Application In Wastewater Treatment Research Articles

Synthesis of Ternary Layered Double Hydroxides and Application for Wastewater Treatment

AbstractThis study systematically investigates the optimization of synthesis parameters for ternary layered double hydroxide (LDH) to achieve a pure phase and high crystallinity. The , LDH is synthesized using the coprecipitation method and applied for wastewater treatment. The ternary LDH is synthesized at 60 °C for 24 h and exhibited maximum crystallinity with a crystallite size of 4 nm. The crystallinity index (CI) is a quantitative indicator of crystallinity, which is calculated using the X‐ray diffraction (XRD) method. The influence of reaction time on the structural characteristics of this LDH was thoroughly investigated, mainly focusing on achieving well‐crystalline LDH. Experimental results revealed a direct correlation between reaction time and crystallinity. This study highlights the significant influence of controlled synthesis and reaction time on producing high crystalline ternary LDH. The role of different parameters, such as solution pH, adsorbent dosage, contact time, and dye concentration, has been investigated. The adsorption isotherm data is analyzed using different isotherm models, which shows this material having a significant adsorption capacity of 82.92 mg/g for Congo Red dye.

Magnetically separable quaternary g-C3N4/Fe3O4/AgBr/rGO nanocomposite for enhanced photocatalytic degradation of ofloxacin in water under visible light irradiation

Novel photocatalytic-magnetic hybrid quaternary nanocomposite (g-C3N4/Fe3O4/AgBr/rGO) was successfully synthesized for the first time via ultrasonication-assisted wet chemistry technique. The nanocomposite was characterized using various advanced characterization techniques and its visible photocatalytic performance was analyzed by using ofloxacin (OFL) as target pollutant. The photocatalytic degradation efficiency was 100 % under conditions (pH 6.65, 0.1 g/L nanocomposite and 10 mg/L OFL) in 5 h. The pseudo-first-order kinetic constant of g-C3N4/Fe3O4/AgBr/rGO was as high as 1.1832 h−1. Evaluation of different catalysts, catalyst dosage, initial concentrations of OFL and initial solution pH have been studied. Based on the scavenging tests, benzoquinone (BQ) significantly decreased the removal efficiency of OFL to 41.4 %, indicating that O2− served as the dominant radical involved in the reaction. More importantly, after undergoing five cycles, the g-C3N4/Fe3O4/AgBr/rGO nanocomposite demonstrated robust stability and was effectively separated from the solution through magnetic means. The remarkable performance of g-C3N4/Fe3O4/AgBr/rGO is linked to substantial utilization of visible light and facilitation of Z-scheme heterojunctions, thereby facilitating charge separation. The quaternary nanocomposite exhibits auspicious potential for effectively degrading emerging organic pollutants and has bright application forecast for practical application in wastewater treatment.

Exploring ammonia adsorption and filtration efficiency of ceramic membranes derived from weathered basalt: Fabrication analysis and application in wastewater treatment

This study aims to develop an innovative ceramic membrane derived from naturally-occurring weathered basalt (NWB) for the effective adsorption and filtration of ammonium ions (NH+4) from wastewater. The NWB was subjected to calcination to produce CWB-750 and further combined with activated carbon to form CWB-AC-950. Comprehensive characterization using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Fourier-Transform Infrared Spectroscopy (FT-IR), and Brunauer-Emmett-Teller (BET) analysis revealed that CWB-AC-950 possessed a significantly high surface area of 121.7 m²/g and a minimal pore volume of 6.2 nm, indicating its enhanced adsorption capabilities. In practical filtration tests, CWB-AC-950 demonstrated a remarkable reduction in NH+4 concentration, decreasing it from an initial 30 mg/L to 15.25 mg/L. This substantial decrease underscores the membrane's efficiency in adsorbing and removing ammonium ions from contaminated water. Furthermore, the integration of activated carbon with calcined basalt not only improved the adsorption performance but also maintained the structural integrity and reusability of the membrane. These findings illustrate the potential of CWB-AC-950 as a promising and cost-effective medium for adsorption and filtration in wastewater treatment applications.The development of CWB-AC-950 contributes significantly to environmental remediation efforts by offering an efficient and low-cost alternative to conventional filtration materials. Its ability to maintain performance across multiple cycles underscores its potential for practical applications in large-scale wastewater treatment facilities, thus providing a sustainable solution to address the growing global water pollution crisis.

