Sorbent Particle Size Research Articles

Chromium Disarmament from Veritable Tanneries Sewer Water Utilizing Carbonic Rice Straw as a Sorbent: Optimization and Carbonic Rice Straw Characteristics

This exploration focuses on the removal of chromium from actual tannery wastewater, collected from the HARBY TANNERY factory in Rubiki (Badr City), using an economical sorbent made from activated carbon derived from rice straw (CRS). The CRS sorbent is activated using H3PO4. The experiment aims to assess the impact of various parameters, including chromium initial concentration, sorbent dosage, treatment time, agitation velocity (rpm), sorbent particle size, and solution pH, on chromium removal from tannery wastewater. Structural, morphological, and electronic distinctive of raw and treated CRS, as well as carbonized CRS, were analyzed using FTIR, SEM, and TEM techniques. XRF analysis was conducted to investigate the chemical elemental composition of carbonized CRS before and after sorption. Zeta potential measurement was performed to assess the electrical charges of particles present in a suspension. The adsorption data was tested for both Langmuir and Freundlich adsorption isotherms, and most of the factors suggested that it follows the Langmuir adsorption isotherm with an R2 value of 99.67%. Additionally, adsorption kinetics were performed to identify the reaction order, which exhibited that sorption pursued pseudo-second-order kinetics with a rate constant (k) of 0.0658 g/mg g/min, a high correlation factor (R2) of 99.76%, and an estimated equilibrium chromium ion adsorption capacity (qe) of 1.597 mg/g, which closely matched the experimental data (1.4835 mg/g). The improved surface morphology and increased surface area of CRS resulted in approximately 98.9% chromium removal. Mechanism studies confirmed that intraparticle diffusion is not the sole rate-controlling step, and Boyd’s model demonstrated that film diffusion limited the rate of chromium adsorption. The desorption of chromium from the carbonized rice straw surface could be achieved by up to 96.4% of the sorbed amount by raising the solution pH to 10, indicating the potential reusability of carbonized rice straw for additional adsorption cycles. Finally, a statistical regression analysis and least square multivariate analysis were used to establish a correlation for predicting efficiency, yielding an R2 value of 97.54%.

Maize cob (Zea mays) as natural biomass sorbent for crude oil biosorptive removal from contaminated seawater: Taguchi process optimization and biosorptive removal mechanism.

Crude oil pollution poses a serious threat to the aquatic environment. Hence, there is an increasing interest in developing an efficient cleaner process technique for oil spill cleanup via agricultural biomass waste-organic sorbent utilization. This work evaluated the effects of independent biosorptive removal at three varying levels (initial concentration of crude oil (Z1, 7.8-15.6 g/L), seawater-oil temperature (Z2, 25-45 °C), sorbent dose (Z3, 1-3 g), and sorbent particle size diameter (Z4, 1.18-4.72 mm)) on the biosorptive removal efficiency and biosorptive capacity performance of maize cob sorbent for crude oil biosorptive removal from seawater. Experiments were designed based on Taguchi orthogonal array experimental design (L9(34)) to study the effects and process optimization. The results revealed that the maize cob sorbent's crude oil biosorptive removal efficiency is related to Z1, Z3, and Z4, while the biosorptive capacity is related to Z1 and Z3. The optimum biosorptive removal efficiency and the biosorptive capacity values were 96.53% and 12.64 g/g, respectively, achieved at optimum factors of Z1 (7.8 g/L), Z3 (3 g), and Z4 (1.18 mm), as well as at Z1 (15.6 g) and Z3 (1 g). The isotherm and kinetic data, respectively, followed the Langmuir isotherms and the pseudo-second-order kinetics with a maximum monolayer biosorptive capacity of 23.31 g g-1. The mechanism of biosorptive crude oil removal was by physical sorption and film diffusion control. Therefore, the maize cob represents an inexpensive and effective natural sorbent for oil spill removal from water bodies.

