Acid mine drainage (AMD) is a major environmental concern characterized by low pH and elevated concentrations of heavy metals such as iron and manganese, requiring effective and sustainable treatment methods. This study investigates the use of industrial fly ash waste as a low-cost adsorbent, enhanced through alkali-leaching modification to produce a zeolite-like material with improved adsorption performance. The novelty of this work lies in the application of alkali-leached fly ash to simultaneously enhance adsorption capacity and neutralization ability for AMD treatment. Adsorbent characterization was conducted using scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray diffraction (XRD) and Brunauer–Emmett–Teller (BET) analyses. BET results showed that modification significantly increased the specific surface area (14 m2/g) and pore volume (0.025 cm3/g). SEM-EDX results revealed a predominantly spherical morphology and changes in elemental composition following modification. XRD analysis showed partial dissolution of minor phases during alkali leaching, resulting in increased dominance of the quartz (SiO2) phase with a main peak at 2θ = 26.59°. Batch adsorption experiments were performed under varying adsorbent dosages (10–100 g) to evaluate metal removal and pH improvement. The results demonstrated that modified fly ash increased AMD pH from 3.45 to 7.21 and achieved high removal efficiency of Mn, reducing its concentration to 0.05 mg/L (removal efficiency > 95%). Compared to untreated fly ash, the modified adsorbent exhibited significantly enhanced performance. The treated AMD met Indonesian Class I water quality standards. These findings highlight the potential of alkali-leached fly ash as an effective and sustainable adsorbent for AMD remediation.
This study investigates the impact of a novel copper(II)-based flame retardant on the combustibility and fire risk of epoxy composites. The flame retardant is a chelate-type coordination compound of copper(II) chloride and diethylenetriamine (deta) – [Cu(deta)2]Cl2 – and was synthesized through the direct reaction of CuCl2 and polyethylenepolyamine (pepa). When incorporated into epoxy resin, the synthesized coordination compound exhibites bifunctional properties, acting as both a flame retardant and a curing agent. Epoxy composites containing [Cu(deta)2]Cl2 are significantly less combustible, as demonstrated by a decrease in the maximum temperature of the gaseous combustion products and the mass loss of composite samples due to combustion. The flammability of the synthesized composition was evaluated using the vertical burning method in accordance with the UL 94 standard, and the composition met the criteria for the V-1 class. Incorporating the synthesized flame retardant-hardener into the epoxy resin reduces smoke emission intensity during burning and smoldering. The increased fire resistance of the modified compositions is due to the formation of Cu–N coordination bonds in the polymer matrix and the catalytic effect of copper-containing centers on carbonization and oxidation processes. This is in addition to the formation of a dense, carbonized protective layer during thermal decomposition. These results confirm the potential of using copper(II) chelate coordination compounds as multifunctional components in epoxy systems that combine the roles of curing agent and flame retardant. This opens up opportunities for creating a new generation of polymer materials with enhanced fire safety for various applications.
The present study focuses on the microwave-assisted transesterification (MAT) employed in Bauhinia variegate (BV) biodiesel production in a shorter reaction time with a better yield. The oil was extracted and characterized for physiochemical, fatty acid composition, and Fourier transform infrared analysis. The lower acid value (<2) indicated that the oil can be processed to the transesterification process. MAT was optimized for maximum biodiesel production using the statistical tool with maximum biodiesel yield of 96.83% at the optimum condition of oil to methanol ratio - 1:7 (v/v), catalyst concentration - 1 (wt%), power - 450 W at 10 min. The result was well in agreement with the physicochemical properties of ASTM D6751 standard prescribed limits. Nevertheless, the BV diesel physiochemical properties were higher than that of petrodiesel. It is then blended with petrodiesel to investigate the calorific value, density, kinematic viscosity, flash point, cloud and pour point. It was found that up to 20% biodiesel blending gives close results with petrodiesel properties. From experimental results, the MAT process was efficient in a shorter time technique for BV biodiesel production. This beneficial approach leads to reducing the production cost of biodiesel in a continuous mode.
The occurrence of pharmaceutical contaminants in aquatic and terrestrial environments has become a major environmental concern due to their persistence, continuous release, and biological activityat lowconcentrations. Metformin hydrochloride, a widely prescribed antidiabetic drug, is frequently detected in water and soil systems owing to its high consumption and resistance to biodegradation. This work couples photocatalysis with soil transport modeling to assess removal efficiency and environmental fate.This study investigates the transformation of metformin from aqueous solutions using ZnO-assisted photocatalysis under UV irradiation, combined with an assessment of its transport behavior in porous media. The influence of key operational parameters, including catalyst loading, initial concentration, and pH, was systematicallyevaluated. Under optimal conditions (pH 9.7, 0.3 g L-1 ZnO), a removal efficiency of 77% was achieved within 180 min. Kinetic analysis confirmed pseudo-first-order behavior, demonstrating the effectiveness of photocatalysis compared to adsorption alone. It should be noted that UV-Vis spectrophotometry reflects primary transformation rather than complete degradation due to the possible formation of transformation products such as guanylurea. The transport of metformin was further simulated in light sand and biosolid-amended soil using a nonlinear physical nonequilibrium (PNE) model. Breakthrough curve analysis revealed rapid transport with limited retention in lignt sand, whereas delayed migration and enhanced sorption were observed in biosolid-amended soil, indicating nonlinear sorption behavior. These findings highlight the importance of integrating advanced treatment processes with subsurface transport analysis to provide a more comprehensive environmental risk assessment of pharmaceutical contaminants.
This paper addresses the fundamental challenges of efficiency and temporal stability in poly(3-octylthiophene) (P3OT):[6,6]-phenylC61-butyric acid methyl ester (PCBM)-based organic solar cells, which often suffer from instability in the active-layer micromorphology under operating conditions. A comparative study of three additive classes with different physical states was conducted: a high-boiling solvent (1,8-diiodooctane, DIO), a solid organometallic additive (ferrocene, Fc), and a polymeric additive (polyethylene glycol, PEG). Optical (UV-Vis), structural (XRD, Raman), and morphological (atomic force microscopy) characterizations reveal that each additive regulates film formation through a distinct mechanism. DIO slows solvent evaporation and promotes refined nanophase separation and enhanced ordering; Fc induces nucleation-driven ordering; and PEG smooths the surface and suppresses defects. These effects translate into improved photovoltaic performance, particularly in short-circuit current density and fill factor. The DIO-treated device achieved the highest power conversion efficiency (3.33%) compared to 1.93% for the reference device. Aging studies further demonstrate that solid and polymeric additives provide superior resistance to thermal and photo-induced degradation compared to solvent-treated devices. These findings highlight that selecting an appropriate additive class is an effective strategy to simultaneously enhance efficiency and long-term stability in P3OT:PCBM organic solar cells.
