Increasing Bed Height Research Articles

Investigating the Amenability of a PGM-Bearing Ore to Coarse Particle Flotation

Coarse particle flotation (CPF) is one of the strategies employed to reduce energy consumption in mineral-processing circuits. HydrofloatTM (HF) technology has been successfully applied in the coarse flotation of industrial minerals and sulphide middlings. However, this technology has not yet been applied in platinum group minerals (PGMs)’ flotation. In this paper, the amenability of platinum group minerals to CPF was investigated. Extensive flotation testwork was conducted to optimise the hydrodynamic parameters, i.e., bed level, air and water flow rates, in the flotation of coarse PGM feed using Hydrofloat. Mineralogical analysis of the feed and selected flotation products was conducted to understand the reasons for the recovery and loss of the valuable minerals. The results showed that the HF separator could upgrade the PGM ore with particles as coarse as +106 − 300 µm. For the optimised test, a reasonable Pt, Pd and Au recovery of 84% was achieved at a grade of 10 g/t and 16.5% mass pull, despite the platinum group minerals being poorly liberated (4.5 vol% fully liberated). The results demonstrated that HF achieved high recovery efficiencies across the 150–300 microns size fraction. The HF was therefore able to substantially increase the upper particle size that can be successfully treated by flotation in PGM operations. It was found that an increase in bed height, water rate and air flow rate resulted in an increase in recovery to a maximum. A further increase in the hydrodynamic parameters resulted in a decline in recovery. Hydrofloat outperformed the conventional Denver flotation machine across the following size fractions: +106 − 150 µm, +150 − 212 µm, +212 − 250 µm and +250 − 300 µm. The practical implications of the findings on the modification of existing circuits and the design of novel flowsheets for the processing of PGM ores with less water and energy consumption are discussed.

Experimental investigation of the lateral mixing of large and light particles immersed in a fluidized bed

Fluidized bed reactors for solid fuel conversion are characterized by the presence of a small fraction of fuel particles that are significantly larger (usually 1–2 orders of magnitude larger) and lighter (2–20-fold less dense) compared to the bulk solids. This difference in physical properties strongly influences the mixing of the fuel particles and therefore affects the mass, momentum and heat transfers between the fuel particles and the surrounding bed. This work uses Magnetic Particle Tracking (MPT) to acquire highly resolved trajectories for single tracer particles immersed in a bubbling fluidized bed operated under ambient conditions and with a cross-sectional area of 0.45 m2. This bed size is sufficiently large to abrogate the influence of the reactor walls, allowing data post-processing to study the free movement of the tracer particle, which has not been available to date. This required the enhancement of the MPT system from that in previous works: 12 sensors and a communication protocol in series are here applied, which showed good performance in both spatial accuracy (1 mm) and time resolution (100 Hz). The bed material used in the experiments was glass beads (mean particle size of 106 µm, particle density of 2,486 kg/m3). Two different tracer particles, with diameters of 18 mm but with different densities (572 kg/m3 and 1,015 kg/m3) were used to mimic the sizes and densities of the solid fuel particles. Fluidization velocity was varied within 0.2–0.7 m/s and two fixed bed heights (50 mm and 130 mm) were tested. Based on the trajectories, dispersion coefficients were calculated for quantitative evaluation of the solids mixing. The results reveal that increased bed height yields higher dispersion coefficients with a higher sensitivity for fluidization velocity. The properties of the tracer particles appear, within the tested range, to exert little impact on its lateral dispersion. From the velocity maps generated, a swirling pattern was observed in the vicinity of the walls, while zones of preferential ascendent or descendant movement were observed in the cross-section centre, although clearly defined mixing cells were not exhibited.

Investigation on water defluoridation via batch and continuous mode using Ce–Al bimetallic oxide: Adsorption dynamics, electrochemical and LCA analysis