DETERMINATION OF MIANSERIN IN BIOLOGICAL MATERIAL BY HIGH PERFORMANCE LIQUID CHROMATOGRAPHY

Introduction. Mianserin is a derivative of tetracyclic antidepressants, belongs to the piperazine-azepine derivatives. Chemically, it is (±)-2-methyl-1,2,3,4,10,14b-hexahydrodibenzo[c,f]pyrazino[1,2-a]azepine. Mianserin exhibits anti-stress activity, which is very important in the treatment of patients with depression that is combined with anxiety.
 The aim of the study – development of an effective technique for isolating mianserin from biological tissues and selecting optimal conditions for determination by HPLC in the presence of metabolites.
 Research Methods. Identification and quantification of mianserin isolated from biological material was performed by HPLC. The research was carried out on an Agilent 1200 liquid chromatograph, an Eclips C18 column, 150,0 mm long, 4,6 mm in diameter, and the sorbent particle size was 5 μm. The sample was injected into the chromatograph in the isocratic mode, the volume of the injected sample was 20 μl, the column temperature was 25 °C. A comparative evaluation of the efficiency of isolation of mianserin was performed from model liver samples acidified with 30 % acetic acid.
 Results and Discussion. During the study of rat liver extracts simultaneously with the peak of mianserin (retention time of 3.37 min), the peak of the metabolite of mianserin, identified by us as demethylmianserin – M-7 (retention time of 2.52 min.) is recorded.
 Conclusions. The efficiency of isolation of mianserin from model liver samples by two methods was compared. It was established that 28.9–33.6 % of mianserin is isolated with water acidified with oxalic acid. 56.5–59.8 % of the studied drug can be isolated with an acidified 30 % solution of acetic acid. To prepare the sample for analysis by HPLC, the conditions for their purification were worked out, the degree of extraction of mianserin from the studied sample is 99.8–100.0 %. Developed conditions for identification and quantification of mianserin by HPLC on an Eclips C18 column and detection at a wavelength of 214 nm. The limit of quantitative determination of mianserin in solutions is 0.5 μg/ml.
 
 

Kinetics of H2S removal using alkaline residue as in-bed sorbent in fluidized bed gasification of biomass and wastes

The use of alkaline residue from the acetylene industry (carbide slag, CS) as in-bed sorbent to remove H2S from syngas from biomass/waste fluidized bed (FB) gasification was investigated. Measurements were conducted in a laboratory FB applying differential conversion technique, tracking the reaction using both gas measurements and solid analysis. Apparent reaction kinetics was obtained, without external mass transfer limitations, for different gas mixtures containing CO2, H2O, CO, H2 and CH4, having relatively low H2S concentration (500–1000 ppm). The addition of CO2 and H2O to an N2-H2-H2S mixture showed that the reaction rate was reduced in the presence of these species. Varying the H2 concentration between 7 and 14% in simple (N2-H2-H2S) reactive gas mixtures did not affect the results, while both CO and H2 potentially affected the reaction rate if also CO2 was present in the gas. Other operating parameters, such as sorbent particle size, sulfidation- and calcination temperature also affected the CaO sulfidation rate, which increased with temperature between 800 and 900 °C and was enhanced by higher calcination temperature. Specific surface area and pore size distribution of the calcined CS was measured before and after the sulfidation reaction, showing that CS maintained a large fraction of its original pore volume even after most of the CaO had been converted into CaS. The sulfidation rate of calcined limestone was also measured for comparison showing that the reaction rate using CS was slightly lower, but similar to that using limestone, showing that CS is a promising alternative to conventional calcium-based sorbents for high temperature H2S removal, contributing to promote the circular economy, while avoiding the current stacking of CS at the acetylene production sites.

The Application Of Coagulants And Adsorbents For Textile Production Waste Water Purification

Wastewater from the textile industry is highly complex and highly toxic and poses a serious environmental hazard. Wastewater treatment in textile production is a multi-stage process that requires correct step-by-step processing, since textile auxiliary substances can be toxic. The effective conditions for the sorption of the dye from an aqueous solution selected by the sorbent have been determined. It was found that the effective mass of the sorbent is within 0,2; 0,3; 0,4; 0,5; 0,6 g per 100 ml of solution. The regularities of the dependence of the adsorbent mass in the process of removing an active dye of various types from the solution on the optical density have been revealed. It was found that an increase in mass significantly increases the purification of the solution from the dye, and leads to a decrease in the optical density at the points corresponding to 0,4 and 0,6 g. At the same time, it was determined that the maximum (up to 97%) wastewater treatment from surfactants and dyes by a chemical method when using the composition K-5 and K-6 is achieved with a particle size of sorbents of 0,5-0,6 nm.

