Solute Removal Research Articles

Methotrexate degradation in artificial wastewater using non-thermal pencil plasma jet.

The rising global cancer rate is driving up the consumption of anticancer drugs. This causing a noticeable increase in the levels of these drugs in wastewater. The drugs are not metabolized effectively by the human body, leading to their presence in human waste, as well as in the effluent from hospitals and drug manufacturing industries. Methotrexate is a commonly used drug for treating various types of cancer. Its complex organic structure makes it difficult to degrade using conventional methods. The present work proposed a non-thermal pencil plasma jet treatment for methotrexate degradation. The air plasma produced in this jet setup is electrical characterized and plasma species/radicals are identified using emission spectroscopy. The degradation of drug is monitored by studying the change in solution physiochemical properties, HPLC-UV analysis, and removal of total organic carbon, etc.Results show that a 9-min plasma treatment completely degraded the drug solution that followed first-order degradation kinetics with rate constant 0.38 min-1 and 84.54% mineralization was observed. Additionally, an increase in electrical conductivity and dissolved solids compared to virgin water-plasma interaction indicated the formation of new, smaller compounds (2,4-Diaminopteridine-6-carboxylic acid, N-(4-Aminobenzoyl)-L-glutamic acid, etc.) after drug degradation. The plasma-treated methotrexate solution also showed lower toxicity toward freshwater chlorella algae compared to the untreated solution. Finally, it can be said that non-thermal plasma jets are economically and environmentally friendly devices that have the potential to be used for the treatment of complex and resistive anticancer drug-polluted wastewaters.

Removal of Chromium (VI) in Aqueous Solution by Charcoal Adsorbent derived PET Plastic Waste

This study was conducted to assess the potential of charcoal and activated charcoal derived Polyethylene Terephthalate (PET) as adsorbent through the experiment of chromium hexavalent [Cr (VI)] removal from aqueous solution. The study aims to investigate the optimum adsorption conditions for Cr (VI) removal in aqueous solution under diverse adsorption operating conditions, namely pH, contact time, agitation speed, adsorbent dosage, and initial concentration. The diameter of the charcoal produced was 600 μm. The results showed that 80 % and 90 % of Cr (VI) removal were achieved by using charcoal and activated charcoal, respectively, at pH 5, 150 rpm, 60 min of contact time, 0.5 g of adsorbent dosage, and 0.1 mg/L of Cr (VI) initial concentration. The removal of Cr (VI) was mainly affected by adsorption operating conditions and the physicochemical properties of adsorbents. Langmuir and Freundlich adsorption isotherms were applied to model the adsorption behaviour and determine the adsorption capacity of both PET charcoal adsorbents. The adsorption isotherm plot was well fitted with the Langmuir model.

Exploring The Potential of Mango Seed as A Bioadsorbent for Pb(II) Removal in Aqueous Solution

Various industrial activities produce heavy metals as by-products or wastes. Lead is a metal trace element from sewage disposal, vehicle fumes, and atmospheric emissions from industrial activities. Mango seeds are composed of cellulose, lignin, and hemicellulose, which have many potential binding groups. Mango seeds, which are often considered waste, can be utilized as a low-cost biosorbent due to their various functional groups, such as hydroxyl, carboxyl, carbonyl, alcohol, amide, and aromatic groups. Mango seed are organic waste with potential as low-cost biosorbent for heavy metals removal. The purposes of the study are: (1) to explore the optimum condition of biosorbent in absorbing heavy metal species (Pb (II)), and (2) to analyze the adsorption model of synthetic waste containing Pb(II). Mango seeds have a considerable potential to be used as a biosorbent to absorb heavy metal ions. The optimum conditions for Pb2+ ion adsorption is at pH 6 with contact time 70 minutes, and concentration of biosorbent 2.0 g/L. Adsorbate adsorption follows the Freundlich model, and adsorption occurs only in a few surface layers. The kinetic parameters of adsorbent satisfied pseudo-second-order reaction. The optimum adsorption capacity (qm) of mango seed biosorbent in absorbing Pb ions is 43.86 mg/g.

