ABSTRACT This study provides an insight into the development of an economical and sustainable activated carbon derived from date seeds, modified with NaOH and HCl. The synthesized adsorbents efficiently remove Brilliant Cresyl Blue (BCB) and Coomassie Brilliant Blue R-250 (CBB) dyes. Microstructural changes at the surface of adsorption confirmed with the help of powder X-ray diffraction (PXRD), scanning electron microscope equipped with energy dispersive X-rays (SEM-EDS) and Fourier transform infrared (FTIR) techniques. BCB was removed within 20 min, upto 99.8% by NaOH activated date seeds carbon (OH-ADSC) at pH 6.2, while CBB were removed within 45 min, upto 99.7% by HCl activated date seeds carbon (H-ADSC) at pH 4.2. Both BCB and CBB dyes reveal monolayer adsorption with maximum capacity of adsorption (qmax) of 77.52 mg/g and 27.13 mg/g, respectively. The adsorption process was best described by the Ho and McKay model with R2 value 0.999 (BCB) and 0.997 (CBB). Thermodynamic study shows the endothermic (ΔHo = 31.92 and 20.46 kJmol−1 for BCB and CBB) and spontaneous nature (ΔGo < 0) of adsorption in both dye cases. Adsorption-desorption experiments reveal OH-ADSC and H-ADSC could be recycled/reused up to six times with removal efficiency of 82.4% (BCB) and 86.7% (CBB), making them efficient and reusable adsorbents. Agricultural waste valorization for environmental applications has gained significant attention as a sustainable waste management approach.

ABSTRACT Membrane biofouling persists not because we do not understand its mechanisms, but because diagnostic and intervention strategies are often misaligned with the stage of fouling. As a result, monitoring and control methods are typically applied without considering whether the adhesion is still reversible or has progressed to a more stable biofilm. In this work, we introduce a stage-specific framework that connects early physicochemical adhesion, extracellular polymeric substance (EPS) buildup, and quorum-sensing-driven maturation to the most appropriate diagnostic tools and control strategies. By comparing offline characterization, in situ imaging, and real-time monitoring techniques, we highlight true early-warning tools that can detect reversible attachment, as opposed to methods that mainly capture established biofilms. Our review of the available evidence shows that fouling reversibility is not only affected by biomass buildup but by the transition from surface-force-driven attachment to EPS-mediated biofilm consolidation and quorum-sensing-regulated resistance. Based on these insights, we suggest a stage-dependent approach to biofouling management: focusing on surface modifications and nutrient control during early adhesion, enzymatic and quorum-quenching treatments during matrix development, and more intensive physical-chemical methods for mature biofilms. The evidence supports that intervening early, before EPS consolidation occurs, is the most effective way to prevent fouling from becoming irreversible. When diagnostics and control strategies do not match, fouling accelerates, but combining stage-specific management techniques offers the best potential for long-term stability. This framework provides a clear path to translate laboratory-based diagnostics and antifouling innovations into practical, field-ready solutions.

ABSTRACT Nickel phosphate/chitosan nanocomposite (NPO/chitosan) was successfully prepared to study its removal efficiency and selectivity for adsorption of strontium ions from a multicomponent solution containing cobalt and cesium ions. The prepared composite was characterized and identified. The average crystallite particle size and pore diameter of the produced composites were found to be 34 and 2.574 nm, respectively. The prepared composite exhibited strong selectivity due to adsorption of strontium, displaying rapid kinetics with the selectivity order and removal % (Sr 2+; (89%) >>Co2+ ;(25%) >Cs+ ;(15%)). Additionally, 0.05 M HNO3 proved to be the most effective for the removal and separation of strontium ions. The adsorption of strontium was endothermic, spontaneous in nature, and more applicable to Freundlich and Timken isotherms. The complex formation and ion-pair reaction mechanisms, as well as intra-particle and film diffusion mechanisms, are involved in the adsorption mechanism of Sr2+ ions. 0.1 M of NaNO3 was a suitable concentration for desorption of about 85.4% (38.36 ppm) of adsorbed strontium (44.95 ppm) after 2 h of contact time. The sample was reused six times successfully. All of the results suggest that the produced NPO/chitosan nanocomposite has efficient potential for eliminating and separating Sr2+ from nuclear wastewater for environmental remediation.

