Solute Removal Efficiency Research Articles

Ultrasound and microwave-assisted synthesis of copper-activated carbon and application to organic dyes removal

ABSTRACT Organic dyes as toxic pollutants are difficult to treat, so an urgent challenge is to develop an efficient and economical adsorbent for dye wastewater treatment. In this work, ultrasound and microwave were used to synthesize copper-activated carbon (Cu-AC). The results indicated that Cu-AC exhibited much higher adsorption capacity than regenerated-activated carbon (R-AC) due to its large surface area and developed pore structure. The Cu-AC was employed as photocatalyst for degradation of methylene orange (MO) and cango red (CR) solution under UV light and visible light irradiation. The removal efficiency of CR solution was higher under UV light irradiation. The adsorption behaviors of Cu-AC and R-AC to MO were also investigated. The effects of different parameters such as pH, initial concentration and contact time on adsorption behaviors were performed in batch models. The results indicated that using Cu-AC to remove organic dyes was a cost-efficient way, which can realize the comprehensive utilization of waste resources.

Intermittent Infusion Hemodiafiltration: The Principle and Its Clinical Application.

The present study aimed to propose a new hemodiafiltration (HDF) method (intermittent infusion HDF) that repeats intermittent infusion during hemodialysis to temporarily enhance peripheral circulation and improves solute removal efficiency through (a) correcting blood distribution (increase in effective vascular surface area), (b) stirring body fluids, and (c) promoting solute removal and examining its clinical effects.

Examining hemodialyzer membrane performance using proteomic technologies.

The success and the quality of hemodialysis therapy are mainly related to both clearance and biocompatibility properties of the artificial membrane packed in the hemodialyzer. Performance of a membrane is strongly influenced by its interaction with the plasma protein repertoire during the extracorporeal procedure. Recognition that a number of medium–high molecular weight solutes, including proteins and protein-bound molecules, are potentially toxic has prompted the development of more permeable membranes. Such membrane engineering, however, may cause loss of vital proteins, with membrane removal being nonspecific. In addition, plasma proteins can be adsorbed onto the membrane surface upon blood contact during dialysis. Adsorption can contribute to the removal of toxic compounds and governs the biocompatibility of a membrane, since surface-adsorbed proteins may trigger a variety of biologic blood pathways with pathophysiologic consequences. Over the last years, use of proteomic approaches has allowed polypeptide spectrum involved in the process of hemodialysis, a key issue previously hampered by lack of suitable technology, to be assessed in an unbiased manner and in its full complexity. Proteomics has been successfully applied to identify and quantify proteins in complex mixtures such as dialysis outflow fluid and fluid desorbed from dialysis membrane containing adsorbed proteins. The identified proteins can also be characterized by their involvement in metabolic and signaling pathways, molecular networks, and biologic processes through application of bioinformatics tools. Proteomics may thus provide an actual functional definition as to the effect of a membrane material on plasma proteins during hemodialysis. Here, we review the results of proteomic studies on the performance of hemodialysis membranes, as evaluated in terms of solute removal efficiency and blood–membrane interactions. The evidence collected indicates that the information provided by proteomic investigations yields improved molecular and functional knowledge and may lead to the development of more efficient membranes for the potential benefit of the patient.

Evaluation of humic acid removal efficiency in aqueous solution by feather protein granules

Evaluation of humic acid removal efficiency in aqueous solution by feather protein granules

A Comparative Study on the Use of Seawater and Sea Salt in Nutrient Elimination

An excess in the nutrients such as nitrogen and phosphate leads to a phenomenon called eutrophication. In order to avoid this, numerous methods have been used to remove excess nutrients in the water. In this study, the use of a chemical method was assessed through the formation of magnesium ammonium phosphate. The difference in the removal efficiency of seawater and sea salt solution as primary sources of Mg 2+ ions and Ca 2+ ions for the formation of magnesium ammonium phosphate (MAP) and hydroxyapatite (HAP) respectively, were observed, taking into account the changes in pH and concentration. The results showed that seawater removed about 90 % phosphate and less than 50 % ammonia in sewage water condition, whereas the sea salt solution removed almost 90 % phosphate and 70 % ammonia in solution at pH 9 and 10 mM concentration of sea salt which further increases as the optimum Mg/PO₄ 3- , NH₄⁺ ratio reaches 2. The difference in the removal efficiency of seawater and sea salt was due to the fact that the set-ups were prepared in different conditions. This study suggests that both seawater and sea salt can be used to remove nutrients from the water. The relatively higher removal of phosphate can be explained by the formation of HAP from free Ca 2+ ions initially present in seawater and sea salt solution.

