New Evidence of the Enhanced Elimination of a Persistent Drug Used as a Lipid Absorption Inhibitor by Advanced Oxidation with UV-A and Nanosized Catalysts

Insights into Recent Advances of Biomaterials Based on Microbial Biomass and Natural Polymers for Sustainable Removal of Pharmaceuticals Residues

Pharmaceuticals are acknowledged as emerging contaminants in water resources. The concentration of pharmaceutical compounds in the environment has increased due to the rapid development of the pharmaceutical industry, the increasing use of human and veterinary drugs, and the ineffectiveness of conventional technologies to remove pharmaceutical compounds from water. The application of biomaterials derived from renewable resources in emerging pollutant removal techniques constitutes a new research direction in the field. In this context, the article reviews the literature on pharmaceutical removal from water sources using microbial biomass and natural polymers in biosorption or biodegradation processes. Microorganisms, in their active or inactive form, natural polymers and biocomposites based on inorganic materials, as well as microbial biomass immobilized or encapsulated in polymer matrix, were analyzed in this work. The review examines the benefits, limitations, and drawbacks of employing these biomaterials, as well as the prospects for future research and industrial implementation. From these points of view, current trends in the field are clearly reviewed. Finally, this study demonstrated how biocomposites made of natural polymers and microbial biomass suggest a viable adsorbent biomaterial for reducing environmental pollution that is also efficient, inexpensive, and sustainable.

Fast and Complete Destruction of the Anti-Cancer Drug Cytarabine from Water by Electrocatalytic Oxidation Using Electro-Fenton Process

The fast and complete removal of the anti-cancer drug cytarabine (CYT) from water was studied, for the first time, by the electro-Fenton process using a BDD anode and carbon felt cathode. A catalytic amount (10−4 M) of ferrous iron was initially added to the solution as catalyst and it was electrochemically regenerated in the process. Complete degradation of 0.1 mM (24.3 mg L−1) CYT was achieved quickly in 15 min at 300 mA constant current electrolysis by hydroxyl radicals (●OH) electrocatalytically generated in the system. Almost complete mineralization (91.14% TOC removal) of the solution was obtained after 4 h of treatment. The mineralization current efficiency (MCE) and energy consumption (EC) during the mineralization process were evaluated. The absolute (second order) rate constant for the hydroxylation reaction of CYT by hydroxyl radicals was assessed by applying the competition kinetics method and found to be 5.35 × 109 M−1 s−1. The formation and evolution of oxidation reaction intermediates, short-chain carboxylic acids and inorganic ions were identified by gas chromatography-mass spectrometry, high performance liquid chromatography and ion chromatography analyses, respectively. Based on the identified intermediate and end-products, a plausible mineralization pathway for the oxidation of CYT by hydroxyl radicals is proposed.

Investigation into Biosorption of Pharmaceuticals from Aqueous Solutions by Biocomposite Material Based on Microbial Biomass and Natural Polymer: Process Variables Optimization and Kinetic Studies

Biosorbtive removal of the antibacterial drug, ethacridine lactate (EL), from aqueous solutions was investigated using as biosorbent Saccharomyces pastorianus residual biomass immobilized in calcium alginate. The aim of this work was to optimize the biosorption process and to evaluate the biosorption capacity in the batch system. Response surface methodology, based on a Box–Behnken design, was used to optimize the EL biosorption parameters. Two response functions (removal efficiency and biosorption capacity) were maximized dependent on three factors: initial concentration of EL solution, contact time, and agitation speed. The highest values for the studied functions (89.49%, 26.04 mg/g) were obtained in the following operational conditions: EL initial concentration: 59.73 mg/L; contact time: 94.26 min; agitation speed: 297.57 rpm. A number of nonlinear kinetic models, including pseudo-first-order, pseudo-second-order, Elovich, and Avrami, were utilized to validate the biosorption kinetic behavior of EL in the optimized conditions. The kinetic data fitted the pseudo-first-order and Avrami models. The experimental results demonstrated that the optimized parameters (especially the agitation speed) significantly affect biosorption and should be considered important in such studies.