ABSTRACT Polyamide (PA)-based ultrafiltration membranes offer low-cost and energy-efficient separation for wastewater treatment. In this study, nanocomposite PA membranes were synthesized using the non-solvent induced phase inversion (NIPS) technique with controlled thickness (200–400 µm) and incorporation of 0.1 wt.% titanium dioxide (TiO2), copper sulfide (CuS), and xanthan gum (XG) nanoparticles to enhance morphology, hydrophilicity, permeability, and mechanical strength. Nanofiller addition significantly improved the permeability–selectivity balance. The PA@TiO2 membrane exhibited the highest pure water flux of 250 ± 50 L/m2h, nearly ten times higher than pure PA (25 L/m2 h), due to enhanced porosity, improved pore interconnectivity, and Ti-OH functional groups that reduced water transport resistance. The PA@CuS membrane achieved superior BSA rejection of 85.23% compared to 71.89% for pure PA, along with a reduced contact angle of 33.13°, confirming enhanced hydrophilicity. PA@TiO2 also demonstrated 68% NaCl rejection and 56% dye rejection, with effective TSS, COD, and BOD removal in synthetic wastewater. Mechanical analysis showed significant reinforcement, with PA@XG exhibiting the highest tensile strength (3755 Pa). Overall, low nanoparticle loading and scalable NIPS fabrication produced durable, high-performance membranes suitable for sustainable ultrafiltration applications.

ABSTRACT This study introduces cellulose acetate nanoparticles (CANPs) as an eco-friendly adsorbent for JG, synthesized in situ using the nanoprecipitation technique. The proposed mechanism consists of the formation of a cellulose acetate thin film upon the injection of the organic phase, followed by the rapid formation of spherical particles that entrap the dye solution. DLS analysis confirmed the successful formation of CANPs with a Z-average hydrodynamic diameter of 128.6 nm. The particle size distribution using the TEM technique was 93 ± 22 nm. The specific surface area, average pore diameter, and total pore volume of the CANPs were 1.141 m2 g−1, 28.7 nm, and 0.0082 cm3 g−1, respectively. The pHpzc of the CANPs was determined to be 6.2. The results showed that surface adsorption, upon aging the spherical particles, does not contribute significantly to the overall removal efficiency. Therefore, physical occlusion accounts for the observed high removal efficiency. Key parameters, pH, temperature, adsorbent dosage, and contact time, were optimized, with pH 8.0 at 20°C and a 15 min contact time yielding a maximum adsorption capacity of 52.64 mg g−1. Kinetic and isotherm studies suggest a pseudo-second-order model and Langmuir isotherm, indicating monolayer adsorption. Thermodynamic analysis confirms the process is exothermic and spontaneous.

ABSTRACT Tubular Axial Vortex Separator (TAVS) utilizes a high-speed rotating impeller to create a strong swirling flow for oil-water separation, boasting a single-tube capacity of 10,000 m3/d. It is anticipated to streamline oilfield produced water treatment and reduce carbon emissions. However, prototype tests have revealed that increasing the impeller’s speed does not consistently enhance separation efficiency. To investigate the decline mechanism and establish operational limits, a visualized TAVS test platform was constructed. High-speed cameras recorded oil core deformations, while FFT analysis studied its oscillation. Results showed separation efficiency peaks at 90.4% (water outlet oil droplet size: 55 μm) at 1000 rpm, stable up to 1500 rpm (droplet size rises to 90 μm). However, as rotational speed rises from 2500 to 4000 rpm, efficiency drops significantly (87% to 74.1%), mainly due to enhanced entrainment of large droplets. Above 3500 rpm, the oil core’s radial acceleration is 76.6% of centrifugal acceleration, and its oscillating area nears the oil outlet (A o/A out ≈0.85), causing oil discharge through the water outlet. Additionally, FFT confirms the oscillation frequency is directly tied to impeller speed, identifying it as the root cause. Field data corroborates the 1000 rpm optimum, aligning with experiments to support TAVS speed optimization.

