Optimum Conditions For Removal Research Articles

Fluoxetine removal by anodic oxidation using different anode materials and graphite cathode

ABSTRACT Fluoxetine (FLX) is a selective serotonin reuptake inhibitor (SSRI) medication commonly used to treat mental health disorders, but it can be harmful to the environment if not properly disposed of due to incomplete metabolism. In this study, electrochemical anodic oxidation with mixed metal oxide anodes was studied as a method to remove FLX from water and wastewater. Iridium dioxide-coated titanium (Ti/IrO2) and ruthenium dioxide-coated Ti (Ti/RuO2) electrodes were found to be more effective than platinum-coated Ti (Ti/Pt) electrodes, with removal efficiencies of 91.5% and 93.9%, respectively. Optimal conditions for FLX removal were determined to be an applied current of 150 mA, initial pH of 5, and oxidation time of 120 min. The rate of FLX degradation (kFLX) for the Ti/Pt, Ti/IrO2, and Ti/RuO2 electrodes were determined to be 0.0081 min−1 (R2:0,8161), 0.0163 min−1 (R2:0,9823), and 0.0168 (R2:0,9901) min−1 for 25 mg/L initial FLX concentration, respectively. The kFLX values varied based on the initial FLX concentration and decreased as the initial FLX concentration increased. The specific energy consumption (SEC) after 120 min of operation was 51.0 kWh/m3 for the Ti/Pt electrode, 39.6 kWh/m3 for the Ti/IrO2 electrode, and 48.6 kWh/m3 for the Ti/RuO2 electrode under optimised conditions. Overall, electrochemical anodic oxidation is an effective method for removing FLX from water and wastewater, with Ti/IrO2 and Ti/RuO2 electrodes providing superior performance compared to Ti/Pt electrodes.

A sustainable nano-hybrid system of laccase@M-MWCNTs for multifunctional PAHs and PhACs removal from water, wastewater, and lake water

This study examined the use of modified multiwall carbon nanotubes (M-MWCNTs) with immobilized laccase (L@M-MWCNTs) for removing ciprofloxacin (Cip), carbamazepine (Cbz), diclofenac (Dcf), benzo[a]pyrene (Bap), and anthracene (Ant) from different water samples. The synthesized materials were characterized using an array of advanced analytical techniques. The physical immobilization of laccase onto M-MWCNTs was confirmed through Scanning electron microscope (SEM)-dispersive X-ray spectroscopy (EDS) analysis and Brunner-Emmet-Teller (BET) surface area measurements. The specific surface area of M-MWCNTs decreased by 65% upon laccase immobilization. There was also an increase in nitrogen content seen by EDS analysis asserting successful immobilization. The results of Boehm titration and Fourier transform infrared (FTIR) exhibited an increase in acidic functional groups after laccase immobilization. L@M-MWCNTs storage for two months maintained 77.8%, 61.6%, and 57.6% of its initial activity for 4 °C, 25 °C, and 35 °C, respectively. In contrast, the free laccase exhibited 55.3%, 37.5%, and 23.5% of its initial activity at 4 °C, 25 °C, and 35 °C, respectively. MWCNTs improved storability and widened the working temperature range of laccase. The optimum removal conditions of studied pollutants were pH 5, 25 °C, and 1.6 g/L of M-MWCNTs. These parameters led to >90% removal of the targeted pollutants for four treatment cycles of both synthetic water and spiked lake water. L@M-MWCNTs demonstrated consistent removal of >90% for up to five cycles even with spiked wastewater. The adsorption was endothermic and followed Langmuir isotherm. Oxidation, dehydrogenation, hydroxylation, and ring cleavage seem to be the dominant degradation mechanisms.

