Removal Process Research Articles

Insights into the mechanism of phosphorus enrichment and stripping in side-stream enhanced biological phosphorus removal and enrichment process

In-depth research on the side-stream enhanced biological phosphorus removal (S2EBPR) process holds promise for addressing the challenge of low phosphorus (P) enrichment concentration. This study developed a side-stream enhanced biological phosphorus enrichment/removal (S2EBPE/R) reactor by improving a S2EBPR process. The P removal, enrichment, and mass balance were used to evaluate polyphosphate-accumulating organisms (PAOs) activity. Microbial community structures were investigated to reveal the mechanism of P enrichment and stripping. The results showed that the P removal efficiency reached up to 93% in the S2EBPE/R process. Approximately 13% of P-rich liquid could be stably obtained from the side-stream system, with a concentration of 108.85 ± 4.53mgP/L. Apart from responses to EBPR activity (P/HAc) of up to 0.41 P-mol/C-mol, enrichment of typical PAOs of up to 12.0% enhanced the P enrichment and removal performance. The abundance of functional microorganisms (PAOs and glycogen accumulating organisms (GAOs)) related to P was as high as 13.4%. These findings highlighted the outstanding advantages of the S2EBPE/R process in P enrichment and removal, thereby making significant contributions to P recovery from wastewater.

Synergistic adsorption and photocatalytic degradation of tetracycline using a Z-scheme kaolin/g-C3N4/MoO3 nanocomposite: A sustainable approach for water treatment

This research focuses on the synthesis and application of a novel kaolin-supported g-C3N4/MoO3 nanocomposite for the degradation of tetracycline, an important antibiotic contaminant in water systems. The nanocomposite was prepared through a facile and environmentally friendly approach, leveraging the adsorption and photocatalytic properties of kaolin, g-C3N4 and MoO3 nanoparticles, respectively. Comprehensive characterization of the nanocomposite was conducted using techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR) and optical spectra. The surface parameters were studied using N2 adsorption-desorption isotherm. The elemental composition was studied using X-ray photoelectron spectroscopy. The efficiency of the developed nanocomposite in tetracycline degradation was evaluated and the results revealed an efficient tetracycline degradation exhibiting the synergistic effects of adsorption and photocatalytic degradation in the removal process. The tetracycline degradation was achieved in 60 min. Kinetic studies and thermodynamic analyses provided insights into the degradation mechanism, suggesting potential applications for the nanocomposite in wastewater treatment. Additionally, the recyclability and stability of the nanocomposite were investigated, demonstrating its potential for sustainable and long-term application in water treatment.

Enhancing CdSe/ZnS Quantum-Dot Light-Emitting Diode Performance: The Impact of Thermal Treatment Atmospheres on Fabrication Processes

We explored the thermal treatment impact on the performance of quantum-dot light-emitting diodes (QLEDs). The QLEDs comprised multiple layers: a 2.2-μm thick epoxy buffer layer; a bottom cathode composed of 12-nm MoOx/10-nm Ag/12-nm MoOx; a 20-nm ZnO electron transporting layer (ETL); a 10-nm CdSe/ZnS quantum dot light emission layer (EML); a 40-nm 4,4′,4″-Tris(carbazol-9-yl) triphenylamine hole transporting layer; a 10-nm WOx hole injection layer; and a 100-nm Ag top anode. We applied thermal treatments to the cathode, ETL, and EML separately to assess their effects on the QLEDs. Additionally, we evaluated the impact of the thermal treatment atmosphere. Vacuum thermal treatment on the cathode and EML resulted in minor improvements in QLED performance, whereas treatment of the ETL led to a decline in performance. In contrast, air thermal treatment on the cathode and EML decreased QLED performance but significantly improved it by 15% in current efficiency when applied to the ETL. The performance differences attributable to the thermal treatment atmosphere are likely due to ligand removal and oxidation processes, facilitated by thermal energy and oxygen. Our study highlights that air thermal treatment on the ETL substantially improves QLED performance, offering crucial insights into the significance of thermal treatment in QLED development.

Synthesis of CS-Fe3O4/GO nanocomposite for adsorption of heavy metal in aqueous environment.