Fabrication of a 2D/2D g-C3N4@ZnTDA nanosheets catalyst for highly efficient degradation of 2,4-dibromophenol and improved flame retardancy of polyurethane foam

High charge separation and transfer efficiency are considered as key factors of photocatalysts in wastewater treatment applications. In this work, a high performance photocatalyst g-C3N4@ZnTDA was designed and applied through a facile solvothermal strategy. The microstructural, morphological, physicochemical, and photoelectrochemical properties of g-C3N4@ZnTDA were fully characterized. The photocatalytic activity of g-C3N4@ZnTDA nanoparticles under visible light source in degrading the 2,4-dibromophenol(2,4-dB) contaminants was also successfully studied. Additionally, the g-C3N4@ZnTDA composite demonstrates easy operation and good regeneration ability, making it highly promising for the efficient removal of phenolic pollutants from wastewater. Besides, a novel reutilization method for used catalyst as flame retardant and for PU foams was successfully testified. The MCN-3 as a fire-safety coating could reduce the heat release and improve flame retardancy of PU composites. This work opens a new window for valuable inspiration and structural design of reutilized MOF composites.

Cationic polymer-mediated interbacterial aggregation: A novel approach for rapid aerobic granules development

This study introduces a novel approach to aerobic granular sludge technology that minimizes the start-up time and guarantees the formation of stable granules. This is achieved by seeding the reactor with a cationic polymer without using inoculated sludge. Three cationic polymers (Hydrofloc C4400SA, C8896, and polyelectrolyte emulsion) were tested to determine the most appropriate polymer for aerobic granular sludge (AGS) startup based on the optimal dose and formation of aerobic granules. Hydrofloc cationic polymer C4400SA has excellent granule-forming properties in the AGS reactor compared to their counterparts. The formation of granules was boosted by adding 15 ppm of polymer, resulting in densely packed aerobic granules after 10 days. This improvement can be due to the more cationic properties of hydrofloc, which play a key role in bridging between cells and particles because the cationic charges of hydrofloc attract negatively charged bacteria in wastewater, thereby promoting aggregation and the formation of initial flocs. These flocs serve as the foundation for the development of granules. After 80 days of operation, 40–50% of particles with an average size range from 0.6 to 0.9 mm were observed. The AGS SBR operation was closely monitored and showed consistent efficiency in removing solids, where TP, TN, NH+4 –N, and the total soluble COD were removed at average efficiencies of 62%, 73%, 97%, 93%, and 79% respectively, during steady-state cycles conducted at room temperature. Overall, this study highlights the potential of hydrofloc cationic polymer C4400SA to enhance the performance and resilience of AGS in wastewater treatment applications.

Facile fabrication of Cu/kaolin nanocomposite as highly efficient heterogeneous catalyst for 4-nitrophenol reduction in aqueous solution

Hazardous organic pollutants in industrial wastewaters are becoming a major global challenge that threatens life on earth and particularly poses a serious health risk to human beings. 4-Nitrophenol (4-NP) is a highly hazardous organic contaminant that has been extensively utilized across multiple industries, and their wastewater disposal into water streams leads to a higher accumulation of 4-NP. It is therefore important for both academia and industry to make catalysts that are cheap, very effective, good for the environment, easy to recover, and can be used more than once for reducing 4-NP in normal conditions. This paper reports the synthesis, characterization, and application of Cu/kaolin nanocomposite (NC) as an efficient heterogeneous catalyst for decomposing 4-NP, a model organic molecule. The catalyst was synthesized by incorporating a copper precursor into layered kaolin clay and directly reducing the metal precursor using sodium borohydride (NaBH4). The morphology, structure, surface property, and interaction of the resulting Cu/kaolin NC were characterized by ultraviolet–visible spectroscopy, Fourier transform infrared spectroscopy, scanning electron spectroscopy/energy-dispersive X-ray spectroscopy, selected area electron diffraction, X-ray diffraction, and N2 adsorption/desorption, and the results clearly demonstrated the growth of copper nanoparticles on the kaolin surface. It was discovered that the Cu nanoparticles (NPs) on the kaolin surface had a crystallite size of about 23.6 nm. The significance of Cu NPs and the high catalytic activity of the synthesized Cu/kaolin NC toward 4-NP reduction by NaBH4 were evaluated by the catalytic reduction experiments. Among the different nanocomposites synthesized, 30-Cu/kaolin showed the highest catalytic activity for 4-NP reduction, with a reduction efficiency of over 99 % within 4 min with a pseudo-first-order rate constant, kapp, of 1.23 min−1. Furthermore, the reusability test indicated that Cu/kaolin NC can be reused for up to six runs efficiently without significant decrease in its catalytic performance, indicating the nanocomposite has excellent stability and great potential applications in industrial and agricultural wastewater treatment.

