Adsorptive removal of apramycin antibiotic from aqueous solutions using Tween 80-and Triton X-100 modified clinoptilolite: experimental and fixed-bed modeling investigations.

This study examined the performance of natural clinoptilolite (NC) modified with two surfactants of Triton X-100 (NC-Triton) and Tween 80 (NC-Tween) on apramycin (APR) adsorption from wastewater in batch and continues systems. The optimum pH, contact time, adsorbent dosage, and temperature were achieved. The findings revealed that the sorption was best described using the Langmuir isotherm compared to other isotherms. The maximum adsorption capacity of NC-Triton was greater than NC and NC-Tween. The lumped method was applied to solve the fixed-bed equations; predict breakthrough curve; determine axial dispersion coefficient and overall mass transfer coefficient parameters; and compare theoretical results with experimental results. Good fitness of experimental data with kinetic models of intra-particle diffusion, pseudo-first-order/liquid film diffusion and pseudo-second-order for NC, NC-Tween and NC-Triton, respectively, indicated that they were more suitable than the other models. Endothermic and spontaneous processes were resulted from positive enthalpy and negative Gibbs free energy changes, respectively.

Study of the adsorption and photocatalytic properties of copper oxide with different morphologies in removal of Cr(III) ion from aqueous media.

Chromium Cr(III) is considered as a toxic pollutant in industrial wastewater. Photocatalytic processes can be used as an efficient method for the treatment of heavy metal wastewaters. This study was conducted to synthesize copper (II) oxide (CuO) with dendrite, leaf and feather morphologies. Synthesized CuO with dendrite and leaf morphologies were characterized by XRD, SEM, and BET/BJH and CuO with feather morphology by XRD, SEM, BET/BJH, FTIR, TEM and DRS techniques. Parameters such as morphology CuO, the contact time (h), and adsorbent dosage (g) in adsorption of Cr(III) and morphology CuO, pH and initial concentration of Cr(III) in the photocatalytic oxidation were investigated. The results demonstrate that CuO feather at 24 h contact time with 0.1 g adsorbent with an adsorption efficiency of 57.24% has the highest efficiency compared to CuO of dendrite and leaf. Oxidation results demonstrate that CuO feather at 2 h with 0.1 g adsorbent dosage and pH = 7 had 89.14% removal efficiency. Also, oxidation results demonstrate that CuO feather at 2 h with 0.1 g adsorbent dosage and pH = 8 had 99.99% removal efficiency, which indicates the high efficiency of the feather.

The study of CaO and MgO heterogenic nano-catalyst coupling on transesterification reaction efficacy in the production of biodiesel from recycled cooking oil.

BACKGROUND: Fossil fuels' pollution and their non-renewability have motivated the search for alternative fuels. Some common example of seed oils are sunflower oil, date seed oil, soy bean oil. For instance, soy methyl and soy-based biodiesel are the main biodiesel. Biodiesel is a clean diesel fuel that can be produced through transesterification reaction. Recycled cooking oil, on the other hand, is one of the inexpensive, easily available sources for producing biodiesel. RESULTS: This article is aimed at production of biodiesel via trans-esterification method, Nano CaO synthesis using sol-gel method, and Nano MgO synthesis using sol-gel self-combustion. Two catalysts' combination affecting the reaction's efficacy was also discussed. Optimum conditions for the reaction in the presence of Nano CaO are 1.5 % weight fracture, 1:7 alcohol to oil proportion and 6 h in which biodiesel and glycerin (the byproduct) are produced. Moreover, the optimum conditions for this reaction in the presence of Nano CaO and Nano MgO mixture are 3 % weight fracture (0.7 g of Nano CaO and 0.5 g of Nano MgO), 1:7 alcohols to oil proportion and 6 h. CONCLUSIONS: Nano MgO is not capable of catalyzing the transesterification by itself, because it has a much weaker basic affinity but when used with Nano CaO due to its surface structure, the basic properties increase and it becomes a proper base for the catalyst so that CaO contact surface increases and transesterification reaction yield significantly increases as well. This study investigates the repeatability of transesterification reaction in the presence of these Nano catalysts as well.

Dynamics of Pb(II) adsorption on nanostructured γ-alumina: calculations of axial dispersion and overall mass transfer coefficients in the fixed-bed column.

In the present study, the removal of metal ions Pb(II) using nanostructured γ-alumina was investigated by tests on batch operations and fixed-bed columns. Optimization was determined for factors effective on adsorption such as pH, contact time of metal solution with adsorbent and initial solution concentration. The optimum pH level was determined at 4.5 and the maximum adsorption percentage was achieved at 150 minutes. pHpzc was measured 8.3 for nanostructured γ-Al2O3. The Langmuir, Freundlich and Temkin isotherms were used to analyze the experimental data. The Langmuir isotherm model showed the best agreement with the experimental data. The model showed evaluations for maximum adsorption capacity of adsorbent at 119.04 mg/g and adsorbent bed performance for different flow rates, bed heights and influent concentrations were also investigated. The lumped method was used to solve the bed equations, to predict the breakthrough curve and model overall mass transfer coefficient (Koverall) and axial dispersion coefficient (Dz) parameters to make comparisons with experimental results.

Optimized photocatalytic degradation of Reactive Blue 2 by TiO2/UV process.

The photocatalytic degradation of synthetic dye solution of Reactive Blue 2 was investigated using UV irradiation in aqueous suspension of nanotitania as photocatalyst and H2O2 as electron acceptor in a slurry photoreactor. To determine the optimum condition of decolorization, the influential parameters including initial dye concentration, catalyst quantity, hydrogen peroxide concentration, pH value and UV light intensity were evaluated using the Taguchi statistical method. The results indicated that compared to the other parameters, UV light intensity was the most effective. The theoretically predicted value of decolorization efficiency (95.48%) was confirmed by the experimental value (95.22%). The mineralization was considered significant with regard to the obtained values of total organic carbon (TOC) analysis (92.52%) and chemical oxygen demand (COD) analysis (94.05%) in the optimum condition. Investigations were also carried out to determine the appropriate adsorption isotherm and kinetic model in the optimum condition. The obtained optimum condition for dye removal was finally examined applying a real sample of textile wastewater containing the dye.