Chromium (VI) Removal from Wastewater by Electrocoagulation Process Using Taguchi Method: Batch Experiments

Electrocoagulation is an electrochemical method for treatment of different types of wastewater whereby sacrificial anodes corrode to release active coagulant (usually aluminium or iron cations) into solution, while simultaneous evolution of hydrogen at the cathode allows for pollutant removal by flotation or settling. The Taguchi method was applied as an experimental design and to determine the best conditions for chromium (VI) removal from wastewater. Various parameters in a batch stirred tank by iron metal electrodes: pH, initial chromium concentration, current density, distance between electrodes and KCl concentration were investigated, and the results have been analyzed using signal-to-noise (S/N) ratio. It was found that the removal efficiency of chromium increased with increasing current density and KCl concentration, and decreases with increasing initial chromium concentration and distance between electrodes, while pH shows peak performance curve. Experimental work have been performed for synthetic solutions and real industrial effluent. The results showed that the removal efficiency of synthetic solution is higher than industrial wastewater, the maximum removal for prepared solution is 91.72 %, while it was 73.54 % for industrial wastewater for the same conditions.

Biocompatibility of Hemodiafilters.

Biocompatibility and the efficiency of solute removal are important considerations in blood purification therapy. Improvement of biocompatibility is expected to lead to the prevention of dialysis-related complications (e.g. amyloidosis, arteriosclerosis, and malnutrition) and to the delay of disease progression by alleviating microinflammation. The biocompatibility of dialyzers is greatly influenced by the interaction between blood and the treatment materials, in which the chemical and physical characteristics of membrane materials play important roles. In hemodiafiltration (HDF), treatment characteristics such as dilution modes are also considered to greatly affect this interaction between blood and materials. Studies have reported that the levels of C-reactive protein are decreased in patients receiving HDF. Thus, the improvement of biocompatibility is an important factor in HDF. Key Messages: To improve the biocompatibility of HDF, it is essential to improve the biocompatibility of hemodiafilters. This article outlines the importance of biocompatibility and related factors in HDF.

Evidence for Targeting Low-Molecular-Weight Proteins in Hemodialysis and Hemodiafiltration.

With the identification of β2-microglobulin (β2MG) as an active participant in dialysis-related amyloid fibril formation, low-molecular-weight proteins (LMWPs) are now recognized as a distinct class of uremic toxins, and numerous compounds in this category have been identified. The class of LMWPs, although not precisely defined, has a molecular weight range of approximately 1,000-50,000 Da. With this in mind, dialysis prescriptions have been modified to increase the efficiency of uremic solute removal. Many studies have characterized the dialytic removal of β2MG and it is therefore regarded as a surrogate for LMWPs. In Japan, dialysis membranes that can efficiently remove β2MG are recommended. Recently, researchers have reported that β2MG is not only a uremic toxin that should be removed, but also a predictor of the prognosis of dialysis patients. In Japan, hemodiafiltration (HDF), especially on-line HDF, and protein-permeable hemodialysis (HD) is being actively carried out, and it is often reported that prognosis is improved by decreasing the concentrations of substances larger than β2MG. It is important, then, that dialysis prescriptions achieve effective clearance of such substances. Key Messages: Over 2,000 uremic substances have been identified that form or accumulate because of renal failure and cause various symptoms and complications. Focusing on these facts, HD or HDF therapy, which is associated with albumin loss, was implemented targeting the LMWPs. Here, we report the effects of albumin-losing blood purification (HD/HDF) for the purpose of removing LMWPs.

