[en] This study explores the capacity of synthesized Fe₂O₃ nanoparticles (NPs) under sunlight for the degradation of dissolved organic matter (DOM) from synthetic (Procion blue dye) solution as well as from textile wastewater (TWW). Fe₂O₃ NPs were properly synthesized and confirmed by UV absorbance, FTIR spectra and SEM image analysis. Photocatalytic degradation of DOM from TWW and synthetic solution was performed by catalyst Fe₂O₃ NPs (5 mg/L) in the presence of solar irradiation (up to 40 h). The DOM degradation of the TWW and synthetic solution has been analyzed by fluorescence 3D excitation emission matrix (3D EEM). Synergistic effect was expected and it was found that the rate of decrease of fluorescence intensity increased with time. Within 20 h, for the synthetic solution, reduction of fluorescence intensity (80%) reaches an equilibrium. In contrast, the rate of decrease in the fluorescence intensity is highest (91%) in 40 h of irradiation for TWW. This reduction of fluorescence intensity indicates the degradation of DOM and can be expressed well by second-order model kinetics. Reduction of TOC, BOD₅ and COD load again validated the degradation of DOM from TWW by catalyst Fe₂O₃ NPs-induced solar irradiation. We applied the treated wastewater on the plant to observe the reusability of the treated TWW, and the morphological data analysis of the plant demonstrates that the catalyst Fe₂O₃ NPs-induced solar-irradiated wastewater exhibits less adverse impact on plant morphology.

[en] In this work, the preparation, characterization, and sorption of rhodamine 6G and humic acids on a composite sodium alginate–bentonite were investigated. Their structure and morphology were analyzed by several techniques, including Fourier transform infrared spectroscopy, X-ray diffraction, and N₂ adsorption at − 196 °C. A synergetic sorption mechanism was observed in binary systems; humic acids adsorption was enhanced by the presence of Rh6G in the mixture. The kinetic studies revealed that the sorption follows a pseudo-first-order kinetic model and the sorption capacities of Rh6G increased with the pH value. The Langmuir isothermal model well described the adsorption isotherm data, showing a maximum adsorption capacity for Rh6G up to 429.5 mg/g at 20 °C. On the basis of the data of the present investigation, it is possible to conclude that the composite exhibited excellent affinity for the dye and humic acids, and it can be applied to treat wastewater containing dye and natural organic matter.

[en] Cu₂ZnSnS₄ QDs (5–7 nm) were synthesized by chemical coprecipitation route. Using prepared Cu₂ZnSnS₄ QDs, a new type of BiOCl–Cu₂ZnSnS₄ heterostructures were prepared using bismuth nitrate as a precurssor and potassium chloride as a source of chlorine at 100 °C, 4 h. BiOCl–Cu₂ZnSnS₄ heterostructures were analyzed by XRD, TEM, UV–visible NIR, PL and surface area studies. The diffracted peaks of BiOCl–Cu₂ZnSnS₄ heterostructure show the presence of tetragonal BiOCl and did not show the intense peaks of Cu₂ZnSnS₄ QDs. TEM images of BiOCl–Cu₂ZnSnS₄ showed the deposition of Cu₂ZnSnS₄ QDs on the BiOCl microsphere surface. The surface area of BiOCl, Cu₂ZnSnS₄ and BiOCl–Cu₂ZnSnS₄-1 was of 1.91 m²/g, 3.06 m²/g and 13.39 m²/g, respectively. BiOCl–Cu₂ZnSnS₄-1 had a higher photodegradation rate for Congo red dye than BiOCl and Cu₂ZnSnS₄ QDs under sunlight, and that higher photoactivity was due to the heterostructure effect between BiOCl and Cu₂ZnSnS₄ QDs along with increased optical absorption in the visible region. Scavenger study endorses the involvement of superoxide and holes radicals in the degradation of Congo red.

[en] In this research, zinc oxide (ZnO) nanostructure was prepared by using zinc acetate (as precursor) and carboxylic derivative of activated carbon (as matrix). Activated carbon was modified by oxidation with nitric acid to get carboxylic derivative (AC–COOH). Then, zinc was loaded on the surface of modified activated carbon by an impregnation method. The ZnO nanostructure was characterized by BET, XRD and SEM that confirmed achieving of ZnO nanoparticles with a size of 21–31 nm and surface area of 17.78 m² gr⁻¹. The efficiency of the catalyst was evaluated in the photocatalytic decomposition of aqueous solution of azo dye methyl orange (MO). Major parameters such as pH, dose of catalyst, stirring effect, initial concentration of dye and solution oxygen effect were considered. Activity measurements under UV radiation showed acceptable results for the photodegradation of MO. The efficiency of catalyst prepared with non-modified activated carbon for the photodegradation of MO was also evaluated. The results confirmed that ZnO prepared using carboxylic derivative of activated carbon as matrix had better photocatalytic activity than ZnO prepared by non-modified carbon matrix.