Assessment of Cyprinus carpio Scales as a Low-Cost and Effective Biosorbent for the Removal of Heavy Metals from the Acidic Mine Drainage Generated at Rosia Montana Gold Mine (Romania)

In the present study, the biosorptive potential of Cyprinus carpio scales for the removal of Fe, Mn, and Zn ions from real acidic mine drainage (AMD) generated at the Rosia Montana gold mine (Romania) was explored for the first time. The collected AMD solution is very acidic, and the concentrations of Fe, Mn, and Zn ions exceed more than 34 to 56 times the disposal standards imposed by legislation. Batch adsorption experiments were carried out to study the effect of the sorbent dosage, sorbent particle size, pH, and contact time on the adsorption performance of the fish scales. Before and after the adsorption process, the biosorbent was characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy, and energy-dispersive X-ray spectroscopy (SEM-EDX). In the investigated experimental conditions, about 100%, 87.1%, and 100% of Fe, Mn, and Zn ions were removed from the AMD after 240 min of contact with the finest-grained Cyprinus carpio scale samples using a solid:liquid ratio of 20:1 (g:L). The adsorption data were analyzed using the pseudo-first order, pseudo-second order, intraparticle diffusion rate, and Elovich equations. The adsorption process was found to follow the pseudo-second-order kinetic model. The maximum adsorption capacities of the fish scales were about 2.46 mg/g for Mn and 0.85 mg/g for Zn ions, respectively. Aside from their significant efficiency in the removal of metals from AMD, Cyprinus carpio scales also have the potential to neutralize the acidic wastewater. Thus, the removal process of metal ions from AMD is ruled by a complex mechanism, including adsorption and iron precipitation. The recycled scales are still able to remove the metal ions from AMD with a better performance during the first regeneration cycle. Based on the obtained results, it might be assessed that the low-cost biowaste of Cyprinus carpio scales have great potential and could be effectively used for the remediation of real acidic mine drainage from a sustainable perspective.

Study of the Biochemical Method for Wastewater Purification from Textile Productions from Dyes and Suspended Substances

Wastewater treatment in textile production is a multi-stage process that requires correct step-by-step processing, since textile auxiliary substances can be toxic. In this regard, this article discusses the combined, i.e. sorption-coagulation-flocculation treatment of waste water from textile production. The use of a combined cleaning method contributes to a more complete removal of surfactants, inorganic and organic substances, dyes, suspended solids and various salts. The effective conditions for the sorption of the dye from an aqueous solution selected by the sorbent have been determined. It was found that the effective mass of the sorbent is within 0.2; 0.3; 0.4; 0.5; 0.6 g per 100 ml of solution. It was found that an increase in mass significantly increases the purification of the solution from the dye, and leads to a decrease in the optical density at the points corresponding to 0.4 and 0.6 g. It has been determined that the initial values of the main indicators of wastewater entering the deep purification at a bubbling adsorption unit correspond to the values of the indicators of these flows passing through a system consisting of kaolin-bentonite-aluminum sulfate-ferric chloride. Since the main indicators of pollution are the intensity of coloring and surfactants for wastewater from textile and silk-winding factories, studies on the effect of the size of adsorbent particles and speed on the adsorption process were primarily carried out for these indicators. At the same time, it was determined that the maximum (up to 97%) wastewater treatment from surfactants and dyes by a chemical method when using the composition K-5 and K-6 is achieved with a particle size of sorbents of 0.5-0.6 nm.

Sediment Remediation Using Activated Carbon: Effects of Sorbent Particle Size and Resuspension on Sequestration of Metals and Organic Contaminants.