ABSTRACT Many researchers have reported toxicity concerns along with ambiguous environmental fate of nanoparticles used in wastewater treatment applications. The current study embedded the biogenic zinc oxide nanoparticles (ZnO NPs) in calcium alginate beads to evaluate their photocatalytic efficiency in degrading direct blue 1 (DB-1) and wastewater treatment. After characteristic spectral confirmation of nanoparticles, the spherical surface morphology and size range (10.29–26.89 nm) of ZnO NPs were confirmed through scanning and transmission electron microscopy. Further, XRD and FTIR analysis elucidated the crystallite structure and functional groups attached to the surfaces of ZnO NPs, respectively. Approximately 85% DB-1 color was removed by the beads immobilized with 2 mg/mL ZnO NPs after exposure to a dye concentration of 100 mg/L for 5 hours in sunlight. The beads decreased the pH (27.8%), EC (53.1%), turbidity (85.9%), TSS (71.9%), COD (75.9%), and hardness (45.1%) of actual wastewater as compared to untreated samples. The immobilized ZnO NPs-based textile effluent remediation process, if scaled up, has the capability to tackle the issues associated with the toxicity and environmental fate of nanoparticles.

ABSTRACT The co-production of melanin during Aureobasidium pullulans fermentation compromises the purity and functionality of pullulan. To address this, acid-activated date seed biochar was evaluated for the selective removal of melanin from crude pullulan. A central composite design of experiment was adopted to vary solution pH, contact time (CT), and biochar concentration (BC) in the batch adsorption process, while quantifying melanin and pullulan recovery through a rapid, nondestructive chemometric Partial Least Square Regression (PLSR) model (R2 CV 0.99) built on designed blends. Hyperparameter-optimized Artificial Neural Network (ANN) models trained on Gaussian noise-augmented data demonstrated excellent prediction performance for both melanin adsorption (R2: 0.97, R2 CV: 0.95) and polymer loss (R2: 0.99, R2 CV: 0.99). Explainable machine learning tools, such as Shapley Additive Explanation (SHAP) and Local Interpretable Model-Agnostic Explanations (LIME), were used to interpret the developed ANN models. Genetic algorithm-based multi-objective optimization suggests melanin removal of 87.56% and polymer loss of 14.55% under optimal biosorption conditions (i.e. pH: 5.16, CT: 36.59 min, and BC: 20.00 g L−1), closely matching the observed melanin removal (86.85%), polymer loss (17.42%) in the validation run. Combining green adsorbents, chemometric tools, and a machine learning model provides a robust, scalable solution for downstream processing of biopolymers.

ABSTRACT Humic acid-activated carbon (HAAC) was prepared using weathered coal humic acid as the raw material, and its adsorption performance for methylene blue (MB) was systematically investigated. The results showed that pH, temperature, and the amount of adsorbent used had considerable effects on MB adsorption. Moreover, weathered coal HAAC demonstrated an adsorption capacity of 1039.8 mg/g at 298.15 K (pH = 3). When the addition amount of HAAC was 150 mg/L, the MB removal rate reached its highest of 99.41%. After repeating the adsorption and desorption experiments five times, the HAAC derived from weathered coal exhibited a remarkably high adsorption capacity for MB, approaching 850 mg/g. Kinetic analyses revealed that the adsorption rate of MB on HAAC derived from weathered coal is proportional to the square of the dye concentration. This quadratic dependence provides clear evidence that the process can be accurately described using a pseudo-second-order kinetic model. Finally, it was confirmed that humic acid derived from weathered coal can be converted into activated carbon for the purification of industrial wastewater, broadening its industrial applications. This study also realizes the diversified utilization of weathered coal.