Global NEST Journal

In this research, capability of adsorption of modified chitosan Nano composites with functionalized mesoporous silica which synthesized by electrospinning method in the removal of direct black ANBN dye has been studied. Silicate mesoporous were functionalized during synthesis process and then the intended Nano fibers were produced by using of electrospinning device. Synthesized Nano fibers were recognized by analyzing the FT-IR, XRD, FE-SEM, and TEM and tension test. The removal of direct black ANBN dye from aqueous solution in a continuous system was done by this adsorbent by studying the effects of some parameters such as type and amount of adsorbent, pH, initial concentration of colored solution and contact time; And at the end finding appropriate isotherms for direct black dye adsorption was done. The result show that simple CTS/SBA-15 have the best removal efficiency in 40 min of contact time, in acidic pH, with 0.05 gr adsorbent and 60 mg/L initial concentration. By examining the adsorption isotherms, it has been clearly defined [that] Removal of this dye follows Freundlich model. In order to compare accurately and evaluate the efficiency of the synthesized sample, the adsorption of Direct Black ANBN was investigated by two different adsorbents: CTS/SBA-15 and Chitosan. According to the results, CTS/SBA-15 Nano fibers have suitable efficiency for removal of direct black ANBN dye.

The temperature, feed rate, length of mass transfer zone, utilization factor and partial pressure are the parameters considered for fixed bed sorption of CO2 from N2/CO2 mixture. The breakthrough time relies strongly on the temperature and feed rate. The prolonged breakthrough and saturation times have been realized for AC. The response curves of AC are vastly steep signifying the maximal utilization of bed capacity at the breakpoint. In general, the length of MTZ increases with raised temperature and feed flow rate. The capacity utilization factor reduces with raised temperature and feed flow rate. A utilization factor of 0.919 was determined for AC. The maximal capacity for CO2 reduces significantly with an increased temperature. The maximal capacities of 32.99 gm CO2/Kg was determined at a temperature of 298 K for AC. The capacity improves considerably with CO2 partial pressure and AC exhibited higher adsorption capacity compared to SG. The capacity improves considerably with increased feed rates and maximal capacity of 39.14 g CO2/Kg adsorbent was determined for AC at the feed rate of 8.33 x10-3 m3/sec. Owing to higher sorption capacity and utilization factor, the AC may be used for economical separation of CO2 from N2/CO2 mixture

The intraseasonal low-frequency oscillation is studied by using gridded rainfall dataset from 1979 to present. Multivariate Singular Spectrum Analysis (SSA) was used in the extraction of these modes. We have found out that there is a significant increasing trend in the relative strength of low frequency ISO. However, this happened only after the years 1979 to 1984 was removed in the trend analysis. A previous study found that the increased rainfall during the break and transition phase of low-frequency ISO could be a contributing factor to the decreasing trend during the active phase. In this study, the implication is rather the opposite - the increasing trend in rainfall, in terms of extreme events occurrence during the active phase of low-frequency ISO had been the contributor to the increasing trend of low-frequency ISO.

Wind erosion is mainly a phenomenon of arid and semiarid areas, and the porosity of shelterbelts is an important quantitative index for estimating windbreak structure. However, there appears to be considerable variation in the optimal degree of porosity. With the example of an oasis–desert ecotone in Junggar Basin, the physical mechanisms responsible for wind erosion were used to investigate the optimal porosity of shelterbelts for wind speed reduction and a mathematical model relating porosity of shelterbelts to relative wind speed was constructed. The results show significant correlation among total shelterbelt porosity, crown area, average crown height, and average clear bole height (r2 = 0.968, p = 0.000). A sharp inflection point was found near a porosity of 0.35 based on the emission mechanisms. Both emission mechanisms and the mathematical model showed that the optimal porosity of shelterbelts is between 0.35 and 0.37, confirming the results of previous research.