Thin‐layer capping using activated carbon has been described as a cost‐effective in situ sediment remediation method for organic contaminants. We compared the capping efficiency of powdered activated carbon (PAC) against granular activated carbon (GAC) using contaminated sediment from Oskarshamn harbor, Sweden. The effects of resuspension on contaminant retention and cap integrity were also studied. Intact sediment cores were collected from the outer harbor and brought to the laboratory. Three thin‐layer caps, consisting of PAC or GAC mixed with clay or clay only, were added to the sediment surface. Resuspension was created using a motor‐driven paddle to simulate propeller wash from ship traffic. Passive samplers were placed in the sediment and in the water column to measure the sediment‐to‐water release of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), and metals. Our results show that a thin‐layer cap with PAC reduced sediment‐to‐water fluxes of PCBs by 57% under static conditions and 91% under resuspension. Thin‐layer capping with GAC was less effective than PAC but reduced fluxes of high–molecular weight PAHs. Thin‐layer capping with activated carbon was less effective at retaining metals, except for Cd, the release of which was significantly reduced by PAC. Resuspension generally decreased water concentrations of dissolved cationic metals, perhaps because of sorption to suspended sediment particles. Sediment resuspension in treatments without capping increased fluxes of PCBs with log octanol–water partitioning coefficient (K OW) > 7 and PAHs with log K OW of 5–6, but resuspension reduced PCB and PAH fluxes through the PAC thin‐layer cap. Overall, PAC performed better than GAC, but adverse effects on the benthic community and transport of PAC to nontarget areas are drawbacks that favor the use of GAC. Environ Toxicol Chem 2022;41:1096–1110. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Modeling and experimental approaches for determining fluoride diffusion kinetics in bone char sorbent and prediction of packed-bed groundwater defluoridator performance

Fluoride (F) in groundwater (GW) in excess of 1.5 mg/L is a globally distributed problem impacting the health of hundreds of millions of people, many of whom cannot access centralized treatment infrastructure. Animal (e.g., cow) bone char has received emerging interest as a low-cost F sorbent for use in decentralized household and community water treatment. Pilot column tests using full-sized granular bone char particles can be used to assess treatment performance of fixed-bed contactors, but are costly, time consuming, and require large amounts of test water. Rapid small-scale column tests (RSSCTs) can be used to simulate F uptake in bone char contactors if the relationship between F intraparticle diffusion kinetics and bone char particle size is known. Two common approaches to the RSSCT assume either constant (CD) or linear proportional (PD) sorbate diffusivity as a function of sorbent particle size. This study used experimentally determined pseudo-equilibrium and kinetic F sorption data in model groundwater as inputs to the homogeneous surface diffusion model (HSDM) to determine F intraparticle diffusion coefficients for different-sized bone char particles, and to fit RSSCT and pilot column breakthrough data to evaluate CD and PD approaches. Results of this study, corroborated by incorporation of additional literature data, indicate approximately linearly proportional diffusivity of F as a function of bone char particle size. Congruently, the PD-RSSCT approach provided a superior simulation of pilot column F breakthrough compared to the CD-RSSCT. PD-RSSCT breakthrough data closely matched pilot breakthrough on a scaled service time basis up to around 500 bed volumes, corresponding to a relative F breakthrough of about 40%, and provided a slightly conservative indicator of F removal thereafter. The PD-RSSCT was compared with a hybrid modeling and empirical workflow using the HSDM with experimentally determined pseudo-equilibrium and kinetic parameter inputs as time-and-cost-saving approaches to evaluating full-sized groundwater treatment system performance. This comparison and a sensitivity analysis of HSDM input parameters used in the hybrid workflow indicated that greater precision can be obtained using the PD-RSSCT.

