Enhanced Removal Efficiency Research Articles

Modulating structure of Ce-UiO-66 by introducing fluorinated terephthalic acid for enhanced removal efficiency of antibiotics: Insights into degradation kinetics and pathways

In this work, the 2-fluoroterephthalic acid with asymmetric structure and high electronegative F species was introduced in the assembly of Ce-UiO-66 catalysts to increase the defect density and enlarge pore structure for enhancement in removal efficiency of sulfamethoxazole. Owing to the strong coordination ability from high electronegative F species of 2-fluoroterephthalic acid with Ce-oxo nodes, the designed CUF exhibited improved interfacial properties (accelerated electron transfer rate, available active sites and enhanced interaction with PMS), which was favorable for the exploration and accessibility of active sites with sulfamethoxazole and PMS to decrease the adsorption barrier and accelerate PMS activation. As a result, the CUF catalysts exhibited higher adsorption capacity (173.4 mg/g) than that of CUH (117.8 mg/g), the enhanced degradation efficiency of sulfamethoxazole with a rate constant higher than 2.3 times CUH, good elimination (>95 %) of methylene blue, tetracycline and ibuprofen. In addition, the CUF/PMS system possessed satisfactory stability in wide solution pH, recycling and real water and good potential application in continuous wastewater treatment based on the designed dynamic catalytic reactor. This work provided deep insight into the design of catalysts with high adsorption performance and degradation efficiency based on the structure–activity relationship.

Enhanced Photocatalytic Degradation of Ciprofloxacin Antibiotics using Fe3O4-SiO2-EN@Zn-Al Layered Double Hydroxide Nanocomposites under the COVID-19 pandemic

A novel layered double hydroxide nanocomposite, Fe3O4-SiO2-EN@Zn-Al-LDH, was synthesized and employed as a photocatalyst for the degradation of ciprofloxacin (CIP) in aqueous solutions. Characterization of the photocatalyst was performed using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) techniques. The results indicated successful synthesis of particle with specific surface area of 28.67 m²/g, pore size of 1.64 nm, and pore volume of 6.58 cm³/g. Optimal degradation of CIP was observed under the following conditions: pH 5, photocatalyst dosage of 0.6 g/L, initial CIP concentration of 25 mg/L, and an irradiation duration of 60 minutes. Comparative experiments demonstrated that incorporating Zn-Al LDH with core-shell nanoparticles (Fe3O4-SiO2-EN) enhanced removal efficiency by 2.5 to 6 times compared to individual materials. The composite exhibited efficient activation under UV, visible light, and solar radiation, resulting in 100% degradation of CIP under UV, 100% under visible light, and 81.4% under solar radiation. Biodegradability, indicated by the BOD5/COD ratio, increased from 0.28 to 0.73 after 120 minutes of photocatalytic oxidation under visible light, with 80.83% COD removal and 74.17% TOC removal. Reactive species generation, such as •OH, •O2-, and h+, was confirmed by introducing scavengers (TBA, BQ, and TEOS) into the reaction medium. The photocatalytic activity of the nanocomposite was slightly decreased over 5 consecutive CIP treatment cycles. Toxicity assessment of treated wastewater using E. coli and Daphnia magna bioassays revealed a significant decrease in E. coli growth inhibition rate with prolonged treatment time. The EC50 percentage improved from 1.27% to 97.4% after 4 hours of CIP treatment under visible light. In conclusion, the development of the Fe3O4-SiO2-EN@Zn-Al-LDH presents a noteworthy advancement in photocatalysis for the degradation of CIP in aqueous solutions.