Effective synthesis and application of artichoke and orange peels-based bio-sorbents for Ketoprofen removal from wastewater: Process optimization using Factorial methodology

Two new bio-adsorbents were successfully synthesized by doping method with zinc chloride salt (ZnCl2) of raw artichoke leaves (RAL) and raw orange peels waste (ROP). Different analysis techniques (i.e. BET, SEM, XRD, FTIR) were used for characterizing the synthesized materials. Ketoprofen (KTF) nonsteroidal anti-inflammatory drug was effectively removed from water using the synthesized bio-adsorbents, under different operating conditions. The specific surface areas increased from 1009.960 and 997.816 m2/g for ROP and RAL natural materials, respectively, to 1511.278 and 3415.951 m2/g for ROP- and RAL-doped materials. More interestingly, maximum Ketoprofen removals of 90% and 96% were obtained using ROP- and RAL-doped bio-adsorbents, against null removal for natural ROP and RAL materials. The kinetic study shows that the pseudo-second order model simulated adequately the obtained Ketoprofen removal data with R2 superior to 99%. A DOE based on (23) full factorial design was used to evaluate the effect of pH, bio-adsorbent dosage and initial KTF concentration on Ketoprofen removal efficiency. The optimum conditions for KTF removal with both the activated wastes were pH= 2, bio-adsorbent dose of 0.1 g/L and C0,KTF= 5 mg/L with removal efficiency of 98.14% for ROP-ZnCl2, and pH= 2, bio-adsorbent dose of 0.3 g/L and C0,KTF = 20 mg/L with a removal efficiency of 99.84% for RAL-ZnCl2 bio-sorbent.

Efficient cationic dye removal from water through Arachis hypogaea skin-derived carbon nanospheres: a rapid and sustainable approach.

The present study investigates the potential of Arachis hypogaea skin-derived carbon nanospheres (CNSs) as an efficient adsorbent for the rapid removal of cationic dyes from aqueous solutions. The CNSs were synthesized through a facile, cost-effective, catalyst-free and environmentally friendly process, utilizing Arachis hypogaea skin waste as a precursor. This is the first reported study on the synthesis of mesoporous carbon nanospheres from Arachis hypogaea skin. The structural and morphological characteristics of the CNSs were confirmed by different nano-characterization techniques. The adsorption performance of the carbon nanospheres was evaluated through batch adsorption experiments using two cationic dyes-methylene blue (MB) and malachite green (MG). The effects of the initial dye concentration, contact time, adsorbent dosage, and pH were investigated to determine the optimal conditions for dye removal. The results revealed that the obtained CNSs exhibited remarkable adsorption capacity and rapid adsorption kinetics. Up to ∼98% removal efficiency was noted for both dyes in as little as 2 min for a 5 mg L-1 dye concentration, and the CNSs maintained their structural morphology even after adsorption. The adsorption data were fitted to various kinetic and isotherm models to gain insights into the adsorption mechanism and behaviour. The pseudo-second-order kinetic model and Redlich-Peterson model best described the experimental data, indicating multi-layer adsorption and chemisorption as the predominant adsorption mechanism. The maximum adsorption capacity was determined to be 1128.46 mg g-1 for MB and 387.6 mg g-1 for MG, highlighting the high affinity of the carbon nanospheres towards cationic dyes. Moreover, CNS reusability and stability were examined through desorption and regeneration experiments, which revealed sustained efficiency over 7 cycles. CNSs were immobilised in a membrane matrix and examined for adsorption, which demonstrated acceptable efficiency values and opened the door for further improvement.

Decontamination of textile effluents via the adsorption process on various raw clay minerals enhanced by ozonation: a modeling approach and optimization.

This study seeks to characterize three different clays and compare their capability to decontaminate a textile effluent using the adsorption process and to explore the synergistic effects of ozonation on the treatment. Response surface methodology, based on central composite design, was used to investigate the impact of three key parameters, namely, solution pH, clay dosage, and contact time, on the adsorption process. The three clays were sourced from distinct regions across Tunisia: Rommana, Tabarka, and Medenine. The analysis of the clays revealed that the Rommana green clay (RGC) was predominantly composed of smectite, the Tabarka white clay (TWC) was rich in kaolinite, and the Medenine red clay (MRC) contained a combination of illite and kaolinite. Under optimal conditions for color removal, the attained efficiencies for removing color, chemical oxygen demand (COD), and total suspended solids (TSS) were as follows: 86.89%, 57.2% and 80.7% for RGC; 80.56%, 55.02% and 75.28% for TWC; and 81.7%, 56.8% and 75.5% for MRC, respectively. Results show that RGC exhibited the highest adsorption percent of dye removal (≅87%) at the optimal conditions evaluated via the CCD design of the response surface methodology (pH ≈ 3.98, adsorbent dose 7 g L-1, contact time = 89 min). The enhancement of the adsorption process through ozonation achieved color removal efficiencies of 98.2%, COD removal efficiencies of 71.4%, and TSS removal efficiencies of 89.3% for RGC; 98.15%, 70.13%, and 88.74% for TWC; and 98.3%, 70.32%, and 88.56% for MRC, respectively, in compliance with the Tunisian standard for river discharge. The treated effluent can be used in the irrigation of saline plants.

