Study On The Modified Zeolite Adsorption Test Of Ammonia-nitrogen And Organic In Water

With the accelerated development of the urbanization and industrialization in China,water quality is increasing severe. A large number of industrial sewage containing highconcentration of refractory organics, heavy metal ions, nitrogen-phosphorus and otherpollutants could cause serious injury to people’s health, if discharged into rivers, lakes andother waters, the creatures in water and human health will suffer serious harm. In order toreduce water pollution and control the pollutant emission, scholars at home and abroad havecarried out researches how to remove contaminants from water economically, efficiently andquickly.In this paper, the clinoptilolite in Baiyin Gansu province is used as adsorbent,ammonia-nitrogen, humic acid and oil as the object to be removed, to find out the effect andmechanism of adsorption by inorganic acid, high temperature, inorganic salts and cetyltrimethyl ammonium bromide （CTAB）modified zeolite. The results show that the effect ofH₂SO₄、HCl and HNO₃on zeolite modification is not ideal for he ammonia adsorbed modifiedzeolite, and the adsorption of ammonia nitrogen is lower than the pristine zeolite under thesame experimental condition. The effect of inorganic acid modified zeolite shows that HNO₃modified zeolite is best, while H₂SO₄shows the worst effect. Zeolite modification performsthe best when the temperature is controled at200³00℃. The modified zeolite under suchtemperature performs better on the adsorption of ammonia-nitrogen than the unmodifiedzeolite,with increase of4.024%to4.752%. Adsorption of ammonia-nitrogen with NaClmodified zeolite is better than KCl and CaCl₂. When the concentration of NaCl is1.6mol/L,the adsorption capacity of ammonia-nitrogen by NaCl was5.541mg/g,21.711%higher thanthat by the unmodified zeolite;and the adsorption capacity of ammonia-nitrogen by CTABwas weaker than the unmodified zeolite.In the adsorption tests of humic acid with modified zeolite, CTAB modified zeolite isbetter than the unmodified zeolite in adsorption capacity of humic acid, and the modificationeffect is the best when the concentration of CTAB was0.02mol/L. The adsorption capacity ofhumic acid is0.325mg/g, which was3.17times than the unmodified zeolite. In the adsorptiontests of oil by CTAB modified zeolite, the adsorption capacity of CTAB modified zeolite isbetter than that of the unmodified zeolite,and the modification effect is the best when theconcentration of CTAB was0.024mol/L. The adsorption capacity of oil was0.352mg/g,which was18.92%higher than the unmodified zeolite. In the adsorption isotherm model fitting, the absorption of ammonia nitrogen on pristineand modified zeolite, humic acid and oil adsorption process are in accordance with bothFreundlich isotherm model and Langmuir isotherm mode, but the correlation coefficients R2of the Langmuir adsorption isotherm is higher than the Freundlich adsorption isotherm. Thenthe Langmuir adsorption isotherm is more suitable to describe the adsorption characteristics.In the kinetic model fitting, absorption of ammonia nitrogen on pristine and modified zeolite,humic acid and oil adsorption research shows that the correlation R2of pseudo-second kineticmodel is higher than the pseudo-first-order reaction kinetics model, which means that theunmodified and modified zeolite adsorption of ammonia nitrogen, humic acid and oil aremore in line with the pseudo-second kinetic model.The unmodified and modified zeolite scanning electron microscope （SEM） shows that:the pristine zeolite in Gongyi, Jinyun and Baiyin surface are all rough, with differences inmany grooves and trench, showing the characteristics of the crystal structure and anisotropy,the surface of pristine zeolite in Baiyin is the roughest, with the most obvious pits,followedthe pristine zeolite is Jinyun, the least one being Gongyi. Compared to the CTAB modifiedzeolite with unmodified zeolite （silver pristine zeolite）, the color of the CTAB modifiedzeolite becomes lighter, with less trench.X-ray Photoelectron Spectroscopy （XPS） shows that Unmodified and modified zeoliteare mainly composed of Si and O.Compared to the unmodified zeolite, the elements Na issignificantly increased in NaCl modified zeolite, and the element C in the CTAB modifiedzeolite is also significantly increased, indicating the good modification effect.Fourier Transform Infra-Red Spectroscopy （FTIR） shows that, compared tothe unmodified zeolite,-CH3stretching vibration absorption peak,-CH2stretching vibrationand bending vibration peak appear in the CTAB modified zeolite, indicating that CTAB hassuccessfully grafted on the zeolite; Compared to the CTAB modified zeolite, after theadsorption of humic acid and oil,-OH and C=O stretching vibration absorption peaks appearin the modified zeolite, indicating that the humic acid and the oil are successfully absorbentby CTAB modified zeolite.