With variable atomic ratios, Ce–Al bimetallic oxides were fabricated using the sol-gel combustion method and utilized for efficient fluoride removal. The synthesized bimetallic oxides were extensively studied using advanced characterization techniques, including TGA, XRD, FTIR, BET surface area analysis, EDX-assisted FESEM, XPS and impedance analysis. These techniques facilitate the interpretation of the chemical and physical properties of the synthesized material. The Ce–Al (1:1) bimetallic oxide was selected as an adsorbent for the defluoridation. The Ce–Al (1:1) oxide demonstrates a moderately high surface area of 108.67 m2/g. The sorption behaviour of fluoride on Ce–Al (1:1) was thoroughly investigated using batch and column modes. The maximum fluoride removal efficiency (99.4%) was achieved at a temperature of 45 °C and pH of 7.0 using an adsorbent dose of 0.18 g/L for 35 min. Pseudo-second-order kinetic model appropriately describes the sorption process. Freundlich's adsorption isotherm was more pertinent in representing fluoride adsorption behaviour. The maximum fluoride adsorption capacity is 146.73 mg/g at 45 °C. Thermodynamics study indicates fluoride adsorption on Ce–Al (1:1) bimetallic oxide is spontaneous and feasible. The adsorption mechanism was interpreted through XPS spectra, indicating that the physisorption process is mainly responsible for fluoride adsorption. An in-depth investigation of the adsorption dynamics was carried out using mass transfer models and found that the external diffusion process limits the overall adsorption rate. An electrochemical investigation was performed to understand the effect of fluoride adsorption on the electrochemical behaviour of bimetallic oxide. The fixed-bed column adsorption study suggested that the lower flow rate and increased bed height favourably impacted the overall defluoridation process, and column adsorption results were suitably interpreted through both the Adam–Bohart model and Yoon–Nelson dynamics model. The sustainable aspect of the defluoridation process was elucidated in terms of carbon footprint measurement using life cycle assessment analysis. The carbon footprint of the entire treatment process was calculated as 0.094 tons/year.

Remediation of Pb (II), Cd (II), and Zn (II) from aqueous solutions using porous (styrene-divinylbenzene)/Cu-Ni bimetallic nanocomposite microspheres: continuous fixed-bed column study.

Bimetallic nanoparticles (BNPs) have been used as a new line of defence against heavy metal contamination among several types of nanoparticles (NPs) due to their enhanced, synergistic activity. In this study, we investigated the adsorption behaviour of porous (styrene-divinylbenzene)/CuNi bimetallic nanocomposite (P(St-DVB)/CuNi BNC) in a continuous flow fixed-bed column and its ability to remove Pb (II), Cd (II), and Zn (II) ions from aqueous solutions. We examined how the initial metal concentration, flow rate, and bed height affected the adsorption characteristics. Experimental results confirmed that the adsorption capacity increased with increase in influent metal concentration and bed height and decreased with increase in flow rate. The breakthrough and the column kinetic parameters were successfully predicted with three mathematical models: Thomas, Yoon-Nelson, and Adams-Bohart models. Both Thomas and Yoon-Nelson models showed good agreement with the experimental results for all the operating conditions. Successful desorption of heavy metals from the P(St-DVB)/CuNi BNC was performed using 0.5 M NaOH solution, and it showed good reusability of the adsorbent during four adsorption-desorption cycles. The results show that P(St-DVB)/CuNi BNC are effective and low-cost adsorbents, and they can be used in real-time large-scale industrial water treatment processes for the removal of heavy metals.

Numerical modeling of laminar and turbulent annular flows of power-law fluids in partially blocked geometries

The presence of cuttings bed in deviated wellbores has an undesirable effect on wellbore hydraulics by reducing the open flow area. In addition, pipe eccentricity affects the annular frictional pressure gradient under such configurations. The lack of practical correlations to account for the combined effects of cuttings bed and eccentricity on frictional pressure gradient of power-law fluids is the major motivation of this study. Thus, the effect of partially blocked eccentric annuli on frictional pressure gradient of power-law fluids is investigated. A numerical model is first developed to realize the laminar and turbulent annular flow of power-law fluids in eccentric configurations. The numerical solution of the governing equations is pursued using the finite difference method. The results of our numerical model are verified through comparisons with the published results of frictional pressure gradients in the literature. The numerical results indicate that with an increase in cuttings bed height the frictional pressure gradient can increase exponentially. Numerous simulation scenarios are considered for the flow of power-law fluids in partially blocked eccentric annuli. Then, the simulation results are fitted using regression analysis to obtain explicit correlations for the prediction of laminar and turbulent frictional pressure losses. The proposed correlations are essential for an accurate estimation of the annular frictional pressure gradient and equivalent circulating density, which ensures safe and optimized drilling operations.