Phytolacca acinosa Roxb. with Arthrobacter echigonensis MN1405 enhances heavy metal phytoremediation

ABSTRACTThe growth and metal-extraction efficiency of plants when exposed to toxic metals can be enhanced by inoculating with certain bacteria, but the mechanisms of this process remain unclear. We report results from glasshouse experiments on the effect of Arthrobacter echigonensis MN1405 in promoting Phytolacca acinosa Roxb. growth when exposed to 100 mg/L Mn solution. Mn removal efficiency in solution was significantly enhanced by bacterial inoculation; Mn was accumulated in the root of P. acinosa Roxb. plant. The bacteria oxidized the Mn on root surface, which formed a Mn plaque to serve as a barrier or a containment to prevent metal toxicity. In this process, pH condition was an important factor on the effects of microbial-assisted heavy metal phytoremediation. Our finding suggests that A. echigonensis MN1405 assisted P. acinosa to achieve high remediation efficiency of Mn removal and accumulation in Mn contamination area.

Pressure cycling extraction as an alternative to percolation for production of instant coffee

Abstract Pressure cycling (300 s at 91.4 kPa + 300 s at 338.2 kPa per cycle) was performed to extract water-soluble compounds from ground coffee at ≈17 °C. The efficiency of solute removal (E) at equilibrium, and the extraction rate constant by dispersing the solids in the solvent (k) were examined. The obtained aqueous solution was freeze-dried at ≈2.25 Pa for 48 h and the produced instant coffee was analyzed by GC–MS to speculate about its quality. For comparison, an additional set of experiments by involving three different extraction procedures was also carried out (i: infusion at 91.4 kPa and ≈17 °C; ii: infusion at 91.4 kPa and ≈100 °C; iii: pressurized extraction at 338.2 kPa and ≈17 °C). Pressure cycling extraction presented the optimal E (79 ± 6%), and a k (2.9 × 10−3 s−1, or 1033 s to reach equilibrium) comparable to that found at 100 °C in percolator batteries of commercial extractors. The qualities of lyophilized coffee from pressure cycling extraction and from the best expected condition of extraction for the purpose of retention of coffee volatiles (i.e.; 91.4 kPa and ≈17 °C) were analogous.

Impact of Precipitants on the Structure and Properties of Fe-Co-Ce Composite Catalysts

Fe-Co-Ce composite catalysts were prepared by coprecipitation method using CO(NH2)2, NaOH, NH4HCO3, and NH3·H2O as precipitant agents. The effects of the precipitant agents on the physicochemical properties of the Fe-Co-Ce based catalysts were investigated by SEM, TEM, BET, TG-DTA, and XRD. It was found that the precipitant agents remarkably influenced the morphology and particle size of the catalysts and affected the COD removal efficiency, decolorization rate, and pH of methyl orange for catalytic wet air oxidation (CWAO). The specific surface area of the Fe-Co-Ce composite catalysts successively decreased in the order of NH3·H2O, NH4HCO3, NaOH, and CO(NH2)2, which correlated to an increasing particle size that increased for each catalyst. For the CWAO of a methyl orange aqueous solutions, the effects of precipitant agents NH3·H2O and NaOH were superior to those of CO(NH2)2and NH4HCO3. The catalyst prepared using NH3·H2O as the precipitant agent was mostly composed of Fe2O3, CoO, and CeO2. The COD removal efficiency of methyl orange aqueous solution for NH3·H2O reached 92.9% in the catalytic wet air oxidation. Such a catalytic property was maintained for six runs.

Adsorptive removal of phenol from aqueous solutions by copper (cu)-modified scoria powder: process modeling and kinetic evaluation

Phenol compounds are regarded as hazardous pollutants due to their toxicity and carcinogenic properties to human health at low concentrations. So, this study was aimed to investigate the phenol adsorption by copper (Cu)-modified scoria powder, which is a low-cost adsorbent for the removal of organic compounds. All the experiments were performed based on the full face-centered central composite design experimental plan and analyzed using response surface methodology. The samples were analyzed using various conditions including adsorbent dose (0.1–1 g/l), phenol concentration (50–250 mg/l), and contact time (5–100 min). Three-dimensional plots reveal the relationship between the phenol removal efficiency and the paired factors, which describe the behavior of scoria powder in the removal of phenol from aqueous solution. The models showed that phenol removal efficiency in aqueous solution affected by four studied factors. A maximum removal efficiency of phenol achieved was more than 96% at the optimum conditions (scoria dosage of 1 g/l, phenol concentration of 50 mg/l, and contact time of 100 min). Process of kinetic parameters were also evaluated and modeled using five kinetic models including pseudo-first-order equation, second-order equation, modified Freundlich, pore diffusion, and Elovich. The best fit of experimental adsorption data was calculated by means of the pseudo-second-order model. Equilibrium data obeyed the Freundlich and Langmuir isotherms, and found that the equilibrium data well obeyed the Langmuir isotherm.

