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Abstract The performance of carbon mineral-combined adsorbents in a batch and fixed column study was examined for removing chemical oxygen demand (COD) and ammoniacal nitrogen (NH3-N), which typically found in landfill leachate. The batch experiment was carried out using various factors including adsorbent dosages and retention time, while column performance was evaluated by optimizing the influent flow rate. The surface of the composite adsorbent was examined using X-ray fluorescence (XRF), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM) to determine any changes before and after column operations. The XRF analysis of the composite adsorbent reveals a high concentration of calcium oxide and silica oxide as the primary compounds. The main functional groups in the composite adsorbent included O–H, N–H, O–C, C–N, C–O, and Si–O–Si. The SEM analysis revealed that the composite adsorbent contains heterogeneous pores and a rough surface. The reduction rates achieved were 86% for COD, with an optimum adsorption capacity of 31.3 mgg−1, and 80% for NH3-N, with an optimum adsorption capacity of 29.8 mgg−1. The breakthrough capacities for COD and NH3-N adsorption were 6.55 and 4.24 mgg−1, respectively. However, optimal empty-bed contact times (EBCTs) in minutes were 480. The performance efficiency of the column for COD and NH3-N was 0.9978% and 0.9913%, by utilizing fresh composite adsorbent, and these number figures increased to (≥ 0.9998%) respectively after the regeneration process. The Adams–Bohart constant for COD from 5.30 × 10–6 to 4.92 × 10–6 mL/min-mg and NH3-N from 2.90 × 10–5 to 4.52 × 10–5 mL/min-mg respectively was found to increase with increasing flow rates from 1.5 to 3.0 mLmin−1. Therefore, COD and NH3-N adsorption on composite adsorbent at flow rates of 1.5 mLmin−1 was considered appropriate from the context of this study. In summary, this research has successfully shown that the use of composites as an adsorbent is a viable and suitable for the removal of COD and NH3-N from leachate, indicating their potential for use in real-world industrial wastewater treatment could further enhance their practical applications.

Abstract Microwave extraction of active compounds from plants offers an efficient alternative to traditional methods, highlighting the need to investigate its modeling and kinetic mechanisms for comprehensive understanding. This study evaluated kinetic models for the microwave-assisted hydrodistillation (MAHD) of ethanimidic acid from hibiscus flowers. Experimental data, including ethanimidic acid concentration as a function of time, power, and solid-to-liquid ratio, were analyzed using three-parameter empirical models. The second-order model demonstrated superior accuracy (R² = 0.954), outperforming the first-order model, and effectively described the two-stage extraction process: washing and diffusion. The second-order kinetic model ensures precise control of ethanimidic acid extraction, enabling efficient scalability for industrial production and consistent quality for pharmacological applications, emphasizing sustainable and cost-effective manufacturing practices. This model provides a robust framework for advancing MAHD applications in the industrial production of bioactive compounds, promoting innovation in sustainable technologies, and enhancing the economic feasibility of bioactive compound recovery.

This study provides a comprehensive investigation into the antioxidant and antibacterial properties of Hibiscus flower extracts, highlighting their potential for future applications in functional foods. The research addressed key challenges by employing a multi-faceted approach, including four distinct methods for evaluating antioxidant potential: DPPH and FRAP assays, reducing power, and chelating ability of Fe ions. Total phenolic content was quantified using the Folin–Ciocalteu method, while tannins and flavonoids were assessed via vanillin–HCl and aluminum chloride assays. Additional analyses included spectrophotometric measurement of total flavonols and anthocyanins. Antibacterial activity was determined using a modified agar disk diffusion method, with results indicating significant inhibition of Salmonella typhimurium and Staphylococcus aureus by both aqueous and methanolic extracts. Colorimetric analysis revealed a reduction in chroma and hue angles, while FTIR spectroscopy identified key functional groups, such as suberin, lipids, and polysaccharides. Notably, the antioxidant efficacy varied depending on the solvent used, with aqueous extracts showing higher total phenolic content (4325.12 mg GAE/100 g) compared to methanolic extracts (3487.05 mg GAE/100 g). The study concludes that Hibiscus flower extracts, rich in antioxidants like tannins and anthocyanins, possess significant potential for use as natural preservatives and colorants in food products, supporting their role in developing novel functional foods.

Abstract The paper industry is a major environmental polluter due to paper waste sludge (PWS), often disposed of in hazardous ways. The techniques are employed to disposing of PWS are posing significant environmental hazards and risks to well-being. This study aims to evaluate PWS as a potential replacement for commercial adsorbents like AC and ZEO in treating stabilized leachate. Contact angle analysis of PWS was 92.60°, reveals that PWS to be hydrophobic. Batch adsorption experiments were conducted with parameters set at 200 rpm stirring speed, 120 min contact time, and pH 7. Optimal conditions for COD and NH3–N removal were identified at 120 min contact time, 200 rpm stirring speed, pH 7, and 2.0 g PWS ratio. Removal percentages for COD and NH3–N were 62% and 52%, respectively. Based on the results of the isotherm and kinetic studies, it was observed that the Langmuir and Pseudo second order (PSO) model exhibited greater suitability compared to the Freundlich and Pseudo first order (PFO) model, as indicated by higher values of R-squared (R2). The R-squared of Langmuir for COD and NH3–N were 0.9949 and 0.9919 and for Freundlich model were 0.9855 and 0.9828 respectively. Whereas the R-squared of PFO for COD and NH3–N were 0.9875 and 0.8883 and for PSO were 0.9987 and 0.9909 respectively.