Electronic structure of biochar modified through self-doping with boron, nitrogen and sulfur atoms for rapid and efficient adsorption of COVID-19 drug residues

Self-doping of biochar with various heteroatoms can significantly modify its electronic structure and surface properties, thereby enhancing its adsorption capacity. Allium mongolicum Regel (AM) was a desert herb known for hyperaccumulating boron and possessing a cavity structure. AMAC-3 derived from the pyrolysis of AM, exhibited a high specific surface area (2754 cm2g−1), a larger pore volume (2.513 cm3g−1), an appropriate degree of graphitization (IG/ID = 0.99), and a certain content of heteroatoms (boron, nitrogen and sulfur). AMAC-3 achieved equilibrium adsorption of 20 mg L−1COVID-19 drugs residues within 5–8 min, with equilibrium adsorption capacity ranging from 158 to 195mg g−1 and the drug removal rate between 79 % and 98 %. Furthermore, AMAC-3 maintained high adsorption efficiency in the presence of coexisting anions and spiked real water samples. The shorter adsorption equilibrium time and higher removal rate of AMAC-3 were attributed to the rapid mass transfer in the 3D pores, as well as the rapid binding of more electrons. Boron was the preferred binding site for heteroatom sites due to its electron deficient nature. This study offered insights into the utilization of self-doped heteroatoms for modulating the electronic structure of adsorbent, thereby reducing adsorption equilibrium time and enhancing removal efficiency.

Significant improvement in the removal performance of decimeter-sized zero-valent iron plates for mixed heavy metal ions in wastewater by enhancing surface sharpness

This study aims to lower the work function (Wa) of a decimeter-sized zero-valent iron plate (DZVIP) by introducing surface sharpness (TDZVIP) during stirring. Sharpness was achieved by cutting isosceles triangles with heights of 1 cm and varying apex angles (α) of 10˚, 20˚, 30˚, 40˚, and 50˚. A mixed simulated wastewater containing Cu(II), Te(IV), Se(IV), As(III), Bi(III), and Pb(II) at concentrations exceeding emission standards was prepared. Results indicate that the removal process exhibits mixed kinetic behavior, and sharpness significantly enhances the removal capacity (Re), mean removal rate (Vm), recycling performance, and final discharge quality. The Vm values for Cu(II), Te(IV), Se(IV), As(III), Bi(III), and Pb(II) over TDZVIP with optimized α are 2.34, 1.97, 1.51, 1.59, 4.09, and 1.53 times higher, respectively, than those over PDZVIP (without sharpness). UPS measurements provide direct evidence of Wa reduction, while XRD offers indirect confirmation. This is the first time the Wa of the amorphous shell has been identified and verified as a critical potential barrier for core electrons transferring from the DZVIP surface to wastewater. Additionally, it has been successfully reduced by incorporating surface sharpness and stirring, leading to enhanced removal efficiency, improved recycling performance, and higher final discharge quality.

Adsorption of aqueous insensitive munitions compounds by graphene nanoplatelets

Mitigation strategies for potential environmental impacts of insensitive munition (IM) compounds, including 2,4-dinitroanisole (DNAN), 3-nitro-1,2,4-triazol-5-one (NTO), nitroguanidine (NQ), and methylnitroguanidine, (MeNQ) are being considered to enhance sustainability of current or potential IM formulations. Graphene nanoplatelets (GnPs) were investigated for adsorptive removal of each compound. GnPs were characterized to determine surface areas, along with particle size and zeta potential at different pH and ionic strength conditions. Adsorption kinetics and isotherm studies were conducted, comparing results against granular activated carbon (GAC). Ionic strength, pH, and temperature were adjusted to inform impacts on adsorptive behaviors and performance. The results indicated that GnPs adsorbed IM compounds more rapidly than GAC. Additionally, GnPs removed DNAN with greater capacity compared to GAC, likely due to π-π interactions. GnPs removed other compounds via van der Waals forces, while GAC exhibited greater adsorption capacities due to higher surface area. Although negative charges associated with GnPs and dissociated NTO species hindered adsorption, pH and ionic strength did not impact other compounds. Moreover, this study reports the first environmental treatment technique for MeNQ. Overall, these findings suggest that GnPs are a promising treatment technology for IM-laden waters, particularly those with compounds like DNAN where specific interactions enhance removal efficiency.