Fluoride removal from phosphogypsum: A study on pre-industrial scale and its mathematical analysis

This study discusses fluoride removal efficiency from phosphogypsum (PG) on a lab-scale experiment matrix designed by the Box-Behnken method. Temperature, solid/liquid ratio, and time were supposed to influence fluoride removal efficiency from PG by various salt solution media. Experiment matrices were designed according to salt solution types: seawater, 5% NaCl, and 10% NaCl solutions. The factor-response analysis showed a direct proportionality between fluoride removal efficiency and temperature. The optimum fluoride removal conditions based on the experimental data obtained by the multi-variable design matrix were determined by the Design Expert v.12 software. The optimum temperature, time, and solid/liquid ratio were 80 ?C, 3 h, and 0,174 for seawater. The software predicted a 73,31% fluoride removal efficiency at the optimum conditions, whereas the experimental value was 74,99%. Since the actual vs. predicted data show high consistency, results might also be useful when industrial-scale fluoride removal to a predetermined level is required prior to a particular use of PG. PG has a high potential as an alternative raw material, and fluoride removal might be important in recycling applications. This study provides a novel pre-industrial scale fluoride removal inventory, especially for the fertilizer and cement industry.

Central composite design for the removal of copper by an Adansonia digitata

Biosorption, an alternative to traditional methods such as precipitation, ion exchange, electrochemical treatment, and evaporative recovery, is being considered as a potential means for removing heavy toxic metals from waste solution. This method is especially effective when the concentration of the heavy metal ion is low. A central composite design (CCD) was used in this study to maximize copper removal utilizing Adansonia digitata (baobab) as a biosorbent. Using response surface approach, the impacts of initial copper content, biosorbent dose, Temperature and pH were examined. The CCD enabled the discovery of optimal copper removal conditions. The percentage of metal clearance (CCD) was examined as a result of the influence of various process parameters utilizing a central composite design. A quadratic model based on the CCD was used to model the reaction. The analysis of variance (ANOVA) identified the most significant experimental design response factor. The optimal circumstances for Adansonia digitata (baobab) were pH of 7.1, bio sorbent dose of 0.3 g, beginning copper content of 48.4 mg/L, Temperature 390 C and metal removal of 84.26%. Under these optimal conditions, the experimental biosorption percentage was 76.93. The findings suggest that Adansonia digitata has the capacity to efficiently remove copper from aqueous solutions. This study adds to our understanding of the use of natural materials for heavy metal cleanup.

Upcycling of sugar refining mud solid waste as a novel adsorbent for removing methylene blue and Congo red from wastewater.

The feasibility of utilizing the mud solid waste (MSW) produced during the carbonation process of sugar refining as a cost-effective and environmentally friendly alternative for the water removal of methylene blue (MB) and Congo red (CR), being highly utilized organic dyes representing cationic and anionic species, respectively is presented. Prior to its use, the MSW was dried at 110 °C for 24 h and sieved through a 100-mesh screen. The chief constituent of the MSW utilized was CaCO3, with a point of zero charge (PZC) found at pH 8.4 and 7.96 m2 g-1 total surface area. XRD and FTIR data indicate the presence of interactions between the dyes and the MSW surface, indicating effective adsorption. Different variables, such as initial dye concentration, MSW weight, solution pH, contact time, and temperature, were all examined to determine the optimal dye removal conditions. A central composite design (CCD) approach based on response surface methodology (RSM) modeling was utilized to identify statistically significant parameters for MB and CR adsorption capacities onto the MSW adsorbent. The removal equilibrium was typically reached in 120 minutes, with the greatest removal efficiency of CR taking place at pH 2 and 328 K, while the highest MB removal efficiency was obtained at pH 12 and 296 K. Kinetic studies suggest the adsorption of both dyes on the MSW follow pseudo-second-order rates, as evident through the high correlations obtained. Linearized and non-linearized Langmuir models showed strong correlations indicating maximum adsorption capacities of 86.6 and 72.3 mg g-1 for MB and CR, respectively. High regeneration and reusability potential of the MSW was demonstrated especially for the adsorption of CR, where the removal efficiency was nearly constant throughout five adsorption cycles, ranging from 93 to 91%, while the reduction in the removal for MB was much more significantly impacted, diminishing from 95 to 79% after the five cycles.