Column adsorption of biological oxygen demand, chemical oxygen demand and total organic carbon from wastewater by magnetite nanoparticles-zeolite A composite

Herein, magnetite nanoparticles (NPs), zeolite A and magnetite-zeolite A (MAGZA) composite was developed by green methods. The produced nanomaterials were characterized and the effect of process parameters such as flow rate, adsorbent bed height and adsorbate inlet concentration was evaluated for the removal of biological oxygen demand (BOD), chemical oxygen demand (COD) and total organic carbon (TOC) in a column. The characterization results demonstrated the successful synthesis of magnetite NPs, zeolite A and MAGZA composite. The performance of the MAGZA composite in the fixed-bed column was superior to zeolite A and magnetite NPs. The parametric influence indicates that an increase in bed height and a decrease in the flow rate and inlet adsorbate concentration improved the performance of the adsorption column. The adsorption column demonstrated maximum performance at a flow rate (4 mL/min), bed height (5 cm) and inlet adsorbate concentration (10 mg/L). Under these conditions, the highest percent removal of BOD, COD and TOC were 99.96, 99.88 and 99.87%. Thomas and Yoon-Nelson's model suitably fitted the breakthrough curves. After five reusability cycles, the MAGZA composite demonstrated removal percent of BOD (76.5%), COD (55.5%) and TOC (64.2%). The produced MAGZA composite effectively removed BOD, COD and TOC from textile wastewater in a continuous operating mode.

Adsorption modelling and fixed-bed column study on milk processing industry wastewater treatment using chitosan zinc-oxide nano-adsorbent-coated sandfilter bed.

This study aims to develop a chitosan-zinc oxide nano-adsorbent-coated sand (CZOCS) filter bed for getting rid of milk processing industry wastewater (MPIW) in a safe way. Chitosan zinc oxide nano-adsorbent (CZnO) of 88.35 ± 2.89 d.nm size was used to coat naturally available sand through a calcination process at 200°C for a heating rate of 5°C/min. The characteristics of the diffraction peaks and functional groups are attributed to the nature of CZnO loading on the sand surface. The increase in breakthrough and exhaustion times is caused by the biological oxygen demand (BOD) and chemical oxygen demand (COD) of influent having more time to interact with the adsorbent as bed height increases, resulting in higher reduction efficiencies. Lower bed heights (10cm) which saturate faster than higher bed heights (40cm) result in a shorter mass transfer time. Adsorption capacity at the 95% column exhaustion point increased from 611.04 to 1089.63mg/g for BOD and from 4512.29 to 5600.81mg/g for COD. Different kinds of kinetic models have been used to forecast breakthrough curves employing experimental data. Statistical and error function parameters were used to choose the best-fit model. Among the modelsinvestigated, the Thomas model was shown to be the best-fit with the highest R-square values of 0.9942 and 0.9939. The CZOCS has high reusability and could be used for up to six cycles of organic pollutant adsorption. Aside from that, novel CZOCS could be used to clean real MPIW, andmaking it one of the most promising adsorbents.

Arsenic removal from aqueous water using pectin stabilised nano zero valent iron particles/neem bark supported (P-NZVI/NBP) treatment system

ABSTRACT Exposure to arsenic (As) contaminated groundwater may be lethal to human health, paving the way to develop remediation strategies. This study aims at assessing the efficiency of pectin stabilised nano zero valent iron particles (P-NZVI) in arsenic removal through batch and column experiments. Results from batch experiment reveals that, As (III) removal efficiency of P-NZVI particles is directly proportional to contact time, quantity of P-NZVI with decreasing pH of the aqueous solution. Complete removal (2 ppm) of As (III) was achieved in 10 minutes with the mass concentration of P-NZVI at 0.5 g L−1 at pH 4.0 under batch experiment. The adsorption kinetics data were well fitted with pseudo second order model and the adsorption data obeyed the Langmuir and Freundlich equation with maximum adsorption capacity of 28.44 mg g−1 under batch study. Furthermore, column study with P-NZVI under Neem Bark Powder (NBP) supported treatment column with different bed height (10 cm, 20 cm) indicates that P-NZVI is superior in As(III) and As(V) removal under NBP supported treatment column. The breakthrough time, exhaustion time and bed capacity q o of the column increased with increasing bed height for both As(III) and As(V). The column experimental data fits well in Thomas and Yoon-Nelson theoretical model with coefficients of determination ranging from 0.92 to 0.94. Thus, the synthesised P-NZVI particles were eco-friendly and can easily be separated after their application in removing arsenic.