Supramolecular-Coordinated Nanofiltration Membranes with Quaternary-Ammonium Cyclen for Efficient Lithium Extraction from High Magnesium/Lithium Ratio Brine

Ion-selective membranes (ISM) with sub-nanosized pore channels hold significant potential for applications in saline wastewater treatment and resource recovery. Herein, novel synergistic ion channels featuring bi-periodic structures were constructed through the coordination of functional Cyclen (quaternary_1,4,7,10-tetraazacyclododecane, Q_Cyclen) and Cu2+-m-Phenylenediamine (Cu2+-MPD) to develop supramolecular membranes for lithium extraction. The exterior quaternary ammonium-rich sites exhibit a significant Donnan exclusion effect, resulting in tremendous mono/divalent (Li+/Mg2+) ion selectivity; while the interior regular-confined channels of Cyclen yield a fast vehicular pathway, facilitating water molecules and Li+ ion-selective transport. The optimized membrane exhibited an increased water permeance of 19.2 L·m-2·h-1·bar-1 and simultaneously promoted Li+/Mg2+ selectivity (achieving a selectivity of 18.5 under a Mg2+/Li+ mass ratio of 30), surpassing the trade-off limit of conventional nanofiltration membranes. Due to the acquired excellent Li+/Mg2+ selectivity, lithium extraction from simulated salt-lake brines was successfully achieved through a two-stage nanofiltration process, reducing the Mg2+/Li+ mass ratio from 40 to 1.1. This work validates the applicability of macrocyclic with intrinsic sub-nanosized channels and desired multifunctionality for developing high-performance ISM for efficient lithium separation and beyond.

Novel biomass carbon dots/chitosan hydrogel-modified TiO2: An effective reduction of Cr(VI) in various wastewater under sunlight

Hexavalent chromium (Cr(VI)) poses a serious threat to the environment and human health owing to its inherent toxicity. Photocatalysis technology has garnered widespread attention owing to its efficiency and environmental friendliness. However, existing photocatalysts are constrained by light conditions, low reduction rates, and lack of studies in real wastewater. In this study, biomass carbon dots (P-CDs) were synthesized from peanut shell powder, then combined with chitosan (CS) and TiO2 to create a novel photocatalyst (9:1 1 % P-CDs/TiO2@CS). The photocatalyst exhibited a smaller band gap and a broader light absorption range than TiO2, while the porous structure of the hydrogel increased the contact area between P-CDs/TiO2@CS and Cr(VI), thereby enhancing its photocatalytic performance. Our study demonstrates that under simulated sunlight using a xenon lamp, 0.2 g of 9:1 1 % P-CDs/TiO2@CS reduced 50 mg/L Cr(VI) at a rate of 99.64 % in 30 min (pH 7). The photocatalyst also exhibited excellent reduction capabilities for Cr(VI) across a pH range (pH 2–9), at different concentrations (10, 20, 30, 40, 50, and 60 mg/L), and in various real wastewater samples (influent, effluent, and electroplating wastewater). After five cycles, the reduction rate was still maintained at 90.38 %. Experiments conducted under natural sunlight and ion interference further confirmed its outstanding photocatalytic performance and stability in real-world applications. Free radical trapping experiments indicated that electrons (e-) and holes (h+) were the primary active species. Additionally, antibacterial experiments showed that the reactive oxygen species generated by the photocatalyst under light irradiation effectively inhibited the proliferation ofEscherichia coli. Thus, P-CDs/TiO2@CS holds significant potential for practical application in environmental wastewater treatment.