In this study, magnetic material based on graphene oxide (GO) was developed for enhanced adsorption capacity for heavy metals. The Fe3O4 nanoparticles were combined with the GO material using a chitosan (CS) binder to obtain the CS-Fe3O4/GO nanocomposite. The adsorption capacity of this nanocomposite was evaluated by removing heavy metals including Ni2+ ions. When GO was composed with Fe3O4 and CS, the GO films were densely covered with ferromagnetic particles, which were bound and densely distributed on the GO film surface due to the interaction between GO and CS. The optimal conditions for the complexation of Ni2+ and 4-(2-pyridyl azo)-rezoxine (PAR) are 1 mL Ni2+, 2 mL PAR 100 mg/L, pH = 6 (adjusted with 0.7 mL of the 0.1 M K2HPO4 solution) and a complexation time of 20 min. After 50 min of adsorption, the Ni2+ removal efficiency of the CS-Fe3O4/GO nanocomposite reached 81.21 % and the corresponding adsorption capacity was 2.03 mg/g. The Ni2+ removal process followed the first-order model and Freundlich isotherm. This process was spontaneous (∆Go < 0) and an exothermic process (∆Ho = -1128.875 J.mol-1). In addition, the factors affecting this process were investigated, including the pH solution, the dosage of the CS-Fe3O4/GO nanocomposite and the initial Ni2+ concentration. The CS-Fe3O4/GO nanocomposite showed a potential adsorption capacity in removing Ni2+ at low concentrations from wastewater.

Advances in Nanoparticles and Nanocomposites for Water and Wastewater Treatment: A Review

Addressing water scarcity and pollution is imperative in tackling global environmental challenges, prompting the exploration of innovative techniques for effective water and wastewater treatment. Nanotechnology presents promising solutions through the customization of nanoparticles and nanocomposites specifically designed for water purification applications. This review delves into recent advancements in nanoparticle-based technologies for water treatment, with a particular focus on their synthesis methodologies, intrinsic properties, and versatile applications. A wide range of nanoparticles, ranging from metal nanoparticles to carbon-based nanomaterials, along with hybrid nanocomposites such as metal/metal oxide-based nanocomposites, polymer-based nanocomposites, and others, were emphasized for eliminating contaminants from water and wastewater matrices. Furthermore, this review elucidates the underlying mechanisms governing pollutant removal processes, encompassing adsorption, catalysis, and membrane filtration, facilitated by nanoparticles. Additionally, it explores the environmental implications and challenges associated with the widespread deployment of nanoparticle-based water-treatment technologies. By amalgamating existing research findings, this review provides valuable insights into the potential of nanoparticles and nanocomposites in mitigating water-related challenges and presents recommendations for future research trajectories and technological advancements in this domain.

Removal of beryllium (Be2+) from aqueous solution by 5-sulfosalicylic acid-loaded anion-exchange resin

AbstractThis study presents the preparation and application of a 5-sulfosalicylic acid-loaded anion-exchange resin to remove Be2+ from aqueous solutions. Optimization efforts focused on critical parameters, including resin dosage, initial solution pH, and the influence of interfering ions. Results indicate an optimal resin dose of 0.3 g and a working pH of ≥ 4.0 for maximal Be2+ removal efficiency. Kinetic analysis reveals rapid removal kinetics, with 99% removal achieved within 45 min. Notably, the resin exhibits remarkable selectivity, maintaining consistent removal rates for Be2+ even in the presence of common interfering ions such as Na+, K+, Ca2+, Mg2+, and Fe2+. Sorption isotherms fitting the Langmuir model further support the resin's effectiveness in Be2+ removal. Thermodynamic evaluation suggests the removal process is spontaneous (∆G° &lt; 0) and endothermic (∆H° &gt; 0), indicating favorable energetics. Crucially, the Be-loaded resin is easily regenerated using 0.1 M HCl, enhancing its practical applicability. These results highlight the effectiveness and potency of the prepared resin in Be2+ removal, suggesting promising solutions for addressing environmental contamination.