Phosphorus removal from wastewater using Ca-modified attapulgite: Fixed-bed column performance and breakthrough curves analysis

The adsorbent calcium-modified attapulgite (Ca-GAT) prepared by calcium chloride modification and high temperature treatment (700 °C) has proved to remove phosphorus in low-concentration phosphorus wastewater in batch adsorption experiments. Dynamic adsorption performance and industrial application potential still need further determination. This study explored the effects of various parameters on the dynamic phosphorus adsorption, including initial phosphate concentration (2–10 mg/L), flow rate (1–3 mL/min) and adsorption bed height (2–6 cm). Phosphorus adsorption ability improved and the breakthrough time increased with the increase of bed height, flow rate, and a decrease in initial phosphorus concentration. Breakthrough curves fitted four models, the Adams-Bohart, Thomas, Yoon-Nelson and Bed depth service time (BDST). The maximum adsorption amount determined by the Thomas model obtained 13.477 mg/g. The saturated fixed-bed column were regenerated with NaOH, NaOH + NaCl and HCl, among which 0.5 mol/L NaOH had the best regeneration effect. During the utilization of a large fixed-bed to treat the actual membrane bioreactor (MBR) effluent, the breakthrough point (0.5 mg/L) was obtained after 177 h. These results implied that Ca-GAT had an application potential for the treatment of low-concentration phosphorus wastewater (2 mg/L).

Adsorption of Safranin dye, an emerging contaminant from wastewater by modified bamboo (Bambusa Tulda): Characterization and column model analysis

AbstractA fixed‐bed column study was studied to assess the performance of sodium bicarbonate modified Bambusa Tulda to remove Safranin from wastewater. Fourier Transform Infrared Spectroscopy analysis shows the existence of carboxyl as well as hydroxyl bonding and grouping. Scanning Electron Microscope analysis shows the enhanced structure of Bambusa Tulda before and after chemical modification, and Energy dispersive X‐ray analysis shows the existence of Na, O after chemical modification with sodium bicarbonate. The maximum removal was found at higher bed depth and low flow rate. The breakthrough analysis time and exhaust time increase with an increase in bed height. At 5 ml/min flow rate, with initial concentration of 50 mg/L and bed height of 15 cm of adsorbent, shows best removal rate of safranin dye in column analysis. The Bed Depth Service Time (BDST) model and Thomas model analysis remained similar with experiment results, which indicates that they are suitable for the design of column study. It is being concluded that sodium bicarbonate modified Bambusa Tulda is an effective, low cost and readily available adsorbent for the adsorption of Safranin from wastewater.

Synthesis of novel carbon-supported iron oxide sorbents for adsorption of dye from aqueous solutions: equilibrium and flow-through studies

Textile effluents contain dyes that negatively affect water bodies and inhibit photosynthesis by reducing sunlight penetration. This study investigated the adsorption capacity of an iron oxide sorbent immobilised on naturally derived carbon foam for the removal of organic methylene blue dye from water. In this study, the carbon precursor and iron oxide precursor were mixed and carbonised in a single vessel. Baking and carbonization of the natural grain combination produce a porous structure that can act as an effective support for the iron oxide particles. The carbon foam prepared had a self-assembled structure with flour as a basic element. Sorbents of 6 weight (wt)%, 15 wt% iron, and a 0 wt% iron control sample were prepared. Transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) techniques were used to examine the synthesised carbon foam physical properties and surface morphology. The adsorption capabilities were investigated in batch tests by determining the effects of an increase in iron content, sorbent dosage, contact time, and dye concentration. Breakthrough curves were obtained by varying the height of the sorbent bed and varying the flowrate of the dye solution. A higher bed height corresponds to a greater amount of adsorbent. The breakthrough and equilibrium adsorption capacities were found to increase with increasing bed height. When the flow rate is high, the dye solution leaves the column before equilibrium, resulting in shorter breakthrough and saturation times. Higher bed heights and lower flow rates resulted in optimal dye removal in the flow through the system. Breakthrough time increases with increasing iron content. The 15 wt% iron sample displayed superior adsorption capabilities than the 6 wt% sample, while the 0 wt% iron control sample displayed minimal adsorptive capabilities. The pseudo-first order kinetic model was the best fit model for this study (R2 > 0.96), and the adsorption equilibrium is best described by the Freundlich isotherm (R2 > 0.99). The results showed that an iron oxide sorbent immobilised on carbon foam made from natural sources is a good adsorbent for removing methylene dye.