Micro-nano bubbles in action: AC/TiO2 hybrid photocatalysts for efficient organic pollutant degradation and antibacterial activity

Developing highly active and sustainable photocatalysts is crucial for environmental remediation. This work focuses on the enhanced photocatalytic degradation efficiency of synthetic dyes using TiO2-coated AC hybrid photocatalysts under MNB aeration. The TiO2-coated AC hybrid photocatalyst (HP) was synthesized via a sol-gel method and characterized using XRD, FTIR, SEM, EDS, HR-TEM, and DRS. The study investigated the photocatalytic degradation of three dyes indigo carmine (IC), reactive black 5 (RB5), and methylene blue (MB) in wastewater, with initial dye concentrations ranging from 10 to 100 μM. Under UVA irradiation, the hybrid photocatalyst with MNB aeration (HP + UVA + MNB) achieved the highest degradation efficiencies of 69.09%, 60.06%, and 55.19% for IC, MB, and RB5, respectively. Further analysis showed that the chromophores and complex structures of these dyes were broken into intermediate products. The Langmuir-Hinshelwood kinetic model was used to describe the reaction mechanisms. The HP + UVA + MNB system demonstrated superior photocatalytic degradation activity, making it suitable for operational and environmental applications in dye wastewater treatment. Additionally, the antibacterial properties of AC and HP were tested at 100 μg/mL, showing effectiveness against both Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli.

Preparation of activated biochar from durian shells for the extraction of phytohormones from waste coconut water via adsorption

Abstract The demand for activated carbon increases due to its effectiveness in wastewater treatment and other soil applications. However, its growing demand in the market resulted to higher price, thus, this study aimed to develop a cheaper alternative. The use of agricultural waste for biochar production has been the focus of several studies nowadays. Aside from the cheaper cost of the feedstock and the process, the problem on waste generation in the country will be lessened. In this study, activated biochar derived from Durian (Durio zibethinus) shells was prepared as adsorbent for the extraction of phytohormones from waste coconut water. Phytohormones or plant hormones are all-natural substitute to synthetic plant growth regulators (PGRs) used for different tissue culture practices in the country. Chemical activation conditions (alkali-to-raw biochar ratio and holding time) were determined to maximize phytohormone adsorption efficiency of the activated biochar. The activation of the durian shell-derived biochar was done using potassium hydroxide as chemical activating agent. Factors such as KOH-biochar ratio (high level: 5:1 (w/w), low level: 1:1 (w/w) ) and carbonization holding time (high level: 90 mins, low level: 45 mins) were applied to test its significance on the activation of durian shell biochar with percent phytohormones removal from waste coconut water as a response. The parametric study showed that KOH-biochar ratio as a main effect was significant and its interaction with holding time was also significant. This result will be used in the ongoing study to produce optimized activated biochar and will be used for batch and column adsorption. The prepared durian shell activated biochar will then be used for the extraction of phytohormones from waste coconut water via adsorption.

Facile hydrothermal synthesis of Bi2Fe4O9/rGO composite for catalytic reduction of 4- nitrophenol

Reduced graphene oxide (rGO) based composites have shown encouraging results in the application field of environmental protection, biology, energy harvesting and energy storage. This article presents a detailed study on the structural, microstructural, optical, and magnetic properties of hydrothermally prepared bismuth ferrite (Bi2Fe4O9)/rGO composite. The catalytic reduction of the toxic 4-nitrophenol into useful 4-aminophenol using the synthesized composite was illustrated. The Bi2Fe4O9/rGO composite sample demonstrated superior catalytic activity compared to pure Bi2Fe4O9, with a reaction rate constant of 0.26398 min–1. The stability and reusability tests forecasted the use of the composites as a low-cost catalyst for wastewater treatment applications.

Fluffy LDH/GO 2D Membrane for Rapid Removal of Soluble Pollutants and Enhanced Catalytic Self-Cleaning Performance