Вдосконалення конструкції промковша машини безперервного лиття круглої заготовки за допомогою чисельного моделювання

As the requirements to fineness of continuously cast round billets used in manufacture of critical products (railway wheels, special purpose pipes, etc.) demonstrate substantial growth, comprehensive technological solutions are needed to improve the quality of steel, primarily by reducing the number and size of non-metallic inclusions. Herewith, the tundish as the last unit with refractory lining plays a special role in this by removing inclusions through optimization of the liquid steel flows. Since the metal flow pattern is the basic component for productivity of continuous casting tundishes, the purpose of this study was to evaluate and optimize the hydrodynamics inside the four-strand tundish by using a comprehensive approach to changing its internal geometry. To ensure optimal conditions for removal of non-metallic inclusions in the tundish, it is necessary first of all to ensure long-term contact of metal and slag both by directing the metal flows to the metal-slag interface surface and by increasing the time of metal staying in the tundish. In regulation of the metal flows inside the tundish the main focus has been historically on the design and technological features of the impact pads in the zone of metal inflow from the steel ladle to reduce turbulent flows. Therefore, in the conducted studies, the attention was mainly paid to evaluating changes in the liquid steel flows inside the tundish through the use of other additional flow "modifiers" such as skimmers and baffles. It should be noted that in addition to the effect on the distribution of flows, an assessment was made of the possible impact of changes on prevention of excessive erosion of the refractory lining of the tundish. The evaluation was performed using the finite element numerical simulation method on the commercial software Thercast from Transvalor (France). The results of the actual evaluation of non-metallic inclusions in the finished products showed a substantial reduction in the interval of the existing inclusions from the initial 50-100 microns to 20-50 microns, with a stable trend towards a substantial decrease in the number of inclusions after the changes were implemented.

Studi Awal Sintesis ZnO/SiO2 dengan Silika dari Limbah Padat Geothermal dan Uji Performansinya dalam Penghilangan Metilen Biru

Industrial development impacts environmental problems, such as the emergence of wastewater containing methylene blue. In this research, SiO2 was composited with ZnO to remove methylene blue. The steps of this study include SiO2 extraction from geothermal solid waste, ZnO/SiO2 synthesis, and methylene blue removal test. The process of extracting SiO2 from geothermal solid waste used the sol-gel method. The FTIR analysis showed that SiO2 contains siloxane group (Si-OH) and silanol group (Si-O-Si). ZnO/SiO2 synthesis was done by making SiO2 suspension and continued with adding the addition of several Zn(NO3)2.6H2O. The FTIR analysis of ZnO/SiO2 showed no absorption at the wavenumber 960 cm-1 and there is a shoulder around the number 950 cm-1 which indicates the vibration of Si-O-Zn. Meanwhile, methylene blue removal tests were carried out on artificial wastewater. Based on the research results, the highest percent removal (99%) was obtained under operating conditions, including a dose of 500 mg/L, pH 10, and contact time of 30 minutes. Based on box-benkhen analysis, it is known that dose and pH singularly affect the percent removal, while contact time does not affect the percent removal. The optimization results obtained optimum conditions for methylene blue removal at a dose of 581.952 mg/L, pH of 10, and contact time of 30 minutes. Percent removal in conditions without irradiation and with irradiation of UV light were 98.758% and 99.178%. It shows that the adsorption process is the main process in removing methylene blue, while the photocatalytic process has little effect because it is possible that only a small amount of ZnO can attach to the surface of SiO2.