[en] Bisphenol A (BPA) is an organic compound which is often used as plasticizer and has been reported to be hazardous to man. In this research the efficiency of removal of BPA from water by magnetite through adsorption process was studied. The magnetite was synthesized using reverse co-precipitation method and fully characterized. Various physicochemical parameters affecting the adsorption of BPA using magnetite were studied as well. The optimum time for the adsorption process was found to be 60 min at pH of 6, adsorbent dose of 0.2 g and 50 ppm of BPA. The adsorption data were fitted by the Langmuir adsorption isotherm best with a regression value of 0.957. The R_L value was 0.179 which revealed that the process is favorable. The Freundlich constant n which was 1.901 also revealed that the adsorption is normal and favorable. The data were in agreement with the pseudo-second-order kinetics with regression value of 0.98. From the thermodynamic studies, the process was found to be exothermic and the Gibb’s free energy value which was negative showed that the adsorption was spontaneous. The synthesized magnetite therefore offers great potential for the remediation of bisphenol A-contaminated media.

[en] Refined natural Fe-chromite was characterized by XRD, FT-IR, reflected polarized microscope, XRF and UV spectrophotometer. Photocatalytic degradation and photo-Fenton oxidation of Congo red dye by Fe-chromite was investigated using 1 mL H₂O₂. The degradation of dye was studied as a function of illumination time, chromite mass, initial dye concentration, and pH. Fe-chromite acts as binary oxide system from chromium oxide and ferrous oxide. Thus, it exhibits photocatalytic properties under UV illumination and photo-Fenton oxidation after addition of H₂O₂. The degradation in the presence of H₂O₂ reached the equilibrium stage after 8 h (59.4%) but in the absence of H₂O₂ continued to 12 h (54.6%). Photocatalytic degradation results fitted well with zero, first order and second order kinetic model but it represented by second order rather than by the other models. While the photo-Fenton oxidation show medium fitting with the second order kinetic model only. The values of kinetic rate constants for the photo-Fenton oxidation were greater than those for the photocatalytic degradation. Thus, degradation of Congo red dye using chromite as catalyst is more efficient by photo-Fenton oxidation. Based on the response surface analysis, the predicted optimal conditions for maximum removal of Congo red dye by photocatalytic degradation (100%) were 12 mg/l, 0.14 g, 3, and 11 h for dye concentration, chromite mass, pH, and illumination time, respectively. Moreover, the optimum condition for photo-Fenton oxidation of dye (100%) is 13.5 mg/l, 0.10 g, 4, and 10 h, respectively.

[en] Properties of raw bentonite clay of Afuze in Edo state which are abundant and cheap bentonite mineral in Nigeria as adsorbents for the removal of atrazine in aqueous solution were investigated. The bentonite clay-types were characterized using scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectrophotometry and X-ray diffraction (XRD). Batch adsorption experiments were carried out to determine the equilibrium characteristics, thermodynamics and kinetics of the sorption processes. The data obtained were subjected to Langmuir, Freundlich and Temkin isotherm equations, while pseudo-first-order, pseudo-second-order rate equations, intra-particle diffusion and Elovich models were considered for kinetics and mechanism. The results showed that the adsorption processes were described by different isotherm models; they were all spontaneous (∆G ranges from − 938.34 to − 6263.58 kJ/mol) and exothermic (range of ∆H is − 252.73 to − 1057.08 kJ/mol), and with decreased randomness, ∆S (− 3.110 to − 0.581 J.mol/K). Pseudo-second-order kinetics model gave the better fit for all the sorption processes which implies physisorption process as the rate limiting step. Thus, bentonite clay-types can be used to adsorb atrazine.

