Synthetic Aqueous Solutions Research Articles

PREPARATION AND CHARACTERIZATION OF POLYMER INCLUSION MEMBRANES BASED ON BIODEGRADABLE CELLULOSE/ALGERIAN CLAY FOR HEAVY METALS REMOVAL FROM WASTEWATER

Separation membranes have gained attention as promising options for water and wastewater treatment due to their financial sustainability, and eco-friendliness. However, practical challenges have limited their application in water separation. To overcome these limitations, inorganic-organic hybrid membranes have been developed in this study. The present work deals with two attractive aspects: (i) economical, through the valorization of a local clay (Algerian kaolin), and (ii) environmental, which is based on the membrane selectivity for metal ions. The principal objective of this work is the development of enhanced nanocomposite membranes. It is achieved with low costs, based on cellulose triacetate (CTA) as a polymeric matrix modified by the addition of a lamellar filler, i.e. yellow clay obtained from Jijel, located in the east of Algeria, and plasticized by dioctyl phthalate (DOP). A further objective of this paper was the treatment of wastewater polluted by lead (Pb2+) and cadmium (Cd2+). The prepared membranes were characterized by various characterization techniques, including scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy and thermogravimetric analysis (TGA). All synthetized membranes had an amorphous structure, with homogeneous pore morphology and distribution. Moreover, the presence of nanocomposite clay showed effective integration into the membrane matrix and led to a significant improvement in thermal resistance. These membranes were applied to treat a synthetic aqueous solution contaminated with heavy metals, namely Pb2+ and Cd2+. The results revealed a rejection rate higher than 50%, suggesting the potential effectiveness of a stable and environmentally sustainable polymer inclusion membrane system for water purification.

Removal of antibiotics from aqueous solutions: insights of competitive adsorption onto Ni-impregnated biochar of spent coffee grounds

Antibiotics are among the most widely used pharmaceutically active compounds. Possessing the capability to adversely impact the ecological system, existence of antibiotics in the environment is an escalating concern. With the purpose of removing two widely used antibiotics efficiently from aqueous solutions, the competency of two biochar (BC)-based sorbents derived from spent coffee (SC) grounds was investigated. Both pristine (SCBC) and nickel (II) oxide-impregnated (Ni-SCBC) biochars were utilized as sustainable and cost-effective sorbents to remove daunorubicin (DAYN) and tigecycline (TIGY) from single synthetic aqueous solutions and binary combinations. Batch adsorption experiments were controlled implementing Box–Behnken design. The removal efficiency of Ni-SCBC was superior compared to SCBC (TIGY: 67.06%, DAYN: 94.30%). Results of characterizations showed that impregnation with NiO changed the degree of crystallization with a remarkable increase in the surface area from 49.23 m2/g in SCBC to 86.06 m2/g in Ni-SCBC. Adsorption of DAYN and TIGY (single solutions) conformed well to Freundlich, and Langmuir isotherms, respectively. A maximum adsorption capacity (qmax) of 136.62 mg/g (DAYN) and 73.15 mg/g (TIGY) was reported in single solutions, compared to 23.50 mg/g (DAYN) and 58.42 mg/g (TIGY) in binary mixture. Adsorption kinetics onto Ni-SCBC fitted well with the pseudo-second-order (PSO) and Elovich models. Acquired results demonstrated that SCBC and Ni-SCBC are promising adsorbents for remedying antibiotics.

Adsorptive performances and valorization of green synthesized biochar–based activated carbon from banana peel and corn cob composites for the abatement of Cr(VI) from synthetic solutions: Parameters, isotherms, and remediation studies

