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•Modification of zeolite with SDS as a novel adsorbent in the KHI adsorption was studied.•The results showed pseudo-second order and the Freundlich isotherm models were compatible ...with experimental data.•Optimum experimental conditions were KHI initial concentration of 200 mg/L, pH 11, adsorbent dosage of 45 g/L, and temperature of 25 ℃.•SMZ exhibited a KHI removal efficiency of 53.1 % in synthesis wastewater due to its superior properties.•Excellent reusability of adsorbents revealed cost effective and highly efficient for removing contaminants from water.
In present research, natural and modified zeolites with sodium dodecyl sulfate (SDS) were investigated for removing kinetic hydrate inhibitor (KHI) compounds from waterbodies. Natural zeolite (NZ) and SDS-modified zeolite (SMZ) presented BET surface area of 44.83 and 23.71 m2/g and pore volume of 0.031 and 0.078 cm3/g, respectively. Experimental conditions namely the effect of solution pH (3–9), temperature (15–45 ℃), initial concentration (100–500 mg/L), and varying adsorbent dosage (15–45 g/L) were surveyed. The maximum removal efficiency of KHI was attained at 53.1 % and 43.6 % for SMZ with an increase in adsorbent quantity and solution pH. The findings exhibited that the KHI removal percentage and capability of KHI decreased from 46 to 37 % and 0.86 to 0.68 mg/g for SMZ, respectively. Furthermore, the pseudo-second order was fitted on the adsorption mechanism with R2 > 0.98 at different concentrations and the experimental data was illustrated by Freundlich isotherm R2 > 0.98 at different temperatures. It was found that values of ΔH° in the KHI adsorption on NZ and SMZ were −12.99 and −10.3 kJ mol−1, which predicted an exothermic adsorption and ΔS° < 0 showed the solid-solute interface declined randomness. The results of this study suggest that SMZ is an economical and high potential adsorbent for KHI wastewater treatment.
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Biological treatment, due to the formation of hazardous chemicals to remove organic compounds such as dimethyl sulfoxide (DMSO) and N, N-dimethylacetamide (DMAC), has limited ...potential. Advanced oxidation processes (AOPs) are regarded as a viable alternative for treating molecules containing carbon-hydrogen bonds that cannot be broken down by traditional physico-chemical methods. In this investigation, various AOPs such as Photo-Fenton, Electro-Fenton, and Photo-Electro-Fenton processes were studied to treat wastewaters containing DMSO and DMAC. The effects of the operating parameters, including various initial concentrations of DMSO and DMAC, initial pH, reaction time, different concentrations of Fenton’s reagent, power of UV lamp, different concentrations of electrolytes, the distance between electrodes and current intensity, were investigated. The findings of the experiments revealed that a pH of 3 and a reaction time of 120 min were optimal. At 2000 mg L−1 of DMSO, maximum degradation and the final concentration of TOC were 98.64 % and 256.8 mg L−1, respectively, by the Electro-Fenton process under the optimal conditions. The Electro-Fenton process was successful in determining the maximum degradation of DMAC (96.31 %) and the final TOC concentration (10.03 mg L−1) at 250 mg L−1 of DMAC under optimal conditions. Finally, it can be concluded that the Electro-Fenton process was the best process for the efficient removal of DMSO and DMAC. The second step of the kinetic model follows a pseudo-first-order reaction for 250 and 500 mg L−1 of pollutants and obeyed a pseudo-second-order kinetic model for concentrations of 1000, 2000 mg L−1.
One of the most advantageous methods for lowering water hardness is the use of low-cost adsorbents. In this research, the effectiveness of natural zeolite (clinoptilolite type), activated carbon, and ...activated alumina was evaluated. These adsorbents were sequentially modified by NaCl, HCl, and NaCl-HCL to improve their ability to adsorb. The contact time and the amount of adsorbent used in the adsorption process were investigated experimentally to determine their effects. The results indicated that the best contact time for hardness reduction was 90 min, and the best concentrations of adsorbents in drinking water for zeolite, activated carbon, and activated alumina were 40, 60, and 60 g/L, respectively. In addition, for groundwater, these figures were 60, 40, and 40 g/L, respectively. The greatest possible decreases in total hardness under the best conditions by natural zeolite, activated carbon, and activated alumina adsorbents were 93.07%, 30.76%, and 56.92%, respectively, for drinking water and 59.23%, 15.67 %, and 39.72% for groundwater. According to the results obtained from experiments, NaCl-modified zeolite, natural zeolite, and NaCl-HCl-modified activated carbon performed better in terms of parameter reduction. The equilibrium data were well fitted by the Langmuir isotherm model, whereas the kinetic data for the adsorption process were consistent with the pseudo-second-order model. The equilibrium study of the adsorption process by the Morris–Weber model revealed that both chemical and physical adsorption are involved.