Bibliometric Analysis of Nitrogen Removal in Constructed Wetlands: Current Trends and Future Research Directions

Nitrogen pollution in water environments has reached critical levels globally, primarily stemming from agricultural runoff, industrial discharges, and untreated sewage. The excessive presence of nitrogen compounds poses a significant threat to water quality, leading to adverse impacts on ecosystems and human health. Reaching a breakthrough in the technology of constructed wetlands (CWs) for mitigating nitrogen pollution is hindered by existing knowledge gaps regarding the mechanisms involved in the removal process. Reaching this understanding, we offer a comprehensive summary of current advancements and theories in this research field. Initially, bibliometric techniques were employed to identify yearly patterns in publications and areas of research focus. Subsequently, the chosen documents underwent statistical analysis using VOSviewer_1.6.20 to determine countries’ annual productivity, significant publication years, influential authors, keyword clustering analysis, and more. Finally, a comprehensive overview is provided on the elimination of nitrogen through CWs, encompassing insights into microbial communities and structure types. This analysis aims to uncover potential strategies for optimizing the rate of nitrogen removal. Furthermore, this study elucidates the current research trend concerning the nitrogen removal performance of CWs and identifies challenges and future research directions in this field.

Evaluation of Electro-Fenton Process for Removal of Amoxicillin from Simulated Wastewater

&lt;p&gt;The purpose of this work is to examine the efficiency of the Electro-Fenton process (Fenton oxidation) for the elimination of amoxicillin from simulated wastewater through response surface methodology (RSM). The effect three operating parameters that were selected for this evaluation were electrolysis time, hydrogen peroxide concentration, and the current density. The Electro-Fenton method was assessed by a set of experiments that were designed using the Box-Behnken model. The results conclude optimum parameters conditions, at 30 min electrolysis time, 30 ppm H2O2, and current density 2 amps by fixing the other two parameters; 20 ppm concentration of amoxicillin and pH of 3. The maximum removal efficiency at these conditions was 98.11%. The mathematical model concluded has a high correlation coefficient (R2= 98.3). Depending on the results, the Electro-Fenton process has proven an excellent method for the elimination of antibiotics from wastewater.&lt;/p&gt;

Surface-Enhanced Raman Spectroscopy Detection for Fenthion Pesticides Based on Gold Molecularly Imprinted Polymer Solid-State Substrates.

Current label-free surface-enhanced Raman spectroscopy (SERS) assay for the detection and analysis of organophosphorus pesticides has achieved initial success, but the application still faces constraints of substrate portability and specificity. To this end, this paper demonstrates a method for portable, rapid, and specific detection of low concentrations of fenthion pesticides based on a solid substrate of gold nanoparticle monolayers combined with molecularly imprinted polymers (MIPs). The nano-monolayers were transferred to the surface of mercapto-silicon wafers by interfacial self-assembly technique to form a stable connection with S-Au bonds and, at the same time, prevent nanoparticles from dropping off during the surfactant removal process. Then, the fenthion MIPs were directly generated on the surface of the monolayer film by spin-coating with a pre-polymerization solution and ultraviolet-induced polymerization. Tests showed that the molecular imprint was able to accurately bind to fenthion, but not other molecules, in a mixture of structural analogs, achieving a low concentration detection of 10-8 mol/L. The composite substrate maintained a signal uniformity of a relative standard deviation (RSD) = 7.05% and a batch-to-batch reproducibility of RSD = 10.40%, making it a potential pathway for the extended application of SERS technology.

Exploring the maximum nitrite production rate through the granular sludge-type reactor to match the needs of anammox process realizing efficient nitrogen removal

The reliable and efficient nitrite production rate (NPR) through nitritation process is the prerequisite for the efficient running of subsequent processes, like the anammox process and the nitrite shunt. However, there has been scant research on stable and productive nitritation process in recent years. In this study, at a stable hydraulic retention time of 12.0 h and with precise and strict DO control, the upper limit of the NPR was initially investigated using a continuous-flow granular sludge reactor. The NPR of 1.69 kg/m3/d with a nitrite production efficiency of 81.97% was finally achieved, which set a record until now in similar research. The median sludge particle size of 270.0 μm confirmed the development of clearly defined granular sludge. The genus Nitrosomonas was the major ammonium oxidizing bacteria. In conclusion, this study provides valuable insights for the practical application of the effective nitritation process driving subsequent nitrogen removal processes.