Locally available agroresidues as potential sorbents: modelling, column studies and scale-up

Sawdust, cotton stalk and groundnut shell were used for removal of methylene blue from aqueous solution using batch sorption. Effect of initial dye concentration, temperature, and particle size of sorbents on methylene blue removal was investigated. Sorption capacity increases with rise in initial dye concentration and temperature. Impact of particle size on sorption of methylene blue was investigated and indicated that removal of dye increases with decrease in particle size of sorbents. Maximum sorption for sawdust, cotton stalks and groundnut shell were 9.22 mg g−1, 8.37 mg g−1 and 8.20 mg g−1 respectively; at 60 °C and 100 ppm initial dye concentration. Sorption isotherms were analyzed using fundamental Freundlich isotherm. Subsequently, sips isotherm model was employed for better fitting. Kinetic study shows that, biosorption process is pseudo-second-order in nature. During the course of this study, adsorption dynamics revealed that film diffusion was key step for biosorption. In addition, thermodynamics of sorption was studied; and it was found that Gibbs free energy (∆G°) decreases with increase in temperature. Sawdust was found to be best among all the sorbents. Therefore, column studies and breakthrough curve modelling were performed using sawdust. Furthermore, it was estimated that a scaled-up column using sawdust can treat 6672 L of wastewater in 24 h with 80% efficiency.

Synthesis, characterization and analytical applications of Ni(II) ion-imprinted polymer prepared by N-(2-hydroxyphenyl)acrylamide

In the present study, a novel Ni(II) ion-imprinted polymer (Ni(II)-IIP) was successfully synthesized by copolymerization of N-(2-hydroxyphenyl)acrylamide as a functional monomer, 2,2′-Azobis(2-methylpropionitrile) (AIBN) as an initiator and ethylene glycol dimethacrylate (EGDMA) as a cross-linker in the attendance of nickel nitrate as a template ion. The nickel ions in the Ni(II)-IIP were eliminated by ethylenediaminetetraacetic acid (EDTA) leaching. The functional monomer, complex and the obtained polymer particles were characterized by 1H NMR, FT-IR, CHNS, FESEM and the concentration of Ni(II) ions in the solution were determined by flame atomic absorption spectrophotometer (FAAS). The effects of pH, flow rate, temperature, sample concentration, sorbent particle size, desorption eluent conditions, selectivity and reusability on the extraction of Ni(II) ions were surveyed. The results of the study revealed that most favorable pH value for quantitative enrichment was 7 and maximum adsorption capacities of Ni(II) ions on the IIP was 38 mg/g. In addition, the relative standard deviation (RSD) for six separately experiments with a nickel concentration of 20.0 μg/L was 2.72% and limit of detection was found to be 0.7 μg/L.

Clarification of sunflower oil with nanocarbon sorbent and analysis of product quality indicators

The concept of Industrie 4.0 involves the introduction of innovative industrial technologies. Sunflower oil is the most common vegetable oil in Russia. Improvement of sunflower oil quality is required taking into account changes in the domestic and foreign markets of Russia. The process of oil clarification with nanocarbon structures is proposed in the article. The influence of fullerene-containing sorbent on the efficiency of sunflower oil clarification process was investigated in the work. The mathematical model of the process is developed with the complete factorial experiment. Colour, acid number, mass fraction of moisture and volatile substances were taken as quality indicators. Variable indicators were the amount of fullerene-containing sorbent, the particle size of the fullerene-containing sorbent and the clarification process temperature. Series of experiments were carried out. According to them the values of color and acid numbers, mass fraction of moisture and volatile substances of the oil were obtained. The indicators obtained were compared with the oil indicators after the traditional clarification method. According to the built mathematical models graphs, a comprehensive quality indicator was determined as well as the optimal values of the conditions for the clarification process. It was found out that the use of fullerene-containing carbon as a sorbent for sunflower oil clarification improves the acid number by 80%, the mass fraction of moisture and volatile substances – by 74%, and the color index – twice. Thus, the use of fullerene-containing carbon as an adsorbent makes it possible to obtain world-class sunflower oil.