Silica SBA-16, an efficient photocatalyst support with cubic (bottle-ink) mesoporous structure, large specific surface area, large pore volume and uniform pore size and titanium oxide (TiO
2
), a ...semiconductor compound as the active site were synthesized facilely via one-pot method and photocatalysts denoted as x%TiO
2
/SBA-16 where x = 2, 5, 10 and 20, in order to examine their photocatalytic ability for phenol degradation in different experimental conditions such as different phenol concentration in water (ppm), various pH of the solution and amount of applied photocatalyst (g/l). In order to confirm the correct structure of the SBA-16 support and prepared photocatalysts, various types of characterization analyses such as N
2
adsorption/desorption, X-ray diffraction (XRD), TEM, SEM–EDX, UV–VIS and FT-IR were applied. Based on the employed analyses, it can be claimed that the SBA-16 support and synthesized photocatalysts demonstrated mesoporous structures with cubic pores that are in agreement with reliable literature. After carrying out all of the experimental factors for the phenol degradation process, it was found that the 10%TiO
2
/SBA-16 photocatalyst in the specific experimental conditions including pH 7, phenol concentration of 100 ppm and 1 g/l photocatalyst dosage achieved the highest performance which was approximately 90% degradation of phenol. Hence these mentioned conditions were chosen as the optimum experimental conditions. COD and TOC tests were employed to study the final products of the process and their results showed that the 10%TiO
2
/SBA-16 photocatalyst was able to reduce the COD and TOC of phenol solution up to 80% and 85%, respectively, means that the major amount of phenol converted to water and CO
2
that are the final products of phenol degradation process.
•Treatment of wide range concentrations of synthetic DMSO and DMAC wastewaters was investigated.•Effect of operating parameters of Fenton’s process plus Kinetic Study was investigated.•DMSO and DMAC ...wastewaters with concentrations of 250, 500, 1000 and 2000 mg.L−1 were treated.•Maximum degradation efficiency for treatment of DMSO and DMAC wastewaters was 97.6 and 95.8 % respectively.•Different kinetic reaction of DMSO and DMAC degradation was observed for various initial concentration of DMSO and DMAC.
Nowadays, the treatment of dimethyl sulfoxide (DMSO) and N, N-dimethylacetamide (DMAC) wastewaters are a serious concern because of the use of these materials as a solvent in various industries such as pharmaceutical, electronic and acrylic fiber manufacturing process. In this research, employing of Fenton process for treatment of DMSO and DMAC wastewaters by considering the effect of operating parameters such as different initial DMSO and DMAC concentration, reaction time, initial pH, and different concentrations of Fenton’s reagent were investigated. Experimental results illustrated that the maximum degradation efficiency for the treatment of synthetic DMSO wastewater was equal to 89.9 %, 89.7 %, 94.5 %, and 97.6 %, for initial concentration of DMSO equal to 250, 500, 1000, and 2000 mg.L−1, respectively. The maximum degradation efficiency of 81.9 %, 92.9 %, 94.8 %, and 95.8 % was reached at best operational conditions of the Fenton process for 250, 500, 1000, and 2000 mg.L−1 initial concentration of synthetic DMAC wastewater respectively. Kinetics study results presented that the kinetic reaction of DMSO and DMAC degradation by the Fenton process at all initial concentrations were well fitted with the BMG model.
In this experimental research, it is aimed at evaluating a novel composite ceramic membrane for treating and recycling on-site greywater. Therefore, three types of tubular microfiltration ceramic ...membrane including Mullite, Mullite/SiC and Mulite/SiC/AC composite were fabricated and sintered at a relatively low temperature (1250 °C) under N2 atmosphere. Field Emission Scanning Electron Microscopy (FE-SEM) and Atomic Force Microscopy (AFM) analyses showed that the presence of silicon carbide and activated carbon can improve the surface roughness. Besides, the changes in open porosity, radial and longitudinal shrinkage, mean pore size and mechanical strength were measured and compared for the pure Mullite and composite membranes to determine the most appropriate membrane for the treatment of greywater. The highest pure-water permeability of 3954 kg/m2h.br was associated with the Mullite/SiC/AC membrane with the highest porosity of 64.7% and an acceptable appropriate mechanical strength (17.2 MPa approx.). Furthermore, the highest removal efficiency was related to Mullite/SiC/AC in comparison with Mullite and Mullite/SiC membranes. It was observed that using the Mullite/SiC/AC membrane, the removal efficiencies for chemical oxygen demand (COD), biochemical oxygen demand (BOD), total sulfate, total nitrate, phosphate, and detergent (ABS) were 88.0%, 87.0%, 71.5%, 86.5%, 94.3%, and 40.4%, respectively.