Degradation of tetracycline under a wide pH range in a heterogeneous photo bio-electro-fenton system using FeMn-LDH/g-C3N4 cathode: Performance and mechanism

The widespread use of antibiotics and the inefficiency of traditional degradation treatments pose threats to the environment and human health. Previous studies have reported the potential of bio-electro-Fenton (BEF) processes for antibiotic removal. However, some drawbacks, such as a strict pH range of 2–3 and iron sludge generation, limit their large-scale application. Thus, to overcome the narrow pH range of traditional BEF processes, a photo-BEF (PBEF) system was established using a novel FeMn-layered double hydroxide (LDH)/graphitic carbon nitride (g-C3N4) (FM/CN) composite cathode. The performance of the PBEF system was investigated by degrading tetracycline (TC) under low-power LED lamp irradiation. The results indicated that the pH range of the PBEF system could be expanded to 3–11 using an FM/CN cathode, which exhibited a TC removal efficiency of 63.0%–75.9%. The highest TC removal efficiency was achieved at pH 7. The efficient mineralization of TC by the PBEF system can be high, up to 67.6%. In addition, the TC removal mechanism was discussed in terms of reactive oxygen species, TC degradation intermediate analyses, and density functional theory (DFT) calculations. Strong oxidative hydroxyl radicals (·OH) were the dominant reactive oxidizing species in the PBEF system, followed by ·O2− and h+. Three pathways of TC degradation were proposed based on the analysis of intermediates, and the reactive sites attacked by electrophilic reagents were explored using DFT modeling. In addition, the overall toxicity of TC degradation intermediates effectively decreased in the PBEF system. This work offers deep insights into the TC removal mechanisms and performance of the PBEF system over a wide pH range of 3–11.

Point-of-care human milk concentration by passive osmosis: comprehensive analysis of fresh human milk samples.

Preterm infants need enrichment of human milk (HM) for optimal growth. This study evaluated a novel, point-of-care human milk concentration (HMC) process for water removal from fresh HM samples by passive osmotic concentration. Nineteen fresh HM samples were concentrated by incubation with the HMC devices for 3 h at 4 °C. Pre- and post-concentration HM samples were compared by HM properties for: pH, osmolality, macronutrients, enzyme activity, bioactive, and total cell viability. Passive osmotic concentration reduced HM volume by an average of 16.3% ± 3.8% without a significant effect on pH or cell viability. Ten of the 41 HM components did not differ significantly (p > 0.05) between pre- and post-concentration samples. Twenty-three increased within the expected range by volume reduction. Six increased more than expected, two less than expected, and none decreased significantly. Passive osmotic concentration of fresh HM can concentrate HM components by selective removal of water. HM osmolality and pH remained within neonatal feeding parameters.

Production of Porous Biochar from Cowdung and its Application

Porous activated carbon (PAC) powder is prepared from solid bio-waste - cow dung samples (CD). UV- Spectroscopy confirms the absorption rate of activated porous biochar at different concentration solutions(in ppm).The activation process is carried out by phosphoric acid and sodium hydroxide treatment followed by calcination at different temperature condition. XRD pattern confirms the amorphous phase formation with graphitic nature for different precursor utilization. SEM analysis shows the uniform and hierarchical porous network formation and aggregated particle with tiny. X- ray analysis confirms the formation of graphitic carbon and porous morphology for sample activated at increased calcination temperature. The elemental composition of as prepared carbon samples is determined by SEM and confirms the formation major carbon content existence. The obtained product is observed for the dye removal process wherein the specific amount of PAC is added to the Methylene Blue(MB) dye solutions and the absorption rate is observed through uv-spectroscopy.

Unraveling the path to osteoarthritis management: targeting chondrocyte apoptosis for therapeutic intervention

Osteoarthritis (OA) is a chronic disease affecting joints and further causing disabilities. This disease affects around 240 million people worldwide. It is a multifactorial disease, and its etiology is difficult to determine. Although numerous therapeutic strategies are available, the therapies are aimed at reducing pain and improving patients’ quality of life. Hence, there is an urgent need to develop disease-modifying drugs (DMOAD) that can reverse or halt OA progression. Apoptosis is a cell removal process that is important in maintaining homeostatic mechanisms in the development and sustaining cell population. The apoptosis of chondrocytes is believed to play an important role in OA progression due to poor chondrocytes self-repair abilities to maintain the extracellular matrix (ECM). Hence, targeting chondrocyte apoptosis can be one of the potential therapeutic strategies in OA management. There are various mediators and targets available to inhibit apoptosis such as autophagy, endoplasmic reticulum (ER) stress, oxidative stress, and inflammation. As such, this review highlights the importance and potential targets that can be aimed to reduce chondrocyte apoptosis.

