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Due to its widespread use in medicine and veterinary medicine, tetracycline has a high percentage of release in the environment and enters the drinking water ecosystem more than others, and on the other hand, its persistence in water causes an increase in antibiotic resistance and genotoxicity. It occurs in humans and aquatic animals, so their removal is one of the important challenges for researchers. Due to its special structure, including uniform pores and a very high specific surface area, zeolites are of great interest in the process of removing toxic and dangerous substances. However, the structure the uniqueness of zeolite, and the different applications that have been investigated. In this research, zeolite was modified with iron and aluminum and characterized by different techniques such as X-ray diffraction, transmission electron microscopy, scanning electron microscopy, atomic force microscopy and Fourier-transform infrared spectroscopy, then its ability to remove tetracycline was studied (pH 2–11), tetracycline concentration (10–60 mg/L), time (30–100 min), mL/mg of zeolite modified/Al/Fe. One of the advantages of this method is that the structure is synthesized at 1,000°C, which causes a heat-resistant structure, and also the ability to recycle the adsorbent after five steps have been studied and the removal ability does not change much at each stage and can be negligible.

Drugs are essential pollutants in the environment due to their resistant structure, and their high consumption in treating humans and animals. The entry of antibiotics as hospital waste into aquatic environments is considered one of the critical environmental means due to their high stability. The design and synthesis of Fe2O3/Ag/Zn as a new structure of Fe2O3were reported, because of its resistance of the structure to air and high temperature, the adsorbent of azithromycin in wastewater was studied. After characterization of Fe2O3/Ag/Zn by scanning electron microscopy, energy-dispersive X-ray spectroscopy, mapping, transmission electron microscopy, X-ray diffraction and Fourier-transform infrared spectroscopy. Then, to remove azithromycin, the effect of factors such as pH, the concentration of azithromycin solution, adsorbent dose, time and temperature was evaluated using an optimization process. The results showed that the optimal conditions for removing of 96% of azithromycin (10 mg/L) with 1.5 g/L of Fe2O3/Ag/Zn, pH = 5, and 30 min at room temperature, In other words, the nano absorbent has a good ability to remove azithromycin from water solution, which is very important from environmental aspects.

The characterization of membrane properties represents an essential step towards the understanding and prediction of membrane filtration performance. Herein, surface properties of commercial polymeric membranes were investigated in terms of surface charge and wetting characteristics. Streaming potential measurements showed that the studied membranes (NF270, NF90, BW30LE and BW30) were negatively charged in electrolytic solutions at neutral pH which is related to the polymeric composition of the active layer. Contact angle measurements were performed to evaluate qualitatively the wettability/hydrophilicity of the membranes and quantitatively by evaluating electron donor and acceptor functionalities and interfacial free energies of each membrane surface. NF270 was the most hydrophilic membrane with a high wettability degree (θ = 33.2°, –ΔGSw= 133.55 mJ/m2), Furthermore, the wettability parameters were correlated to membrane permeability, in order to better understand the wetting/hydrophilic behavior. This study on the electrical and wettability properties are of importance to select the appropriate membrane prior operation where the performance is related to the surface characteristics.

Bentonite/copper catalysts (CuB) were synthesized using solid-phase ion exchange at different temperatures (200°C and 300°C) and times (2 and 10 min) as heterogeneous catalysts for photo-Fenton treatment of methyl orange (MO) under UV irradiation. Prepared composites were identified by X-ray diffraction spectroscopy, scanning electron microscopy, Measurement of Brunauer– Emmett–Teller, transmission electron microscopy, energy-dispersive X-ray spectroscopy. The activity of the prepared CuB catalyst was assayed in the degradation of MO in the presence of the catalyst, H2O2, and UV irradiation. According to the decolorization of the MO solution, the sample prepared at 200°C and 10 min was selected as the optimal catalyst. Under optimal conditions (pH = 2.0, 30 mM H2O2, and 0.8 g/L catalyst), 100% of 100 ppm MO solution was removed at 135 min. The result of reusability studies shows the acceptable reusability of the catalyst.