Magnetic Nanoparticles for Oil Removal from Water: A Short Review of Key Findings

This mini review provides an overview of the potential use of magnetizable nanoparticles for de-oiling water, drawing on the findings of several studies in the field. Magnetic nanoparticles demonstrate significant promise for oil removal due to their magnetic properties, which enable them to be separated from contaminated water using a magnetic field. Additionally, the surface of these nanoparticles can be modified with oil-attracting agents to enhance their oil-removal efficiency. Our systematic search in Scopus revealed that "oil," "water," "magnetic," "nanoparticles," and "removal" were the most commonly used words in the literature corpus. Through our analysis of four case studies, we gained valuable insights into the practical applications of magnetic nanoparticles for oil removal from water and observed that their unique magnetic properties make them an ideal solution for this purpose. Furthermore, our summary of key findings from the four studies revealed that optimal conditions for oil removal include a nanoparticle size range of 2-10 nm, surface modification with cationic coatings or silica and ammonium, and a concentration range of 0.31 to 5 mg/cm3 to 30-50 mg/L. The recyclability of these nanoparticles was found to be efficient, with an oil removal efficiency of approximately 97% after ten cycles. However, further research is needed to determine the optimal conditions for oil removal from water using magnetic nanoparticles, as these conditions may vary based on specific applications. In conclusion, magnetic nanoparticles offer a promising avenue for effective water de-oiling and are an area of significant interest in oil removal from water research.

Rapid and efficient removal of methylene blue dye from aqueous solutions using extract-modified Zn–Al LDH

Environmental pollution, particularly water pollution caused by organic substances like synthetic dyes, is a pressing global concern. This study focuses on enhancing the adsorption capacity of layered double hydroxides (LDHs) to remove methylene blue (MB) dye from water. The synthesized materials are characterized using techniques like FT-IR, XRD, SEM, TEM, TGA, EDS, BET, BJH, AFM, and UV–Vis DRS. Adsorption experiments show that Zn–Al LDH@ext exhibits a significant adsorption capacity for MB dye compared to pristine LDH. In addition, Zn–Al LDH@ext shows a significant increase in stability, which is attributed to the presence of phenolic compounds in the extract and the interactions between the functional groups of the extract and LDH. The pH and adsorbent dosage optimizations show that pH 7 and 0.7 g of Zn–Al LDH@ext are optimal conditions for efficient MB removal. The study assessed adsorption kinetics through the examination of Langmuir, Freundlich, and Temkin isotherms. Additionally, four kinetic models, namely pseudo-first-order, pseudo-second-order, intraparticle diffusion, and Elovich, were analyzed. The results indicated that the Temkin isotherm (R2 = 0.9927), and pseudo-second-order (R2 = 0.9999) kinetic provided the best fit to the experimental data. This study introduces a novel approach to enhance adsorption efficiency using modified LDHs, contributing to environmentally friendly and cost-effective water treatment methods.

Fabrication of network nanocomposite of polyaniline coating chitosan-graphene oxide-functionalized carbon nanotube and its efficacy in removing dyes from aqueous solution

In this investigation, we employed chemical oxidative copolymerization techniques to produce cross-linked polyaniline/chitosan-graphene oxide-oxidized single-wall carbon nanotubes (Cross PANI/Chito-GO-OXS NCs) as a network to increase the surface area, as well as the active centers to enhance the efficiency of the adsorption of anionic and cationic dyes. This novel material was utilized as an adsorbent for decontaminating water by eliminating acid red dye (AR1) and brilliant green dye (BG). Several analytical techniques were employed to assess the composition and structure of the synthesized adsorbent, including scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HR-TEM), X-ray powder diffraction (XRD), infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), and Raman spectroscopy. To assess the efficacy of Cross PANI/Chito-GO-OXS NCs in dye removal, batch experiments were carried out under diverse conditions, such as varying pH, adsorbent quantity, agitation duration, ionic strength, and temperature. The results indicated that the optimum conditions for AR1 removal were achieved at pH 2, using 5 mg of Cross PANI/Chito-GO-OXS NCs at a concentration of 20 mg/L for 120 min. Conversely, for BG removal, the most favorable outcomes were observed at pH 6, with the use of 5 mg of Cross PANI/Chito-GO-OXS NCs at a concentration of 5 mg/L for 120 min. Under these operating conditions, the maximum removal efficiency for actual wastewater was determined to be 96.73% for AR1 dye and 95.55% for BG dye. Additionally, we analyzed the adsorption isotherm data utilizing various models. The adsorption kinetics were elucidated through a pseudo-second-order model, supported by regression data, which yielded R2 values of 0.9839 for AR1 and 0.9928 for BG, respectively, describing the adsorption of both dyes onto Cross PANI/Chito-GO-OXS NCs. Furthermore, the thermodynamic analysis revealed that the removal of AR1 dye is an endothermic process, while BG dye removal is exothermic, and both removal of AR1 and BG dyes are spontaneous and chemisorption processes.