Impact of Silver-Decorated Graphene Oxide (Ag-GO) towards Improving the Characteristics of Nanohybrid Polysulfone Membranes.

The utilization of membranes has been extensively employed in the treatment of water and wastewater. Membrane fouling, attributed to the hydrophobic nature of membranes, constitutes a noteworthy concern in the realm of membrane separation. The mitigation of fouling can be achieved through the modification of membrane characteristics, including but not limited to hydrophilicity, morphology, and selectivity. In this study, a nanohybrid polysulfone (PSf) membrane embedded with silver-graphene oxide (Ag-GO) was fabricated to overcome problems related to biofouling. The embedment of Ag-GO nanoparticles (NPs) is the aim towards producing membranes with antimicrobial properties. The fabricated membranes at different compositions of NPs (0 wt%, 0.3 wt%, 0.5 wt%, and 0.8 wt%) are denoted as M0, M1, M2, and M3, respectively. These PSf/Ag-GO membranes were characterized using FTIR, water contact angle (WCA) goniometer, FESEM, and salt rejection. The additions of GO significantly improved the hydrophilicity of PSf membranes. An additional OH peak at 3380.84 cm-1 of the nanohybrid membrane from FTIR spectra may be related to hydroxyl (-OH) groups of GO. The WCA of the fabricated membranes decreased from 69.92° to 54.71°, which confirmed the improvement in its hydrophilicity. In comparison to the pure PSf membrane, the morphology of the finger-like structure of the fabricated nanohybrid membrane slightly bent with a larger bottom part. Among the fabricated membranes, M2 achieved the highest iron (Fe) removal, up to 93%. This finding proved that the addition of 0.5 wt% Ag-GO NPs enhanced the membrane water permeability together with its performance of ionic solute removal (Fe2+) from synthetic groundwater. In conclusion, embedding a small amount of Ag-GO NPs successfully improved the hydrophilicity of PSf membranes and was able to achieve high removal of Fe at 10-100 mg L-1 towards purification of groundwater for safe drinking water.

#6814 A NEW SORBENT DEVICE FOR MULTIPLE CLINICAL PURPOSES: CURRENT EVIDENCE AT A PRIVATE HOSPITAL IN MEXICO

Abstract Background and Aims Adsorption is an extracorporeal technique utilized for blood purification, it also complements convection and diffusion for solute removal. Since 1991 we had used blood purification techniques, over the years, new adsorption cartridges had been developed, the new ones involving treatment for inflammatory conditions, chronic uremic symptoms and autoimmune diseases. HA130, HA230, and HA330 (Jafron, Zhuhai City, China) are among the widely used adsorption cartridges in China. We report highlights of the use of hemoperfusion using HA130 cartridges in the Mexican population cohorts in the context of multiple chronic inflammatory conditions in order to support evidence of effectiveness and safety. Method We retrospectively analyzed the medical records of 14 critically ill patients in the context of chronic inflammatory conditions such as acute kidney injury in chronic kidney disease, acute lung injury due to SARS-COV-2 infection and sepsis. Hemoperfusion in addition to standard therapy (fluid resuscitation, vasopressors, antimicrobial therapy and ventilatory support) resulted in the improvement of inflammatory substances levels when compared to standard therapy alone. Out of the 14 patients, 7 patients used HA130 cartridges and 7 patients with standard therapy alone. Results There were no significant side effects associated with HA130 cartridge use. HA 130 cartridges were found to be effective in reducing uremic symptoms in chronic hemodialysis patients, improvement of pruritus score and decreased parathyroid hormone and phosphate product (p<0.5) when compared to HD alone, creatinine (MARS: −24 μmol/L, −19.5 to −10.46, p < 0.001; SPAD: −2 μmol/L, −9.0 to +7.0/L, p = 0.314) and urea (MARS: −0.9 mmol/L, −318 to −0.189, p = 0.024; SPAD: −0.1 mmol/L, −1.0 to +0.68, p = 0.523). 66.6% of cost-effectiveness when compared to standard therapy. Conclusion In the group of patients that used HA130 cartridges we found statistically significant (p <0.05) reduction of pruritus score, PTH, phosphate product, creatine and urea when compared to the group of patients with standard therapy alone. The development in new cartridges technology allows more wide applications for renal patients. As we expand to involve other indications for this therapy there is cost-effectiveness improvement for the patients.More studies in different clinical settings are needed in order to achieve adsorption therapy national recommendations. We also found that the HA130 cartridges are effective in reducing uremic symptoms and microinflammatory status in acute kidney injury in chronic kidney disease patients due to the elimination of middle and small molecule uremic toxins and inflammatory mediators and endotoxins. This may translate as an improvement of quality of life and survive rates in patients with chronic hemodialysis, even though more studies are needed in order to prove this assumption.

