Min Of Contact Time Research Articles

Sorption capacity of biochars obtained by gasification of rice husks and wild sugarcane: removal of malachite green and arsenic from water solutions

AbstractThe presence of contaminants in water has been of great concern worldwide, as it causes health risks to living organisms and general deterioration of the environment. Therefore, their elimination is essential. In the present study, rice husk (BRH) and wild sugarcane (BWS) biochars obtained by gasification were evaluated for their use as sorbents of malachite green dye (MG) and arsenite [As (III)] in aqueous solution. The chemical composition and physical structure of the two biochars were characterized by various techniques, including elemental analysis, N2 adsorption–desorption isotherms, FTIR, and Z potential. In addition, the adsorbate removal rate was determined using the pseudo-first-order and pseudo-second-order models. Batch sorption studies were carried out to remove arsenite and MG from aqueous solutions, considering the operating parameters such as initial solution pH, temperature, contact time, concentration, and temperature. The results showed that 120 min contact time is enough to reach sorption equilibrium. The percent removal of BRH and BWS to MG was 61.99% and 97.46%, respectively, while for arsenite, it was 82.79% and 82.36%, respectively. The kinetic analysis concluded that the sorption process predominantly followed the pseudo-second-order kinetic model for both case studies since the R2 value is approximately one. The sorption capacity calculated based on this model fitted better with the sorption capacity experimental. Finally, it was demonstrated that BRH and BWS biochars obtained as a by-product of rice husk and wild sugarcane gasification could be used as low-cost sorbent materials to remove MG dye and arsenite from an aqueous solution.

Zirconium/lanthanum-modified chitosan/polyvinyl alcohol composite adsorbent for rapid removal of fluoride

A novel and easily separable adsorbent in the shape of a membrane for the rapid removal of fluoride from water was prepared after testing Zr, La and LaZr to modify a chitosan/polyvinyl alcohol composite adsorbent (CS/PVA-Zr, CS/PVA-La, CS/PVA-LA-Zr). The CS/PVA-La-Zr composite adsorbent can remove a large amount of fluoride within 1 min of contact time, and the adsorption equilibrium can be reached within 15 min. The fluoride adsorption behavior of the CS/PVA-La-Zr composite can be described by pseudo-second-order kinetics and Langmuir isotherms models. The morphology and structure of the adsorbents were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD). The adsorption mechanism was studied using Fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS), and which showed that ion exchange occurred mainly with hydroxide and fluoride ions. This study showed that an easily operable, low-cost and environmentally friendly CS/PVA-La-Zr has the potential to remove fluoride effectively from drinking water in a short time.

Removal of heavy metals, turbidity and coliform from contaminated raw drinking water using Saccharomyces cerevisiae, the Baker's yeast

The efficiency of Saccharomyces cerevisiae (baker's yeast) was investigated for biosorption of Ni, Cu and Al, turbidity and total coliform reduction from raw drinking water and as coagulant aid with alum (aluminum sulphate). Optimization of metal biosorption (at 50 mg/L initial metal ion concentration) using dried baker's yeast was performed using different pH (1–7), bio-sorbent (yeast) dosage (0.02 –2.0 g/L) and contact time (5.0–90 min). S. cerevisiae exhibited high selectivity towards Cu removal compared to Al and Ni at pH 7, 0.5 g yeast dosage and 30 min contact time, which considered the optimum conditions. Concurrently with metal removal bioassay, baker's yeast was tested as a coagulant aid in a parallel assay. Addition of 1.5 mg/L baker's yeast to the optimum dose of alum (24 mg/L) enhanced turbidity removal reaching 95.43% compared to 90% achieved when alum was used alone. Also, total coliform (TC) was reduced by 92.86% from initial density of 280 CFU/100 mL in the raw water when 1.0 mg/L baker's yeast was added to the optimum alum compared to 67.86% with alum alone. Therefore, it is recommended to use baker's yeast as coagulant aid with alum as primary coagulant. Results of the present study confirmed the important role of the baker's yeast for the removal of heavy metals, turbidity and coliform bacteria associated with the raw drinking water at the tested area. Moreover, results exhibited high efficiency of baker's yeast as a coagulant aid in the improvement of the drinking water treatment process performance.

