Removal Of Pollutants In Wastewater Research Articles

Carbon Ink Enhanced Calcium Alginate-Based Hydrogel with Response Surface Methodology Optimized for Solar-Driven Salt-Tolerant Desalination.

The global shortage of freshwater resources is becoming more and more serious; therefore, it is necessary to obtain freshwater by desalinating seawater resources. Solar-driven interfacial photothermal evaporation, which is an environmentally friendly and energy-efficient technology, has been used to desalinate seawater for water purification and production. Herein, the IPCA hydrogel with abundant pores consisting of carbon ink as a photothermal conversion material and PU sponge loaded with calcium alginate as a water transport medium was successfully prepared and used to obtain portable water. The parameters of the synthesized IPCA are optimized by Response Surface Methodology analysis, and it was found that the IPCA exhibits a high evaporation efficiency of 3.779 kg m-2 h-1 and up to 95.98% of photothermal conversion capacity under one solar intensity. It maintains a high evaporation efficiency and salt resistance after 10 cycles of evaporation in actual seawater. Moreover, IPCA shows a high removal of various organic dye pollutants in wastewater. The results suggest a new approach for the preparation of simple, efficient, and green solar evaporators in practical application.

Synthesis of phthalocyanine/C3N4 structures and investigation of photocatalytic activities in the oxidation reaction of 4-nitrophenol

Photocatalytic oxidation is an advanced oxidation technique widely preferred for the removal of pollutants in wastewater. In this work, paramagnetic metallo-phthalocyanines EB2 and EB3 (Co(II)phthalocyanine and Cu(II)phthalocyanine) have been synthesized and characterized. They were interfaced with C3N4 (graphitic carbon nitride) to prepare metallophthalocyanines/C3N4 structures (EB2-C3N4 and EB3-C3N4) using ultrasonic methods. New structures were identified with FT-IR, SEM and TGA. The photocatalytic performances of EB2-C3N4 and EB3-C3N4 for reaction with p-nitrophenol (p-NP) were established. The product selectivity for industrially important benzaldehyde was 85.1% for EB2-C3N4 and 80.6% for EB3-C3N4. EB2-C3N4 showed good potential for p-NP photocatalyic oxidation with high turn-over number (TON) and turn-over frequency (TOF) (390 and 1565) over 15 min. Upon excitation of EB2-C3N4 and EB3-C3N4 with light, 4-nitrophenol was easily reduced to hydroquinone, prompted by electron transfer from C3N4 to phthalocyanine and from phthalocyanine to 4-nitrophenol. Computational investigations were used to determine the energies of the highest occupied molecular orbitals (HOMO) and the lowest unoccupied molecular orbitals (LUMO) of EB2, EB3 and C3N4.

Photochemical Action of Far‐UVC Radiation (222 nm) in Wastewater Treatment and Indoor Air Disinfection

Ultraviolet‐ C irradiation can effectively disinfect various pathogens present in air, surfaces, and water. Various recent research studies suggest use of KrCl* (krypton‐chloride) excimer lamps to disinfect high‐risk public spaces having pathogenic bateria and viruses, as they emit Far‐UVC radiation (222 nm) with lower health risks than germicidal UVC (254 nm). The purification of water and air having pollutants and pathogens is a critical challenge in environmental protection and public health assurance. Far‐UVC excimer lamps (222 nm) have shown potential in decontaminating various organic pollutants, however, their efficacy against inorganic pollutants present in wastewater and indoor air as well as associated chemistry requires further investigations for wider acceptance. This review examines various photochemical action of Far‐UVC radiation (222 nm) in wastewater treatment and indoor air disinfection, elaborating their potential for inorganic pollutant removal in wastewater as well as challenges associated with their application in disinfection of indoor air.