Biosorption Potential of Microbial and Residual Biomass of Saccharomyces pastorianus Immobilized in Calcium Alginate Matrix for Pharmaceuticals Removal from Aqueous Solutions

Two types of biosorbents, based on Saccharomyces pastorianus immobilized in calcium alginate, were studied for the removal of pharmaceuticals from aqueous solutions. Synthetized biocomposite materials were characterized chemically and morphologically, both before and after simulated biosorption. Ethacridine lactate (EL) was chosen as a target molecule. The process performance was interpreted as a function of initial solution pH, biosorbent dose, and initial pharmaceutical concentration. The results exhibited that the removal efficiencies were superior to 90% for both biosorbents, at the initial pH value of 4.0 and biosorbent dose of 2 g/L for all EL initial concentrations tested. Freundlich, Temkin, Hill, Redlich-Peterson, Sips, and Toth isotherms were used to describe the experimental results. The kinetic data were analyzed using kinetic models, such as pseudo-first order, pseudo-second order, Elovich, and Avrami, to determine the kinetic parameters and describe the transport mechanisms of EL from aqueous solution onto biosorbents. Among the tested equations, the best fit is ensured by the pseudo-second-order kinetics model for both biosorbents, with the correlation coefficient having values higher than 0.996. The many potential advantages and good biosorptive capacity of Saccharomyces pastorianus biomass immobilized in calcium alginate recommend these types of biocomposite materials for the removal of pharmaceuticals from aqueous solutions.

Biosorptive Removal of Ethacridine Lactate from Aqueous Solutions by Saccharomyces pastorianus Residual Biomass/Calcium Alginate Composite Beads: Fixed-Bed Column Study

In this study, ethacridine lactate removal from aqueous solution using a biosorbent material based on residual microbial biomass and natural polymers in fixed-bed continuous column was investigated. Composite beads of Saccharomyces pastorianus residual biomass and calcium alginate were obtained by immobilization technique. The prepared biosorbent was characterized by Fourier transformed infrared spectroscopy, scanning electron microscopy, and analysis of point of zero charge value. Then, laboratory-scale experiments by fixed-bed column biosorption were conducted in continuous system. To this purpose, the column bed high (5 cm; 7.5 cm), initial pollutant concentration (20 mg/L; 40 mg/L), and solution flow through the column (0.6 mL/min; 1.5 mL/min) were considered the main parameters. Recorded breakthrough curves suggest that lower flow rates, greater bed heights, and a lower concentration of ethacridine lactate led to an increased biosorption of the target compound. The biosorption dynamic was investigated by nonlinear regression analysis using the Adams–Bohart, Yoon–Nelson, Clark, and Yan mathematical models. Conclusively, our research highlights, firstly, that the obtained biosorbent material has the required properties for retaining the ethacridine lactate from aqueous solution in continuous system. Secondly, it emphasizes that the modeling approach reveals an acceptable fitting with the experimental data for the Yoon–Nelson, Clark, and Yan models.

Encapsulation of Saccharomyces pastorianus Residual Biomass in Calcium Alginate Matrix with Insights in Ethacridine Lactate Biosorption