One of the important parameters in wastewater treatment is the removal of dye from it. As heterogeneous catalysts for photo-Fenton treatment of dye, iron oxide/bentonite nanocomposites are prepared by the solid-state reaction method at 300°C and 600°C. The catalysts are characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area analysis, X-ray diffraction spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM, TEM, and XRD analysis show γ-Fe2O3(hematite) particles that are formed and distributed on the bentonite. EDX results revealed the increased iron and decreased calcium and magnesium contents in FeB300 and FeB600 compared with the parent bentonite. The results indicate that the prepared nanocomposites have a lower BET surface area than the parent bentonite. XRD patterns of samples prove formation of γ-Fe2O3particles. Finally, the degradation efficiency of MO reached 81% and 75% in the presence of FeB300 or FeB600 and H2O2under irradiation within 90 min, respectively. Therefore, both prepared catalysts exhibit acceptable photo-Fenton catalytic activity.

This study was aimed at the investigation of fluoride (F–) rejection from single and binary solution by nanofiltration process (NF). The influence of various parameters such as the effect of solution pH, initial F–concentration, applied pressure, feed flux, and accompanying cations and anions in feed water has been reported. Besides, the solute rejection and Spiegler–Kedem models were applied for the better understanding of NF performance. In a single solution, the laboratory study demonstrated F–rejections with NF membranes to be higher than 85%. Moreover, as applied pressure and feed flux increased F–rejection was observed to increase marginally whereas the opposite trend was observed when initial F–concentration in feed water was increased. Further, the depletion of F–rejection at 15 mg/L of F–was found to be associated with the presence of co-existing cation and anion in the feed water. The estimated average of pore radius and Δx/Akof the NF membrane were 0.12 ± 0.02 nm and 47.84 ± 25.22 mm, respectively.

Fluorine is found in high concentrations in the earth’s crust and in the groundwater. In this research, fluoride adsorption at the concentrations of 1–10 mg/L in the aqueous solutions was optimized by response surface methodology using sonocatalyst process in a frequency of 30 kHz by zeolitic imidazole framework-8 (ZIF-8) in dosage between 0.01 and 0.09 g/L, and pH from 3 to 11. According to the results, optimum conditions with removal efficiency of 92.17% was found at the fluoride concentration of 1.2 mg/L, ZIF-8 dosage of 0.08 g/L, and pH 6.52. Experimental data were well fitted on the Freundlich model (R2= 0.99); therefore, the adsorption was multilayer with a favorable affinity between fluoride and ZIF-8. The maximum adsorption capacity of ZIF-8 was obtained to be 33.11 mg/g. Also, the pseudo-second order model had the best agreement with data (R2= 0.99). Finally, this study demonstrated that the sonocatalyst process in combination with ZIF-8 is a promising and efficient method for adsorption of fluoride from aqueous solutions.

This study aimed at pre-concentrating Allura Red as a food additive dye and determining it in the environmental samples following its extraction. Dispersive solid-phase extraction was followed by UV–Vis spectroscopy to provide a simple and efficient method with low cost by using sil- ver-zirconium oxide nanoparticles loaded on an activated carbon as the adsorbent. The proposed adsorbent was simply prepared and characterized by different techniques, such as Fourier-transform infrared spectroscopy, X-ray diffraction, and scanning electron microscopy. Evaluation and optimization of the effective parameters on the extraction recovery, including eluent volume (mL), pH, adsorbent dosage (mg), and ultrasound time (min), and their interactions were investigated using a response surface methodology based on a central composite design as an efficient mathematical and statistical tool. The selected model›s precision and accuracy were assessed through the analysis of variance, while the optimum conditions were obtained as follows: eluent volume = 0.3 mL, pH = 3, adsorbent dosage = 10 mg, and ultrasound time = 4.5 min. Under the optimum operational conditions, the limit of quantification of 75.0 ng mL–1, limit of detection of 26.0 ng mL–1, and linear range of 80.0–5,000 ng mL–1were achieved. A high correlation coefficient was obtained via the Langmuir isotherm as best model, from which the maximum adsorption capacity of 52.40 mg g–1was resulted.