Chitosan a Veritable Material for Removal of Some Organic Pollutants in Wastewater: An Empirical Studies

In the present study, Chitosan from cockroaches was successfully prepared, characterized by X-raydiffraction, Fourier transform infrared spectroscopy and scanning electron microscopy, and tested as adsorbent for the removal of p-Nitrophenol and Naphthalene from aqueous solutions. The influence of process variables solution pH, adsorbent dose, contact time and initial adsorbent concentration on the adsorption was evaluated. The equilibrium data was tested by Langmuir and Freundlich isotherm models for the best fit. It found the R2 values of 0.9976 for Freundlich isotherm and 0.9903 forLangmuir isotherm using Naphthalene. R2 values of 0.9843 for Freundlich isotherm and 0.739 for Langmuir isotherm. Maximum removal efficiencies of 98% for Naphthalene at the pH of 6, contact time of 2.5 h, an adsorbent dosage of 2.0 g and initial concentration of 20 mg/L. 92% for p-Nitrophenolat the pH of 6, contact time of 3.0 h, adsorbent dosage of 2.0 g and initial concentration of 60 mg/L were obtained respectively. This result shows that the prepared adsorbent has the capacity for the removal of Naphthalene and p-Nitrophenol from wastewater.

In-situ immobilization of ZIF-67/ZIF-8 on wood biomass for degradation of methylene blue and formaldehyde

Metal-organic frameworks (MOFs) have been extensively studied for the removal of pollutants in wastewater and air. However, the existence of MOF materials in powder form with easy agglomeration and difficult separation has greatly confined their application potential. To address this challenge, ZIF-67/ZIF-8 composites were in-situ grown on wood biomass, with its porous structure providing channels for the growth of MOFs and active sites for MOFs catalysis. The structure, i.e., morphology, crystallinity and chemical components, and optical properties were characterized. The degradation efficiency of methylene blue (MB) by the ZIF-67/ZIF-8@wood composites photocatalyst was more than 85.7 % under visible light irradiation within 90 mins, reflecting the good photocatalytic activity of the composites. The ZIF-67/ZIF-8@wood composites completely adsorbed and decomposed HCHO (22.3 ppm) within 30 mins. The high catalytic performance of the ZIF-67/ZIF-8@wood composites can be attributed to the high surface area of wood that results in a high absorption of contaminants. This simple, low-cost, and green preparation method has promoted the sustainable utilization of biomass resources with great significance for practical environmental remediation.

Novel insights into the biological state in algal-bacterial granular sludge granulation: Armor-like protection provided by the algal barrier

Algal-bacterial granular sludge (ABGS) composed of microalgae and aerobic granular sludge, is a sustainable and promising technology for wastewater treatment. However, the formation mechanism of ABGS has not been clearly defined, and the direct formation of ABGS in saline wastewater has rarely been investigated. This study proposed novel insights into the granulation process of ABGS by assembling the algal barrier, which was successfully cultivated directly in saline wastewater. The results concluded that ABGS with the algal barrier maintained a higher biomass (MLSS of 7046 ± 61 mg/L), larger particle sizes (1.21 ± 0.06 mm), and better settleability (SVI30 of 46 ± 1 mL/g), enabling efficient pollutants removal. Soluble microbial products (SMP) were found to be closely related to the emergence of the algal barrier. In addition, under salinity stress, the high production of extracellular polymeric substances (EPS, 133.70 ± 1.40 mg/g VSS), specifically TB-EPS (90.29 ± 1.12 mg/g VSS), maintained a crucial role in the formation of ABGS. Further analysis indicated that biofilm producing bacteria Pseudofulvimonas and filamentous eukaryote Streptophyta were the key players in ABGS formation with the algal barrier. Furthermore, the enhancement of key genes and enzymes involved in nitrogen metabolism, TCA cycle, and polysaccharide metabolism suggested a more robust protective effect provided by the algal barrier. This study is expected to advance the application of simultaneous ABGS formation and pollutant removal in wastewater.

Advanced Treatment Technologies for Pollutants Removal in Wastewater

Conventional wastewater treatment technologies have been extensively studied for degrading organic matter, suspended solids, nutrient removal, and lowering microbial loads. They produce acceptable-quality effluent, but researchers have reported several limitations. Recently, advanced wastewater treatment technologies have preceded as an alternative to the degradation of recalcitrant wastes such as persistent organic compounds (POPs), pharmaceutically active compounds (PhACs), contaminants of emerging concern (CECs), and heavy metals (H.M). They can be physical, chemical, biological, or integration between one or more technologies. This is to meet the requirements for reuse for different purposes, minimize or prevent the negative impacts on the environment, and create new untraditional water resources to solve the water shortage problem. This article is a collected review of advanced wastewater treatment technologies. Also, the applications of these technologies with special concern for partially/hardly degradable pollutants from wastewater are indicated. They are eco-friendly, cost-effective, low-energy systems with a small footprint. Their selection depends on the characterization of wastewater, biodegradability, available footprint, quality of treated effluent required, cost, availability of funds, and personal skills.