The rapid expansion of the chemical and pharmaceutical industries has resulted in the introduction of various sources of micropollutants into the environment, posing threats to drinking water quality and public health. Membrane separation technology offers a promising solution with low energy use, high-quality effluent, and operational simplicity. Here, we developed fluffy LDH/GO 2D membranes, specifically tannic acid-mediated LDH-GO/GO-TA composite membranes (LG/GT). The integration of GO nanosheets regulated the growth of LDH, enhancing electron transfer and adsorption-driven catalytic performance. This design enabled LDH-GO to activate peroxymonosulfate (PMS) and completely degraded Rhodamine B (RhB) within 10 min. The Gaussian calculation was combined with this finding, which could explain the catalytic self-cleaning in the separation process. The TA-mediated enhancement further increased the RhB rejection of LG/GT-7.5 to 99.23%. Additionally, the needle/sheet structure significantly improved permeance to 358.28 L m-2 h-1 bar-1, surpassing the L/GT-7.5 performance (e.g. 338.53 L m-2 h-1 bar-1), indicating superior pore formation and water mass transfer. The heterostructure between GO and LDH greatly improved cycling stability, with the membrane maintaining a permeance of 282.71 L m-2 h-1 bar-1 and a rejection of 97.97% despite 20 cycles. This work demonstrated the potential of fluffy layered LDH 2D membranes for enhanced wastewater treatment applications. These findings suggested significant potential for practical implementation in industrial wastewater treatment processes, offering a sustainable and efficient solution to water pollution challenges.

Enhanced photocatalytic activity of SnS2 quantum dot modified Sn3O4 nanosheet composite photocatalysts for wastewater treatment applications

The construction of heterojunction is a practical way to boost the separation of photogenerated carriers and photocatalytic activity of single photocatalyst. In this paper, a novel SnS2 quantum dots/Sn3O4 nanosheets (SS/SO) heterojunction was successfully constructed by an in-situ solvothermal method with the aid of ultrasonic exfoliation, where the SnS2 quantum dots were successfully loaded on Sn3O4 nanosheets to form a close contact interface. The prepared SS/SO heterojunction presented much enhanced visible-light photocatalytic degradation of methyl orange (MO) and the reduction of chromium (Cr(VI)) compared with SnS2 quantum dots and Sn3O4. Especially, SS/SO-2 sample showed the best degradation performance of 98.16% for methyl orange (MO) in 24min, and its rate constant was 0.1494min-1, which was 15.42 and 49.87 times higher than those of pure Sn3O4 (0.0097min-1) and SnS2 (0.0030min-1), respectively. The performance for MO degradation was also much superior to some recently reported photocatalysts. In addition, the reduction efficiency of Cr(VI) could reach to 96.22% at 105min for SS/SO-2. The uniform distribution of SnS2 quantum dots and the synergistic effects of SnS2 and Sn3O4 effectively separated the photogenerated charge carriers, resulting in the superior photocatalytic performance of the SO/SS composites. The photoreaction mechanism was also carefully investigated. Parallel experiment and LC-MS were applied to investigate the degradation pathways and intermediates of MO. The construction of SnS2/Sn3O4 heterojunction will lay the foundation for the development of new visible photocatalysts and the efficient removal of pollutants such as dyes and heavy metals Cr (VI) from wastewater.

Fabrication of Ti3CN quasi-MXene based poly glycidyl methacrylate and poly (3,4-ethylene dioxythiophene): Poly (styrene sulfonate) conducting polymer coated materials for photocatalytic eradicator of organic pollutants

MXene, a two-dimensional (2D) transition metal carbide or nitride, has gained significant attention due to its exceptional properties and wide-ranging applications. MXenes exhibit distinctive physical and chemical characteristics, making them suitable for electrocatalysis, supercapacitors, semiconductors, batteries, sensors, biomedicine, water splitting, and photocatalysis. In environmental photocatalysis, efforts have been made to improve conductivity, structural stability, and morphology. This study synthesized a photocatalyst by coating or doping a conducting polymer onto a quasi-MXene (Ti3CN) substrate. Initially, Ti3AlCN was exfoliated using HF to form 2D Ti3CN quasi-MXene, which was then doped with GMA and PEDOT: PSS conducting polymers for photocatalytic dye degradation. The broad heterogeneous interfaces in this network significantly enhance photocatalytic performance and pollutant removal capacity. The Ti3CN@GMA/PEDOT: PSS photocatalyst was characterized through SEM, FTIR, XPS, XRD, BET, and EDX techniques and tested for the degradation of various pollutants in wastewater under visible light. The degradation rates achieved were 94.1 % for Rose Bengal, 91.6 % for Rhodamine B, and 90.6 % for Methylene Blue, with corresponding rate constants of 0.0366 min−1, 0.0400 min−1, and 0.0388 min−1 over 60 min. The photocatalyst demonstrated excellent performance, highlighting several advantages, including low energy consumption, cost-effectiveness, non-toxic properties, and environmental compatibility, making it a promising solution for wastewater treatment applications.