Chitosan/Mesoporous silica/Nano-γ alumina was synthesized and characterized by FTIR, XRD, FESEM, TGA and BET; also, it was applied as an efficient and eco-friendly adsorbent to investigate the adsorption properties of Methylene blue (MB) from the aqueous solution by following the optimization of influential parameters such as pH, contact time, adsorbent mass, and the initial concentration of MB by the central composite design (CCD) under a response surface methodology (RSM). Maximum removal efficiency at the optimum conditions (pH: 7.5, contact time: 45 min, adsorbent dosage: 0.088 mg, and the initial dye concentration: 15 mg/L) was achieved to be 90.23%. Analysis of variance and calculation of the correlation coefficient related to the predicted and experimental values of the removal percentage of MB proved the precision of the equation acquired by CCD. Subsequently, it was found that the adsorption isotherm was well fitted, and it was in a good agreement with the Langmuir isotherm model; the maximum adsorption efficiency (qmax) was found to be 80 mg/g. The study of the relation between time and the adsorption rate indicated that the adsorption of MB onto CS/MCM-41/Nano-alumina obeyed the pseudo-second-order. Besides, thermodynamic parameters calculated in this research, including ∆G°, ∆H°, and ∆S° revealed that the adsorption of MB on the adsorbent was spontaneous and endothermic. According to the results obtained in this research, CS/MCM-41/Nano-alumina could be regarded as an effective adsorbent for MB elimination from the aqueous solution.

The presence of antibiotics in the environment threatens the health of humans and animals, seriously. In this respect, this study applies cerium oxide nanoparticles (CeO2NPs) as an adsorbent to remove tetracycline (TC) from aqueous solutions and investigates the effects of various parameters on the adsorption reaction. The studied parameters include pH‚ electrolyte concentration‚ TC concentration, amount of the adsorbent, flow rate of the solution, and the presence of several coexisting ions. According to the obtained results, the CeO2NPs are quite efficient for removal of TC at room temperature. Furthermore, adsorption of TC onto the CeO2NPs is fast and the corresponding isotherms fit the Langmuir model, perfectly. The proposed adsorption method is successfully employed to remove TC from various aqueous solutions including surface and drinking water samples.

In this study, chitosan-SnO2nanoparticles biocomposite was synthesized and investigated as an efficient green biosorbent for adsorption of Fe(II) ions. The as-prepared bio-nanocomposite was characterized by Fourier-transform infrared spectroscopy, X-ray powder diffraction spectroscopy, transmission electron microscopy, scanning electron microscopy, and energy dispersive X-ray spectroscopy. Furthermore, a dispersive micro-solid phase extraction (D-μ-SPE) based on microvolume spectrophotometric detection technique was developed for preconcentration as well as determination of Fe(II) ions in environmental and wastewater samples. After reduction of Fe(III) ions by the addition of hydroxylamine hydrochloride as reducing agent, the system was applied to the total iron. Different parameters influencing the extraction efficiency including sample pH, the amount of adsorbent, adsorption time, and properties of desorption solvent were optimized. The adsorption isotherms of the synthesized adsorbent were also studied. The adsorption isotherm was well described by the Freundlich model and showed good adsorption capacity for the Fe(II) ions (17.24 mg g–1). The calibration graph was linear in the range 10–1,200 ng mL–1of Fe(II) and total iron. The detection limit of the method for determination of Fe(II) was 2.8 ng mL–1with a relative standard deviation of less than 1.3%. The adsorption capacity of the regenerated adsorbents was maintained at 90% even after the fourth adsorption–desorption cycle.

Evaporation, an important problem in hydrology and water resources engineering, has long been of great interest to many researchers. In this study, the magnetic nanoparticles dispersed in Jojoba plant oil were used to reduce the amount of water surface evaporation. The experiments were conducted in the city of Ardestan in the central part of Iran, using a completely randomized design with four treatments and three replications and taking advantage of Fe2O3and Fe3O4magnetic nanoparticles, dispersed in Jojoba plant oil. Conducted in two stages, it took into account the existing standards available in Class A standard evaporation pans and plastic pans. The results showed that there are significant differences between the treatments, i.e., the highest rate of evaporation reduction (25.4%) was observed when jojoba oil was mixed with 0.02 Fe2O3in the Class A evaporation pan. It was also inferred that evaporation could drop by 32.6% provided that a jojoba oil solution containing Fe3O4nanoparticle is used in plastic pans.