Pharmaceuticals are recognized as emerging water microcontaminants that have been reported in several aquatic environments worldwide; therefore, the elimination of these pollutants is a global challenge. This study aimed to develop a biosorbent based on Saccharomyces pastorianus residual biomass encapsulated in a calcium alginate matrix and to evaluate its biosorption performance to remove Ethacridine Lactate (EL) from aqueous solutions. Firstly, the synthesis and characterization of biosorbent has been carried out. Then, the impact of main parameters on biosorption process were investigated by batch experiments. Finally, the kinetics behavior and equilibrium isotherms were evaluated. The resulted beads have an irregular and elongated shape with about 1.89 mm ± 0.13 mm in size with a homogeneous structure. The best removal efficiency for EL of over 85% was obtained at acidic pH 2 and 25 °C for 50 mg/L initial concentration and 2 g/L biosorbent dose. The pseudo-second-order and intraparticle diffusion kinetics describe the biosorption process. The maximum calculated biosorption capacity was 21.39 mg/g similar to that recorded experimentally. The equilibrium biosorption data were a good fit for Freundlich and Dubinin–Radushkevich isotherms. Our findings reveal that the low cost and eco-friendly obtained biosorbent can be easily synthesized and suitable to remove Ethacridine Lactate from water matrices.

Urea-Assisted Synthesis of Mesoporous TiO2 Photocatalysts for the Efficient Removal of Clofibric Acid from Water

Mesoporous TiO₂ photocatalysts intended for the advanced removal of clofibric acid (CA) from water were synthesized by the sol-gel method in a medium containing cetyl-trimethyl-ammonium bromide (CTAB) and urea, using either ethanol or isopropanol to dilute the TiO₂ precursor. The activation of the samples was undertaken at 550, 650 and 750 °C. The XRD revealed that the nature of the solvent resulted in significant differences in the anatase-to-rutile ratios obtained at different temperatures. The specific surface area values were situated between 9 and 43 m²·g⁻¹ and the band gap values were similar for all the samples. The photocatalytic activity of the prepared samples was examined for the degradation of CA, an emergent water contaminant. The photocatalytic tests performed under UV-A irradiation revealed that the photo-reactivity of these materials depends on the calcination temperature. The best results were obtained for the samples calcined at 750 °C, which showed high yields of CA elimination, as well as almost complete mineralization (over 95%) after 180 min of reaction. Good results in terms of catalyst reusability in the reaction were found for the catalyst showing the highest photo-reactivity. Therefore, the samples can be considered good candidates for future water remediation applications.

Eco-Friendly Biosorbents Based on Microbial Biomass and Natural Polymers: Synthesis, Characterization and Application for the Removal of Drugs and Dyes from Aqueous Solutions

Pharmaceuticals and dyes are a very important part of the nonbiodegradable or hard biodegradable substances present in wastewater. Microorganisms are already known to be effective biosorbents, but the use of free microbial cells involves difficulties in their separation from effluents and limits their application in wastewater treatment. Thus, this study aimed to develop biosorbents by immobilizing Saccharomyces cerevisiae, Saccharomyces pastorianus and Saccharomyces pastorianus residual biomass on natural polymers (alginate and chitosan) and to evaluate the biosorptive potential for removal of pharmaceuticals and dyes from water. Six types of biosorbents were synthesized and characterized by Scanning Electron Microscopy and Fourier Transform Infrared Spectroscopy techniques and their biosorptive capacities for three drugs (cephalexin, rifampicin, ethacridine lactate) and two dyes (orange II and indigo carmine) were evaluated. The obtained results show that the removal efficiency depends on the polymer type used for the immobilization. In case of alginate the removal efficiency is between 40.05% and 96.41% for drugs and between 27.83% and 58.29% for dyes, while in the case of chitosan it is between 40.83% and 77.92% for drugs and between 17.17% and 44.77% for dyes. In general, the synthesized biosorbents proved to be promising for the removal of drugs and dyes from aqueous solutions.