Removal of Middle Molecules and Dialytic Albumin Loss: A Cross-over Study of Medium Cutoff and High-Flux Membranes with Hemodialysis and Hemodiafiltration.

Key Points HDF and MCO have shown greater clearance of middle-size uremic solutes in comparison with HF dialyzers; MCO has never been studied in HDF.MCO in HDF does not increase the clearance of B2M and results in a higher loss of albumin. Background Middle molecule removal and albumin loss have been studied in medium cutoff (MCO) membranes on hemodialysis (HD). It is unknown whether hemodiafiltration (HDF) with MCO membranes provides additional benefit. We aimed to compare the removal of small solutes and β2-microglobulin (B2M), albumin, and total proteins between MCO and high-flux (HFX) membranes with both HD and HDF, respectively. Methods The cross-over study comprised 4 weeks, one each with postdilutional HDF using HFX (HFX-HDF), MCO (MCO-HDF), HD with HFX (HFX-HD), and MCO (MCO-HD). MCO and HFX differ with respect to several characteristics, including membrane composition, pore size distribution, and surface area (HFX, 2.5 m2; MCO, 1.7 m2). There were two study treatments per week, one after the long interdialytic interval and another midweek. Reduction ratios of vitamin B12, B2M, phosphate, uric acid, and urea corrected for hemoconcentration were computed. Dialysis albumin and total protein loss during the treatment were quantified from dialysate samples. Results Twelve anuric patients were studied (six female patients; 44±19 years; dialysis vintage 35.2±28 months). The blood flow was 369±23 ml/min, dialysate flow was 495±61 ml/min, and ultrafiltration volume was 2.8±0.74 L. No significant differences were found regarding the removal of B2M, vitamin B12, and water-soluble solutes between dialytic modalities and dialyzers. Albumin and total protein loss were significantly higher in MCO groups than HFX groups when compared with the same modality. HDF groups had significantly higher albumin and total protein loss than HD groups when compared with the same dialyzer. MCO-HDF showed the highest protein loss among all groups. Conclusions MCO-HD is not superior to HFX-HD and HFX-HDF for both middle molecule and water-soluble solute removal. Protein loss was more pronounced with MCO when compared with HFX on both HD and HDF modalities. MCO-HDF has no additional benefits regarding better removal of B2M but resulted in greater protein loss than MCO-HD.