Influence of an in-vessel debris bed on the heat load to a reactor vessel under an IVR condition

We measured the heat load to a reactor vessel with and without the in-vessel debris bed under an IVR-ERVC condition. Mass transfer methodology was adopted based on heat and mass transfer analogy to achieve high Ra′H of order ∼1015 with compact test rigs. We postulated the in-vessel debris bed has a flat top and particulate debris was simulated as an identical diameter spheres. We conducted experiments varying the height of the debris bed and the results showed that Nusselt numbers decreased in both uppermost and curved surfaces with the increasing bed height. Once the debris bed is formed, it acts as an obstacle to the natural convective flow, which reduces the buoyancy. The reduction of driving force results in the impaired heat transfer in both upward and downward heat transfers.

Batch and continuous studies on adsorptive removal of hexavalent chromium [Cr(VI)] using reduced graphene oxide

AbstractIn this study, the reduced form of graphene oxide (RGO) has been synthesized by using hydrazine hydrate as a reducing agent and used for Cr(VI) removal. The physicochemical properties of the as‐synthesized material were studied by FESEM, XRD, RAMAN, and FTIR. The optimized adsorption parameters were time of 75 min, solution pH 3.0, temperature 35°C, and dosage of 0.3 g/l. The isotherms were perfectly simulated by the Langmuir model, and the kinetic data followed the pseudo‐second‐order model. The maximum uptake capacity was 787.401 mg/g at 35°C. Thermodynamic analysis indicated an endothermic and spontaneous process occurs. Competition from interfering ions (SO42−, NO3−, Cl−, HCO3−, Co2+, and Cu2+) proved insignificant. After five cycles of regeneration, the removal remains at 85.75%. From the column study, it was observed that the parameters like breakthrough time (tb), bed capacity (qbed), and exhaustion time (te) increase with an increase in bed height and decrease with an increase in Cr(VI) flow rate. Adsorption performance for industrial effluents shows up to 55.32% removal. The above superior adsorption performance validated the application of the RGO as an efficient adsorbent for the remediation of Cr(VI) ions from wastewater.

Th(ІV) biosorption from a three-component feed solution by Ca-pretreated Cystoseria indica alga in a fixed-bed column: Experimental tests and modeling

In this work, Th(ІV) biosorption by Ca-pretreated Cystoseria indica alga from a three-component feed solution containing Th(ІV), V(V), and Fe(ІІІ) ions was studied in a fixed-bed column at various bed heights (3.5–7 cm), and Th(ІV) concentrations (10–90 mg/L) with constant concentrations of 40 and 20 mg/L for V(V) and Fe(ІІІ), respectively. The results showed a minimum Th(ІV) biosorption capacity (54.15 mg/g) by increasing bed height and a maximum Th(ІV) biosorption capacity (104.6 mg/g) by increasing Th(ІV) concentration. Also, the results showed the effect of V(V) and Fe(ІІІ) ions at low Th(ІV) concentrations on breakthrough curve is more significant, and the binding sites on the surface of Cystoseria indica alga have a stronger affinity towards Th(ІV) ions compared to V(V) and Fe(ІІІ) ions. The breakthrough curves were analyzed by empirical models such as Bohart Adams, Belter, modified dose-response, and Clark models. Furthermore, a new empirical model was proposed to improve the breakthrough curves prediction. Also, using this new empirical model, the Th(ІV) biosorption capacity was presented as separate functions of bed height and Th(ІV) concentration. Moreover, mass transfer models include internal and external mass transfer, biosorption on active sites, and Henry models were used to determine the rate-limiting step and mass transfer mechanism. The results showed that the Henry model performed better, and it was concluded that the equilibrium in the biosorption process is instantaneous and occurs rapidly.