Waste tea as absorbent for removal of heavy metal present in contaminated water

The goal of this study is to investigate the efficacy of tea-derived absorbents for the removal of heavy metals from contaminated water. For this, absorbents were prepared from milk tea (MT) waste, Ilam tea (IT) waste, and various types of tea leaves, including Immature (IML), mature (ML), and old leaves (OL). The characterization of the absorbents revealed distinct physical and chemical properties from X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), with varying degrees of effectiveness observed across different absorbent types. Heavy metal removal efficiency was assessed using a chemical-free UV-spectrophotometer. The results show that the maximum removal efficiency for Cd using the IT absorbent reaches up to 82.14 % with 100 ppm cetyltrim ethylammonium bromide (CTAB), while the minimum removal efficiency is 32.14 % using the OL absorbent with 20 ppm CTAB. For Zn, the OL absorbent demonstrates a maximum removal efficiency of 52.59 % with 100 ppm CTAB, whereas the minimum efficiency is 3.70 % using the ML absorbent with 20 ppm CTAB. For Ni, the highest removal efficiency is achieved with the ML absorbent, reaching up to 97.73 % with 100 ppm CTAB, and the lowest is 31.82 % with the MT absorbent with 20 ppm CTAB. The addition of a catalyst further enhanced removal efficiencies in both absorbents and metals. Also, the removal of heavy metal ions using 0.05 g of tea absorbent combined with CTAB at varying concentrations. Results show that the addition of 20 ppm and 100 ppm CTAB significantly reduces metal ion concentrations from an initial 100 mg/L. The metal ion concentration decreases as CTAB concentration increases, demonstrating the effectiveness of CTAB in enhancing the absorption capacity of tea absorbent for heavy metal removal. The investigation of selective adsorption of Ni, Zn, and Cd by an adsorbent, revealing competitive adsorption behavior with Ni and Zn being adsorbed more rapidly than Cd, suggesting the impact of metal ion interference on adsorption efficiency. However, limitations were observed with certain absorbent types; for instance, immature leaves did not effectively remove Ni. Overall, this study underscores the potential of tea-derived absorbents as sustainable solutions for mitigating heavy metal pollution in industrial wastewater. Further research is needed to optimize absorbent formulations and explore their applicability in real-world environmental remediation scenarios.

Silver nanoparticle-decorated reduced graphene oxide/ nanocrystalline titanium metal-organic frameworks composite membranes with enhanced nanofiltration performance and photocatalytic ability

Nanofiltration (NF) has garnered significant attention for removing persistent dyes from industrial wastewater. However, limited membrane separation efficiency and performance deterioration due to membrane fouling are the primary challenges hindering the broader application of NF technology. Herein, we developed high-performance silver nanoparticle-coated reduced graphene oxide/nanocrystalline MIL125(Ti) composite NF membranes (nAg-rGO/n-MIL), which feature self-cleaning capabilities through photocatalytic activity. This was achieved by intercalating nanocrystalline MIL-125(Ti) (n-MIL) metal-organic frameworks between graphene oxide (GO) nanosheets, followed by reducing the GO nanosheets and decorating them with silver nanoparticles (nAg) via UV exposure. The nAg-rGO/n-MIL demonstrated high water permeability (21.7 LMH/bar) and achieved excellent removal efficiencies for targeting dyes with relatively small molecular weights ranging from 300 to 500Da. Additionally, when operated in an NF system equipped with a UV side-emitting optical fiber, the nAg-rGO/n-MIL exhibited significantly reduced water flux decline and enhanced removal efficiencies, achieving up to 97.5% for methylene blue. Moreover, the nAg-rGO/n-MIL demonstrated high durability under the tested operating conditions, indicating its potential for long-term use in industrial applications. The GO composite membrane, with nanosized MOF-intercalated nanochannels and photocatalytic activity via nAg decoration and GO reduction, offers a promising solution to performance limitations and fouling issues in current nanofiltration membranes.

