Abbas J. Sultan

A five factor, three-level Central composite design (CCD) combining with response surface (RSM) was employed for maximizing crystal violet adsorption capacity (q_e) and removal dye from aqueous solution using a low-cost biosorbent prepared from a 50 : 50 mixture of two microalgae species: green (Chlorella vulgaris) and blue-green (Arthrospira platensis). The biosorbent was characterized by Fourier-transform infrared spectroscopy (FT-IR). Central composite design within response surface methodology (RSM) was employed to optimize five critical factors affecting crystal violet (CV) removal: pH 3‒11, biosorbent dose 250‒750 mg, temperature 20‒50°C, initial CV concentration 10‒30 ppm, and adsorption time 5‒15 min. MINITAB 18 software was used to maximize the adsorption capacity. The highest experimental crystal violet dye capacity of 140 mg/g was found in the lowest algae dose, consistent with calculated values based on numerical optimization. Kinetic modeling revealed the best fit with the pseudo-first-order model R² (0.9829), while equilibrium isotherm data were best described by the Langmuir model R² (0.9960). Thermodynamic parameters (ΔG⁰, ΔH⁰, and ΔS⁰) indicated the spontaneity and endothermic nature of the biosorption process. Finally, the study of mass transfer adsorption models was examined using the Weber and Morris model, the liquid film diffusion model, and Bangham and Burt’s model. When comparing these models, Bangham’s and Burt’s model has the highest R² (0.9971). The rapid dye uptake suggests the potential of this algal biosorbent for efficient and simultaneous dye removal in real-world contaminated environments.

A fin-fluidized bed heat exchanger was examined experimentally to improve the bed-to-surface heat transfer coefficient. The investigation was carried out in four stages (single tube heater, five internals equipped with a tube heater, single longitudinal fin tube heater, and five internals equipped with longitudinal fin tube heater) and was placed and moved at a different position in and around the center. The effect of vertical longitudinal fins with heat-exchanging tube bundles on the heat transfer coefficient (HTC) in a gas-solid fluidized bed has been studied locally and instantly. A sophisticated heat transfer technique and silica sand as a solid particle of 600 µm average size with a bulk density of 1570 kg/m³ were used. The experiments were performed in a Plexiglas fluidized bed reactor 0.13 m diameter with varied gas flow rates (0.215‒0.353 m/s). The study was initially without a fin, the tube heater was 0.012 m in diameter and 40 cm in length, then with a longitudinal fin (1.5 mm thickness, 7 mm height, and 400 mm length). The fluidized bed reactor with longitudinal fins and vertical tubes has been found to have a 47% lower local heat transfer coefficient than the reactor with bare vertical tubes. The findings show that even though using fins reduces the heat transfer coefficient, the overall heat transfer increases due to the increased surface area. It is observed that smooth and finned tube heat transfer coefficients increase as the fluidizing velocity increases.

Spouted bed reactors (SBRs) are highly valued for their effectiveness in chemical and biochemical processes due to their mixing and heat transfer capabilities. Understanding the heat transfer mechanisms in these reactors is necessary. This research delves into the heat transfer behavior of SBRs, which plays a role in enhancing their performance under operational conditions. The study conducted experiments to measure the heat transfer coefficient (HTC) at varying gas velocities (ranging from 0.32 to 0.74 m/s) at radial positions (r/R = 0, ±0.28, ±0.56, and ±0.85) and axial levels (H/D = 0.8, 2.1, and 3.5) within the spouted bed (SB) column using a technique, for the assessment of local heat transfer coefficients (LHTCs). The results we obtained revealed the velocity of the gas, its radial position in the reactor, and its axial height. For instance, higher gas speeds led to heat transfer efficiency and variations in radial positions highlighted how the reactor’s shape influences heat transfer dynamics. It’s worth noting that increasing the gas speed from the lowest to the level tested resulted in a 25% increase in heat transfer coefficients. These discoveries provide insights for improving the design and performance of SBRs with ranging applications in industries that rely on effective heat transfer processes.

Metals’ potential hazards have drawn greater attention to the influence of metal pollution on water, making it a crucial subject of study in recent environmental research. This research aligns with the Sustainable Development Goals (SDGs), that aim to protect the world by addressing environmental concerns. As a consequence, understanding the impact of metal pollution on water is an essential aspect of the SDGs’ efforts to improve environmental preservation. This study provides insight into the removal of zinc ions from industrial wastewater using emulsion liquid membrane (ELM) technology. A study was conducted to investigate the use of ELM technology for removing zinc ions from industrial wastewater. Previous studies have shown that ELM can easily remove metals in their ionic form, but the presence of other organic or inorganic compounds like sulfates, phosphates, and carbonates in industrial wastewater increases their solubility and complexity of the removal. To develop the liquid membrane, a surfactant called Sorbitan monooleate (Span 80), an extractant called bis-2-ethylhexyl phosphoric acid (D2EHPA), hydrogen chloride as a reagent, and kerosene as a diluent were used. The study investigated the impact of surfactant concentration, homogenizer speed, extractant concentration, and external phase pH on zinc ion removal using a Box-Behnken design based on Response Surface Methodology (RSM). The results showed that surfactant concentration and pH had the greatest impact on removal efficiency, while homogenizer speed and surfactant extractant had a lower impact on zinc removal. The investigation adjusted numerous parameters to achieve a zinc recovery rate of more than 93% from the bioleaching solution. The most beneficial conditions were a stirring speed of 250 rpm for 10 min, 4.75% v/v Span 80, a homogenizer speed of 11 212 rpm for 8 min, a feed phase pH of 5 or 4.9, and 6% v/v D2EHPA in kerosene.