Verification of the optimal kinetics behaviour during the methyl blue dye adsorption onto quaternized starch derivative

This paper reports the adsorption of methyl blue dye onto a quaternized starch derivative (S-Quat) from an aqueous solution. The starch derivatization was achieved via the reaction between (3-chloro-2-hydroxypropyl) tri-methyl ammonium chloride (Quat-188) and maize starch in the presence of aqueous sodium hydroxide. Various instrumental characterization techniques were deployed to confirm the presence of important functional groups, crystalline structure and surface texture/morphology, which played key roles during the dye uptake. The Brunauer–Emmett–Teller (BET) surface area and pore size of the S-Quat were recorded as 41.328 ​m2. g−1 and 1.763 ​nm, respectively. The effect of solution pH, contact time and adsorbent concentration on the adsorption capacity of the S-Quat were examined via batch mode. Maximum adsorption of ∼260 ​mg/g was achieved at pH 2.0 ​and 75 ​min contact time. Furthermore, the kinetic data modelling showed that the Fractional power, Brouser–Weron–Sotolongo (BWS), and Fractal-like PFO (FPFO) models, respectively, were the top three models of best fit. Thus, the quaternized starch derivative (S-Quat) showed good dye adsorption potentials.

Phytoremediation of Wastewater Containing Lead and Manganese Ions Using Algae.

Heavy metal pollution of water from industrial discharge is a major problem worldwide. Thus, the quality of the environment and human health are severely affected. Various conventional technologies have been applied for water treatment, but these can be expensive, especially for industrial water treatment, and may have limited treatment efficiencies. Phytoremediation is a method that is successfully applied to remove metal ions from wastewater. In addition to the high efficiency of the depollution treatment, this method has the advantages of a low cost of the operation and the existence of many plants that can be used. This article presents the results of using algae (Sargassum fusiforme and Enteromorpha prolifera) to treat water containing manganese and lead ions. It was observed that maximum efficiencies for wastewater treatment were obtained when was used the algae Enteromorpha prolifera for a 600 min contact time period. The highest wastewater treatment efficiency obtained using Sargassum fusiforme was 99.46%.

Effective removal of Rhodamine B using the hydrothermal carbonization and citric acid modification of furfural industrial processing waste

ABSTRACT In this study, the removal of RhB from water by furfural residue (FR) biochar was prepared by hydrothermal carbonization (HTC) and citric acid (CA) modification and named this biochar as CHFR (C refers to citric acid, H refers to hydrothermal carbonization and FR is furfural residue). The CHFR were characterized by SEM, FT-IR and XPS, and CHFR was investigated by the effects of initial concentration, adsorbent dosage, pH, and contact time on the removal of RhB, and the experimental data were analyzed using the adsorption isotherm models, the adsorption kinetic models and thermodynamics, et al. The results showed that CHFR has strong adsorption performance, and the theoretical maximum adsorption capacity of RhB was 39.46 mg·g−1 under the reaction conditions of pH3, the dosage of 1.5 g·L−1, and 120 min contact time, with a removal efficiency close to 100%. the adsorption of RhB by CHFR is spontaneous and endothermic, which is consistent with the Freundlich adsorption, and the isotherm model fits well with the pseudo-second-order model, and the adsorption rate could still be as high as 92.74% after five regenerations, therefore, CHFR is an environmentally friendly and efficient adsorbent with excellent adsorption regeneration performance.