Removal of antibiotic residue from aqueous solution by advanced oxidation process

Advanced oxidation processes are low-cost, highly efficient, and eco-friendly technologies in the removal of organic pollutants in wastewater using hydroxyl radicals for oxidation. Hydroxyl radicals possess high oxidation potential and can react with organic compounds, resulting in the complete mineralization of these compounds into carbon dioxide, water, and inorganic salt or their conversion into other compounds. The present investigation deals with the removal of tetracycline from water using simulated ultraviolet radiation and hydrogen peroxide, assessing the effect of operational parameters like the solution's initial pH, retention time, hydrogen peroxide dosage in terms of chemical oxygen demand (COD) removal from the standard aqueous solution of tetracycline. Results indicate that alkaline conditions and larger hydrogen peroxide dosage negatively affect the degradation. The removal efficiency of 68 % was achieved at 150 min of batch reaction under optimum conditions: pH = 4, and a dose of hydrogen peroxide of 0.3 ml per 100 ml of the solution to be treated. At optimum conditions, LC-MS/MS (liquid chromatography tandem mass spectrometry) analysis results showed a reduction in initial concentration of aqueous solution of tetracycline. Photocatalytic degradation followed pseudo-first-order kinetics with the rate constant (k) of 0.0061 min-1. Photocatalysis based on hydrogen peroxide is effective in the degradation of tetracycline in an aqueous solution and can be applied as a pretreatment of hospital wastewater containing tetracycline residues.

ZIF‐8 Composites for the Removal of Wastewater Pollutants

AbstractThe presence of dyes in wastewater poses a significant environmental challenge due to their permanence toxicity and potential to harm ecosystems. Because of their high porosity and adjustable characteristics, metal‐organic frameworks (MOFs) have become attractive materials for effective dye removal. Among various MOFs, zeolitic imidazolate frameworks (ZIFs) have garnered significant attention, especially ZIF‐8, for its excellent stability, significant porosity, adjustable pore size and remarkable adsorption capacity. This review article provides a comprehensive overview of recent advances in the implementation of ZIF‐8 and its composites for the removal of pollutants from wastewater. The various synthesis methods, structural characteristics and dye adsorption performance of ZIF‐8 and its composites are discussed. Furthermore, impact of the different factors such as pH, temperature, dye concentration, contact time etc. were also highlighted. Moreover, the detailed adsorption mechanism was also discussed. Finally, the current challenges and future perspectives in the production of materials based on ZIF‐8 for the removal of dyes were also presented.

Pollutant Removal in Wastewater from Anaerobic Digesters by Water Lettuce (<i>Pistia stratiotes</i> L.) at Both Still-Water and Running-Water Stages

Pollutant Removal in Wastewater from Anaerobic Digesters by Water Lettuce (<i>Pistia stratiotes</i> L.) at Both Still-Water and Running-Water Stages

Development of a novel polydopamine-imprinted MOFs targeted for removal of refractory organic pollutants: Synergistic mechanisms of adsorption and degradation

In this study, a novel dopamine-imprinted MOFs (metal organic frameworks) was developed for the first time to achieve targeted degradation of refractory organic pollutants (ROPs) in advanced oxidation process. The targeted adsorption and degradation capacity of sulfamethoxazole (SMX) by molecularly imprinted catalyst (Fe-MOFs@MIP) was 3.17 times and 5.47 times that of Fe-MOFs, respectively. The results showed that the polydopamine (PDA) imprinted layer not only enhanced the targeted adsorption of SMX, but also improved the activity of the catalyst by promoting electron transfer. The physicochemical properties of Fe-MOFs@MIP were investigated. In situ Fourier transform infrared spectroscopy and molecular dynamics theory were used to investigate targeted adsorption mechanism. The active species were identified by quenching experiments and electron paramagnetic resonance (EPR). The reaction sites of SMX were predicted using density functional theory (DFT) and the possible degradation pathways of SMX were proposed. Finally, the targeted degradation mechanism of Fe-MOFs@MIP was elucidated. This study has a guiding significance for the deep removal of refractory organic pollutants in wastewater.