Application of Saccharomyces cerevisiae/Calcium Alginate Composite Beads for Cephalexin Antibiotic Biosorption from Aqueous Solutions

Cephalexin (CPX) is recognized as a water pollutant, and it has been listed in a number of countries with a risk factor greater than one. Herein, the present work focused on the synthesis, characterization and biosorption capacity evaluation of Saccharomyces cerevisiae immobilized in calcium alginate as a biosorbent to remove CPX from aqueous solutions. Biosorbent was characterized by SEM and FTIR techniques. Batch biosorption experiments were conducted in order to evaluate the effect of the initial pH, biosorbent dose and CPX initial concentration. The removal efficiency, in considered optimal conditions (pH = 4, CPX initial concentration = 30 mg/L, biosorbent dose = 1 g/L) was 86.23%. CPX biosorption was found to follow the pseudo–second-order kinetics. The equilibrium biosorption data were a good fit for the Langmuir model with correlation coefficient of 0.9814 and maximum biosorption capacity was 94.34 mg/g. This study showed that the synthesized biosorbent by immobilization technique is a low-cost one, easy to obtain and handle, eco-friendly, with high feasibility to remove CPX antibiotic from aqueous solution. The findings of this study indicate that the biosorbents based on microorganisms immobilized on natural polymers have the potential to be applied in the treatment of wastewater.

TiO2 Doped with Noble Metals as an Efficient Solution for the Photodegradation of Hazardous Organic Water Pollutants at Ambient Conditions

This work highlights new insights into the performance of TiO2 doped with noble metal catalysts for the photocatalytic degradation of organic water pollutants. Different samples of titanium dioxide doped with noble metals (Au and Pd) were successfully synthesized via incipient wet impregnation (IWI) and ultrasound-assisted impregnation (US) methods. X-ray diffraction, scanning electron microscopy and UV-Vis reflectance spectroscopy were used for the characterization of the obtained materials. Their photocatalytic efficiency was investigated in aqueous suspension thorough a series of laboratory tests performed under ultraviolet (UV-A) irradiation conditions using 2,4 dinitrophenol (2,4 DNP) as a target molecule. The results clearly show that the method used for the catalyst synthesis affects its photocatalytic activity. It was found that the samples prepared by the IWI method exhibited high photocatalytic activity, and the removal rate obtained with TiO2-Pd/IWI was higher than that found for TiO2-Au/IWI. Furthermore, for the best catalyst, some extra photocatalytic experiments were conducted with rhodamine 6G (R6G), a highly stable molecule with a very different chemical structure to 2,4 DNP, in order to check the reactivity of this material. Moreover, the recycling experiments carried out with TiO2-Pd/IWI clearly demonstrated the high photocatalytic stability of this material for the degradation of 2,4 DNP. All of the collected data confirmed the interesting photocatalytic potential of the selected catalyst in the elimination of organic pollutants with no obvious change in its reactivity after four reaction cycles, which is very promising for promoting future applications in water depollution.

Zn/La Mixed Oxides Prepared by Coprecipitation: Synthesis, Characterization and Photocatalytic Studies

Mixed oxides containing zinc and lanthanum were prepared by coprecipitation in alkaline medium, followed by calcination at 400 °C. The initial precipitation product and the calcined form were characterized by Brunauer-Emmett-Teller (BET) method adsorption of nitrogen at -196 °C, Scanning Electron Microscopy/Electron-Probe Microanalysis (SEM/EPM), Ultraviolet-Diffuse Reflectance Spectroscopy (UV-DRS) and Infrared (IR) spectroscopy. The band gap slightly changes from 3.23 eV to 3 eV by calcination. The photocatalytic performance of the solids were investigated in diluted aqueous medium, by using clofibric acid (CA), a stable and toxic molecule used as precursor in some pesticides and drugs, as test compound, possibly found in the wastewaters in low concentrations. The effects of the degradation extent, determined by high performance liquid chromatography (HPLC) and total organic carbon (TOC) measurements, were investigated at different initial concentrations of CA. Within about 60 min the CA degradation is almost total at low concentration values (3 ppm) and reaches over 80% in 180 min for an initial concentration of 50 ppm. Moreover, the CA removal performance of photocatalyst remains excellent after three cycles of use: the removal yield was practically total after 60 min in the first two cycles and reached 95% even in the third cycle.