Sorption behavior of 6:2 chlorinated polyfluorinated ether sulfonate (F-53B) on four kinds of nano-materials

6:2 chlorinated polyfluorinated ether sulfonate (with the trade name F-53B, a substitute for PFOS) is one type of Per- and polyfluoroalkyl substances (PFASs), which is widely used as a chromium mist inhibitor in China. It has been found in environment commonly. In this study, the sorption behavior of F-53B on four kinds of nano-materials: alumina nanopowder (ANP), alumina nanowires (ANW), hydrophilic bentonite nanoclay (HBNC) and surface modified nanoclay (SMNC) were investigated. The kinetics results indicated that the sorption of F-53B on four nano-materials reached equilibrium within 2 h and the sorption process were fitted better by the pseudo-second-order kinetic model than the pseudo-first-order kinetic model. The thermodynamic study showed that the sorption of F-53B on nano-materials were exothermic and spontaneous. As the increase of temperature, the maximum sorption capacity of ANP, ANW, HBNC, SMNC increased, and reached 868.75, 91.35, 5.15, 2465.09 μg/g at 25 °C, respectively. The surface modified nanoclay (SMNC) was better than the others for removing F-53B from aquatic environment. To investigate the effects of pH and ion strength, the particle size and zeta potential of sorbents at different pH and ion strength were measured by Dynamic Light Scattering (DLS), and concluded that the sorption mechanism of F-53B on two kinds of nanoalumina mainly included electrostatic attraction and agglomeration effects, while hydrophobic interaction played an important role on the sorption of F-53B on nanoclay. This study revealed the sorption behavior and mechanism of F-53B on four kinds of nano-materials, and the results provided theoretical support for removing F-53B from electroplating wastewater with nano-materials.

Linear driving force analysis of adsorption dynamics in stratified fixed-bed adsorbers

The linear driving force (LDF) model has been used to study adsorption dynamics in many gas and liquid phase applications and is particularly useful in the simulation of cyclic sorption operations. It is computationally a simpler alternative to the more complex models that use partial differential equations to represent diffusion within the sorbent particle. In this study, an LDF model that takes into account sorbent particle size distribution (PSD) within the adsorber is developed to study adsorption dynamics in fixed-bed adsorbers with different geometries and layering of particles of different sizes. Phenol and 2, 4-dichlorophenol (DCP), two trace contaminants in water supplies and wastewaters with differing adsorption characteristics, are studied in different adsorber configurations to determine the effects of bed geometry on bed capacity utilization. The convergent tapered stratified bed with eight granular activated carbon (GAC) particle sizes was found to enhance bed capacity utilization by 20% and 50% respectively for phenol and DCP over that of conventional stratified cylindrical bed adsorbers. The LDF model was found to provide good prediction and representation of adsorption dynamics in stratified fixed-bed adsorbers at much reduced computational effort. Sensitivity analyses indicate that the adsorption affinity of solute, bed geometry, and particle stratification play key roles in the enhancement of bed capacity utilization in fixed-bed adsorbers.

DEVELOPMENT AND VALIDATION OF METHODS FOR QUANTITATIVE DETERMINATION OF SODIUM HYALURONATE IN THE COMPOSITION OF COMBINED DENTAL GEL

According to the EP monograph "Sodium hyaluronate" for identification they use the infrared transmission spectrum of the substance, quantification is carried out by spectrophotometry. The aim of the work was to develop a method for quantitative determination of hyaluronic acid in the gel in the presence of other substances and its validation. Materials and Methods. The object of the study were samples of combined dental gel of the following composition: metronidazole benzoate 16 mg/g, miramistin 5 mg / g, sodium hyaluronate 2 mg / g. Identification and quantification of sodium hyaluronate was performed by liquid chromatography (SPhU, 2.2.29, 2.2.46). The test solution and the reference solution were chromatographed, obtaining the number of parallel chromatograms not less than when checking the suitability of the chromatographic system. Chromatography is performed on a liquid chromatograph with a diode-matrix detector under the following conditions: chromatographic column PL-aquagel-OH, Agilent size 300 mm × 7.5 mm, with a particle size of sorbent 8 μm; mobile phase A: 0.1 M sodium sulfate solution; mobile phase B: acetonitrile for chromatography P; detection at a wavelength of 210 nm. Results. The retention time of sodium hyaluronate on the chromatogram of the test sample of the gel coincides with the peak and the retention time on the chromatogram of the comparison solution of the standard sample of the substance. The suitability of the chromatographic system for 3 parallel determinations was checked: the relative standard deviation (RSD) is equal to 0.25, the number of theoretical plates is 980, the symmetry coefficient is 1.293. The validation characteristics of the developed methodology meet the established eligibility criteria. The spectral purity coefficients (Fp) of the sodium hyaluronate peak on the chromatograms of the model solution are Fp1=997.665 and Fp2=997,802. The method is linear in the range of sodium concentration of hyaluronate 80–120 %, the calculated linear dependence of the reduced area of the chromatographic peak on the reduced concentration of sodium hyaluronate is |a|=1.9490≤Δa=2.56. The confidence interval of the unit value for the sample of relations is found / entered Δz=1.08, which corresponds to the condition Δz≤1.6 %. The value of the systematic error is equal to δ=0.12, which satisfies the condition δ≤0.51 %. Conclusions. The method of quantitative determination of sodium hyaluronate by the method of high-performance liquid chromatography has been developed and investigated. The method allows the identification and quantification of sodium hyaluronate in the composition of the dental gel, in the presence of metronidazole benzoate and miramistin. Validation of the methodology was performed and the main validation characteristics were determined. In terms of specificity, linearity, correctness, convergence of the method meets the eligibility criteria established by the SPhU.

