Abstract Fractional-order controllers are recognized for their enhanced tuning flexibility, while the Smith predictor (SP) is a widely used approach for compensating time delays in control systems. This study explores a hybrid approach that integrates the advantages of both fractional-order control and SP structure to address challenges in time-delay process control. In this study, a predictive modified fractional-order internal model control (MFOIMC) strategy is proposed, wherein the fractional-order controller C FOC ( s ) is designed based on maximum sensitivity and phase margin specifications to achieve desired robustness and performance. The proposed controller is tested in four benchmark case studies: a proton exchange membrane fuel cell (PEMFC), a bioreactor, a continuous stirred tank reactor (CSTR), and a cryogenic distillation process. Simulation results demonstrate the superior performance of the proposed MFOIMC approach in terms of tracking, disturbance rejection, and robustness, compared to existing methods. The effectiveness is quantitatively validated using error indices and the integral square of control input (ISU). Robust stability under parametric uncertainties is also verified. Practical viability is confirmed through real-time implementation on a two-tank level control setup, showcasing the industrial applicability of the proposed method.

Abstract In this study, a simulated model was developed using Aspen Plus software to investigate the pyrolysis of four different biomasses and waste plastics: Coconut shell (CS), Granular bacteria (GB), Azolla, and High-density polyethylene (HDPE). The primary goal was to produce valuable syngas and biofuel and analyze the impact of key operating conditions, temperature and pressure, on product distribution (bio oil, biogas, biochar), gaseous composition (H 2 , CO, CO 2 , CH 4 ), and the H 2 /CO ratio. The simulation results revealed that the highest bio oil yield (54 wt%) was obtained from High-density polyethylene at a temperature of 525 °C and pressure of 1 bar, while the maximum biogas yield (46 wt%) belonged to Azolla at a temperature of 600 °C and a pressure of 1 bar. The H 2 /CO ratio for all feeds decreased with increasing temperature but increased with rising pressure. High-density polyethylene consistently showed the highest H 2 /CO ratio, confirming its potential as an ideal feedstock for hydrogen-rich syngas production. These findings provide critical insights for optimizing the pyrolysis process and selecting suitable feedstocks for high-value biofuel production. This research offers a fundamental understanding for the design and optimization of industrial-scale pyrolysis reactors and contributes to the broader framework of the circular economy by demonstrating the feasibility of converting specific waste streams into valuable energy products.

Abstract In the hydrometallurgical processing of high-grade nickel matte, oxygen pressure sulfuric acid leaching produces substantial residues containing hematite precipitates. In this study, high-grade nickel matte oxygen pressure leaching residue, generated during the hydrometallurgical processing of high-grade nickel, was used as the research subject. The investigation focused on the effects of various factors in the reduction leaching process on the behavior of copper (Cu) and iron (Fe), as well as on the enrichment of precious metals. A comprehensive recovery process was designed for Cu and Fe recovery. Under the conditions of an initial sulfuric acid (H 2 SO 4 ) concentration of 100 g/L, a liquid–solid ratio of 6 mL/g, a reaction time of 3 h, a temperature of 90 °C, and a sulfur dioxide (SO 2 ) partial pressure of 0.15 MPa, high leaching efficiencies were achieved: 99.35 % for Fe and 77.46 % for Cu. Concurrently, silver content was enriched from 1,200.1 g/t to 36273.5 g/t (a 30.2-fold increase). Notably, for Cu recovery, when the H 2 SO 4 concentration was 20 g/L–30 g/L at 70 °C, with 5.7 g/L of Fe powder and a reaction time of 40 min, displacement precipitation achieved 99.70 % Cu recovery, with the precipitate containing 67.91 % Cu. Subsequently, freeze crystallization of the post-Cu solution at −10 °C, with a holding time of 30 min and an initial H 2 SO 4 concentration of 150 g/L, yielded ferrous sulfate heptahydrate with 72.6 % Fe precipitation and > 99 % purity. The crystallization mother liquor was recycled into the reduction leaching process for recovery. This integrated process exhibited high metal recovery efficiency, significant precious metal enrichment, and zero wastewater discharge, representing an environmentally friendly and sustainable approach to nickel matte residue processing.

Abstract Nanoparticulate novel ternary photocatalysts comprising SnO 2 , TiO 2 and g-C 3 N 4 was successfully synthesized by the wet impregnation method with ethanol. Ternary SnO 2 /TiO 2 /g-C 3 N 4 was fully characterized by XRD, UV–vis diffuse reflectance spectroscopy, FTIR, TEM and HRTEM. The results confirmed that the photocatalyst was formed with four phases TiO 2 anatase, TiO 2 rutile, tetragonal rutile-type structure of SnO 2 and g-C 3 N 4 . The band gap energy value of prepared SnO 2 /TiO 2 /g-C 3 N 4 was 2.81 eV indicating that this composite can work under both near UV and Visible light. The degradation of ciprofloxacin hydrochloride, a persistent pharmaceutical contaminant of environmental interest, was used as a model to evaluate the photocatalytic efficiency of the synthesized materials. The test of photocatalytic degradation of ciprofloxacin showed a synergistic effect among SnO 2 , TiO 2 and g-C 3 N 4 because 90 % of CIP removal was achieved in 150 min. This performance was faster than pristine and binary materials. The ternary photocatalyst SnO 2 /TiO 2 /g-C 3 N 4 showed the highest value of the apparent reaction rate constant (0.0142 min −1 ). A novel activation mechanism for SnO 2 /TiO 2Anatase /TiO 2Rutile /g-C 3 N 4 under near UV Light was proposed. Comparing the power of the lamps and the reaction volume, this work suggests that the ternary photocatalyst SnO 2 /TiO 2 /g-C 3 N 4 achieved a better performance with respect to what was reported in previous works.