Investigation of flow behaviors in a fluidized bed reactor with binary mixture of Geldart-A and B particles

Flow dynamics in bubbling and turbulent fluidized beds containing both Geldart-A and B particles were investigated in this research. The numerical model was validated against experimental data, with a 6.16% average deviation. Results show that binary mixture segregation is enhanced as superficial gas velocity decreases. A larger flotsam packing ratio promotes homogeneous flotsam distribution; Second, bed density decreases with increasing bed height or superficial gas velocity. As the flotsam packing ratio decreases from 81.10 to 10.70%, bed density reaches the maximum at 41.50%, indicating the most severe volume contraction; Third, when the flotsam packing ratio decreases, the local mixing index's variances between upper and lower sections in dense phase first increases, then decreases, with stronger radial fluctuation detected; Fourth, as superficial gas velocity or flotsam packing ratio increases, the full mixing height ratio improves; Finally, multivariate correlations for dense phase bed expansion are established, yielding a 3.94% average error. • A modified EMMS drag model was adopted to examine flow features in a bidisperse fluidized bed. • The quantified impacts of superficial gas velocity and packing state on flow are obtained. • Multivariate correlations for dense phase bed expansion were fitted with high accuracy.

Experimental study on heat transfer and hydrodynamics of a concentric double-pipe pulsed fluidized bed using microencapsulated phase change material and sand

This paper presents an experimental study on the heat transfer and hydrodynamic of a concentric double-pipe gas-solid pulsed fluidized bed filled in outer tube with microencapsulated phase change material and inner tube with sand. The effect of flow velocity, frequency and bed height are investigated on the heat transfer. Experiments are carried out at frequency in the range of 1 to 5Hz with the bed height of 15, 18.5and 22 cm and the ratio of air velocity to minimum fluidization velocity ( U / U mf ) of 1, 1.1, 1.2, 1.3, 1.4, 1.5. Results show that heat transfer enhances as the frequency, bed height and U / U mf increase. Besides, it is found that pulsed flow has higher heat transfer enhancement than continuous flow. For example, at U / U mf of 1.5, the heat transfer coefficient of the pulsed flow increases by 7.5% than that of the continuous flow at the bed height of 22 cm. • Hydrodynamics and heat transfer in a concentric double-pipe pulsed bed are studied. • Pulsed flow in bed has higher heat transfer coefficient than continuous flow. • Heat transfer coefficient increases as U / U mf , frequency, and bed height increase. • Heat transfer becomes higher as the fluidity increases.

Sand coated with graphene oxide-PVA matrix for aqueous Pb2+ adsorption: Insights from optimization and modeling of batch and continuous flow studies

In the present study, a composite of graphene oxide-polyvinyl alcohol coated sand (GO-PVA@sand) was prepared and examined for adsorption of aqueous Lead ion (Pb2+) in batch and fixed-bed columns. The characterization of GO-PVA@sand revealed that GO-sheets were randomly immobilized into the PVA-matrix and formed a stable complex surrounding sands particles. And hence, preventing leaching of GO from the GO-PVA@sand and avoiding agglomeration of GO-PVA@sand inside the column that leads to no column chocking. The adsorption of Pb2+ onto GO-PVA@sand was endothermic in nature, attained equilibrium in ≤ 45 min, followed the pseudo-second-order kinetics, and the Langmuir adsorption isotherm with the maximum adsorption capacity of 8.25 mg/g. Moreover, the fixed-bed column study revealed that the adsorption capacity (qeq) decreased from 7.4 to 7.0 mg/g by increasing inlet flow rate from 5 to 15 mL/min because of drop in the contact time between Pb2+ and GO-PVA@sand. In contrast, the qeq increased from 7.2 to 7.6 mg/g, with an increase of bed-height from 2 to 6 cm, due to greater contact time and surface exposure. Besides increasing inlet concentration from 20 to 40 mg/L, the qeq increased from 7.2 to 8.0 mg/g, apparently because of the presence of a higher mass driving force. To understand the potential for process scale-up, breakthrough modeling was performed and found that the Thomas and Yoon-Nelson model best described the adsorption behavior. The post-adsorption characterization of GO-PVA@sand showed Pb2+ adsorbed through ion-exchange, cation-π, electrostatic interaction, and hydrogen bonding. The regeneration and reuse potential of the GO-PVA@sand up-to five adsorption-desorption cycles, signify its relevance in low-cost continuous water treatment.