Efficient nitrite accumulation in partial sulfide autotrophic denitrification (PSAD) system: insights of S/N ratio, pH and temperature

ABSTRACT To provide the necessary nitrite for the Anaerobic Ammonium Oxidation (ANAMMOX) process, the effect of nitrite accumulation in the partial sulfide autotrophic denitrification (PSAD) process was investigated using an SBR reactor. The results revealed that the effectiveness of nitrate removal was unsatisfactory when the S/N ratio (mol/mol) fell below 0.6. The optimal conditions for nitrate removal and nitrite accumulation were achieved within the S/N ratio range of 0.7-0.8, resulting in an average Nitrate Removal Efficiency (NRE) of 95.84%±4.89% and a Nitrite Accumulation Rate (NAR) of 75.31%±6.61%, respectively. It was observed that the nitrate reduction rate was three times faster than that of nitrite reduction during a typical cycle test. Furthermore, batch tests were conducted to assess the influence of pH and temperature conditions. In the pH tests, it became evident that the PSAD process performed more effectively in alkaline environment. The highest levels of nitrate removal and nitrite accumulation were achieved at an initial pH of 8.5, resulting in a NRE of 98.30%±1.93% and a NAR of 85.83%±0.47%, respectively. In the temperature tests, the most favourable outcomes for nitrate removal and nitrite accumulation were observed at 22±1 ℃, with a NRE of 100.00% and a NAR of 81.03%±1.64%, respectively. Moreover, a comparative analysis of 16S rRNA sequencing results between the raw sludge and the sulfide-enriched culture sludge sample showed that Proteobacteria (49.51%) remained the dominant phylum, with Thiobacillus (24.72%), Prosthecobacter (2.55%), Brevundimonas (2.31%) and Ignavibacterium (2.04%) emerging as the dominant genera, assuming the good nitrogen performance of the system.

Deep eutectic solvent mediated synthesis of ZnO nanoparticles and their catalytic activity for the removal of hazardous organic dyes

Zinc oxide, ZnO, nanoparticles have been synthesized using a deep eutectic solvent (DES) consisting of choline chloride and D-Lactic acid. The presented method proved to be simple, efficient, cost-effective, and eco-friendly for the formation of ZnO nanoparticles with specific morphology and properties. A variety of techniques have been used to investigate the composition, size, shape, and crystallinity of the nanoparticles, including UV–Visible spectroscopy, FT-IR spectroscopy, XRD, FE-SEM, and EDX. The UV–Visible spectroscopy confirmed the synthesis of stable ZnO, with a band gap of 3.55 eV between 300 and 400 nm. The FT-IR spectroscopy revealed the presence of DES functional groups on ZnO nanoparticles. The average size of the ZnO nanoparticles was estimated to be 39 nm using XRD calculations, while the FE-SEM images showed that the particles are rod-like elongated and spherical in shape and have high surface activity causing their agglomeration. The synthesized ZnO nanoparticles were used as a catalyst to remove the organic dyes from the synthetic wastewater. Various factors were studied to achieve optimum conditions for the effective dye removal. The results showed that an adsorbent dose of 5 mg/50 mL removed 84 % and 99 % of Congo Red and Crystal Violet, respectively, within 70 min. The kinetic models used revealed that the adsorption followed the pseudo-first-order kinetics. Langmuir, Freundlich, and Temkin isotherms were used to explain the adsorption mechanism. Finally, the thermodynamic parameters for the removal of both dyes using ZnO nanoparticles demonstrated that adsorption was spontaneous.