A novel adsorbent was prepared by the functionalization of asphaltenes, which were isolated from crude oil and used for the removal of organic pollutants in aqueous solution. The functionalized asphaltenes were characterized by Fourier transform infrared, scanning electron microscope and elemental analysis and found to contain higher amounts of oxygen atoms and carbonyl and hydroxyl functional groups. The impact of different variables such as pH, adsorbent dose, dyes concentration, reaction temperature and contact time were studied during the adsorption process. At 5 h contact time, the best pH for the high efficient adsorption of bromophenol blue (BPB) and methyl orange (MO) were found to be 6.30 and 2.75, respectively. The adsorption isotherms fitted well the Langmuir, Freundlich, Temkin as well as Lagergren models. The adsorption isotherm data of BPB and MO were in good conformity with all models studied, however, BPB was more closely fitted with Freundlich and Temkin isotherms while MO was more closely fitted with Langmuir and Lagergren models thereby implying that the adsorption occurred as a monolayer as well as a heterogeneous surface adsorption. The calculated maximum adsorption capacity for Langmuir model was 7.44 and 2.24 mmol/g for BPB and MO, respectively. Several adsorption kinetic models were fit with experimental data and pseudo-second-order kinetic model was found to be best fitting model. The separation factor (RL) values found between 0 and 1 that indicates the favorability of the adsorption process on adsorbent surface. The thermodynamic parameters were calculated and the respective values for BPB and MO dyes were found to be ΔG° (–11.808 and –14.057 kJ/mol), ΔH° (8.509 and 6.460 kJ/mol) and ΔS° (65.954 and 66.613 J/K mol), which exhibited that the adsorption of dyes on functionalized asphaltenes was spontaneous, endothermic with increased randomness. The functionalized asphaltene showed high adsorption capacity with highly efficient removal for BPB and MO dyes.

AbstractZirconia nanoparticles were modified by sodium dodecyl sulfate (SDS) under ultrasonic action and used as a new adsorbent for the removal of brilliant cresyl blue dye from aqueous solutions. The effect of different parameters such as pH, salt concentration, and amount of adsorbent on the removal procedure was studied and optimum conditions were established. The adsorption data were fitted to Langmuir, Freundlich, and Temkin isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model. The kinetic studies indicated that the experimental data were fitted well by the pseudo-second-order model. The maximum adsorption capacity was found to be 34.4 mg g−1of adsorbent for brilliant cresyl blue. The removal procedure was applied to the removal of brilliant cresyl blue form water samples.

Zirconia nanoparticles were modified by sodium dodecyl sulfate (SDS) under ultrasonic action and used as a new adsorbent for the removal of brilliant cresyl blue dye from aqueous solutions. The effect of different parameters such as pH, salt concentration, and amount of adsorbent on the removal procedure was studied and optimum conditions were established. The adsorption data were fitted to Langmuir, Freundlich, and Temkin isotherms and the equilibrium adsorption was best described by the Langmuir isotherm model. The kinetic studies indicated that the experimental data were fitted well by the pseudo-second-order model. The maximum adsorption capacity was found to be 34.4 mg g−1of adsorbent for brilliant cresyl blue. The removal procedure was applied to the removal of brilliant cresyl blue form water samples.