[en] The indiscriminate consumption of antibiotics and their introduction into the environment have caused global concerns. Typically, following consumption, these compounds are introduced into the environment after incomplete metabolism, and a large portion of them are impossible to remove using conventional wastewater treatment systems. The main aim of this study was to determine the feasibility of using a TiO₂/UV-C nanophotocatalyst doped with trivalent iron for the removal of amoxicillin from aquatic solutions. The nanophotocatalyst was prepared and characterized by SEM, XRD, EDX, DRS, and photoluminescence spectrum. The influences of different parameters, including nanocatalyst concentration (30–90 mg/L), initial concentration of amoxicillin (10–45 mg/L), and pH (3–11) at different time intervals (30–120 min) on antibiotic removal efficiency were investigated. Antibiotic concentration was measured with an HPLC device. All experiments were replicated three times according to the Standard Methods for the Examination of Water and Wastewater, 20^th edition. Data were analyzed using SPSS 19 and the ANOVA statistical test. Optimal conditions for removing amoxicillin from a synthetic solution were as follows: pH 11, initial concentration of antibiotic = 10 mg/L, nanocatalyst = 90 mg/L, and contact time = 120 min. The optimal conditions were also used to remove amoxicillin from Dana Pharmaceutical Company wastewater. The removal efficiencies of antibiotic for synthetic and pharmaceutical wastewater were 99.14 and 88.92%, respectively. According to the results, the nanophotocatalyst TiO₂/UV-C may be used for the removal of significant amounts of amoxicillin from pharmaceutical wastewater.

[en] Polyamide thin-film composite (TFC) was fabricated on polysulfone (PS-20) base by interfacial polymerization of aqueous m-phenylenediamine (MPD) solution and 1,3,5-benzenetricarbonyl trichloride (TMC) in hexane organic solution. Multi-wall carbon nanotubes (MWCNT) were carboxylated by heating MWCNT powder in a mixture of HNO₃ and H₂SO₄ (1:3 v/v) at 70 °C under constant sonication for different periods. Polyamide nanocomposites were prepared by incorporating MWCNT and the carboxylated MWCNT (MWCNT–COOH) at different concentrations (0.001–0.009 wt%). The developed composites were analyzed by Fourier transform infrared spectroscopy-attenuated total reflection, scanning electron microscopy, transmission electron microscopy, contact angle measurement, determination of salt rejection and water permeate flux capabilities. The surface morphological studies displayed that the amalgamation of MWCNT considerably changed the surface properties of modified membranes. The surface hydrophilicity was increased as observed in the enhancement in water flux and pure water permeance, due to the presence of hydrophilic nanotubes. Salt rejection was obtained between 94 and 99% and varied water flux values for TFC-reference membrane, pristine-MWCNT in MPD, pristine-MWCNT in TMC and MWCNT–COOH in MPD were 20.5, 38, 40 and 43 L/m²h. The water flux and salt rejection performances revealed that the MWCNT–COOH membrane was superior membrane as compared to the other prepared membranes.

[en] Water shortage is among the critical challenges facing many countries located in the arid zone of the southern the Mediterranean region. In the northern Sinai, El-Salam Canal and shallow groundwater in the Quaternary aquifer are considered the main irrigation sources for reclamation of 62,000 acres situated along the Mediterranean coast. The chemistry of surface water of El-Salam Canal varies greatly from the western to the eastern sides. Additionally, the groundwater chemistry is greatly influenced by dilution due to seepage of El-Salam Canal water. The historical and recent records of water chemistry show great variation of the concentrations of dissolved Al³⁺, Cu²⁺ and Zn²⁺ in both surface and groundwater, based on sampling time and locality. The concentrations of these heavy metals occasionally exceed the international recommended limits for drinking and short-term irrigation standards. The removal of dissolved heavy metals from water is crucial to fill the gap between the water supply and the growing demands using possible techniques of water treatment. Consequently, zeolite nanocomposites are one of the materials that have been used for water treatment. Magnetic zeolite nanocomposites (MZNCs) were prepared by the chemical co-precipitation of Fe²⁺ and Fe³⁺ in the presence of zeolite. The prepared magnetic nanocomposites were characterized by TEM, SEM, EDX, XRD, FTIR, TGA and VSM. The results show that MZNCs have a cubic crystal structure and good thermal stability. The MZNCs were used to remove Al(III), Zn(II) and Cu(II) from simulated water and then were easily separated from the medium by external permanent magnet. Batch adsorption experiments were conducted, and the effects of pH, initial ion concentration, adsorbent dose and contact time were studied. The selected pH range (pH = 5–6) and temperature (27 °C) in the batch adsorption experiments were close to the pH range of the surface and groundwater field data. Furthermore, the chosen initial concentrations and adsorbent doses were within the heavy metals concentration ranges in El-Salam Canal and the adjacent groundwater. The MZNCs show great removal capacity of heavy metals where 0.1 g is able to clean contaminated water with high concentrations (0.5–3 g/l) of Cu(II) and Zn(II) within 20 min and within 30 min for Al(III). The adsorption kinetics data of the system were well fitted to pseudo-second-order model, which indicates a faster kinetic sorption by the composites. Adsorption isotherms were studied using Langmuir and Freundlich isotherms. Although both of them fit the data, the Freundlich isotherm had the best fit for the selected metals.