This study intended to remove Cr(VI) from an aqueous synthetic solution employing synthesized biochar adsorbent from a blend of locally sourced banana peel, and corn cob biomass wastes. An equal ratio of the prepared powder was activated with ZnCl2 solution (1:1 wt basis) and carbonized for 2 h at 600 °C. The proximate analysis of the selected BP-CCAC@ZC3 biochar was conducted. Subsequently, its surface area, surface functions, and morphology were examined using BET analysis, FTIR, and SEM techniques, respectively. The proximate analysis of BP–CCAC@ZC3 showed a moisture content of 2.37 ± 0.80 %, an ash content of 8.07 ± 0.75 %, volatile matter of 19.38 ± 2.66 %, and fixed carbon of 70.18 %. It was found that the synthesized BP–CCAC@ZC3 had 432.149 m2/g of a specific area as per the BET surface area analysis. The highest efficiency for Cr(VI) removal was determined to be 97.92 % through adsorption batch tests using a dose of 0.4 g of BP-CCAC@ZC3, an initial Cr(VI) concentration of 20 mg/L, pH of 2, and 35 min contact time. Likewise, the adsorption process was effectively described by the Langmuir isotherm model, which had a high correlation coefficient (R2 = 0.9977) and a maximum adsorption capacity of 19.16 mg/g, indicating a monolayer adsorption mechanism. The BP-CCAC@ZC3 biochar exhibited reusability for up to four cycles with only a slight decrease in effectiveness, highlighting its potential for sustainable wastewater treatment. Overall, using corn cob and banana peel composites to synthesize activated carbon with ZnCl2 offers a promising method for effectively removing Cr(VI) containing wastewater.

Application of Aptenia cordifolia powder as a biosorbent for methylene blue retention from an aqueous medium: Isotherm, kinetic, and thermodynamic investigations

In this study, Aptenia cordifolia powder was utilized as a biosorbent material to effectively treat a synthetic aqueous solution polluted with methylene blue. The characterization of Aptenia cordifolia was conducted according to several analyses, including Fourier transforms infrared, scanning electron microscopy, the point of zero charge and energy dispersive X-ray. The retention process was investigated considering several factors including biosorbent mass, contact time, initial solution pH, temperature, and the initial concentration of methylene blue. The results obtained indicate that the optimal dose of adsorbent was 2 g.L−1. The equilibrium time was approximately 120 min, and the biosorption capacity of the biosorbent increases with an increase in pH. The pseudo-second-order model describes adequately the retention of methylene blue using Aptenia cordifolia. The Langmuir model proved to be more applicable in the analysis of the isotherm data, indicating a maximum retention amount of 51.82 mg.g−1. Moreover, the removal of methylene blue was thermodynamically endothermic, spontaneous, and favorable. These findings demonstrate the potential of Aptenia cordifolia biomass as an effective biosorbent for the treatment of dyes contaminated effluents.

Performance Assessment of a New Flat Sepiolite Clay-Based Ultrafiltration Membrane for the Removal of Paracetamol and Indigo Blue Dyes from Two Synthetic Aqueous Solutions

In the last decade, the development of a new generation of membranes based on low-cost materials has been widely studied. These membranes demonstrate significantly higher performance than the conventional ceramic membranes currently used in membrane separation technology. This work is focused on the development of a low-cost flat UF ceramic membrane composed completely of sepiolite using a uniaxial pressing method with dimensions of 5.5 cm of diameter and 3 mm of thickness. The sintering temperatures used were from 650 to 800 °C. Several properties, such as morphology, porosity, permeability, mechanical strength, and chemical resistance, are investigated. The results show that the mean pore diameter is increased from 40 to 150 nm when the sintering temperature increases from 650 °C to 800 °C. At these temperatures, excellent mechanical strength of 18 MPa to 22 MPa and high chemical resistance were achieved. SEM results revealed a crack-free structure with a uniformly smooth surface. Permeability tests were conducted using dead-end filtration. The sepiolite membrane demonstrated an improvement in its water permeability from 18 to 41 L·m−2·h−1·bar−1 when the sintering temperature increased from 650 °C to 750 °C. The efficiency of the sepiolite membranes sintered at 650 °C and 700 °C were evaluated with the application of the removal of paracetamol (PCT) and indigo blue (IB) dye separately from two synthetic aqueous solutions representing the pharmaceutical and textile sectors. Excellent removal efficiency of almost 100% for both contaminants was observed at ambient temperature and a pressure of 3 bars. Membrane regeneration was achieved through simple rinsing with deionized water. According to this finding, the UF sepiolite membrane demonstrated reversible fouling, which is consistent with the fouling coefficient “FRR” value higher than 90%.

