thus affecting theadsorption performance.2. Prepared hybrid membranes through blending calcinated magnesium silicate,sepiolite, palygorskite, layered double and PES/DMF respectively, and determinedsuitable proportion by the adsorption experiments：to adsorb methylene blue, sixmagnesium silicate added18%; to adsorb free fatty acid in biodiesel, magnesiumoxide based adsorption material adding amount is18%. To adsorb cobalt, sepiolitecontent is14%and attapulgite was18%; fluoride ion adsorption, Mg-Al layereddouble hydroxide added18%.Prepared molded particles through blending magnesium silicate, sepiolite, palygorskite, layered double and PVDF by extrusion granulation, and determinedsuitable proportion by the adsorption experiments: to adsorb methylene blue, sixmagnesium silicate added23%; to adsorb free fatty acid in biodiesel, magnesiumoxide based adsorption material adding amount is23%. To adsorb cobalt, sepiolitecontent is19%and attapulgite was23%.3. Through characterized with modern analysis instruments, we can foundmagnesium silicate, sepiolite, palygorskite and layered double hydroxides aredispersed in the adsorption material uniformly. The polymer plays the role of networkto fix adsorbent granules and with the increase of content of adsorbent, adsorptioncapacity changed accordingly.4. MB is selected as adsorption object to investigate the magnesium silicatemolded adsorbent’s adsorption, the effects of time, temperature, initial concentrationof MB and adsorbent dosage on adsorption properties were investigated. The resultsshow that, in the temperature range of the experiments, respectively, methylene blueadsorption maximum is: six magnesium silicate membrane:157mg/g, six magnesiumsilicate particles:85mg/g. The adsorption thermodynamics showed Frendlichadsorption model could describe the adsorption process and the studies of kineticsproved Pseudo second-dynamics equation could describe the adsorption behavior inthe experimental temperature range.5. Magnesium Oxide based molded adsorbent for the adsorption of free fattyacids in biodiese were investigated, we studied the effects of adsorption time,temperature, and adsorbent dosage on adsorption properties. Under the bestexperimental conditions, the maximum adsorption capacity is, respectively: sixmagnesium silicate membrane:210mg/g, sepiolite membrane:250mg/g, attapulgitemembrane:210mg/g, Mg-Al layered double membrane:455mg/g, six magnesiumsilicate particles:175mg/g, sepiolite particles:185mg/g, attapulgite particles:145mg/g, Mg-Al layered double hydroxide particles:218mg/g.The adsorptionthermodynamics showed Frendlich adsorption model could describe the adsorptionprocess. For magnesium silicate, both the hybrid membrane and shaped particles canbe described their adsorption behavior by Pseudo first-dynamics equation, and for LDHs, both the hybrid membrane and shaped particles can be described theiradsorption behavior by Pseudo second-dynamics equation. For sepiolite andpalygorskite, their hybrid membranes can be described by Pseudo first-dynamicsequation, and their shaped particles can be described their adsorption behavior byPseudo second-dynamics equation. Particle dispersion was the major controlling stepof adsorption rate but intra-particles diffusion was not the unique control step.6. Cobalt ion is selected as adsorption object to observe the molded adsorbent’sadsorption of sepiolite and palygorskite. Under the best experimental conditions, theadsorption of cobalt is, respectively: sepiolite membrane:13mg/g, attapulgitemembrane:12.7mg/g, sepiolite particles:16.1mg/g, attapulgite particles:12.4mg/g.The adsorption thermodynamics showed Langmuir adsorption model coulddescribe the adsorption process of palygorskite shaped particles and Frendlichadsorption model could describe the adsorption process of sepiolite and palygorskitehybrid membranes. For sepiolite, neither Langmuir nor Frendlich adsorption modelcould describe t the shaped particles for its complicated adsorption process. Thestudies of kinetics proved Pseudo second-dynamics equation could describe theadsorption behavior in the experimental temperature range and intra-particlesdiffusion was not the unique control step.7. Fluorinion adsorption on LDHs hybrid membranes was investigated. Theresults proved the rate of removal increased with increasing adsorbent dosage andadsorb time, and it was decreased with increasing pH value. Under the bestexperimental conditions, the maximum adsorption capacity of fluoride ions is2.65mg/g. The studies of kinetics proved Pseudo second-dynamics equation coulddescribe the adsorption behavior in the experimental temperature range andintra-particles diffusion was not the unique control step.The results of the study show that, a series of shaped Magnesium Oxide basedadsorption materials were prepared and they have good adsorption performance andwide application prospect. The organic polymer employed as network to fix theadsorption material, and the shaped Magnesium Oxide based adsorption materialsused to biodiesel refining and pollutant removal, which provides a new idea for the widely utilized of powder adsorbent.