REMOVAL OF PHENOLIC COMPUNDS FROM AQUEOUS SOLUTIONS BY ADSOPTION ONTO ACTIVTED CARBONS PREPARED FROM DATE STONES BY CHEMICAL ACTIVATION WITH FeCl3

Activated carbon prepared from date stones by chemical activation with ferric chloride (FAC) was used an adsorbent to remove phenolic compounds such as phenol (Ph) and p-nitro phenol (PNPh) from aqueous solutions. The influence of process variables represented by solution pH value (2-12), adsorbent to adsorbate weight ratio (0.2-1.8), and contact time (30-150 min) on removal percentage and adsorbed amount of Ph and PNPh onto FAC was studied. For PNPh adsorption,( 97.43 %) maximum removal percentage and (48.71 mg/g) adsorbed amount was achieved at (5) solution pH,( 1) adsorbent to adsorbate weight ratio, and (90 min) contact time. While for Ph adsorption, at (4) solution pH, (1.4) absorbent to adsorbate weight ratio, and (120 min) contact time gave maximum removal percentage( 86.55 %) and (43.27 mg/g) adsorbed amount. Equilibrium adsorption data of PNPh and Ph onto FAC were well represented by Langmuir isotherm model, showing maximum adsorbed amounts of (185.84 mg/g) and (159.27 mg/g) for PNPh and Ph, respectively.

Effective removal of selected pharmaceuticals from sewerage treatment plant effluent using natural clay (Na-montmorillonite)

The consumption of pharmaceuticals has rapidly increased on a global scale due to the serious increase in Covid-19, influenza and respiratuar sinsityal virus, which is called “triple epidemic” in the world. The use of non-prescription analgesic and anti-inflammatory drugs (AAIDs), especially paracetamol, is higher compared to pre-pandemic. This increased the AAIDs load discharged to the aqueous media through sewerage treatment plant (STP). Therefore, simple and effective treatment options for removing AAIDs from STP effluents are needed. The aim of the study was to remove AAIDs (paracetamol, acetylsalicylic acid, codeine, diclofenac, ibuprofen, indomethacin, ketoprofen, mefenamic acid, naproxen, and phenylbutazone) from STP effluents by nearly pure natural clay Na-montmorillonite. The Na-montmorillonite taken from the Ordu region in the northern part of Turkey. Surface area of the Na-montmorillonite is 99.58 m2/g and CEC is 92.40 meq/100 g. The removal efficiencies of AAIDs using Na-montmorillonite were between 82 ± 5% (ibuprofen) and 94 ± 4% (naproxen). Paracetamol was used as a model compound in kinetic and isotherm model studies. Freundlich isotherm model and the pseudo second order kinetic model were the best-fit using the obtained experimental data. Film diffusion governed its rate mechanism. The paracetamol adsorption capacity was acquired as 244 mg/g at 120 min contact time at pH 6.5 at 25 °C. With this study, it could be shown that montmorillonite can be used effectively to eliminate paracetamol from STP effluent. Natural clay can be used as a simple, inexpensive and effective adsorbent for removing AAIDs from STP effluents.

Graphene quantum dots decorated MIL-100(Fe) composites for dye degradation

The present work outlines the synthesis of a visible light responsive photocatalyst by incorporating graphene quantum dots (GQD) in an iron-based metal organic framework (MOF) (i.e., MIL-100(Fe). The composite was synthesized via one-pot solvothermal approach and applied for degradation of Congo red (CR) dye from contaminated water. The composite was characterized in terms of structure, functionality, morphology, and optical properties. Noteworthy, the composite showed significant improvement in the photocatalytic activity in comparison with nascent MIL-100(Fe). Incorporation of GQD in the MOF framework resulted in increased surface area and pore volume and reduced PL intensity. MIL-100/GQD showed maximum dye degradation of 93.8% within 5 min of contact time using photocatalyst dose of 0.025 g/L. The incorporation of GQD resulted in increased charge separation between holes and electrons compared to pre MIL-100 (Fe) as evident from the PL spectra. The Mott-Schottky plot and the trapping experiment demonstrated that the active species like h+ and ̇O2− were responsible for degradation of CR dye. The photocatalyst exhibited appreciable reusability even after four cycles of reuse.

The Effectiveness of Ionized Water as a Radiodecontaminant for 99mTc-Pertechnetate and 131I.

