| Sulfated zirconia (SZ), a solid superacid, is the most representative solid acid. Arsenic as a metalloid highly toxic substance widely exist in water. Arsenic in drinking water can lead to chronic arsenic poisoning, there have been endemic arsenic poisoning patients in China's Taiwan, Inner Mongolia, Xinjiang. World Health Organization and International Agency for Research on Cancer has classified arsenic as a carcinogen, arsenic has been regard as the most toxic substance by the USEPA as well. Recently, arsenic pollution incident occurs frequently due to human-factors. So, it is imperative to carry on water arsenic pollution control technology research.As energy demand and consumption continues to rise whilst increasing serious environmental problems, researches are increasingly directed towards alternative renewable fuels. Biodiesel, as a high quality alternative diesel fuel, is a promising renewable, biodegradable, environmentally beneficial fuel comprised of methyl esters of long chain fatty acids. Biomass energy has been brought into national major technology projects in China.Nanometer mesoporous SZ (NMSZ) was made application to environmental field in this work, the research contents are as follows:(1) Exploration of one-step prepared method of NMSZ; (2) Investigation of adsorption behaviors of As (Ⅴ) in water on NMSZ; (3) Research on transesterification of methanol and soybean oil catalyzed by NMSZ.1. One-step synthesized NMSZ propertiesTheoretically nanometer mesoporous SZ could be synthesized by one step using surfactants contained sulfate, the mesoporous structure is formed through S-I+, alleged S-I+ is the interaction of positively charged polymer zirconium ion and anionic surfactant. (1) Nanometer mesoporous SZ has been synthesized by SDS and CSS successfully. (2) The amorphous phase of ZrO2 further shift from tetragonal phase into monoclinic with increasing temperature, and the transformation of crystal phase can be retarded by sulfate. (3) Before calcination, the SBET and mean pore size of NMSZ are 336 m2/g and 3.98 nm respectively, and the SBET and mean pore size of NMSZ after calcination at 550℃are 141 m2/g and 10.83 nm. (4) NMSZ is spherical particle with an average crystal size of 8.85nm. (5) Although the total acidity and acid site density of one-step NMSZ are weaker than conventional two-step SZ, the superacidity of one-step NMSZ is stronger than conventional two-step SZ. (6) Mesoporous structure of NMSZ can be stabilized by treatment with phosphoric acid, but it will reduce the specific surface area of NMSZ significantly.2. Adsorption of As (V)(1) Scarcely any change in removal efficiency of arsenic are observed for MNSZ in pH range of 2-10. However, the arsenic removal percent of NMSZ sharply decreases when pH is high than 10. (2) A Langmuir adsorption isotherm equation is fitted well to the experimental data with a correlation coefficient (R2) value of 0.9874 and a maximum adsorption capacity of 63.2 mg/g. (3) Adsorption efficiency increases with increasing temperature makes us conclude that the adsorption process is endothermic and the adsorption behavior belongs to physical adsorption. (4) The kinetics of As (V) adsorption can be described well by pseudo-second-order kinetics model, the correlation coefficient (R2) value can reach more than 0.999 at different temperature. (5) The presence of Cl-, SO42-, NO3- do not interfere with the adsorption of As (V), CO32-, PO43-, SiO42-, F- are the strong interferant. (6) NMSZ can be readily regenerated by using 1 M H2SO4 solution and then calcining at 500℃, and the corresponding arsenic adsorption capacity was restored to 90% of its initial capacity after two adsorption/desorption/regeneration cycles. (7) Ion exchange adsoption can be explained the adsoption precess of As (V) with NMSZ.3. Preparation of biodiesel(1) The one-step NMSZ shows superior catalytic performance compared to the conventional two-step SZ, under the reaction conditions of methanol/oil molar ratio 10,120℃,10 h,4% of SZ gave 92% yield of fatty acid methyl ester (FAME). (2) The main components of soybean oil biodiesel are methyl linoleate (41.16%) and methyl oleate (37.63%), so it is a good choice to use soybean oil as feedstock to produce biodiesel. |
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