AbstractPhenol compounds are regarded as hazardous pollutants due to their toxicity and carcinogenic properties to human health at low concentrations. So, this study was aimed to investigate the phenol adsorption by copper (Cu)-modified scoria powder, which is a low-cost adsorbent for the removal of organic compounds. All the experiments were performed based on the full face-centered central composite design experimental plan and analyzed using response surface methodology. The samples were analyzed using various conditions including adsorbent dose (0.1–1 g/l), phenol concentration (50–250 mg/l), and contact time (5–100 min). Three-dimensional plots reveal the relationship between the phenol removal efficiency and the paired factors, which describe the behavior of scoria powder in the removal of phenol from aqueous solution. The models showed that phenol removal efficiency in aqueous solution affected by four studied factors. A maximum removal efficiency of phenol achieved was more than 96% at the optimum conditions (scoria dosage of 1 g/l, phenol concentration of 50 mg/l, and contact time of 100 min). Process of kinetic parameters were also evaluated and modeled using five kinetic models including pseudo-first-order equation, second-order equation, modified Freundlich, pore diffusion, and Elovich. The best fit of experimental adsorption data was calculated by means of the pseudo-second-order model. Equilibrium data obeyed the Freundlich and Langmuir isotherms, and found that the equilibrium data well obeyed the Langmuir isotherm.

Phenol compounds are regarded as hazardous pollutants due to their toxicity and carcinogenic properties to human health at low concentrations. So, this study was aimed to investigate the phenol adsorption by copper (Cu)-modified scoria powder, which is a low-cost adsorbent for the removal of organic compounds. All the experiments were performed based on the full face-centered central composite design experimental plan and analyzed using response surface methodology. The samples were analyzed using various conditions including adsorbent dose (0.1–1 g/l), phenol concentration (50–250 mg/l), and contact time (5–100 min). Three-dimensional plots reveal the relationship between the phenol removal efficiency and the paired factors, which describe the behavior of scoria powder in the removal of phenol from aqueous solution. The models showed that phenol removal efficiency in aqueous solution affected by four studied factors. A maximum removal efficiency of phenol achieved was more than 96% at the optimum conditions (scoria dosage of 1 g/l, phenol concentration of 50 mg/l, and contact time of 100 min). Process of kinetic parameters were also evaluated and modeled using five kinetic models including pseudo-first-order equation, second-order equation, modified Freundlich, pore diffusion, and Elovich. The best fit of experimental adsorption data was calculated by means of the pseudo-second-order model. Equilibrium data obeyed the Freundlich and Langmuir isotherms, and found that the equilibrium data well obeyed the Langmuir isotherm.

AbstractIn this work, tin sulfide nanoparticles loaded on activated carbon (SnS-NP-AC) was synthesized and characterized using various analytical techniques, such as SEM, BET, XRD, and UV–Vis spectroscopy. The impact of influential parameters such as the contact time, adsorbent dosage, pH, and initial dye concentration was investigated and optimization was carried out using random forest model. The optimized values of influential parameters i.e. pH, contact time, adsorbent dosage, and initial dye concentration were found to be 1, 4 min, 0.03 g, and 15 mg L−1, respectively. At these optimized values CR achieve highest removal percentage (99%) and maximum adsorption capacity (384.6 mg g−1). The experimental equilibrium data were fitted to different adsorption isotherm models i.e. Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich, among them the Langmuir model is found to be the best fitted and well suited model for evaluating and analyzing the actual behavior of adsorption process. The Kinetic experimental data were well fitted and they are in good agreement with pseudo-second-order and intraparticle diffusion model.

In this work, tin sulfide nanoparticles loaded on activated carbon (SnS-NP-AC) was synthesized and characterized using various analytical techniques, such as SEM, BET, XRD, and UV–Vis spectroscopy. The impact of influential parameters such as the contact time, adsorbent dosage, pH, and initial dye concentration was investigated and optimization was carried out using random forest model. The optimized values of influential parameters i.e. pH, contact time, adsorbent dosage, and initial dye concentration were found to be 1, 4 min, 0.03 g, and 15 mg L−1, respectively. At these optimized values CR achieve highest removal percentage (99%) and maximum adsorption capacity (384.6 mg g−1). The experimental equilibrium data were fitted to different adsorption isotherm models i.e. Langmuir, Freundlich, Tempkin, and Dubinin–Radushkevich, among them the Langmuir model is found to be the best fitted and well suited model for evaluating and analyzing the actual behavior of adsorption process. The Kinetic experimental data were well fitted and they are in good agreement with pseudo-second-order and intraparticle diffusion model.