Study on Enhancement of Denitrification Performance of Alcaligenes faecalis

Nitrogen pollution in water bodies presents a serious threat to ecosystems due to its role in eutrophication. In this study, the aerobic denitrifying bacterium Alcaligenes faecalis was used as a model microorganism to investigate the optimal operating conditions for nitrogen removal from nitrogen-containing wastewater by Alcaligenes faecalis under different aeration modes, microbial dosages and C/N ratios. The results showed that the optimal aeration mode for efficient bacterial denitrification was 10 min of aeration with a 30 min interval, and the total nitrogen removal reached 87.82%. At different bacterial doses, NO3−–N was completely denitrified and NO2−–N accumulation levels were reduced, all of which resulted in significant denitrification, and the final total nitrogen removal efficiencies reached 86.39–98.50%. With an increase in the C/N ratio, the pollutant removal performance of denitrifying bacteria increased. When the C/N ratio was 17, the final rates of NO3−–N, TN and COD removal were 100%, 98.50% and 96.13%, respectively. At lower C/N ratios, the growth and metabolism of microorganisms were inhibited and fewer electron acceptors were available during the denitrification process, which seriously affected denitrification performance. In this study, the denitrification performance of aerobic denitrifying bacterium Alcaligenes faecalis was explored in experiments using changes in aeration mode, microbial dosage and C/N ratio, and the optimal operating conditions of Alcaligenes faecalis for treating nitrogenous wastewater were indicated. This provides technical support for Alcaligenes faecalis in improving the remediation effect of nitrogenous wastewater and provides a theoretical basis for further in-depth research on the performance of Alcaligenes faecalis in the future.

Thermal Stability Enhancement of L-Asparaginase from Corynebacterium glutamicum Based on a Semi-Rational Design and Its Effect on Acrylamide Mitigation Capacity in Biscuits.

Acrylamide is present in thermally processed foods, and it possesses toxic and carcinogenic properties. L-asparaginases could effectively regulate the formation of acrylamide at the source. However, current L-asparaginases have drawbacks such as poor thermal stability, low catalytic activity, and poor substrate specificity, thereby restricting their utility in the food industry. To address this issue, this study employed consensus design to predict the crucial residues influencing the thermal stability of Corynebacterium glutamicum L-asparaginase (CgASNase). Subsequently, a combination of site-point saturating mutation and combinatorial mutation techniques was applied to generate the double-mutant enzyme L42T/S213N. Remarkably, L42T/S213N displayed significantly enhanced thermal stability without a substantial impact on its enzymatic activity. Notably, its half-life at 40 °C reached an impressive 13.29 ± 0.91 min, surpassing that of CgASNase (3.24 ± 0.23 min). Moreover, the enhanced thermal stability of L42T/S213N can be attributed to an increased positive surface charge and a more symmetrical positive potential, as revealed by three-dimensional structural simulations and structure comparison analyses. To assess the impact of L42T/S213N on acrylamide removal in biscuits, the optimal treatment conditions for acrylamide removal were determined through a combination of one-way and orthogonal tests, with an enzyme dosage of 300 IU/kg flour, an enzyme reaction temperature of 40 °C, and an enzyme reaction time of 30 min. Under these conditions, compared to the control (464.74 ± 6.68 µg/kg), the acrylamide reduction in double-mutant-enzyme-treated biscuits was 85.31%, while the reduction in wild-type-treated biscuits was 68.78%. These results suggest that L42T/S213N is a promising candidate for industrial applications of L-asparaginase.

Delonix regia biomass as an eco-friendly biosorbent for effective Alizarin Red S textile dye removal: Characterization, kinetics, and isotherm studies

Alizarin Red (ARS), a harmful dye known for its carcinogenic and mutagenic properties, is widely used in textile dyeing, posing a significant environmental concern due to its water-solubility and potential negative impact on aquatic life. This study explores the use of Delonix regia pods, obtained from the Gulmohar or Mayflower tree, as an eco-friendly adsorbent for ARS removal. The adsorption efficiency of Delonix regia pods was investigated by examining the effects of pH, dosage, initial concentration, and contact time. The optimal conditions for ARS removal were determined to be a pH of 2, a dosage of 2 g/L, and a contact time of 60 min, resulting in a significant 55 % removal of the dye. The experimental data exhibited a good fit with the Langmuir isotherm model (R2 = 0.9637), with the maximum adsorption capacity (qm) of the pods calculated as 4.4307 mg g−1 and the binding energy constant (Kl) as −1.0732. These findings highlight the potential of Delonix regia pods as a promising and environmentally friendly option for effective ARS removal. The study emphasizes the significance of utilizing biomass-based adsorbents in addressing the environmental challenges associated with dye removal.