Three-dimensional bioprinted materials in alginate-hyaluronic acid complex based hydrogel based bio-ink as absorbents for heavy metal ions removal

Major environmental and health effects arise from the presence of heavy metals in water, including lead (Pb²⁺), mercury (Hg²⁺), chromium (Cr⁶⁺), cadmium (Cd²⁺), and arsenic (As³⁺), which contribute significantly to water pollution and pose severe risks to ecosystems and human health. This study demonstrates the fabrication of 3D printed self-regenerative functional living materials, a fungi, by using mixture of sodium alginate and hyaluronic acid hydrogel as absorbents to remove the heavy metals from the environment. Bioprinting has emerged as a transformative technology for fabricating complex biological constructs. The bioprinting experiments, conducted with optimized parameters, revealed the viscoelastic behavior of the hydrogel, suitable for 3D bioprinting applications. MicroCT analysis indicated that the hydrogel's porosity and structural properties support fungal growth in a controlled three-dimensional setting. Microscopic analyses, including phase contrast microscopy, FESEM, and HRTEM, provided insights into the cellular morphology of the bioprinted constructs. Cell viability was assessed using flow cytometry with FDA and PI staining, showing a significant population of live cells, affirming the biocompatibility of the hydrogel. Additionally, the study explored the hydrogel's potential for heavy metal removal from water samples. Multi-element standard solutions containing Copper(Cu²⁺), Cadmium(Cd²⁺), Nickel(Ni²⁺), Cobalt(Co²⁺), and Ferrous(Fe³⁺) ions at different concentrations were incubated with hydrogel patches embedded with Aspergillus flavus. Atomic absorption spectrophotometry analysis showed rapid initial removal rates of metal ions, with maximum removal efficiency achieved around the 12th hour. Comparisons with a control hydrogel without the fungal strain demonstrated significantly enhanced removal efficiency due to the presence of Aspergillus flavus. This study highlights the dual functionality of sodium alginate with hyaluronic acid -based hydrogels for bioprinting fungi and for environmental remediation of heavy metals, offering promising applications in environmental cleanup.

Unraveling the synergistic promotion mechanism of Fe0 coupling phragmites australis biomass for nitrogen removal in coastal wetland: From low to moderate salinities

The simulated coastal constructed wetlands supplemented with Fe0 and phragmites australis (P.A) biomass (CW-M) were constructed to improve nitrogen removal under different salinities (0–15‰). Results showed that the denitrification performance of CW-M were improved significantly, with the higher NO3−-N removal of 72–94% and lower N2O emission flux, when compared with mono-P.A biomass(CW-bio), mono-Fe0 system (CW-Fe) and control system. The nitrogen removal showed a trend of first increasing (0‰–7‰) and then decreasing (7‰–15‰) with the highest NO3−-N removal of 94% and enhanced removal efficiency of 41%in CW-M. Fe0 and P.A biomass coupling could reduce the stress of salinity on denitrification. Batch experiments have demonstrated that Fe0 and P.A biomass could mutually stimulate more total organic carbon and total iron (TFe) release as electron donors for denitrification. Meanwhile, appropriate salinity could also promote the release of TFe. The typical heterotrophic denitrifying genera Bacillus and iron autotrophic denitrifying genera Thermomonas have the highest proportion in CW-M, with 21.83% and 0.10%, respectively. Fe0 and P.A biomass adding simultaneously promoted the carbon and iron metabolism, further enhancing the nitrogen metabolism process. The joint enhancement of autotrophic and heterotrophic denitrification contributes to NO3−-N removal in CW-M for treating saline, low C/N wastewater in coastal wetlands.