Synergistic CdS@CeO2 nanocomposites: Harnessing Z-scheme electron transfer for enhanced photocatalytic CO2 conversion and aqueous Cr(VI) reduction

The present work describes the fabrication of CdS-D@CeO2 Z-scheme heterojunctions as highly stable, efficient and recyclable photocatalysts for the visible light assisted reduction of CO2 to methanol as well as Cr(VI) to Cr(III). The bare CeO2 produced methanol with the rate of 111 μmolh−1g−1 that is much lower in comparison to CdS-D@CeO2 (501 μmolh−1g−1). In addition, the photocatalytic efficiency remained nearly same for three successive runs, indicating the higher stability and recycling ability of the heterojunctions CdS-D@CeO2. It was also observed that under direct sunlight irradiation, CdS-D@CeO2 efficiently reduced 100% Cr(VI) to Cr(III) in an aqueous medium in just 40 minutes. Moreover, >95% removal was maintained even after 5 catalytic cycles. Additionally, for mimicking real contaminated water samples, the influence of the foreign ions on Cr(VI) reduction was evaluated by using lake water sample and no adverse effects on the result were observed. Thus, this work showed a way to develop cost-effective, easily synthesized, durable and recyclable composite photocatalysts for CO2 utilization and proficient removal of waste water pollutants by employing the clean, green, and renewable solar energy.

UV/H2O2 produced degradation of 2,4-D and 4-CPA

2,4-dichlorophenoxyacetic (2,4-D) acid and 4-chlorophenoxyacetic acid (4-CPA), as widely utilized organochlorine pesticides, are normally detected in wastewater and atmosphere. Their harmfulness to the ecosystem cannot be ignored. UV/H2O2 is one of the most conventional advanced oxidation processes, which has remarkable advantages for the removal of refractory organic pollutants in wastewater. However, the reaction mechanisms and pathways of pollutants with reactive radicals are still unclear. In this study, the degradation efficacy and mechanisms during the photodegradation of 2,4-D and 4-CPA in UV/H2O2 processes were investigated by experiments and density functional theory calculations. The results showed that 2,4-D was more likely to be degraded by UV/H2O2 treatment than UV photolysis alone. In contrast, 4-CPA can be degraded effectively and rapidly under UV irradiation alone. By LC-MS analysis, the degradation products of 2,4-D and 4-CPA in the UV/H2O2 processes were identified and they were produced by hydroxylation and photolysis. Therefore, we speculated a competition mechanism presented between direct photolysis and indirect photolysis in the UV/H2O2 degradation of 2,4-D and 4-CPA. The OH-initiated reaction mechanisms of 2,4-D and 4-CPA in aqueous environments were investigated using quantum chemical methods SMD/M06–2X/6–311++G (3df, 2p)//SMD/M06–2X/6-311 + G (d,p). The pH dependence of the reaction mechanisms and rate constants in their degradation process induced by ·OH was also investigated. The calculation results showed that the ionic forms (2,4-D- and 4-CPA-) were more prone to react with ·OH in comparison to the corresponding molecular forms (2,4-D and 4-CPA). The total rate constants of 2,4-D and 4-CPA with OH increased with the pH from 1 to 10, and decreased with continued pH increase. The toxicities of 2,4-D, 4-CPA and their products were assessed by the QSAR-based toxicity evaluation software. The results showed that several products were more toxic than their parent compounds, such as 2,4-dichlorophenol, 3,5-dichlorocatechol, 4-chlorophenol and hydroquinone. This work can contribute to clarifying the environmental risks of 2,4-D and 4-CPA and offer a complete understanding for the photodegradation behavior of 2,4-D and 4-CPA in aqueous ecosystems.