A new methodology for the prediction of optimal conditions for dyes' electrochemical removal; Application of copula function, machine learning, deep learning, and multi-objective optimization

In the present study, a new methodology has been introduced for predicting the simultaneous removal optimal conditions of Acid red 33 (AR33), Reactive orange 7 (RO7), Acid yellow 3 (AY3), and Malachite green (MG) dyes. Since industrial wastewater contains a variety of dyes, simultaneous prediction of their removal efficiency is a practical issue. The goal of this research was to address challenges associated with modeling this type of removal process. In the first part of this methodology, the c-vine copula function was used to generate synthetic data since the use of most modeling methods requires a large number of data, and studying different experimental conditions is time- and cost-consuming. Besides, Artificial neural network, Adaptive neuro-fuzzy inference system, Least-square support vector machine, and Long-short term memory algorithms were applied for modeling the dyes' removal efficiency using experimental and synthetic data. Utilizing synthetic data significantly improved the accuracy of modeling. For the purpose of finding the optimal amount of dyes' removal efficiency simultaneously, the removal efficiency of each dye is defined as an objective function. This leads to a problem requiring multi-objective optimization. Hence, the Multi-Objective Adaptive Guided Differential Evolution was employed for multi-objective optimization of dyes' removal efficiency. The optimization process was carried out based on the four objective functions including AR33, RO7, AY3, and MG dyes' removal efficiency. The results indicated a direct relationship between dyes' removal efficiency on the Pareto front as well as a highly oscillating and nonlinear relationship with decision variables (pH, NaCl concentration, current, and Time) under optimal conditions. Finally, the average results of Technique for Order of Preference by Similarity to Ideal Solution and VIekriterijumsko KOmpromisno Rangiranje were utilized to select the best optimal conditions from the Pareto front. With pH, NaCl, Time, and current inputs at 6.60, 0.67 (g/L), 96.93 (min), 0.01 (A) (optimal conditions), the best removal efficiencies of 98.88, 37.02, 91.19, and 98.33 (%) were obtained for AR33, RO7, AY3, and MG dyes, respectively. The introduced method demonstrated excellent promise for predicting optimal conditions for dyes' removal efficiency as well as for making wastewater treatment systems easier to design.

Recombinant Oxidase from Armillaria tabescens as a Potential Tool for Aflatoxin B1 Degradation in Contaminated Cereal Grain.

Forage grain contamination with aflatoxin B1 (AFB1) is a global problem, so its detoxification with the aim of providing feed safety and cost-efficiency is still a relevant issue. AFB1 degradation by microbial enzymes is considered to be a promising detoxification approach. In this study, we modified an previously developed Pichia pastoris GS115 expression system using a chimeric signal peptide to obtain a new recombinant producer of extracellular AFB1 oxidase (AFO) from Armillaria tabescens (the yield of 0.3 g/L), purified AFO, and selected optimal conditions for AFO-induced AFB1 removal from model solutions. After a 72 h exposure of the AFB1 solution to AFO at pH 6.0 and 30 °C, 80% of the AFB1 was degraded. Treatments with AFO also significantly reduced the AFB1 content in wheat and corn grain inoculated with Aspergillus flavus. In grain samples contaminated with several dozen micrograms of AFB1 per kg, a 48 h exposure to AFO resulted in at least double the reduction in grain contamination compared to the control, while the same treatment of more significantly (~mg/kg) AFB1-polluted samples reduced their contamination by ~40%. These findings prove the potential of the tested AFO for cereal grain decontamination and suggest that additional studies to stabilize AFO and improve its AFB1-degrading efficacy are required.