Effects of BixOyIz Self‐Combination and Integration With Magnetic CoFe2O4 on the Enhanced Removal Efficiencies for Tetracycline Residues

ABSTRACTThe BixOyIz and CoFe2O4 combination enhances photocatalytic degradation of tetracyclines (TCs). Three TC antibiotics including TC, oxytetracycline (OTC), and chlortetracycline (CTC) with high concentration (50 mg L−1) were utilized as target pollutant. Bi5O7I/Bi4O5I2, with its Z‐scheme, improves removal efficiency to 1.6 times that of Bi5O7I and 1.4 times that of Bi4O5I2. Ternary Bi5O7I/Bi4O5I2/CoFe2O4 (I/I/Co) composites further increase efficiency, with I/I/Co‐2 achieving 1.6 times that of I/I‐2. The improved performance is due to an optimized microstructure, which promotes light absorption and carrier transfer. CoFe2O4 nanoparticles on nanosheets create a double‐Z band structure, enhancing redox activity. Radical trapping experiments indicated the major active species (•O2−, OH−, and h+) in photocatalytic process of I/I/Co‐2. Based on their enhanced removal efficiencies for high‐concentration TCs, proper magnetic separation capacity, and recycling performance, the practical applications of I/I/Co composites to treat real TC wastewater might be implemented.

Basic and microwave modification processes to produce new activated carbon adsorbents based on Pistacia atlantica Kurdica nuts as carbonaceous raw material; A comparative study on the adsorption and elimination of acid blue 113

The nutshell of the pistachio tree was used as a precursor for producing new activated carbon (AC) adsorbent. The raw material was rinsed in H3PO4 (85 % w/w) and heated in a cylindrical furnace at 350 °C/90 min to 700 °C/60 min in a He and NH3 atmosphere. To change the surface chemistry, basic modification of AC was done under the NH3 atmosphere at 700 °C. The FT-IR spectrum showed apparent changes. The microwave, as second modification method, led to significant changes in the porosity properties of AC, especially in the surface area. The SEM images showed the differences in the morphology of the modified and unmodified samples. In the next step, an improved adsorption process was implemented to remove acid blue 113 (AB113). Basic and microwave-modified AC (BMM-AC) showed an enhanced removal efficiency of more than 97.54 % compared to AC, 60.32 %, microwave-modified AC (MM-AC), 73.08 %, and basic modified AC (BM-AC) 88.72 %, which revealed the positive role of the modification methods. Increasing the SBET from 238.8 to 368.6 m2/g using microwaves and changing the surface chemistry by basic modification were significant results of the study. These changes led to the construction of an improved removal process using BMM-AC to eliminate AB113.

Adsorptive removal of phosphate from water with biochar from acacia tree modified with iron and magnesium oxides

A novel biochar (BC) from Acaciatortilis trees pruning waste was synthesized and tested for the removal of phosphate from aqueous solutions. The BC was prepared by calcination at 600 °C and doped with Fe3O4 and MgO by hydrothermal process. The presence of iron and magnesium ions in the modified BC was confirmed by EDS analysis and X-ray diffraction (XRD) methods. Both unmodified and doped BCs were tested for phosphate removal from synthetic 1–500 ppm aqueous solutions. While the unmodified BC did not show any significant removal of phosphate from aqueous solutions, the modified BC almost completely removed phosphate from water. The enhancement in removal efficiency is due to an increase in the overall surface charge and surface area of BC as a result of doping with Fe3O4 and MgO salts. The average porosity and BET surface area corresponding to the plain BC increased by more than 20% from 322 to 394 m2/g after modification by impregnation with iron oxide and magnesium oxide. The modificaiton of BC with Fe3O4 and MgO nanoparticles was observed to increase the point of zero electric charge (PZC) from pH 3.4 (corresponding to plain BC) to pH 5.3 (corresponding to modified BC). The adsorption process was very fast and a phosphate removal value of 82.5% was reached only after 30 min of adsorption, while the removal efficiency after 4 h of adsorption was 97.5%. The rapid removal efficiency in short contact time is attributed to the high surface area of BC and strong bonding between the modified BC surface and PO43− ions. The highest adsorption capacity was observed to correspond to 98.5 mg/g which was achieved at PO43− concentration of 500 ppm and pH 8.5. Moreover, after fitting the adsorption data onto four of the most widely used adsorption isotherm models, the adsorption of PO43− onto BC can be better described by the Langmuir isotherm model.