Sunlight-mediated efficient remediation of organic pollutants from water by chitosan co-decorated nanocomposites of NiO loaded with WO3: Green synthesis, kinetics, and photoactivity

Azo dyes such as Tropaeolin OOO (TOOO) and Eriochrome black T (EBT) are used in various industrial and laboratory applications. However, their recalcitrant properties make them toxic chemicals and require efficient removal-strategy based on polymer decorated semiconductor nanocomposite. Herein, photodegradation of TOOO and EBT in water was investigated at different reaction parameters through NiO@WO3-chitosan synthesized by green procedure using A. indica. PXRD spectra peaks show semi-crystalline behaviour with spherical morphology and chitosan around metal oxide. In FT-IR, New spectral peaks observed at 1023 cm−1, 870 cm−1, and 540 cm−1 vibration indicated between Ni-O-W, Ni-N, and W-N confirmed effecting coupling. Both dyes (10 mg/L) were found completely colourless within 3 h under sunlight with pH of 7 at 20 mg of catalyst load. Difference in max degradation of 96 % and 92 %, respectively to TOOO and EBT dye credit to structure difference. 1st-order reaction kinetics following early Langmuir adsorption and degradation at optimum condition rate constant k (0.26–0.19-min−1) and half time t1/2(2.68––3.64 min−1). Efficiency of NiO@WO3-chitosan was maintained due to its fine morphology with elevated surface-area (75 m2g−1), large negative zeta potential (−29.5 mV), and lesser value of band distance (2.1 eV). Involvement of •OH, O2–• and holes in photocatalysis mechanism to break complex molecules of TOOO and EBT was revealed in Scavenger analysis. After degradation, small-safer metabolites were confirmed by LC-MS. Reusability up to 8th cycle of NiO@WO3-chitosan without photoactivity reduction makes it a cost-effective cum sustainable composite for industries and wastewater pollutants removal with good surface properties.

Green synthesis of metal nanoparticles from Codium macroalgae for wastewater pollutants removal by adsorption

AbstractAlgae have adsorption properties and reducing agents due to their rich content. In this study, palladium nanoparticles (Pd NP), platinum nanoparticles (Pt NP), and iron oxide nanoparticles (Fe3O4 NP) were prepared from Codium macroalgae using green synthesis. The structure of the synthesized nanoparticles was elucidated by X‐ray diffractometry, Fourier transforms infrared spectroscopy, Brunauer–Emmett–Teller analysis, transmission electron microscopy, ultraviolet‐visible spectroscopy and scanning electron microscopy‐energy dispersive X‐ray spectrometry and their use as nanoadsorbents for the removal of pollutants from aqueous media was investigated in detail. Naproxen (NPX), an anti‐inflammatory drug, and the dyes methylene blue (MB) and cresol red (CR) were selected as pollutants for this study. Batch adsorption experiments were conducted using both real wastewater obtained from the Organised Industrial Zone of Isparta Province and synthetic water samples prepared with tap water from Burdur Province and pure water. Under optimum adsorption conditions, Pd NP showed significant efficiency in the real wastewater sample, with an adsorption capacity of 37.19 and 50.03 mg g–1 for CR and NPX, respectively, within 150 min. In comparison, Pt NP showed an adsorption capacity of 40.01 mg g–1 for MB within the same timeframe. These findings indicate that while Pd NP showed the highest adsorption capacity for both CR and NPX, Pt NP showed the highest adsorption capacity for MB. The Langmuir model and the pseudo‐second‐order equation were more suitable to describe the adsorption behavior of CR, MB, and NPX. In addition, studies on the desorption and reusability of the nanoadsorbents were carried out under the same optimum experimental conditions.

Facile construction of a novel S-scheme Fe2TiO5/BiVO4 photocatalyst for efficient visible light-driven fenton-like degradation of ciprofloxacin

The rational design and fabrication of stable and efficient heterogeneous Fenton-like catalyst is of great significance for wastewater treatment, but is still fraught with obstacles. In this paper, a novel S-scheme Fe2TiO5/BiVO4 nano-heterojunction with high visible-light photocatalytic performance was synthesized by an in-situ growth method. The optimized Fe2TiO5 (20 wt%)/BiVO4 composite exhibited remarkable photocatalytic activity and rapid degradation ability towards CIP (50 mg/L) with the addition of H2O2 (20 mM), achieving a removal efficiency of 94.2 % within 90 mins. This performance is significantly superior to that of pure BiVO4 (43.8 %) or pure Fe2TiO5 (48.2 %). The S-scheme heterojunction formed between Fe2TiO5 and BiVO4 facilitates efficient charge separation, and preserves the powerful photogenerated electrons in CB of Fe2TiO5 and holes in the VB of BiVO4, contributing to the fast degradation of CIP. The synergistic effects of the S-scheme heterojunction and H2O2 activation account for the excellent performance of Fe2TiO5/BiVO4 photocatalyst. The prepared photocatalyst demonstrates remarkable efficiency, non-selectivity, exceptional stability, and adaptability to various environmental conditions. This study proposes a novel approach for designing and synthesizing photo-assisted Fenton-like S-scheme photocatalysts for efficient removal of organic pollutants in wastewater.