Numerical modeling on simultaneous removal of mercury and particulate matter within an electrostatic precipitator

A computational fluid dynamics (CFD) model coupled with gas-particle mass transfer, electrohydrodynamic (EHD) effect, electric field, particle motion and particle charging is established to advance the understanding of combined particulate matter precipitation and mercury capture within industrial electrostatic precipitators (ESPs). The comparisons between experimental data and numerical results demonstrate that this model can reasonably predict the mercury removal efficiency by powdered sorbent injection (PSI). The mechanism of simultaneous removal of mercury and particulate matter is then discussed in detail by considering the complex interactions among multi-physics. The influences of particle size, mercury concentration, particle injection rate and the EHD effect are investigated. The simulation results indicate that the mercury removal process is primarily controlled by the sorbent particle residence time, surface area and mass transfer rate. Accordingly, reducing the size of sorbent particles (activated carbon) can promote mercury removal efficiency while decreasing the particle collection efficiency. Increasing the initial mercury concentration and adsorbent mass loading also benefit mercury adsorption by influencing the mass transfer rate and the surface area. The EHD effect plays important roles in mercury removal and particle collection by means of altering the flow patterns and particle migration. The two mechanisms of in-flight and wall-bounded mercury adsorption affected by ionic wind are also evaluated and some interesting phenomena are observed.

Adsorption-desorption of phenolic compounds from olive mill wastewater using a novel low-cost biosorbent.

Several materials have been investigated for the adsorption of olive mill wastewater phenolic compounds. However, researchers have focused on the development of novel, low-cost, with high adsorption capacity adsorbents, originated from the food industry as by-products. The aim of this work was the investigation of the effectiveness of a juice industry by-product, pomegranate seed, for the adsorption of olive mill wastewater phenols. Furthermore, chemical activation and thermal activation of the adsorbent took place in order to improve total phenols uptake and afterwards, desorption process in hydrochloric acid was studied. After the determination of equilibrium time, the effects of temperature (20-60°C), solution's pH (4.0-8.0), initial sorbate concentration (50-500mg/L), sorbent mass concentration (0.01-0.05g/mL OMW), and sorbent particle size (0.149-1.180mm) on adsorption yield were studied performing batch experiments. The maximum phenols uptake observed was 92.8% after 10min, at 30°C and a pH of 5.0, with an initial sorbate concentration of 162.5mg/L, a sorbent mass concentration of 0.02g/mL, and a sorbent particle size of 0.922mm. Langmuir, Freundlich, and Temkin isotherms were developed for the equilibrium description, while pseudo-first-order, pseudo-second-order, and intra-particle diffusion models were applied to investigate adsorption kinetics. The experimental data were best fitted to the Langmuir model, whereas the kinetic data followed the pseudo-first-order kinetic model. The results of the study were promising indicating that pomegranate seed could be used as a novel and low-cost biosorbent. Graphical abstract.

Use of cork granules as an effective sustainable material to clean-up spills of crude oil and derivatives.