Mixed matrix membranes by post-modified UiO-66-NH2 for efficient treatment of dyeing wastewater

The preparation of modified membranes utilizing the UiO-66 framework for wastewater filtration is regarded as one of the most promising approaches to wastewater treatment, owing to its high efficiency and cost-effectiveness. In this study, a post-modified MOF, UiO-66-RSA, was synthesized via the condensation reaction of UiO-66-NH2 and 2,4-dihydroxybenzaldehyde. PVDF mixed matrix membranes (MMMs) were fabricated for the first time by mixing UiO-66-RSA into PVDF using the non-solvent induced phase separation (NIPS) method. Compared to pure PVDF membranes, the newly developed membrane, M4, demonstrated enhanced compatibility and superior mechanical strength. In dyeing wastewater treatment applications, M4 showed excellent separation efficiency for dye and heavy metal mixed wastewater, achieving rejection rates exceeding 90%. Additionally, it maintained a high flux recovery rate (FRR > 90%) and rejection rate (Rejection > 90%) after six filtration cycles of dye-containing wastewater, indicating strong recyclability. These findings suggest that MMMs embedded with UiO-66-RSA hold significant promise for dyeing wastewater treatment.

Mechanistic insights and performance evaluation of ZnFe-Modified bovine manure biochar in activating peroxymonosulfate for efficient thiamethoxam degradation: A combined DFT calculation and degradation pathway analysis

The study explored the degradation of thiamethoxam (THM) in water using modified bovine manure biochar as a catalyst for the first time, due to its potential harm to living organisms and frequent detection in natural water bodies. Experimental findings revealed that the rate constants for peroxymonosulfate (PMS)-catalyzed THM degradation by bovine manure biochar modified with ZnCl2 and K2FeO4 (ZnFeBC) increased by 76.78 times compared to unmodified biochar (BC), achieving a 100% degradation rate within 60 min. ZnFeBC exhibited excellent PMS activation performance across various pH levels. XPS characterization and Density Functional Theory (DFT) calculations have revealed that Fe element cycling occurs on the ZnFeBC surface, resulting in increased charge transfer rates at the reaction interface. The main active sites responsible for PMS activation were found to be Fe0 and Fe3O4. The degradation mechanism of THM by the ZnFeBC/PMS system involved SO4•-, •OH, 1O2 and electron transfer. This catalyst demonstrated strong pH adaptability and outstanding catalytic degradation capabilities for various pollutants, making it highly suitable for widespread wastewater treatment applications, while also providing a new way for resource reutilization of bovine manure.

Regulating the Surface State of Carbon Dots as Ultrahigh-Capacity Adsorbents for Water Treatment.

Adsorption is one of the most widely researched and highly effective methods for mitigating the environmental threat posed by recalcitrant dyes in aqueous solutions. This paper presents a solvent-free synthesis method for the rapid and large-scale production of nitrogen (N) and phosphorus (P) co-doped carbon dots (N, P-CDs) which possess specific surface states and outstanding dye adsorption properties. Compared to the undoped CDs, the N, P-CDs not only exhibit a higher yield of solid-state luminescence but also endow them with the efficient adsorption and removal of Congo red (CR) from water. Due to the synergistic effects of π-π stacking, hydrogen bonding and electrostatic attraction, the N, P-CDs exhibit an ultra-high adsorption capacity (3118.87mgg-1) and a removal efficiency (97.4%, at 500mgL-1) for CR, and also display excellent selective adsorption in both single-dye and dual-dye systems. This method offers a rational strategy for synthesizing novel CDs-based adsorbents for CR, which provides a demonstration for future dye adsorption studies and practical wastewater treatment applications of CDs.

Characterization and Optimization of Crustacean Shell-derived Activated Carbon for Wastewater Treatment Applications