ADSORPTIVE REMOVAL OF METHYLENE BLUE FROM AQUEOUS SOLUTIONS BY PUMICE POWDER: PROCESS MODELLING AND KINETIC EVALUATION

This study was carried out to investigate the adsorption of methylene blue (MB) onto pumice powder, as a low-cost adsorbent for the removal of dyes. The experiments were designed based on a central composite design (CCD) and the process was analyzed and modeled using response surface methodology (RSM). In order to study the adsorption process, three important factors viz. pumice dosage (20- 50 mg/50mL), MB concentration (20-40 mg/l) and contact times (5- 35 min) were chosen as variables and MB removal was studied as the process response. Three dimensional plots demonstrate relationships between the MB removal efficiency with the paired factors (when other factor was kept at its optimal level), describing the adsorption of pumice powder in a batch process. The model showed that MB removal efficiency in aqueous solution affected by three factors studied. A maximum MB removal efficiency of more than 90% was achieved at the optimum conditions (pumice dosage of 50mg/50 mL, MB concentration of 20 mg/l and contact time of 35 min). Process kinetic parameters were also investigated and modeled using five kinetic models including the pseudo-first-order equation, second-order equation, the modified Freundlich, the pore diffusion model and the Elovich equation. The best fit of experimental adsorption data was obtained by means of the pseudo-second-order models. Equilibrium data were fitted to the Freundlich and Langmuir isotherm equations, and the equilibrium data were found to be well represented by the Langmuir equation.

OPTIMIZATION OF REACTIVE BLUE 19 BIODEGRADATION BY PHANEROCHAETECHRYSOSPORIUM

Problematic dyes extensively used in different industries such as textile, paper, food, plasticsand cosmetics have undesirable environmental effects. White rot fungi demonstrating effective extracellularenzyme system, which is capable of degrading dyes and various xenobiotics. The aim of this study was tooptimize decolorization of reactive blue 19 (RB19) dye using Phanerochaetechrysosporium. A Box-Behnkendesign and Response Surface Methodology (RSM) were used to study the effect of independentvariables, namely glycerol concentration (15, 20 and 25 g/L), temperature (27, 30 and 40oC) and pH (5.5, 6.0 and 6.5) on color removal efficiency in aqueous solution. From RSM-generated model, the optimum conditions for RB19 decolorization were identified to be at temperature of 20oC, glycerol concentration of 120/L and pH: 6.5. At the optimum conditions, predicted decolorization was 98 percent. The confirmatory experiments were conducted, which confirmed the results by 99.8 percent color removal. Thus, the experimental investigation and statistical approach enabled us to improve reactive blue 19 biodegradation process by Phanerochaetechrysosporium up to 1.25 times higher than non-optimized conditions.

Degradation of azo dye C.I. Acid Red 18 in aqueous solution by ozone-electrolysis process

In this paper, the degradation of azo dye C.I. Acid Red 18 (AR18) with initial concentration of 100mgL−1 in aqueous solution by ozone-electrolysis process (OEP) as hybrid method of advance oxidation process was investigated. All experiments were performed in a 450mL mixed semi-batch reactor to obtain the optimal conditions. The effects of NaCl concentration as supporting electrolyte, current density and initial pH on the removal efficiency of AR18 solution were investigated. The efficiency of color and TOC removal were compared as functional of degradation and decolorization of AR18. The results of UV/vis spectra showed that the AR18 structures were destroyed under ozone-electrolysis reaction. This investigation revealed ozone-electrolysis presents good efficiency for both solution decolorization and total organic carbon (TOC) removal. Results of experiments indicated that ozone-electrolysis process has a synergistic effect on decolorization rate of AR18.