Enhanced photocatalytic activity of Ag/ZnO nanocomposite immobilized on kanthal coils

Constructing hybrid semiconductor photocatalysts and increasing the charge-carrier density are effective strategies for enhancing the photocatalytic performance of ZnO. This study elucidates the synergistic effects of electron trapping and surface plasmon resonance (SPR) on the activity of ZnO photocatalysts. Ag/ZnO nanocomposites were synthesized on Kanthal coils using a two-step method involving the immobilization of ZnO on Kanthal coils and the coupling of Ag nanoparticles. XPS and RTPL analyses verified the synergistic effects of electron trapping and SPR on the activity of the Ag/ZnO nanocomposites. The photocatalytic performance of the composite was evaluated in the degradation of rhodamine B (RhB) dye. The Ag/ZnO nanocomposite exhibited significantly enhanced removal efficiency for RhB dye (38.2–70.5% depending on the deposition time). The Ohmic contact at the Ag/ZnO heterojunction extended the lifetime of the photoinduced charge carriers, whereas the SPR facilitated the generation of more electrons for the photocatalytic reaction. However, the excessive deposition of Ag nanoparticles compromised the photocatalytic performance of the Ag/ZnO nanocomposite. This study provides valuable insights for developing efficient ZnO-based photocatalytic materials for addressing environmental challenges.

Mixotrophic aerobic denitrification facilitated by denitrifying bacterial-fungal communities assisted with iron in micro-polluted water: Performance, metabolic activity, functional genes abundance, and community co-occurrence

Low-dosage nitrate pollutants can contribute to eutrophication in surface water bodies, such as lakes and reservoirs. This study employed assembled denitrifying bacterial-fungal communities as bio-denitrifiers, in combination with zero-valent iron (ZVI), to treat micro-polluted water. Immobilized bacterial-fungal mixed communities (IBFMC) reactors demonstrated their ability to reduce nitrate and organic carbon by over 43.2 % and 53.7 %, respectively. Compared to IBFMC reactors, IBFMC combined with ZVI (IBFMC@ZVI) reactors exhibited enhanced removal efficiencies for nitrate and organic carbon, reaching the highest of 31.55 % and 17.66 %, respectively. The presence of ZVI in the IBFMC@ZVI reactors stimulated various aspects of microbial activity, including the metabolic processes, electron transfer system activities, abundance of functional genes and enzymes, and diversity and richness of microbial communities. The contents of adenosine triphosphate and electron transfer system activities enhanced more than 5.6 and 1.43 folds in the IBFMC@ZVI reactors compared with IBFMC reactors. Furthermore, significant improvement of crucial genes and enzyme denitrification chains was observed in the IBFMC@ZVI reactors. Iron played a central role in enhancing microbial diversity and activity, and promoting the supply, and transfer of inorganic electron donors. This study presents an innovative approach for applying denitrifying bacterial-fungal communities combined with iron enhancing efficient denitrification in micro-polluted water.

Analyzing atmospheric plasma's potential for diesel soil remediation: Insightful mechanisms

The remediation of diesel-contaminated soil is a critical environmental concern, driving the need for effective solutions. Recently, the methodology of Non-thermal Atmospheric Plasma (NTAP) technology, which is equipped with a Dielectric Barrier Discharge (DBD) electrode and has become a feasible approach, was proven to be viable. The reactive species from the plasma were exposed to the contaminated soil in this investigation using the NTAP technique. The reacted soil was then extracted using dichloromethane, and the amount of Total Petroleum Hydrocarbon (TPH) removed was assessed. Investigation into varying power levels, treatment durations, and hydrogen peroxide integration revealed significant findings. With an initial concentration of 3086 mg of diesel/kg of soil and a pH of 5.0, 83% of the diesel was removed from the soil at 150 W in under 20 min. Extended exposure to NTAP further improved removal rates, highlighting the importance of treatment duration optimization. Additionally, combining hydrogen peroxide (H2O2) with NTAP enhanced removal efficiency by facilitating diesel breakdown. This synergy offers a promising avenue for comprehensive soil decontamination. Further analysis considered the impact of soil characteristics on removal efficacy. Mechanistically, NTAP generates reactive species that degrade diesel into less harmful compounds, aiding subsequent removal. Overall, NTAP advances environmental restoration efforts by offering a quick, economical, and environmentally benign method of remediating diesel-contaminated soil especially when used in tandem with hydrogen peroxide.