Fly-Cutting Processing of Micro-Triangular Pyramid Arrays and Synchronous Micro-Scrap Removal.

Many micro-scraps are generated when a micro-triangular pyramid array (MTPA) is machined by the fly-cutting method. Micro-scraps are generally not removed quickly enough; therefore, these residual micro-scraps participate in the cutting process again, scratching the workpiece surface and accelerating diamond tool wear. To remove micro-scraps rapidly, a fly-cutting method to produce MTPAs on vertically oriented working surfaces was developed during this study. The results show that an MTPA produced by fly cutting on a vertical workpiece had a clearly outlined structure, high dimensional accuracy, and a low surface roughness. There was no micro-scrap residue on the workpiece surface and the diamond tool wear was small. The cutting inlet edges had no burrs, and the cutting outlet edges had only a small number of burrs. This method of fly cutting MTPAs on vertically oriented working surfaces provides a foundation for the development of high-precision micro-triangular pyramid optical elements.

Photocatalytic degradation of acid violet dye by sunlight exposure using green synthesized magnesium oxide nanoparticles

An aqueous extract of Phyllanthus Emblica fruit extract was used as a precursor in the effective synthesis of Magnesium Oxide Nanoparticles (MgONP) and the same was calcined at different temperatures. The thermal study demonstrated that MgO nanoparticles evolved from Mg(OH)2 by the identification of characteristic weight loss curves and endothermic peaks in TGA and DTA, respectively. UV-visible analysis showed that the peak shifts to a longer wavelength at 350 nm when the calcination temperature rises from 200 to 600 °C, indicating a decrease in the size of MgONP particles. On the other hand, Tauc plot analysis showed that the band gaps between the precursor and calcined MgO samples varied from 5.84 to 3.70 eV. FTIR and XRD analysis confirmed the synthesis of MgONPs from Mg(OH)2 exhibiting spherical shapes of around 20 nm in size.Twenty minutes of exposure to sunshine caused the dye's colour to entirely vanish, demonstrating the remarkable photocatalytic effectiveness of MgONP calcined at 600 °C. The effective breakdown of Acid Violet was confirmed by the rate constant of the photocatalytic behaviour increasing proportionately with the catalyst dose. Furthermore, it was suggested by the Langmuir and Freundlich isotherm models that Acid Violet efficiently adheres to the photocatalyst surface when R2 values are nearer to 1. There are several potential applications for MgO nano adsorbents in dye removal processes, as evidenced by desorption studies that showed their reusability.

Separation of Iron from ZnSO4 solution by oxygen pressure-enhanced hydrothermal precipitation

ABSTRACT This study presented a method for removing iron (Fe) from zinc (Zn) sulfate solution utilising an oxygen (O2) pressure-enhanced goethite process. The study investigated the effects of O2 pressure, reaction temperature (T), pH value, and reaction time (t) on the Fe removal process. The results indicated that the oxidation rate increased with increasing T and O2 pressure. The goethite obtained at an O2 partial pressure of 0.2 MPa exhibited higher Fe content and a distinct acicular morphology, containing 55.7% Fe, 5.4% Zn, and 1.9% Sulphur (S). The increase in temperature from 90°C to 110°C accelerated the Fe hydrothermal precipitation, enhancing the Fe content in the goethite from 55.7% to 57.1%. The goethite products with 56.4% Fe content exhibited 95.0% crystallinity at a pH of 3.2, with a tendency for particle aggregation at lower crystallinity levels. The goethite precipitation occurred within the pH range of 2.2−3.5. Furthermore, as the reaction time increased, the hydrothermal precipitation particles increased in size and exhibited higher Fe content. The proposed method modified the O2 mass transfer process, increasing its solubility to enhance the Fe2+ oxidation rate, facilitating the controlled acicular α-FeOOH production with excellent crystallization performance.