AbstractA solid phase extraction procedure is proposed for the separation and preconcentration trace amounts of Pd (II) in aqueous medium by using a column of multi-walled carbon nanotubes (MWCNTs) modified with 1-(2-pyridylazo)-2-naphtol (PAN). The elution was carried out with 5.0 mL of 2 mol L−1thiourea in 4 mol L−1HCl. The amount of eluted Pd (II) was measured using flame atomic absorption spectrometry. The influences of the various experimental parameters, including pH, eluent type, concentration of eluent, amount of sorbent, and interfering ions on the recovery of palladium ions were investigated. The detection limit for palladium under the optimum condition was 1.0 ng mL−1with enrichment factor of 100 and the relative standard deviation was 1.89% (n = 6, C = 0.5 μg mL−1). The method was applied for the determination of Pd (II) in water samples. The enrichment performance of the method using modified MWCNTs as preconcentration sorbent was also compared with PAN-modified activated carbon.

A solid phase extraction procedure is proposed for the separation and preconcentration trace amounts of Pd (II) in aqueous medium by using a column of multi-walled carbon nanotubes (MWCNTs) modified with 1-(2-pyridylazo)-2-naphtol (PAN). The elution was carried out with 5.0 mL of 2 mol L−1thiourea in 4 mol L−1HCl. The amount of eluted Pd (II) was measured using flame atomic absorption spectrometry. The influences of the various experimental parameters, including pH, eluent type, concentration of eluent, amount of sorbent, and interfering ions on the recovery of palladium ions were investigated. The detection limit for palladium under the optimum condition was 1.0 ng mL−1with enrichment factor of 100 and the relative standard deviation was 1.89% (n = 6, C = 0.5 μg mL−1). The method was applied for the determination of Pd (II) in water samples. The enrichment performance of the method using modified MWCNTs as preconcentration sorbent was also compared with PAN-modified activated carbon.

A novel sol-gel-derived zinc oxide nanostructure has been prepared by spin-coating and investigated for the purpose of producing films. ZnO films were spin-coated on microscope glass slides via methylcellulose (MC) aided sol-gel route using zinc acetate-acetic acid-EtOH as starting materials and heat treatment. Scanning electron microscopy (SEM) investigations showed that relatively dense, crack-free and transparent ZnO composite films, as well as, a decrease in the size of the ZnO nanoparticles, were achieved via the MC assisted sol-gel and single-step deposition at room temperature. Fourier transform infrared spectroscopy (FTIR) and thermal gravimetry analysis (TGA) results demonstrated full decomposition of the organic materials after firing. Photocatalytic activity of the composite films were evaluated through the degradation of a textile dye, Acid Blue R (C.I. Acid Blue 92) as a model pollutant and were compared with those of similar composite film without MC. 2%MC/ZnO thin film showed an interesting decolorization performance, as denoted by an attenuation degree of 99% and decoloration rate, assuming an apparent first order reaction, reaching 9.8×10−2min−1.

A novel sol-gel-derived zinc oxide nanostructure has been prepared by spin-coating and investigated for the purpose of producing films. ZnO films were spin-coated on microscope glass slides via methylcellulose (MC) aided sol-gel route using zinc acetate-acetic acid-EtOH as starting materials and heat treatment. Scanning electron microscopy (SEM) investigations showed that relatively dense, crack-free and transparent ZnO composite films, as well as, a decrease in the size of the ZnO nanoparticles, were achieved via the MC assisted sol-gel and single-step deposition at room temperature. Fourier transform infrared spectroscopy (FTIR) and thermal gravimetry analysis (TGA) results demonstrated full decomposition of the organic materials after firing. Photocatalytic activity of the composite films were evaluated through the degradation of a textile dye, Acid Blue R (C.I. Acid Blue 92) as a model pollutant and were compared with those of similar composite film without MC. 2%MC/ZnO thin film showed an interesting decolorization performance, as denoted by an attenuation degree of 99% and decoloration rate, assuming an apparent first order reaction, reaching 9.8×10-2min-1.