Tetracycline removal using NaIO4 activated by MnSO4: Design and optimization via response surface methodology.

The appearance of recalcitrant organic pollutants such as antibiotics in water bodies has gained a lot of attention owing to their adverse effects on organisms and humans. The current study aims to develop a novel approach to eliminate antibiotic tetracycline (TC) from a synthetic aqueous solution based on the advanced oxidation process triggered by MnSO4-catalyzed NaIO4. A single-factor experiment was performed to observe the impact of pH, NaIO4 concentration, and MnSO4 dosage on TC decomposition, and a three-factor, three-level response surface experiment with TC removal rate as the dependent variable was designed based on the range of factors determined from the single-factor experiment. The single-factor experiment revealed that the ranges of pH, NaIO4 concentration, and MnSO4 dosage need to be further optimized. ANOVA (analysis of variance) results showed that the data from the response surface experiment were consistent with the quadratic model with high R2 (0.9909), and the predicted values were very close to the actual values. After optimization by response surface methodology, the optimal condition obtained was pH = 6.7, [NaIO4] = 0.39 mM, and [MnSO4] = 0.12 mM, corresponding to a TC removal of 96.56%. This optimization condition was fully considered to save the dosage of the high-priced chemical NaIO4.

Evaluation of Illitic-Kaolinite clay as an adsorbent for Cr3+ removal from synthetic aqueous solutions: Isotherm, kinetic, and thermodynamic analyses

This study explores the adsorption capabilities of Illitic-Kaolinite clay (IKC) as an effective adsorbent to remove chromium ions from aqueous solutions. To provide comprehensive insights into the adsorption process, the IKC material was characterized using several techniques including X-ray diffraction (XRD), X-ray fluorescence (FX), Fourier Transform Infrared Spectroscopy (FTIR), and Scanning Electron Microscopy coupled with Energy Dispersive X-ray (SEM-EDX). Qualitative mineralogical analysis of IKC reveals the presence of illite with minor amounts of kaolinite. The investigation encompassed an array of experimental parameters, such as adsorbent dosage (50–500 mg), adsorption contact time (0–180 min), solution pH (2–6), initial Cr3+ ion concentration (10–200 mg.L−1), and temperature (25–55 °C), in order to understand their influence on the adsorption process. The results indicated a clear connection between the efficiency of chromium removal and increases in pH, concentration and temperature, leading to improved chromium removal efficiency. The maximum adsorption capacity of IKC for chromium ions were evaluated as 14.27 mg.g−1. The adsorption data for chromium ion exhibited strong conformity to the Freundlich isotherm model (R²=0.98), while the kinetic data showed a significant correlation with the Elovich model (R²=0.993), suggesting that chemisorption governs the rate-limiting step. Thermodynamic analyses confirmed spontaneous and feasible adsorption, indicated by the negative value of ΔG. The positive values of ΔH and ΔS further revealed the endothermic nature of the process and an increase in molecular disorder at the solid-liquid interface during adsorption. The findings of this study provide valuable insights into the potential of Illitic-Kaolinite clay as an efficient and cost-effective adsorbent for the removal of heavy metals contaminants from aqueous solutions. This contribution supports ongoing efforts to address water pollution and purification challenges.

Cadmium Removal from Synthetic Aqueous Solutions by Adsorption on Peanut Shells: Kinetic and Thermodynamic Studies

Peanut shells were used in this study as an adsorbent carrier in the treatment of wastewater containing a trace metal element (TME), namely cadmium, a pollutant with adverse effects on health and the environment. The influences of contact time between adsorbent and adsorbate, initial cadmium concentration, adsorbent mass, reaction medium temperature and solution pH were evaluated. To determine the optimum parameters, pseudo-first-order and pseudo-second-order kinetic models were applied to the experimental results of the contact time study. Similarly, experimental results relating to the influence of concentration and temperature were modeled. Modeling of the data from the adsorbate-adsorbent contact time study showed that the kinetics of the cadmium adsorption reaction are well described by the pseudo-second-order kinetic model. The isotherm of the adsorption mechanism of cadmium ions (Cd2+) by peanut shells is perfectly described by the Freundlich equation. Thermodynamic studies using temperature variation have shown that adsorption is spontaneous and endothermic. This study led to a low entropy during cadmium adsorption. The best adsorption capacity was obtained at low pH = 5, i.e. favorable adsorption in acidic media.