The use of cork granules for cleaning up crude oil or oil derivative spills and further oil recovery appears as a promising option due to their unique properties, which allow a high oil sorption capacity, low water pickup and excellent reuse. The present work reports the effect of oil viscosity on cork sorption capacity by using five types of oils (lubricating oil, 5.7 goil gcork-1; heavy oil, 4.2 goil gcork-1; light oil, 3.0 goil gcork-1; biodiesel, 2.6 goil gcork-1; and diesel, 2.0 goil gcork-1). The cork sorption capacity for light petroleum was also evaluated as a function of temperature and sorbent particle size. Additionally, improvements on oil recovery from cork sorbents by a mechanical compression process have been achieved as a result of a design of experiments (DOE) using the response surface methodology. Such statistical technique provided remarkable results in terms of cork sorbent reusability, as the oil sorption capacity was preserved after 30 cycles of sorption-squeezing steps. The sorbed oils could be removed from the sorbent surface, collected simply by squeezing the cork granules and further reused. The best operational region yielded near 80% oil recovery, using a cork mass of 8.85 g (particle size of 2.0-4.0 mm) loaded with 43.5 mL of lubricating oil, at 5.4 bar, utilising two compressions with a duration of 2 min each. Graphical abstract.

Removal of uranium from aqueous solution by a permeable reactive barrier loaded with hydroxyapatite-coated quartz sand: Implication for groundwater remediation

Uranium (U) contamination has been widely found in groundwater and greatly threatens human health. The present study investigated U removal from aqueous solution using a permeable reactive barrier (PRB) with hydroxyapatite as a reactive material under appropriate conditions. Different-size hydroxyapatites were loaded to quartz sand and the mineral composition of the composite materials was identified by XRD before being applied to column experiments and after adsorption U. Results showed that U removal processes were influenced by sorbent particle size, initial U concentration and hydraulic loading, and initial U concentration exerted the greatest effect on U removal efficiency. Uranium sorption data were fitted to Thomas and Yoon-Nelson models. The fitting results indicated that Thomas model was better than Yoon-Nelson model for description of U sorption characteristics in this study, which had higher correlation coefficients (>0.97). Adsorbed U formed plate-like crystals and occurred widely on the surface of hydroxyapatite, as visualized by SEM. Determination of XPS and EDS in samples with high U concentration implied that U adsorption was achieved via either dissolution-precipitation reactions involving low-solubility U-bearing minerals or surface complexation with reactive function groups on the surface of hydroxyapatite, which was supported by U speciation calculated at equilibrium atmospheric CO2 and U solid phases. The findings suggest that the hydroxyapatite-based PRB can serve as an effective treatment technique for remediation of U contaminated groundwater.

Removal of Ammonia from the Municipal Waste Treatment Effluents using Natural Minerals.

Due to various ecological problems, it is required to remove the ammonia nitrogen from wastewater. Industrial wastewater that was not subjected to any purification was used in this study, while most processes described in the literature were carried out using synthetically prepared solutions. The study investigated the removal of ammonium ions using ion exchange on various commercial minerals, in 3 h long batch ion-exchange experiments. Furthermore, research on the sodium chloride activation of the selected mineral was conducted. The screening of the mineral with the highest removal potential was conducted taking into account the adsorption capacity (q) and maximal removal efficiency (E), based on the NH4+ ions changes determined using the selective electrode and spectrophotometric cuvette tests. The highest adsorption capacity (q = 4.92 mg/g) of ammonium ions with the maximum removal efficiency (52.3%) was obtained for bentonite, with a 0–0.05 mm particle size. After pretreatment with a 1 mol/L NaCl solution, maximum efficiency increments were observed (55.7%). The Langmuir adsorption isotherm corresponds well with the equilibrium adsorption data (R2 from 0.97 to 0.98), while the Freundlich model was found to be mismatched (R2 = 0.77). Based on these results it was concluded that natural sorbents may be effectively applied in wastewater treatment. It can be observed that as the size of sorbent particles gets lower, the adsorption capacity, as well as the removal efficiency, gets higher. The bentonite pretreatment with the NaCl solution did not result in the expected efficiency improvement. The 2 mol/L solution affected about 3.5% of the removal efficiency yield.