Carbon dioxide and weak magnetic field enhance iron-carbon micro-electrolysis combined autotrophic denitrification

Combining iron-carbon micro-electrolysis and autotrophic denitrification is promising for nitrate removal from wastewater. In this study, four continuous reactors were constructed using CO2 and weak magnetic field (WMF) to address challenges like iron passivation and pH stability. In the reactors with CO2 + WMF (10 and 35 mT), the increase in total nitrogen removal efficiency was significantly higher (96.2 ± 1.6 % and 94.1 ± 2.7 %, respectively) than that of the control (51.6 ± 2.7 %), and Fe3O4 converted to low-density FeO(OH) and FeCO3, preventing passivation film formation. The WMF application decreased the N2O emissions flux by 8.7 % and 20.5 %, respectively. With CO2 + WMF, the relative enzyme activity and abundance of denitrifying bacteria, especially unclassified_Rhodocyclaceae and Denitratisoma, increased. Thus, this study demonstrates that CO2 and WMF optimize the nitrate removal process, significantly enhancing removal efficiency, reducing greenhouse gas emissions, and improving process stability.

Assessing the Suitability of Green Algae (Chlorella Sorokiana) as Biosorbent for Removal of Cu (II) and Zn (II) Ions from Synthetic Wastewater in a Batch System

Heavy metal contamination in wastewater poses a significant threat to environmental and human health. This study investigated the potential of Chlorella sorokiana, a green alga, as a biosorbent for Cu (II) and Zn (II) removal from synthetic wastewater. Batch experiments were conducted at 28°C, pH 6, and a contact time of 60 minutes. Chlorella sorokiana displayed promising biosorption capacity, removing 85% and 75% of Cu (II) and Zn (II), respectively. Further optimization revealed enhanced removal efficiencies at pH 5 (88.5% Cu (II) and 82% Zn (II)) and a biosorbent dosage of 0.5 g/L (90.7% Cu (II) and 87.1% Zn (II)). These findings demonstrate the efficacy of Chlorella sorokiana as a biosorbent for heavy metal remediation. This research highlights the potential of biosorption as a sustainable and environmentally friendly approach for wastewater treatment, offering a promising solution for mitigating heavy metal pollution.

Rapidly reducing cadmium from contaminated farmland soil by novel magnetic recyclable Fe3O4/mercapto-functionalized attapulgite beads

Reducing cadmium (Cd) content from contaminated farmland soils remains a major challenge due to the difficulty in separating commonly used adsorbents from soils. This study synthesized novel millimeter-sized magnetic Fe3O4/mercapto-functionalized attapulgite beads (MFBs) through a facile one-step gelation process incorporating alginate. The MFBs inherit the environmental stability of alginate and enhance its mechanical strength by hybridizing Fe3O4 and clay mineral components. MFBs can be easily separated from flooded soils by magnets. When applied to 12 Cd-polluted paddy soils and 14 Cd-polluted upland soils, MFBs achieved Cd(II) removal rates ranging from 16.9% to 62.2% and 9.8%–54.6%, respectively, within a 12-h period. The MFBs predominantly targeted the exchangeable and acid soluble, and reducible fractions of Cd, with significantly enhanced removal efficiencies in paddy soils compared to upland soils. Notably, MFBs exhibited superior adsorption performance in soils with lower pH and organic matter (OM) content, where the bioavailability and mobility of Cd are heightened. The reduction of Cd content by MFBs is a sustainable and safe method, as it permanently removes the bioavailable Cd from soil, rather than temporarily reducing its bioavailability. The functional groups such as –SH, –OH, present in attapulgite and alginate of MFBs, played a crucial role in Cd(II) adsorption. Additionally, attapulgite and zeolite provided a porous matrix structure that further enhanced Cd(II) adsorption. The results of X-ray photoelectron spectroscopy suggested that both chemical precipitation and surface complexation contributed to Cd(II) removal. The MFBs maintained 87.6% Cd removal efficiency after 5 regeneration cycles. The surface of the MFBs exposed new adsorption sites and increased the specific surface area during multiple cycles with Cd-contaminated soil. This suggests that MFBs treatment with magnetic retrieval is a potentially effective pathway for the rapid removal of Cd from contaminated farmland soils.