Immediate and complete decontamination procedures are essential to restore the functionality, precision, accuracy, and safety of tests done within the nuclear medicine facility. Decontamination is a simple procedure that, if performed correctly, effectively reduces exposure brought about by spills. The determination of a suitable radiodecontaminant may be beneficial in decontaminating patient beds, collimators, probes, and machines. Methods: Two surface types (i.e., stainless steel and vinyl) were contaminated with a predetermined activity of 99mTcO4 and 131I. After air drying, static images of the contaminated surfaces were obtained using a γ-camera to determine the activity counts on each surface before and after decontamination procedures. Different decontaminant contact times (i.e., 5, 10, and 15 min) were used for each decontaminant (i.e., ionized water, 10% bleach, detergent solution, a negative control [no treatment], and a positive control [a commercial radiodecontaminant]). Differences between the effectiveness of ionized water and the other decontaminants against 99mTcO4 and 131I at different contact times were measured, and the mean percentage activity removed (%AR) was compared using 2-way ANOVA at the 0.05 level of significance. Results: 99mTcO4 and 131I contaminants had %ARs of greater than 80% after 5 min of contact time for ionized water and the other decontaminants. At 15 min contact time, ionized water was not as effective as the other decontaminating agents for 131I on vinyl surfaces. There was no significant interaction between the effects of the decontaminants (%AR) and the contact times with stainless steel and vinyl for either 99mTcO4 or 131I. Conclusion: For 99mTcO4 and 131I on stainless steel surfaces, ionized water is an effective decontaminant at contact times of 5, 10, and 15 min. For 99mTcO4 on vinyl surfaces, ionized water is also an effective decontaminant at contact times of 5, 10, and 15 min. For 131I on vinyl surfaces, ionized water is as effective as 10% bleach, detergent solution, and a commercial radiodecontaminant at contact times of 5 and 10 min.

Design of Experiments Study on Scottish Wood Biochars and Process Parameter Influence on Final Biochar Characteristics

Native Scottish wood samples were investigated as potential, locally sourced, raw materials for biochar production. Screening experiments identified pure softwood as the preferable feedstock. Influence of operational parameters, i.e. activating gas flow rate (CO2), heating ramp rate and contact time on final biochar characteristics, was investigated using design of experiments. Surface area and biochar yield were selected as response variables. Minitab was used to define experimental run conditions and suggested an optimal output at 60 min contact time and 15 °C/min ramp rate for maximum responses. The highest surface area (764 m2/g) was achieved at 850 °C from softwood, albeit with a low yield of 15%. Under optimised conditions, the observed surface area was 613 m2/g with ~ 18% yield. Pareto charts suggested no influence of gas flow rate on chosen responses, which correlated well with experimental data. Pore structure was a combination of micro- and mesopores with average pore widths of 3–5 nm and an average point of zero charge of 7.40 ± 0.02. Proximate analysis showed an increase in fixed carbon content from 20%, in the feedstock, to 80%, in the optimised biochar. Morphological analysis showed a layered carbon structure in the biochars. The results show the significance of the selected feedstock as a potential source of biochar material and the relevance of interplay of operational variables in biochar development and their final characteristics.

Microwave–osmotic–vacuum combination drying of mango cubes with maltodextrin moderated sucrose solution

A microwave–osmotic–vacuum combination drying technique was used to evaluate the effect of processing factors such as temperature and concentration with 15% inclusion of maltodetrin (dextrose equivalent, DE 10) during the microwave osmotic drying under continuous medium spray flow (MWODS) and power level during finish microwave vacuum drying (MVD). Moisture loss (ML), solids gain (SG), ML/SG ratio, weight reduction (WR), bulk density (BD), rehydration capacity (RC), drying times, and quality parameters, total color difference (ΔE), texture (hardness and chewiness) were evaluated during the process to assess the product quality. Drying conditions were optimized to maximize ML, ML/SG, WR, BD, RC and minimize ΔE, hardness, chewiness, and drying times. Optimum levels were found at 58.5 °C temperature, 50.0% concentration, and 30 min contact time during MWODS and 20% initial power up to 50% moisture content and 10% final power level to the final moisture content of 20% (32 min). In addition to MVD, freeze drying, vacuum and air drying were also used for comparison for finish drying. Overall, the MWODS with maltodextrin moderated sucrose as solute and MVD for finished drying resulted in better product quality and remained closest to the freeze dried samples.