Ti6Al4V interacting with Al2O3 under ambient and vacuum conditions: Effect of plastic deformation and tribo-chemical reactions on wear mechanisms

Tribological interaction is a synergy between several mechanisms. In this paper, those pivotal mechanisms are studied by investigating the sliding interaction of Ti6Al4V (referred to as Ti64) pins against an Al2O3 disc under both ambient and vacuum environments. The impact of sliding speed was examined by altering the rotation rate (measured in ms−1) of the disc. This assessment utilized a 6.6 mm diameter pin, while keeping the load and environmental conditions consistent across all experimental trials. The findings reveal that in ambient environment, the frictional characteristics and wear rate of the tribological pair are intricately influenced by a synergistic interplay between plastic deformation and tribo-chemical reactions (TCR). A transition in wear mechanism occurs from abrasion to composite type (abrasion + oxidative) to oxidative with step-wise increment in sliding velocity (0.01–1.5 m/s). Coupled action of the TCR sub-mechanisms, viz. tribo-oxidation and formation of mechanically mixed layers (MML) play a pivotal role in the aforementioned wear transition. For vacuum-based experiments, the prevailing wear mechanism is exclusively dictated by plastic deformation. This phenomenon is in turn regulated by adiabatic shear banding (ASB)/strain rate response (SRR) at lower speeds, while at higher speeds, temperature-induced effects (phase transformation assisted thermal softening) come into action. Adhesion takes precedence in governing the material removal process, given that the development and activity of tribo-oxides and MML are impeded in the absence of air. Further, additional tests to study the effect of change in the pin-diameter (2.1, 4.6, and 6.6 mm) on the tribological response are performed and analysed.

Performance of Teflon- reinforced Nafion against microbes and removal of heavy metal ions from aqueous environment

Considering its promising antimicrobial and metal removal capabilities, water filtration systems have not yet widely used ionic polymer membranes. A textile structure made of Nafion polymer reinforced with Teflon (TFRN) was coated with non-precious metals copper and silver using a chemical decomposition technique. Scanning electron microscopy makes it quite evident that a surface coating was formed with evenly distributed metal particles. Water and moisture uptake capacity for Silver (Ag)-Copper (Cu) coated membrane was reduced by 80 and 67 % respectively compared to pure membrane. Inaddition, Ag–Cu coated membrane showed best performance against Escherichia coli (ATCC25922), and Staphylococcus aureus (ATCC 25923) with 2.04 and 1.7 CFU/ml respectively, by considering below level of Quantification as 1.6 CFU/ml. Pure Nafion membrane at pH 6.5, was used to perform the adsorption studies of transition metal ions like Copper, Nickel, Chromium, Barium, Tin and Arsenic at room temperature. The maximum metal ion removal was about 35 % for Copper followed by Nickel (31 %) and the least adsorption was observed for Barium (13.5 %) from multi-heavy metals solution. The study revealed that the potential of TFRN membrane for water purification in terms of metal and microbial removal process.

Influence of argon, helium, and their mixtures on the powder bed fusion of an Al–Cu–Li–Ti alloy using a laser beam: Evaporation, microstructure, and mechanical properties

The role of the inert processing gas during the powder bed fusion of metals using a laser beam (PBF-LB/M) is to prevent oxidation and remove process by-products, such as metal vapor and spatter particles. The present study aims to unveil additional impacts of using argon (Ar), helium (He), and two mixtures thereof as the processing gas on the material properties of a high-strength Al–Cu–Li–Ti alloy fabricated by PBF-LB/M. The part density, microstructure, static tensile properties, and volatile element evaporation were characterized as functions of the processing gas. Decreased porosity levels and increased melt penetration depths were found across a range of processing parameters when increasing the fraction of He in Ar indicating a more stable process and melt pool dynamics. A trend towards increasing yield and ultimate tensile strength was also observed and was attributed to a slightly refined grain size when processing under He-containing gases. The process gas had no significant influence on the evaporation of alloying constituents in the material. Overall, several advantages of using He-containing process gases over pure Ar in PBF-LB/M are demonstrated and discussed.© 2017 Elsevier Inc. All rights reserved.