Abstract The main objective of this study was to investigate the potential use of concrete debris generated from construction and demolition waste at the Technical Landfill Centre (TLC) for eliminating copper and lead ions from synthetic solutions. To assess its suitability, the physicochemical characteristics of the debris were thoroughly examined, including its cation exchange capacity (CEC) and pH at the zero-charge point (pH PZC). Various characterization methods were employed, such as Fourier-transform infrared spectroscopy (FTIR) to predict the functional groups. X-ray diffraction (XRD) was applied to determine the crystalline structure of the materials and identify the phases present, while BET surface area analysis and scanning electron microscopy combined with energy-dispersive X-ray spectroscopy (SEM/EDX) were also used to gain a comprehensive understanding of the concrete debris. Key parameters evaluated included solution pH, initial metal ion concentration, adsorbent mass, stirring speed, and temperature, all analyzed to determine their influence on adsorption capacity. Optimal removal conditions were identified as pH 5.5 for lead and pH 5 for copper, with agitation speeds of 300 and 400 rpm, contact times of 20 and 15 min, and adsorbent masses of 0.3 and 0.4 g for copper and lead, respectively. Furthermore, A kinetic analysis of adsorption was conducted to identify the mechanisms of the process by fitting experimental data to various models. Additionally, different isotherms were utilized to accurately fit the equilibrium adsorption. The results indicate that adsorption is best represented by the Langmuir model. The use of thermodynamics in the removal process revealed that this procedure was endothermic and spontaneous.

Abstract Cavitating jet nozzles play a crucial role in various industries, including oil and gas exploration, cleaning and cutting, and the automotive sector. This study introduces a Venturi cavitation nozzle with two auxiliary flow channels (VWC), derived from the traditional Venturi cavitation nozzle (VN). The flow field of the nozzle is numerically analyzed using the large eddy simulation (LES) and the Zwart–Gerbera–Belamri (ZGB) cavitation model, and the results are compared with those of the traditional VN. This study examines the transient steam distribution and its variation within the two nozzles in the low-pressure range, assessing the influence of minor inlet pressure fluctuations on the internal cavitation flow. Under high-pressure conditions, the jet length and the velocity at the end of the external domain were compared, and the velocity of each section and the velocity change trend of the nozzle outlet and the end of the external flow field in the high-pressure range were analyzed. The numerical results demonstrate that the VWC exhibits enhanced vapor generation and jet performance under identical boundary conditions. In terms of steam generation, the vapor content of the VWC is consistently higher than that of the VN, with a maximum difference of 25 %. Regarding jet strength, under the same pressure, the VWC exhibits a lower axial jet velocity decay rate than the VN, which can be reduced by up to 52.8 %. Additionally, the longitudinal jet velocity of the VWC is slightly higher, surpassing that of the VN by up to 52 %. This research offers valuable insights and a novel reference for advancing the structural design of cavitation nozzles.

Abstract This study presents an intensified degradation strategy for azo dyes using a flow microreactor (6 m-length/1 mm-diameter)-integrated sulfate and hydroxyl radicals advanced oxidation processes (SO 4 •− / • OH-AOPs) platform. Three systems were assessed: thermally activated persulfate (KPS), Fe(II)/KPS, and Fe(II)/sodium percarbonate (SPC), focusing on key parameters – bath temperature (20–70 °C), inlet dye concentration (5–20 µM), Fe(II) dosage (50–100 µM), pH (3–7), and oxidant flowrate (20–120 μL/s). Experiments were conducted with Basic Fuchsin (BF), a persistent dye of mutagenic and carcinogenic properties. Thermal KPS led to full dye conversion at 70 °C but negligible TOC removal at lower temperatures. Fe(II)/KPS and Fe(II)/SPC improved degradation across all temperatures. Fe(II)/KPS led to substantial mineralization (63 % TOC removal), while Fe(II)/SPC achieved only 33 %, and KPS alone 54 %. At 20 °C, Fe(II)/SPC showed slightly higher TOC removal than Fe(II)/KPS (18 % vs. 15 %). Performance was strongly influenced by Fe(II) speciation (pH-dependent) and radical scavenging by intermediates. Removal ratio analyses (Fe(II)/KPS to KPS: up to 5.0; Fe(II)/SPC to Fe(II)/KPS: up to 1.97) highlighted strong catalytic synergy, especially at low pH and low dye concentration. These findings demonstrate the potential of the microreactor-based SO 4 •− / • OH-AOPs platform for scalable, energy-efficient, and high-throughput water treatment applications.

Abstract The degradation of Reactive Black 5 (RB5) dye in a solar pilot plant has been compared where reflective surfaces were added to the reactor to increase solar irradiation. Taking the tubular reactor as a reference, the effect of adding two types of reflective surfaces with different geometry was analyzed: one of the surfaces consisted of composite parabolic concentrators (CPCs) and the other of a flat reflective surface placed under the tube array. Photocatalytic reaction conditions were considered, with TiO 2 and the TiO 2 /rGO nanocomposite as photocatalysts, as well as without catalyst under photolysis conditions. A pseudo first order kinetic model was used to interpret the results, a function of the intensity of solar irradiation and the area of the tube irradiated, both directly and reflected. To estimate the area of the reactor irradiated by the reflecting surfaces, the ray tracing technique was used. For both catalysts, the highest degradation rates occurred in the presence of CPC-type surfaces. From the apparent kinetic constants, an increase of about 11 % was found for the presence of the flat reflective plate and up to 65 % for the CPC, both with respect to the tubular reactor and nanocomposite material. Based on ray tracing analysis, and according to solar time, the active area reflecting rays on the surface of the reactor was, for the CPC, in the order of 50 % greater than that of the flat reflective plate, which was consistent with the kinetic results between both systems.