Application of electric potential and Fe(Ⅲ) to stimulate perfluorooctanoic acid (PFOA) degradation using mixed culture anammox granules

Pollution by perfluorooctanoic acid (PFOA), a highly persistent and toxic substance, is commonly addressed with several approaches, but the need for post-treatment affects their environmental and economic sustainability. Biodegradation, which can efficiently degrade micropollutants in water under optimal conditions, offers a promising solution, but faces challenges from the persistence of the C-F bond and the high reactivity of F-. Despite recent use of various microorganisms for PFOA degradation, performance issues persist. In this study, we aimed to simulate PFOA degradation while mixed culture anammox granules oxidize NH4+ and to confirm the effects of electric potential and Fe(Ⅲ) applications on PFOA degradation. A control reactor containing only anammox granules exhibited NH4+ and PFOA removal efficiencies of 11.52% and 19.2%, respectively, with traceable biodegradation at 3.7%. In contrast, a reactor that applied both electric potential and Fe(Ⅲ) demonstrated enhanced removal efficiencies of 41.98% and 50.93%, with traceable biodegradation at 35.03%. Bio-electrochemical properties also improved, showing an average current generation of 331.95 μA and Coulombic efficiency of 141.79 ± 7.6%. This study shows that mixed-culture anammox granules with electric potential and Fe(Ⅲ) can be introduced for efficient PFOA biodegradation and provides the basis for further studies on overcoming the limitations of PFOA biodegradation.

Evaluation of the impacts of seawater integration to electrocoagulation for the removal of pollutants from textile wastewater

Recent textile industry expansion has a major environmental impact if not addressed. Being a water intensive industry, textile manufacturing is usually associated with wastewater management challenges. Electrocoagulation (EC) is recognized as one of the effective solutions to address these challenges. This study aims to investigate the potential of integrating seawater into the EC process for textile wastewater treatment, targeting optimal pollutant removal efficiencies. A simple electrolytic reactor was designed to investigate the removal efficiency of these treatments for chemical oxygen demand (COD), total suspended solids (TSS), turbidity, and color from textile wastewater at different seawater percentages and retention times. Notably, the addition of seawater not only improves the EC process efficiency but also significantly dilutes pollutants, reducing their concentrations. This dual effect enhances removal efficiency and dilution optimizes the treatment outcome. The highest removal efficiencies were achieved for COD (47.26%), TSS (99.52%), turbidity (99.30%), and color (98.19%). However, pH, dissolved oxygen (DO), and electrical conductivity increased with increasing retention times and seawater percentages in the EC process. Moreover, Seawater − EC integration reduces power usage to 15.769 Am−2 and costs approximately 0.20 USD/m3. To assess the effects of the retention times and seawater percentages on pollutant removal from textile wastewater, an analysis of variance (ANOVA) was conducted utilizing the Design-Expert 11 software. The best model obtained using Central Composite Design (CCD) was quadratic for COD (R2 = 0.9121), color (R2 = 0.9535), turbidity (R2 = 0.9525), and TSS (R2 = 0.9433). This study suggests that higher seawater percentages and longer retention times effectively eliminate contaminants but increase ion concentrations.