A polyurethane foam membrane filled with double cross-linked chitosan/carboxymethyl cellulose gel and decorated with ZSM-5 nano zeolite: Simultaneous dye removal

A novel bio-based polyurethane foam was fabricated using double cross-linked chitosan/carboxymethyl cellulose gel, filled with ZSM-5 nano zeolite, and hot-pressed into the membrane. The prepared foam membrane was characterized using FESEM, FTIR, BET, TGA, and pHZPC analyses and then used for continuous dye removal. The results modification of polyurethane foam with chitosan/carboxymethyl cellulose gel and ZSM-5 nano zeolite would increase the retention ability of positive cationic methylene blue. Also, the foam could simultaneously remove methyl orange, eriochrome black T, and methylene blue from the binary and trinary solutions but could effectively be used to selectively removal methylene blue. In addition, the dye removal ability at the breakthrough was enhanced with decreasing flow rate, and increasing bed height, pH, initial dye concentration, and nano zeolite content in the foam. To describe the breakthrough curves different models were utilized which best fits were obtained with Modified Dose-Response as compared to Thomas, Adams & Bohart, Yoon–Nelson, and Wolborska models.

Chemical Looping Combustion in a Packed Fluidized Bed Reactor─Fundamental Modeling and Batch Experiments with Random Metal Packings

The conversion of gaseous fuels during chemical looping combustion (CLC) was investigated in a packed fluidized reactor. The experimental setup consisted of a cylindrical laboratory-scale bubbling fluidized bed reactor with an inner diameter of 78 mm and a height of 1.27 m. Two types of fuel, syngas (50:50% H2/CO) and carbon monoxide (100% CO), were used. Two different types of packings were assessed and compared to the reference case, which was a bubbling bed with no packings. The investigated packings were 25 mm stainless-steel thread saddle rings (RMSR) with a bulk density of 195 kg/m3 and 25 mm stainless-steel pall rings (Hiflow) with a bulk density of 271 kg/m3. The height of the packed reactor section was kept constant at 1 m. Ilmenite concentrate particles in the size range of 90–212 μm was used as an oxygen carrier. The unfluidized bed height was varied between 10 and 60 cm. The results show that the fuel conversion increases as the bed height increases and that the use of packings have a positive effect on fuel conversion. For RMSR packings, the syngas conversion at 840 °C improves from 0.84 (for 10 cm bed height) to 1.00 (for 60 cm bed height). This should be compared to the bed with no packings, for which the corresponding improvement was from 0.69 to 0.98. The general pattern is consistent for all fuels, packings, and bed heights. The results are interpreted as an improvement in gas–solid mass transfer when packings are used, mainly as a result of the reduced bubble size. A fundamental analysis of the variance in the pressure drop over the bed to estimate the bubble diameter supports this interpretation. It is also shown that the mass-based first-order effective reaction contact factor kf improves up to 109% in the bed with RMSR packings compared to the bed without packings.

Elucidating sorptive eradication of ibuprofen using calcium chloride caged bentonite clay and acid activated alginate beads in a fixed bed upward flow column reactor

The sorptive eradication of ibuprofen (IBP), a pharmaceutical micro-pollutant, from aqueous medium in a fixed bed upward flow column reactor was examined using the adsorbent prepared from amalgamation of calcium chloride caged acid activated tamarind seed and bentonite alginate beads [Ca2+(TAABB)Al]. Surface texture and the presence of constituent elements in the contrived sorbent was characterised by scanning electron microscopy and energy dispersive x-ray analysis at pre-sorption and post-sorption phases. Effect of controlling factors viz. bed height of the column (5–25 cm), influent concentration of IBP (10–25 mg/L), and amount of inflow (2–6 mL/min) on efficacious IBP uptake was evaluated. The column experimentation revealed that there would be a rise in height of the breakthrough curve while the column bed height increases. Along with 97.48% IBP elimination, the maximal adsorbent uptake has been determined to be 17.54 mg/g from an optimum height of column bed of 20 cm, concentration of influent ibuprofen 20 mg/L, and amount of inflow 2 mL/min. Efficiency of the sorbent was investigated using the bed depth service time (BDST) model, and it was observed that bed height of the column was the most important aspects in achieving effective IBP adsorption. The investigational results were well supported by the Yoon–Nelson as well as Thomas model. The desorption analysis demonstrated the performance of adsorbent up to 5 cycles for ibuprofen separation with a column regeneration rate of 38.14%. Hence, the novel sorbent Ca2+(TAABB)Al can be effectively used to eradicate IBP from aqueous phase.