Comparison of the effects of predilution and postdilution hemodiafiltration on neutrophils, lymphocytes and platelets

Numerous studies have been carried out to investigate the solute removal efficiency of hemodiafiltration (HDF). However, the effect of the dilution mode on blood cell damage during HDF has not yet been examined in detail. Here, we compared predilution and postdilution HDF with respect to their effects on blood cells. Five patients were allocated to one session each of predilution HDF and postdilution HDF. Concentrations of interleukin (IL)-6, intercellular adhesion molecule (ICAM)-1, and platelet-derived microparticles (PDMP), and the phagocytotic and sterilizing functions of neutrophils before and after the HDF sessions were evaluated. Lymphocyte blastoid transformation induced by mitogens was also evaluated by measurement of the [(3)H]-thymidine uptake. The IL-6 and ICAM-1 concentrations decreased after predilution HDF, and increased after postdilution HDF. Lymphocyte blastoid transformation was more pronounced after predilution HDF than after postdilution HDF. There was no significant difference in PDMP between the dilution modes. We conclude that predilution HDF could be more favorable for dialysis patients than postdilution HDF from the point of view of the effects on the blood cells, especially neutrophils and lymphocytes.

Degradation of Disperse Red 167 Azo Dye by Bipolar Electrocoagulation

This study investigates the influence of variables on the removal efficiency of solution containing azo dye Disperse Red 167 by bipolar electrocoagulation (BEC). Current density, time of electrolysis, interelectrode distance, supporting electrolyte concentration, and total surface area were the variables that mostly influenced the azo dye removal. The efficiency of different electrode materials (Fe, Al) for azo dye removal is compared. The obtained results showed the effectiveness of the aluminum and iron electrodes for azo dye removal. The present study allows achieving a high level of decolorization (100%) with a short reaction time for both electrodes. The method was found to be highly efficient and relatively fast compared to conventional existing techniques.

A novel approach for blood purification: Mixed-matrix membranes combining diffusion and adsorption in one step

Hemodialysis is a commonly used blood purification technique in patients requiring kidney replacement therapy. Sorbents could increase uremic retention solute removal efficiency but, because of poor biocompatibility, their use is often limited to the treatment of patients with acute poisoning. This paper proposes a novel membrane concept for combining diffusion and adsorption of uremic retention solutes in one step: the so-called mixed-matrix membrane (MMM). In this concept, adsorptive particles are incorporated in a macro-porous membrane layer whereas an extra particle-free membrane layer is introduced on the blood-contacting side of the membrane to improve hemocompatibility and prevent particle release. These dual-layer mixed-matrix membranes have high clean-water permeance and high creatinine adsorption from creatinine model solutions. In human plasma, the removal of creatinine and of the protein-bound solute para-aminohippuric acid (PAH) by single and dual-layer membranes is in agreement with the removal achieved by the activated carbon particles alone, showing that under these experimental conditions the accessibility of the particles in the MMM is excellent. This study proves that the combination of diffusion and adsorption in a single step is possible and paves the way for the development of more efficient blood purification devices, excellently combining the advantages of both techniques.

Atenuação da Contaminação de Nitrato em Aqüíferos com Uso de Serragem como Material Reativo: Ensaios de Colunas com Solos

The attenuation of contaminants in soil and water can be promoted using reactive media that, through physical, chemical or biological reactions, transform harmful forms into environmentally accepted ones. It is important that the study of reactive materials efficiency precede the implementation of permeable reactive barriers at field scale. This paper shows the results of column experiments in which the efficiency of sawdust was tested in the degradation of nitrate, a very common contaminant in aquifers, from in situ sanitation systems. Three columns were set up: one with sediments from the area (C1) and the other two with sediments from the area and 10 cm (C2) and 20 cm (C3) thickness of sand mixed with sawdust. The removal efficiency of nitrate solution in the columns with reactive material was initially quite high: C3 worked for 460 h with an efficiency above 90% and C2, for only 35 h. C3 was on average 2.5 times more efficient in reducing nitrate concentrations than C2

Study on Removal Efficiency of Natural Organic Matter and Lead Metal Solution Using Nanofiltration Membrane

This research studied the remove of lead metal and natural organic matter (NOM) using nanofiltration membrane. The combined effects between NOM and lead ion can cause a loose cake formation at the membrane surface, thus lowering flux decline when compared with that of metal ion alone. The results were possibly caused by increased accumulation of fouled materials at the membrane surface, thus affecting flux, causing complete pore fouling.