In this research, the influence of a variety of operational factors such as the temperature of the reaction, gas flow rate, concentration of NaCl, and the amount of Ca(OH)2 for reducing the ...environmental impacts of desalination reject brine using the calcium oxide-based modified Solvay process were investigated. For this purpose, response surface modeling (RSM) and central composite design (CCD) were applied. The significance of these factors and their interactions was assessed using an analysis of variance (ANOVA) technique with a 95% degree of certainty (p < 0.05). Optimal conditions for this process included: a temperature of 10 °C, a Ca(OH)2/NaCl concentration ratio of 0.36, and a gas flow rate of 800 mL/min. Under these conditions, the maximum sodium removal efficiency from the synthetic sodium chloride solution was 53.51%. Subsequently, by employing the real brine rejected from the desalination unit with a 63 g/L salinity level under optimal conditions, the removal rate of sodium up to 43% was achieved. To investigate the process’s kinetics of Na elimination, three different kinds of kinetics models were applied from zero to second order. R squared values of 0.9101, 0.915, and 0.9141 were obtained in this investigation for zero-, first-, and second-degree kinetic models, respectively, when synthetic reject saline reacted. In contrast, according to R squared’s results with utilizing real rejected brine, the results for the model of kinetics were: R squared = 0.9115, 0.9324, and 0.9532, correspondingly. As a result, the elimination of sodium from real reject brine is consistent with the second-order kinetic model. According to the findings, the calcium oxide-based modified Solvay method offers a great deal of promise for desalination of brine rejected from desalination units and reducing their environmental impacts. The primary benefit of this technology is producing a usable solid product (sodium bicarbonate) from sodium chloride in the brine solution.
Among different hollow nanostructures, the preparation of hollow mesoporous silica nanoparticles (HMSNs) is still a hotspot research field due to their unique properties e.g., large pore sizes and ...volumes, high drug loading capacity, ease of surface modification, large surface area, and biodegradability. Herein, novel uniform HMSNs are prepared for the first time by a combination of heterogeneous oil-water biphase stratification and simple mono-, di-, and tri-valent etching reactions. The biphase stratification reaction allows self-assembly of reactants at the oil-water interface, while the subsequent step is designed for the efficient selective silica etching under mild conditions. We have studied the effect of cation's valence (NH
, Ca
, and Al
) on the silica etching reaction coupled with the biphase stratification reaction both in the absence and presence of the auxiliary pore expanded agent 1, 3, 5 trimethylbenzene (TMB). In the absence of TMB, the Brunauer-Emmett-Teller (BET) analysis confirms that Al
creates materials with the largest pore size (18.0 nm), whereas the use of NH
results in the largest pore volume (2.30 cm
/g). The pores generated using Ca
and Al
as silica etching agents have a volume 2.01 cm
/g and 2.05 cm
/g, respectively. Similar experiments in the presence of TMB leads to the formation of HMSN with larger pore sizes (24 nm and 21.5 nm) and volumes (2.70 cm
/g and 2.12 cm
/g) when using Al
and Ca
, respectively, as etching agents. Drug loading capacity using Langmuir adsorption model indicate our hollow MSN material exhibit the high adsorbing DOX up to 558.23 mg per gram of nanoparticles in pH of 7.2. Furthermore, synthetized NPs exhibited high loading capacity for large protein and biomolecules such as BSA. Our findings confirmed that the charge density of cation has a critical role on selective silica etching in the preparation of HMSNs.
In the work presented here we explore the interest of target localization using multiple-input multiple-output (MIMO) radar systems with widely separated antennas. The time delays between every ...transmit/receive antenna are an integral part of target localization using MIMO radar systems. We assume that these time delays have already been estimated by a preprocessing algorithm. Accordingly, we propose a target localization algorithm using the least squares estimation which has a closed form without requiring any initial condition. Simulation results evaluate the performance of the proposed method in comparison with the Cramer-Rao lower bound (CRLB) and the best linear unbiased estimator (BLUE) method. The effect of the arrangement and number of transmitters and receivers on the algorithm performance is also investigated.
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