Solid-liquid extraction for yttrium recovery using porous polymeric resin (XAD-7) functionalized with D2EHPA

The recovery of yttrium is proposed by applying a solid–liquid extraction process using di-2-ethyl hexylphosphoric acid (D2EHPA) as extracting agent. The extracting agents were supported on a macro porous polymeric resin XAD-7 (solid phase). Yttrium ions extraction and discharge tests were performed, firstly from a synthetic aqueous solution of 100 mg/L Y (liquid phase) at 25 °C with stirring. The effects of pH of aqueous solutions bearing yttrium, volume fraction of extracting agents and the solid/liquid (S/L) ratio on the yttrium recovery were studied. The most favorable conditions for yttrium ions extraction are: 20 vol% D2EHPA functionalized resin, pH = 1.5 and an S/L ratio of 10 mg/mL. The discharge of yttrium ions was done under the same conditions of extraction stage, using a 2 mol/L [H2SO4] as stripping solution. Up to 80% yttrium is extracted, while 75% yttrium is recovered in the striping solution. In all experiments, the reaction equilibrium is reached after 20 min, and the kinetics for the extraction stage was determined as a second-order model. Also, experiments were carried out to discharge the yttrium-loaded resins, and it has been determined that the best pH value to strip the Y ions is 1.5. Cyclic tests of extraction and discharge for yttrium ions show that the functionalized resin can work at least five cycles without decreasing its efficiency. Finally, the proposed process was tested in a real solution with Y ions from a waste fluorescent lamp powder leached in H2SO4, demonstrating the ability to effectively recover yttrium, separating it from various metals from the studied residue.

Effect of butanol, ethanol and acetone feed composition through activated carbon-containing polydimethylsiloxane pervaporation membrane

The ABE route, whose products are acetone, butanol and ethanol, is an industrial process that has been investigated by the possibility of incorporating renewable resources as inputs of chemical compounds and fuels. In view of the toxicity of 1-butanol to the cells of the fermentation broth, pervaporation by means of a polydimethylsiloxane mixed matrix membrane containing 1 wt% activated carbon was used as an alternative to recover this alcohol simultaneously to its production. Synthetic aqueous solution of acetone, 1-butanol and ethanol was investigated with total organic content varied from 1.5 to 2.7 wt%. Permeate flux and selectivity (separation and enrichment factors) were reported. Regarding the organics transport through the membrane, there was not a linear relation of their content in feed stream and flux. Besides, the permeation sequence did not follow a single transport mechanism. High separation and enrichment factors for acetone and butanol were observed.

Adsorption of toxic dye using red seaweeds from synthetic aqueous solution and its application to industrial wastewater effluents