Biofilm formation monitoring using SEM in synthetic wastewater pollutant removal by combination of DAF and modified MBBR

Nowadays, moving bed biofilm reactors (MBBR) and dissolved air flotation (DAF) are frequently used in combination for the biological and physical treatments of synthetic oily wastes. The efficiency of the biocarriers utilized in MBBR is crucial since it has a big impact on the system's overall performance. A study was carried out utilizing a DAF-MBBR technique to treat synthetic oily wastewater in order to evaluate this. Two different kinds of biocarriers were used in this modified MBBR: polyethylene and plastic bottle caps. The result showed the DAF-MMBBRs process demonstrated excellent removal efficiencies for a range of parameters. Moreover, it seemed that DAF had higher COD, nitrite, nitrate, and turbidity removal efficiencies. For COD, the average removal efficiency was 39.62%; for oil and grease, it was 77.05%; and for ammonia, it was 39.71%. In the same way, MBBR1 is effective at eliminating phosphate, ammonia, TSS, and oil and grease. For COD, the average removal efficiency was 39.12%; for oil and grease, it was 94.10%; and for ammonia, it was 85.42%. The average removal efficiencies for COD, oil and grease, and ammonia in MMBBR2 were 38.76%, 84.95%, and 86.49%, respectively. Furthermore, Scanning electron microscopy (SEM) was used to assess the biofilm within the system. This revealed a well-developed biofilm layer on the interior surfaces of the biocarriers, improving the effectiveness of synthetic wastewater treatment. Excellent removal efficiencies were shown by the DAF-MBBR system for a range of parameters during a ten-day operational period.

Biomimetic ZrO2-modified seaweed residue with excellent fluorine/ bacteria removal and uranium extraction properties for wastewater purification

Exploring and developing promising biomass composite membranes for the water purification and waste resource utilization is of great significance. The modification of biomass has always been a focus of research in its resource utilization. In this study, we successfully prepare a functional composite membrane, activated graphene oxide/seaweed residue-zirconium dioxide (GOSRZ), with fluoride removal, uranium extraction, and antibacterial activity by biomimetic mineralization of zirconium dioxide nanoparticles (ZrO2 NPs) on seaweed residue (SR) grafted with oxidized graphene (GO). The GOSRZ membrane exhibits highly efficient and specific adsorption of fluoride. For the fluoride concentrations in the range of 100–400 mg/L in water, the removal efficiency can reach over 99 %, even in the presence of interfering ions. Satisfactory extraction rates are also achieved for uranium by the GOSRZ membrane. Additionally, the antibacterial performance studies show that this composite membrane efficiently removes Escherichia coli (E. coli) and Methicillin-resistant Staphylococcus aureus (MRSA). The high adsorption of F− and U(VI) to the composite membrane is ascribed to the ionic exchange and coordination interactions, and its antibacterial activity is caused by the destruction of bacterial cell structure. The sustainability of the biomass composite membranes is further evaluated using the Sustainability Footprint method. This study provides a simple preparation method of biomass composite membrane, expands the water purification treatment technology, and offers valuable guidance for the resource utilization of seaweed waste and the removal of pollutants in wastewater.

Applications of bismuth-based nanoparticles for the removal of pollutants in wastewater: a review

This review discusses the characteristics and synthesis methods of Bi-based NPs. It delves into the removal efficiency in wastewater, emphasizing traditional/emerging strategies to enhance the performance, mechanisms, toxicology, and challenges.

Utilization of Banana Peels as Active Carbon for Pollutant Removal in Wastewater

Utilization of Banana Peels as Active Carbon for Pollutant Removal in Wastewater