Fabrication and characterization of magnetic eucalyptus carbon for efficient Cr(VI) removal in aqueous solution and its mechanisms

For an exhaustive removal of Cr(VI), three different types of biochar were prepared, modified and evaluated for Cr(VI) removal from wastewater. Magnetic eucalyptus biochar (MBC) was synthesized via a facile pyrolysis process of eucalyptus biochar pretreated with FeCl3 firstly coupled with K2CO3 activation. As a comparison, raw biochar (BC) and FeCl3 modified biochar (FBC) were prepared. The physicochemical property of adsorbent synthesis and removal mechanism was examined using BET, SEM with EDS, zeta potential, XRD, FTIR, XPS and Vibrating sample magnetometer (VSM), and the effect of various reaction conditions and parameters were evaluated for Cr(VI) removal. Results demonstrated that compared to BC and FBC, MBC has a larger specific surface area (870.3264 m2/g), higher content of Fe mainly existed as γ-Fe2O3 and Fe3O4, and higher zeta potential (10.66). This is due to the significant alleviation of pore blockage caused by iron oxides and more efficient conversion of iron oxides with the participation of K2CO3 during modification process. Upon batch tests, the removal efficiency could achieve more than 91% for 200 mg/L Cr(VI) solution with optimum adsorbent dosage (0.01 g) at desired acid condition (pH = 2) within 9 h. The separation behavior of MBC for Cr(VI) was highly identical with elovich and Freundlich model. MBC showed better adsorption performance up to three cycles and under various co-existing ions. Besides, the removal ability of MBC gained an obvious increase of 2–5 folds and 3–10 folds at different initial Cr(VI) concentrations, compared with BC and FBC. Characterization analyses unraveled that physicochemical removal process was responsible for the efficient elimination of Cr(VI) in an aqueous solution, resulting from adsorption, electrostatic attraction, pore filling, complexation, ion exchange, redox reaction and precipitation due to the fabrication of iron oxides into biochar.

The changing face of dialyzer membranes and dialyzers.

The key goals for dialysis treatments are to prevent the progressive accumulation of waste products of metabolism and volume overload. Traditionally uremic solutes have been classified according to molecular weight and termed small, middle sized, and large solutes. Solute clearance during dialysis sessions will potentially be by diffusion, convection and adsorption. Dialyzer membranes act as a semi-permeable membrane restricting solute removal predominantly by size. Small molecules move faster than large molecules, so small solutes are readily removed by diffusion. Increasing the size of the pores in the membrane will potentially allow middle and larger sized solutes to pass through the dialyzer membrane, although in practice there is a limit to increasing pore sizes to prevent the loss of albumin and other important proteins. Differences in membrane surface and charge will influence protein absorption. The removal of fluid during dialysis depends in part on the hydraulic permeability of the membrane. Combining higher hydraulic permeability and larger sized pores increases convective clearance with solutes moving across the membrane with the water movement. Depending upon dialyzer design, higher hydrostatic pressure as blood enters the dialyzer leads to a variable amount of internal diafiltration, so improving the clearance of middle sized solutes. Although the dialyzer membrane plays a key role in solute clearance, the design of the casing and header also play a role in directing the countercurrent blood and dialysate flows to maximize the surface area available for diffusive and convective clearances.

Portable, wearable and implantable artificial kidney systems: needs, opportunities and challenges.

Haemodialysis is life sustaining but expensive, provides limited removal of uraemic solutes, is associated with poor patient quality of life and has a large carbon footprint. Innovative dialysis technologies such as portable, wearable and implantable artificial kidney systems are being developed with the aim of addressing these issues and improving patient care. An important challenge for these technologies is the need for continuous regeneration of a small volume of dialysate. Dialysate recycling systems based on sorbents have great potential for such regeneration. Novel dialysis membranes composed of polymeric or inorganic materials are being developed to improve the removal of a broad range of uraemic toxins, with low levels of membrane fouling compared with currently available synthetic membranes. To achieve more complete therapy and provide important biological functions, these novel membranes could be combined with bioartificial kidneys, which consist of artificial membranes combined with kidney cells. Implementation of these systems will require robust cell sourcing; cell culture facilities annexed to dialysis centres; large-scale, low-cost production; and quality control measures. These challenges are not trivial, and global initiatives involving all relevant stakeholders, including academics, industrialists, medical professionals and patients with kidney disease, are required to achieve important technological breakthroughs.