This study investigated the potential application of dried powder from red seaweed Pterocladia capillacea as an eco-friendly adsorbent for removing Crystal Violet Dye (CV dye) from a synthetic solution. The adsorption conditions for the adsorbent were determined, in batch conditions, by changing different experimental parameters such as initial CV dye concentrations (5, 10, 20, 30, and 40 mg L–1), contact time (15, 30, 60, 120, and 180 min.), adsorbent doses (0.025, 0.05, 0.1, 0.2, and 0.3 g), temperature (25, 35, 45, and 55°C), and pH (3, 5, 7, 9, and 11). The adsorption mechanisms of CV dye onto the P. capillacea biomass were examined using various analytical techniques such as FTIR, BET, UV–Visible, and SEM. These characterizations suggest the average BET surface area of P. capillacea was 87.17 m2 g–1 and a pore volume of 0.10368 cc g−1. Moreover, according to the FTIR study, the dye has been deposited inside the adsorbent’s pores after adsorption. The adsorption behavior of the adsorbent was investigated by performing both kinetic and equilibrium isothermal studies in batch conditions at 25°C. Also, the thermodynamic factors showed the exothermic nature and physisorption of the adsorption process, which tends to be spontaneous at lower temperatures. In addition, Langmuir, Dubinin-Radushkevich, Freundlich, and Tempkin isotherm models were selected to evaluate the adsorption of CV dye on P. capillacea. The equilibrium adsorption data were best represented by the Freundlich, indicating multilayer adsorption on the heterogeneous surface. The qe experiment and calculation values for the Pseudo-Second-Order and interparticle diffusion kinetic models were determined. The results showed that, under optimum conditions P. capillacea exhibited 98% removal of CV dye from synthetic wastewater. Moreover, it will help to regenerate the adsorbents that can be reused to adsorb CV dye ions and develop a successful adsorption process. Finally, this study concluded that the dried powdered form of P. capillacea is an attractive source for adsorbing CV dye from aqueous solution.

Ammonium recovery and concentration from synthetic wastewater using a poly(4-methyl-1-pentene) (PMP) liquid–liquid membrane contactor: Flux performance and mass transport characterization

Hollow fiber membrane contactors are a promising technology for the removal and recovery of ammonia from liquid effluents. However, a better understanding of the process engineering (e.g. mass transport of ammonia over water) and performance optimization is required. In this study, the performance of a hollow fibre liquid–liquid membrane contactor (HF-LLMC), incorporating a new polymer chemistry (i.e., poly (4-methyl-1-pentene (PMP) and an asymmetric fibre structure, for the recovery and concentration of ammonium from synthetic aqueous solutions, was investigated. The influence of the feed and acid flow rates was evaluated experimentally by determining the overall mass transfer coefficient (kov), the ammonium recovery as a function of time and the acid consumption. In addition, the experimental results were fitted to a mathematical model to determine the membrane permeabilities to ammonia (PNH3) and water (Pw) and identify the mass transfer resistance regime. The highest kov values experimentally obtained were in the range of 3·10–3 to 3.51·10–3 m/h with corresponding ammonia recovery rates of 94 and 96.2% after 10 h, operating at a feed and acid flow rates of 180 L h−1 and 500 L h−1, respectively, which are in the upper range of the HF-LLMC literature. The overall results of this study were not only the upper range of the HF-LLMC ammonia recovery literature but a much-lower water transport was confirmed indirectly by the concentration factor (CF) values obtained experimentally. The remarkable selectivity of the membrane towards ammonia over water (i.e., PNH3 = 87–180 L m–2h−1 bar−1 and Pw = 1.2–1.4·10–3 L m−2 h−1 bar−1 at NTP conditions) is attributed to the asymmetrical membrane structure and the polymer chemistry (i.e., PMP). The proven high ammonia selectivity of the HF-LLMC makes it a promising technology for the recovery and concentration of ammonium from urban (e.g. wastewaters) and industrial (e.g. soda ash and fertilizers production) diluted streams.

Removal of Lead (Pb) From Aqueous Solutions Using Exoskeleton of Black Solider Fly (BSF)

Lead (Pb) pollution in water sources poses environmental and public health risk. It is important to mitigate the effects by developed an effective remediation method. The potential use of deceased black soldier fly (Hermetia illucens) to remove Pb from aqueous solutions was studied. The flies were ground into a fine powder, analyzed, and then subjected to adsorption studies using Pb synthetic aqueous solutions. Results showed that the deceased black soldier flies are effective in removing Pb from aqueous solutions. The findings lead to the development of resource-efficient heavy metal remediation methods that use the large biomass of black soldier flies.