Delmopinol hydrochloride inhibits Campylobacter jejuni on skinless poultry meat, stainless steel and high-density polyethylene food contact surfaces.

Delmopinol hydrochloride (delmopinol) is a cationic surfactant that is effective for treating and preventing gingivitis and periodontitis. This study evaluated the effectiveness of delmopinol for reducing attachment of Campylobacter jejuni to chicken meat, stainless steel and high-density polyethylene (HDPE). These test materials were spot-inoculated with a C. jejuni culture. After 10min, samples were sprayed with 0.5% or 1.0% delmopinol, 0.01% sodium hypochlorite, or distilled water. After a 1, 10, or 20min contact time, samples were rinsed which were serially diluted onto Campy-Cefex Agar. For additional samples, solutions were applied before inoculation with C. jejuni. Cultures remained undisturbed for 1, 10, or 20min. Samples were then rinsed and plated as above. When C. jejuni was inoculated before treatments, 1% delmopinol application led to mean log reductions of 1.26, 3.70, and 3.72 log cfu ml-1, greater than distilled water alone, for chicken, steel and HDPE respectively. When C. jejuni was inoculated after spray treatments, 1% delmopinol reduced C. jejuni by 2.72, 3.20, and 3.99 mean log cfu ml-1 more than distilled water for chicken, steel and HDPE respectively. Application of 1% delmopinol, resulted in a significantly (P<0.05) greater log reduction than a 0.01% sodium hypochlorite or distilled water application.

Statistical optimization of process parameters for ultrafast uptake of anionic azo dyes by efficient sorbent: Zn/Cu layered double hydroxide

The extensive use and release of synthetic dyes by various industries is a primary cause of contamination of water resources. Herein, the adsorption efficiency of Zn/Cu layered double hydroxide (LDH) was estimated for the uptake of a series of anionic dyes, out of which maximum removal efficiency was observed for Congo red (CR) dye. The effect of processing parameters, mainly adsorbate and adsorbent concentration, contact time, and pH on the adsorption capacity of CR dye, was analyzed by making use of response surface methodology (RSM). Based on the analysis of variance and experimental results, the modified quadratic regression model was found to be statistically acceptable. Further, the ultrafast removal efficiency of the synthesized material was observed with the maximum percentage removal of dye (&gt;99%) within 4 min of contact time. In addition, batch adsorption experiments were conducted under the optimized reaction conditions for equilibrium and kinetic studies. Langmuir isotherm (R2 = 0.9965) and pseudo‐second‐order model (R2 = 1.0) were found to be the best‐fitted isotherm and kinetic models, respectively. Using Langmuir isotherm, the maximum adsorption capacity of the sorbent was calculated to be 167.22 mg/g. Furthermore, the adsorbent exhibited excellent regeneration capability and can be used efficiently for up to three cycles with &gt;90% dye removal. The adsorption behavior of Zn/Cu LDH in different water matrices, that is, tap water, groundwater, and textile wastewater, was also investigated suggesting it to be an excellent adsorbent for real‐time applications.

Design and photo-Fenton performance of Graphene/CuS/Fe3O4 tertiary nanocomposites for Rhodamine B degradation

