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10 while Cd2+ (979 mg/g) and Cu2+ (877 mg/g) at the initial pH values of 4.14 and 6.13. High Ca(OH)2-bearing chitosan prepared from HCl and H2SO4 treated chtin showed the optimum Cd2+ (978 mg/g) and Cu2+ (852 mg/g) adsorption at an initial pH value of 2.10. Biosorption isotherm and kinetics models showed that the adsorption data of Pb2+, Cd2+ and Cu2+ onto the surface of chitosan was well-fitted by Langmuir model and Pseudo-second-order model with correlation coefficient (R2 > 0.95 and R2 > 0.91, respectively). Pseudo-second-order model showed that the adsorption capacity strongly depended on CBC in chitosan and initial pH value of HM solution. It is concluded that the HM adsorption by the prepared chitosan is a chemical process that was supported by CBC of chitosan through elevating solution pH value.Chlorpyrifos is an organophosphorus insecticide, acaricide and miticide used worldwide for the control of soil-borne insect pests. It must be considered as a substance of growing concern, given its use, toxicity, environmental occurrence, and potential for regional to long-range atmospheric transport. Considering the incomplete removal attained by conventional water treatment processes, we investigated the efficiency of electrolytic radicals production and sonoelectrolysis on the degradation of the pesticide. The treatment has been conducted in a novel electrochemical reactor, equipped with a boron-doped diamond anode and a solid polymer electrolyte (SPE). Different current intensity and times have been tested and coupled with sonication at 40 kHz. Up to 69% of chlorpyrifos was completely removed in 10 min by electrolysis operated at 0.1 mA, while 12.5% and 5.4% was converted into the treatment intermediates 3,5,6-trichloro-2-pyridinol (TCP) and diethyl (3,5,6-trichloropyridin-2-yl) phosphate, respectively. Ultrasound irradiation did not enhance the removal efficiency, likely due to mass transport limitations, while the energy consumption increased from 8.68∙10- 6 to 9.34∙10- 4 kWh µg- 1 removed. Further research is encouraged, given the promising processing by the SPE technology of low conductivity solutions, as pharmaceuticals streams, as well as the potential for water and in-situ groundwater remediation from different emerging pollutants as phytosanitary and personal care products.
Pharmaceuticals are becoming one of the largest environmental concerns when it comes to the water treatment industry. Increased usage of these chemicals poses a serious risk to ecology and human health due to their leakage into surface waters. In the present study, carbide derived carbon (CDC) was used for the first time as a new adsorbent to remove ibuprofen from synthetic water and wastewater effluent.
The morphology, chemical composition, surface area and surface charge of the CDC particles were investigated using the transmission electron microscopy, scanning electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, BET analysis and zeta potential measurements. The effects of CDC dosage, temperature, initial pH and agitation speed on the adsorption process were examined by using batch adsorption experiments. Moreover, the adsorption kinetics, thermodynamics, and isotherms were investigated.
Adsorption and kinetic equilibrium data demonstrate that the adsorption of ibuprofen onto the CDC obeys the Langmuir isotherm model and the kinetics follow the pseudo-2nd order mechanism. The thermodynamic results reveal that ibuprofen adsorption is endothermic and spontaneous. The ibuprofen removal by CDC was mainly controlled by the electrostatic forces at high pH of the feed solution and by the dispersive interactions in acidic media. The ibuprofen removal is promoted at high temperature, high agitation speed and low pH. The highest adsorption capacity of ibuprofen onto the CDC was 367mg/g at pH 3. Furthermore, the CDC efficiently removed ibuprofen from spiked treated sewage effluent.
The obtained data indicate that the CDC provides a fast and efficient adsorptive removal of ibuprofen both from a model aqueous solution and treated sewage effluent.
The obtained data indicate that the CDC provides a fast and efficient adsorptive removal of ibuprofen both from a model aqueous solution and treated sewage effluent.We used Low pressure mercury vapor lamp activated of Sodium Persulfate (UV/SPS) and Fenton processes in two separate reactors to comparison of cephalexin (CPX) degradation in aqueous solution. The effect of pH, initial concentration of SPS, concentration of CPX, concentration of H2O2 and concentration of Fe2+ on the degradation of CPX were investigated. The residue of CPX and metabolites were determined by HPLC and GC/MS. The Total Organic Carbon (TOC) analysis was utilized for surveying the mineralization of CPX. Biodegradability of CPX in both advanced oxidation processes was evaluated by BOD5/COD in optimum condition. The results indicated that the maximum CPX removal was obtained at pH 3, H2O2 3 mM, concentration of initial CPX 10 mg/L and by increasing the doses of SPS from 0.1 to 0.2 mM, the degradation of CPX was enhanced. In this study, the most important factors for AOP efficiency was concentration of initial CPX; and then pH in UV/SPS and H2O2 in Fenton processes. The TOC measurements indicate that the UV/SPS and Fenton can efficiently mineralize CPX. CPX removed enough to achieve suitable biodegradability for a further biological process. Too, analysis of generated intermediates during the degradation of CPX was conducted by GC/MS method and a degradation pathway was proposed.
We aimed to investigate the spatial O
indices (SOMO35 annual sum of maximum daily 8-h ozone means over 35ppb, AOT40 the accumulated exposure over an hourly threshold of 40ppb during daylight hours between 800 and 2000 in the growing seasons of plants) in Tehran (2019-2020).
The data of ambient O
concentrations, measured at twenty-three regulatory ambient air quality monitoring stations (AQMSs) in Tehran, were obtained.
The annual mean O
concentrations were found to be 15.8-25.7ppb; the highest and lowest annual mean concentration of ambient O
were observed in Shahrdari 22 and Shahr-e-Rey stations, respectively. Spatial distribution of exposure to O
across Tehran was in the range of 1.36-1.64; the highest O
concentrations were observed in the northern, west and south-western parts of Tehran, while the central and south areas of Tehran city experienced low to moderate concentrations. selleck chemicals llc The indices of SOMO35, AOT40f and AOT40v across AQMSs in Tehran was in the range of 1830-6437ppb. Days, 10,613-39,505ppb.