Evaluation of the Adsorbent Potential of Biochar obtained by Pyrolysis to Remove Emerging Contaminants

Emerging contaminants (EC) can be harmful to human health and the environment, as many of these compounds are persistent, bioaccumulative, toxic and are not regulated. Drugs are part of this group, including hormones (estrone, β-estradiol) and sunscreens (oxybenzone and octocrylene) used in this study. The adsorption capacity of biochar generated from the pyrolysis of rice husks from the region of Pelotas-RS-Brazil was evaluated in this study. The objective was to characterize the biochar and evaluate its adsorbent potential in the removal of hormones and sunscreens. The characterization of biochar was carried out through surface area (BET), Zero charge point (ZPC), X-ray diffraction (XFR), fixed carbon, volatile, and ash. The effectiveness in removing ECs was evaluated by stirring rice husk pyrolysis biochar (RHPB) (0.2 g and 0.5 g) in synthetic aqueous solutions fortified with 10.0 µg L-1 of the analytes at 25 °C for 1 hour at 150 rpm. The RHPB was filtered off and the analytes were desorbed with acetone and dichloromethane (DCM) under ultrasound for 30 min. The extract was concentrated, derivatized by silylation, and analyzed by gas chromatography coupled to mass spectrometry (GC-MS). Biochar showed promising removal results, reaching values of 60.1% removal for β-estradiol, 59.4% for estrone, 44.6% for octocrylene and 37.4% for oxybenzone.

Eco-Friendly Synthesis of Copper Nanoparticles from Fiber of Trapa natans L. Shells and Their Impregnation Onto Polyamide-12 for Environmental Applications

ABSTRACT In this study, copper nanoparticles were synthesized from Trapa natans L. shells and loaded within polyamide-12 for use as an adsorbent. The synthesized nanocomposite was used for the first time to remove toxic methyl orange and brilliant green dye molecules from synthetic aqueous solutions. In order to characterize the plant-based nanocomposite, its functional groups, surface texture, elemental composition, structure, surface area, and crystallinity were determined. Adsorption efficiency was found to be affected by factors like pH (2–10), time (5–240 min.), and temperature (288–308 K). It was at pH 6 that the adsorbent reached the point of zero charge. During the adsorption process, electrostatic attraction played an influential role. Adsorption isotherms and kinetics data were well-fitted by Langmuir isotherms and pseudo-second-order models, respectively. A maximum adsorption capacity of 166.60 mg/gm was calculated for 93.90% methyl orange removal and 55.24 mg/gm for 97.30% brilliant green removal. The adsorption process was endothermic, spontaneous, and physical. The rapid desorption of dye molecules confirms the potential, and practicality of the nanocomposite as a promising adsorbent for decolorizing colored wastewater on an industrial scale.

Electrochemical reforming of a fusel oil stream from the winery industry: New insights for a circular economy based on renewable hydrogen

Herein, a novel study involving the electrochemical reforming in a PEM electrolyzer of an industrial by-product stream of fusel oil into hydrogen is presented using a Pt-Ni supported on graphene nanoplatelets anodic catalyst. For this purpose, pure fusel oil and various mixtures of this stream with acetic acid and water in different proportions were studied in terms of electrochemical activity and stability. The mixture with a volumetric proportion of 88 % fusel oil, 6.7 % acetic acid and 5.3 % water achieved the highest current density (210.5 mA·cm−2 at 1.4 V cell potential), which is a competitive value in comparison to other studies reporting the electrochemical reforming of synthetic aqueous ethanol solutions. Cyclic voltammetry experiments were performed at different potential ranges in order to select the optimal cell potential which minimizes the electrocatalyst deactivation. Chronoamperometry tests at this selected potential with intercalated open circuit voltage (OCV) steps demonstrated to be a suitable operation procedure, showing a reasonable stability of the system and thus, the viability in the usage of fusel oil as a liquid biofuel for pure hydrogen production. Finally, the FTIR analysis of the outlet anodic stream showed the oxidation of alcohols into carboxylic acids at a cell potential of 1.2 V.