This study describes nanocomposites of graphene flakes (GF) combined with CuS, Fe3O4 and CuS−Fe3O4 nanoparticles prepared by wet chemical methods. The Fe3O4 and/or CuS nanoparticles were directly anchored onto GF without requiring additional chemical treatment. The composition, structure and morphology of the nanocomposites, as well as of the pristine GF and metal oxide/sulfide nanoparticles were characterised by X − ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), powder X − ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The results confirmed the successful attachment of CuS nanophases (size range: 23.7–50.1 nm) and/or Fe3O4 nanoparticles (size range: 10.6–15.8 nm). The adsorption and photocatalytic properties of the GF−based nanocomposites were evaluated at room temperature using Rhodamine B (RhB) as a model contaminant. Theoretical models were fitted to the adsorption kinetic results using the pseudo-first-order, pseudo-second-order and Elovich equations, while the adsorption mechanism was determined using the intraparticle diffusion, Bangham and Boyd models. The RhB adsorption efficiency was 6.5% for GF@CuS−Fe3O4 after 180 min contact time, whereas for the other materials was significantly higher: 97.6%, 60.9% and 31.9% for GF, GF@CuS and GF@Fe3O4, respectively. The adsorption capacity of GF and composites fitted the pseudo−second−order kinetic and Elovich models. The influence of the nanostructures composition on the corresponding photocatalytic activity in the degradation of RhB under a 150 W halogen lamp was also evaluated. The GF@CuS−Fe3O4 nanocomposite totally eliminated the dissolved RhB after 60 min irradiation, whereas the GF@CuS, GF@Fe3O4 and pristine Fe3O4 removed 75.6%, 80.9% and 30.8%, respectively, after 180 min irradiation. It was found that the photocatalytic behaviour of the composites was best described by the first−order kinetic model. The rate constant of the photocatalytic RhB removal for GF@CuS−Fe3O4 (k = 7.05 ×10−2 min−1) was 2.1, 5.1 and 15.0 times higher than those obtained for GF@CuS, GF@Fe3O4 and pristine Fe3O4, respectively, after 60 min of visible light irradiation.

Preparation and characterization of low-cost adsorbents for the efficient removal of malachite green using response surface modeling and reusability studies

Malachite green used in textile and dyeing industries is a common persistent pollutant in wastewater and the environment causing major hazards to human health and aquatic organisms. In this study, the response surface methodology was applied to optimize the adsorptive removal of malachite green using nano-bentonite, MgO-impregnated clay, and Mucor sp. composites. The nano materials and Mucor sp. composite were characterized by FTIR, SEM and X-ray diffractometry. According to the obtained results, nano-bentonite exhibits a maximum MG adsorption efficiency of 98.6% at 35 °C, pH 7.0, 60 min contact time, 1.0 g/L adsorbent dosage, and 50 mg/L initial MG concentration. On the other hand, the maximum efficiency for MG adsorption on MgO-impregnated clay of 97.04% is observed at pH 9.0, 60 min contact time, 0.7 g/L adsorbent dosage, and 50 mg/L initial MG concentration. The Malachite green (MG) adsorption isotherm on MgO-impregnated clay corresponded with the Freundlich isotherm, with a correlation coefficient (R2) of 0.982. However, the Langmuir adsorption isotherm was a superior fit for nano-bentonite (R2 = 0.992). The adsorption activities of nano-bentonite and MgO-impregnated clay were fitted into a pseudo-second-order kinetic model with R2 of 0.996 and 0.995, respectively. Additionally, despite being recycled numerous times, the adsorbent maintained its high structural stability and removal effectiveness for nano-bentonite (94.5–86%) and MgO-impregnated clay (92–83%).

Ti/Zr/O Mixed Oxides for the Catalytic Transfer Hydrogenation of Furfural to GVL in a Liquid-Phase Continuous-Flow Reactor

This work aims to develop an efficient catalyst for the cascade reaction from furfural to γ-valerolactone in a liquid-phase continuous reactor. This process requires both Lewis and Brønsted acidity; hence, a bifunctional catalyst is necessary to complete the one-pot reaction. Ti/Zr/O mixed oxide-based catalysts were chosen to this end as balancing metal oxide composition allows the acidity characteristics of the overall material to be modulated. Oxides with different compositions were then synthesized using the co-precipitation method. After characterization via porosimetry and NH3-TPD, the catalyst with equimolar quantities of the two components was demonstrated to be the best one in terms of superficial area (279 m2/g) and acid site density (0.67 mmol/g). The synthesized materials were then tested using a plug flow reactor at 180 °C, with a 10 min contact time. Ti/Zr/O (1:1) was demonstrated to be the most promising catalyst during the recycling tests as it allowed obtaining the highest selectivities in the desired products (about 45% in furfuryl isopropyl ether and 20% in γ-valerolactone) contemporaneously with 100% furfural conversion.