Comparative studies of the Surface Chemistry, morphology, and physicochemical properties of crustacean shells activated chemically using acid (H2SO4) and base (KOH) were investigated. Following the activation, samples of acid and base activated Periwinkle shells (PSAAC and PSBAC), Clam shells (CSAAC and CSBAC), whelk shells (WSAAC and WSBAC), and a 1:1 Clam/Whelk composite Shells (CWSAAC and CWSBAC) were obtained. The properties investigated were moisture content, specific gravity, surface area, porosity, ash content, carbon yield, fixed carbon, FTIR, and SEM-EDX. The findings demonstrate the good physicochemical qualities of activated carbons made from Periwinkle, Clams, Whelks, and a Clam/Whelk composite by acid and base activation for the treatment of wastewater. Among them, the Clam acid-activated carbon (CSAAC) demonstrated exceptional physicochemical qualities with a surface area of 1277 m2/g, moisture content of 1.4%, ash content of 8.3%, carbon yield of 87%, and fixed carbon of 63.7%. On the other hand, the Clam Shell Base-Activated Carbon (CSBAC) exhibited a greater porosity of 0.88, indicating that it could be a more efficient option for adsorption in wastewater treatment. Both base- and acid-activated carbons generally showed modest ash contents; however, at 12.3%, Whelk Shell Base-Activated Carbon (WSBAC) had the highest ash concentration. The bulk densities of acid- and base-activated carbons were almost identical. The bulk densities, from highest to lowest, were CSBAC > CSAAC > CWSBAC > CWSAAC > PSBAC > PSAAC > WSBAC > WSAAC, with values ranging from 0.687 g/cm³ to 0.454 g/cm³. The porosity of the samples, ranked in descending order, was CSBAC > PSBAC > CSAAC > CWSAAC > PSAAC = CWSBAC > WSAAC > WSBAC, with values from 0.88 to 0.59. FTIR and SEM-EDX indicated that all samples were successfully converted to activated carbon. The results of this study demonstrate that it is possible to chemically activate crustacean shells using either an acid or a base without sacrificing the effectiveness of the activated sample that is produced, which can be used to remove adsorbates from wastewater samples. As a result, the selection of activation is widened since the natural abundance of precursors exists.

Design of ternary GO@AgNPs@g-C3N4 membranes for efficient dye removals in integrated photocatalysis-filtration reactors

Photocatalytic composite membranes (PCMs), which integrate the high degradation efficiency of photocatalysts and the physical separation properties of membranes, have emerged as a promising technology for wastewater treatment. Herein, the ternary GO@AgNPs@g-C3N4 PCM was fabricated through a facile vacuum-filtration assembly of graphene oxide (GO), graphitic phase carbon nitride (g-C3N4), and silver nanoparticles (AgNPs) onto commercial mixed cellulose ester (MCE) substrates. The effects of g-C3N4 synthesized from different precursors and various metal nanoparticles on the performance of PCM were systematically investigated. Interestingly, results show the addition of AgNPs not only significantly improves the photocatalytic performance of PCMs but also enhances the mechanical adhesion between the active layer and the MCE substrate. The resultant PCMs exhibit outstanding photocatalytic performance, maintaining dye removal above 89% even after 25 consecutive cycles. Moreover, dye degradation pathways over the PCMs were investigated through free radical scavenging experiments and electron spin resonance characterizations. This simple assembly method results in a 3–12 times increase in flux compared to the layer-by-layer assembly method. Accordingly, our designed PCMs exhibit significant potential for wastewater treatment and water purification applications.

High-strength TiO2/TPU composite fiber based textiles for organic pollutant removal

Effective integration of nanostructured photocatalysts into polymer matrices is crucial for the broad practical application of fiber-based photocatalytic composite textiles. Herein, highly durable TiO2/TPU composite fibers with high TiO2 content (>30 wt. %) were prepared through wet spinning using 1D electrospun TiO2 nanofibers (TNFs). Due to the fiber reinforcement principle, the TNF/TPU composite fibers exhibited superior mechanical properties compared with pure TPU fibers. Furthermore, the TNF/TPU composite fibers with a ratio of 1:2 process impressive degradation efficiency for rhodamine B (RhB). The orientation of 1D TNFs and stronger interface between TNF and TPU matrices not only enable the excellent load sharing and transfer effects following fiber pullout and crack bridging mechanisms, but also improve photogenerated charge transfer efficiency, resulting in high strength and high photocatalytic activity. In addition, enhanced TNF exposure on the fiber is due to the hollow and porous structures of composite fibers, which is advantageous for photocatalytic degradation. Notably, when the RhB concentration exceeded 15 ppm, the TNF/TPU composite fibers exhibited higher degradation efficiency than the TNF powder. Therefore, TNF/TPU composite fiber–based textiles with high photocatalytic activity and strength are promising for overcoming the separation and recovery issues of nanostructured catalysts in practical wastewater treatment applications.