This study examines the impact of equipping a real heat exchanger in a slurry bubble column SBC on instantaneous and local heat transfer coefficients IHTC and LHTC, as well as the overall heat transfer coefficient U, employing advanced heat transfer techniques. The experiments were conducted in a 0.15 m inner diameter Plexiglas SBC with varying gas flowrates Ug (0.14–0.35) m/s at several radial sites along the column’s diameter (±0.18, ±0.46, and ± 0.74) and three axial locations (H/D = 2, 3 and 4). To simulate the industrial Fischer–Tropsch bubble column reactor FT-BCR, a real heat exchanger consisting of 18 copper tubes, each with a diameter of 0.16 m, were vertically installed, occupying 25% of the column cross-sectional. Glass beads with an average size of 150 μm were used loading up to 40% volume to represent the solid phase. The results demonstrated that both, LIHTC and U, showed significant decreases with increasing gas flow rates at all radial and axial positions. Moreover, the LIHTC near the wall notably decreased compared to the central zone by about 82% at the radial location and about 74% at the axial location. The obtained results and data contribute to understanding the impact of vertical tubes on heat transfer in a slurry bubble column reactor SBCR. Furthermore, the data obtained can validate reactor models, computational fluid dynamics CFD programs, and simulations, thereby improving the design and scale-up of these reactors.

This study explores using iron oxide coatings on glass beads to improve heat transfer efficiency in fluidized bed reactors. Techniques such as BET surface area analysis, SEM imaging, and X-ray diffraction were used to characterize the coated beads. Results showed the successful creation of a crystalline iron layer on the beads’ surface and increased thermal conductivity, especially at elevated temperatures. The study also quantified the impact of air surface velocity and heating power on the heat transfer coefficient, revealing substantial improvements, especially at higher velocities. It was found that the heat transfer coefficient for 600 µm glass beads increases significantly from 336.4 W/m²·K to 390.3 W/m²·K when the velocity is 0.27 m/s and the heating flux is 125 W. This demonstrates the effectiveness of the iron oxide coating in improving heat transfer. The results of this study emphasize the efficacy of iron oxide coatings in augmenting heat transmission characteristics, particularly in fluidized bed reactor.

Nanotechnology with its interdisciplinary nature is widely applicable to almost every facet of contemporary life, especially in the creation of nanomaterials and nanocomposites. The gas and oil industry uses nanofluids for a variety of purposes. By suspending nanoparticles in a base fluid, this method improves the fluid’s mechanical and thermal characteristics. Within the gas and oil sectors, nanofluids are using in hydraulic fracturing, increased oil recovery, drilling fluids, and heat transmission. Fluids utilized in these processes can be made more efficient in heat exchange, perform better as drilling fluids, extract more oil at higher rates, and maximize the efficiency of hydraulic fracturing operations by adding nanoparticles to the fluids. This paper reviews prospective applications of convective heat transfer optimization experimentally and numerically by employing hybrid nanofluid and nanofluids. Over the past twenty years, nanofluids have garnered a lot of attention. The dispersion of nanoparticles significantly enhanced the heat transfer characteristics of the current fluids. The current research also includes comparing the use of different types of nanoparticles and base fluids, methods for preparing nanofluid and hybrid nanofluids, studying their physical properties, and the effect of these properties on improving heat transfer. Many researchers around the world have investigated the feasibility of using nanofluids in various applications and equipment. This research summarizes current research in studies of nanofluids on the performance of convective heat transfer experimentally and numerically. Almost all previous studies have shown the preferred thermal behavior of nanofluids in thermal applications compared to the basic fluid. It also found that the hybrid use of nanoparticles is more efficient than the use of nanoparticles alone.

This research is mainly concerned on studying the effects of heating surface area of immersing heater and particles size of bed packing on values of heat transfer coefficient (HTCs) under different air flow rates. Experiments were conducted in a gas-solid fluidized bed to study the steady-state heat transfer between gas and solid, along with the surface of the bed at various velocities, ranging from static bed to fluidized bed conditions (0.024– 0.387 m/s). The bed column was 172 mm in diameter and 1000 mm in height, attached with a horizontal heating tube of different diameters (19.5, 25.4, and 30 mm). Three different sizes of sand particle were employed (i.e. 200, 300 and 400 µm). HTCs are shown to rise with fluidizing air velocity while exhibiting a reverse association with particle size. The influence of heating tube diameter on HTC has been examined with remarkable fluctuations revealing the bed’s hydrodynamic characteristics.

This work studied heat transfer enhancement in gas-solid fluidized beds by applying copper oxide nanocoating to glass beads. A fluidized bed column with a diameter of 10 cm and a length of 150 cm was used, A heat element placed in the center of the column at a height of 10 cm from the air distributor. The experimental methodology involves coating glass beads (200 and 400 μm) with nano copper oxide using settling deposition method, a characterization using XRD, TEM, BET, SEM, and EDX techniques for the coated beads. A fluidized bed experiment for the coated glass beads showed a significant increase in fluidized bed performance by 23% demonstrating the potential of nanocoating in improving the efficiency of fluidized bed systems for industrial applications. The research also includes conducting analysis using Minitab’s Response Surface Methodology (RSM) for studying the remaining parameter on the fluidized bed performance.