Optimizing ozone dose and contact time for removal of antibiotic-resistant P. aeruginosa, A. baumannii, E. coli, and associated resistant genes in effluent of an activated sludge process in a municipal WWTP.

This study aimed to investigate the impact of ozonation on inactivation of antibiotic-resistant bacteria (ARB) including E. coli, P. aeruginosa, and A. baumannii, as well as on removal of 16S-rRNA gene and their associated antibiotic-resistant genes (ARGs) indigenously present in effluent of municipal wastewater treatment plant. The Chick-Watson model was used to describe bacterial inactivation rates at specific ozone doses. Maximum reduction of total cultivable A. baumannii, E. coli, and P. aeruginosa were found to be 7.6, 7.1, and 4.7 log, respectively, with the highest ozone dose of 0.48 gO3/gCOD at 12min contact time. According to the study results, complete inactivation of ARB and bacterial regrowth was not observed after 72h incubation. The culture methods overestimated the performance of disinfection processes and propidium monoazide combined with qPCR, and showed the presence of viable but non-culturable bacteria after ozonation. ARGs were more persistent to ozone than ARB. The results of this study highlighted the significance of specific ozone dose and contact time in ozonation process considering the bacterial species and associated ARGs as well as the wastewater physicochemical characteristics, in order to help diminish the entrance of the biological microcontaminants into the environment.

Bioactive Azadirachta indica and Melia azedarach leaves extracts with anti-SARS-CoV-2 and antibacterial activities.

The leaves of Azadirachta indica L. and Melia azedarach L., belonging to Meliaceae family, have been shown to have medicinal benefits and are extensively employed in traditional folk medicine. Herein, HPLC analysis of the ethyl acetate fraction of the total methanolic extract emphasized the enrichment of both A. indica L., and M. azedarach L. leaves extracts with phenolic and flavonoids composites, respectively. Besides, 4 limonoids and 2 flavonoids were isolated using column chromatography. By assessing the in vitro antiviral activities of both total leaves extracts against Severe Acute Respiratory Syndrome Corona virus 2 (SARS-CoV-2), it was found that A. indica L. and M. azedarach L. have robust anti-SARS-CoV-2 activities at low half-maximal inhibitory concentrations (IC50) of 8.451 and 6.922 μg/mL, respectively. Due to the high safety of A. indica L. and M. azedarach L. extracts with half-maximal cytotoxic concentrations (CC50) of 446.2 and 351.4 μg/ml, respectively, both displayed extraordinary selectivity indices (SI>50). A. indica L. and M. azedarach L. leaves extracts could induce antibacterial activities against both Gram-negative and positive bacterial strains. The minimal inhibitory concentrations of A. indica L. and M. azedarach L. leaves extracts varied from 25 to 100 mg/mL within 30 min contact time towards the tested bacteria. Our findings confirm the broad-spectrum medicinal value of A. indica L. and M. azedarach L. leaves extracts. Finally, additional in vivo investigations are highly recommended to confirm the anti-COVID-19 and antimicrobial activities of both plant extracts.

Characterization and synthesis of new adsorbents with some natural waste materials for the purification of aqueous solutions

In this study, hexavalent chromium Removal from aqueous environments was investigated by using polyaniline composites with some natural waste materials. Batch experiments were used, and some parameters such as contact time, pH and adsorption isotherms were determined for the best composite with the highest removal efficiency. Scanning Electron Microscope (SEM), Fourier Transform Infrared (FTIR) spectroscopy, and X-ray Diffraction (XRD) were used to characterize the composites. According to the results, the polyaniline/walnut shell charcoal/PEG composite outperformed other composites and showed the highest chromium removal efficiency of 79.22%. Polyaniline/walnut shell charcoal/PEG has a larger specific surface area of 9.291 (m2/gr) which leads to an increase in its removal efficiency. For this composite, the highest removal efficiency was obtained at the pH = 2 and 30 min contact time. The maximum calculated adsorption capacity was 500 mg/g.