Eco‐Friendly Biosorption of Uranium from Aqueous Solutions Using Sepiolite‐Cavex CA37 Composite Biosorbent

AbstractCavex CA37 is a dental material used for positive tooth impressions. After the mold is taken, it hardens through a fast‐chemical reaction with air, then becomes waste after usage. In this study, natural sepiolite and Cavex CA37 are mixed at certain ratios to obtain a composite SCX‐37 biosorbent that is used for the biosorption of ions from a synthetic aqueous solution. Parameters affecting biosorption, such as solution pH, ambient temperature, contact time, and ion concentration, are investigated. The biosorption of ions on SCX‐37 reaches equilibrium in 120 min with 97.56% efficiency at 30 °C and pH 4. The isotherms (Langmuir, Freundlich, and D‐R) and thermodynamic values of the biosorption of ions on the SCX‐37 biosorbent are calculated according to the obtained data. It is determined that there is a high correlation between experimental results and all three isotherm models. The adsorption capacity is found to be 41.39 mg g−1. The biosorption of ions onto the SCX37 biosorbent is a chemisorption process with an adsorption energy of 40.50 kJ mol−1.

Removal of copper and iron from ethanolic solutions by an anion exchange resin and its implication to rare-earth magnet recycling

In the recycling of end-of-life rare-earth magnets, the recovery of non-rare earth constituents is often neglected. In the present study, strong cation and anion exchange resins were tested batchwise for the recovery of the non-rare-earth constituents of permanent magnets (copper, cobalt, manganese, nickel and iron) from synthetic aqueous and ethanolic solutions. The cation exchange resin recovered most of metal ions from aqueous and ethanolic feeds, whereas the anion exchange resin could selectively recover copper and iron from ethanolic feeds. The highest uptake of iron and copper was found for 80 vol% and 95 vol% multi-element ethanolic feeds, respectively. A similar trend in selectivity of the anion resin was observed in breakthrough curve studies. Batch experiments, UV–Vis, FT-IR and XPS studies were performed to elucidate the ion exchange mechanism. The studies indicate that the formation of chloro complexes of copper and their exchange by the (hydrogen) sulfate counter ions of the resin have an important role in the selective uptake of copper from the 95 vol% ethanolic feed. Iron(II) was largely oxidized to iron(III) in ethanolic solutions and was expected to be recovered by the resin in the form of iron(II) and iron(III) complexes. The moisture content of the resin did not have a significant role on the selectivity for copper and iron.

Reduced Graphene Oxide/Waste-Derived TiO2 Composite Membranes: Preliminary Study of a New Material for Hybrid Wastewater Treatment

This work reports the preliminary results of the development of composite self-assembling membranes obtained by the combination of reduced graphene oxide (rGO) with commercial Degussa P25 titanium dioxide (TiO2). The purpose is to demonstrate the possibility of combining, in the same self-standing material, the capability to treat wastewater containing both inorganic and organic pollutants by exploiting the established ability of rGO to capture metal ions together with that of TiO2 to degrade organic substances. Moreover, this study also investigates the potential photocatalytic properties of tionite (TIO), to demonstrate the feasibility of replacing commercial TiO2 with such waste-derived TiO2-containing material, fulfilling a circular economy approach. Thus, rGO-TiO2 and rGO-TIO composite membranes, 1:1 by weight, were prepared and characterized by SEM-EDX, XRD, thermogravimetry, as well as by Raman and UV-Vis spectroscopies to verify the effective and homogeneous integration of the two components. Then, they were tested towards 3-mg L-1 aqueous synthetic solutions of Fe3+ and Cu2+ ions to evaluate their metal adsorption ability, with values of the order of 0.1-0.2 mmol gmembrane-1, comparable or even slightly higher than those of pristine rGO. Finally, the ability of the composites to degrade a common organic pesticide, i.e., Imidacloprid®, was assessed in preliminary photocatalysis experiments, in which maximum degradation efficiencies of 25% (after 3 h) for rGO-TiO2 and of 21% (after 1 h) for rGO-TIO were found. The result of tionite-containing membranes is particularly promising and worthy of further investigation, given that the anatase content of tionite is roughly 1/6 of the one in commercial TiO2.

In Situ Synthesis of Bimetallic Cu/Al for Removal of Cr(VI) from Synthetic Aqueous Solution

In Situ Synthesis of Bimetallic Cu/Al for Removal of Cr(VI) from Synthetic Aqueous Solution