Bio-Electrochemical Recovery of Copper from Dilute Acidic Solutions as a Function of External Resistance, Copper and Iron Concentrations

Bioelectrochemical systems provide a promising tool for the copper recovery from the heap leaching solutions which usually contain low copper and high iron concentrations. In this study, the role of copper and ferrous ion concentrations, and external resistance in the removal of synthetic sulfuric acid solutions by a lab-scale Microbial Fuel Cell (MFC) was investigated and good results were obtained in the removal of copper.

Resource recovery from RO concentrate using nanofiltration: Impact of active layer thickness on performance

Modelling the removal of monovalent and divalent ions from seawater via nanofiltration is crucial for pre-treatment in seawater reverse osmosis systems. Effective separation of divalent ions through nanofiltration and allowing the permeate containing only monovalent ions to pass through the reverse osmosis system produces pure NaCl salt from the concentrate. However, the Donnan steric pore model and dielectric exclusion assume a uniformly distributed cylinder pore morphology, which is not representative of the actual membrane structure. This study analyzed the impact of membrane thickness on neutral solute removal and investigated the effect of two different methods for calculating the Peclet number on rejection rates of monovalent and divalent salts. Results show that membrane thickness has a significant effect on rejection rates, particularly for uncharged solutes in the range of 0.5–0.7 solute radius to membrane pore size ratio. Operating pressures above 10 bar favour the use of effective active layer thickness over the membrane pore size to calculate the Peclet number. At low pressures, using the effective active layer can lead to overestimation of monovalent salt rejection and underestimation of divalent salt rejection. This study highlights the importance of appropriate Peclet number calculation methods based on applied pressure when modelling membrane separation performance.

Catalytic activation of persulfate by 3D Cd(II) coordination polymers based on a flexible cyclotriphosphazene-functionalized ligand

Dye removal in wastewater can be done by catalytic reaction with coordination polymers. Herein, Two 3D Cd(II) coordination polymers, namely, {[Cd3(L)(H2O)4].(H2O)(DMF)}n (GTU-1) and {[Cd3(L)(4,4-bpy))(H2O)2].(H2O)}n (GTU-2), were prepared with a novel hexapod-shaped molecular building block, hexakis(methyl-2-(4-phenoxyphenyl)acetatebenzene) cyclotriphosphazene (H6L), by solvothermal reactions in dimethylformamide with nitric acid as the modulator. Cd(II) coordination polymers were characterized by Fourier transform infrared spectroscopy, thermal analysis, scanning electron microscopy, powder X-ray diffraction analysis and single crystal X-ray diffraction technique. GTU-1 represents a 3D pillared-layered coordination polymer structure containing 2D Cd-carboxylate (Cd(COO)n)-based inorganic building unit (IBU) whereas GTU-2 is a 3D coordination polymer derived from 1D IBU bridged together by deprotonated L6- and judiciously chosen ancillary linker 4,4-bipyridine (4,4-bpy). In both complexes, the flexible multisite cyclotriphosphazene bridging ligand (H6L) is completely deprotonated. GTU-2 exhibited relatively good catalytic activity towards rhodamine B (RhB), Methylen Blue (MB) and Acid Red 17 (AR-17) removal in aqueous solution.

Revealing the Combined Effect of Active Sites and Intra-Particle Diffusion on Adsorption Mechanism of Methylene Blue on Activated Red-Pulp Pomelo Peel Biochar.

Phosphoric acid-activated biochar has been proven to be a promising adsorbent for pollutant removal in an aqueous solution. It is urgent to understand how surface adsorption and intra-particle diffusion synergistically contribute to the adsorption kinetic process of dyes. In this work, we prepared a series of PPC adsorbents (PPCs) from red-pulp pomelo peel under different pyrolysis temperatures (150-350 °C), which have a broad specific surface area range from 3.065 m2/g to 1274.577 m2/g. The active sites on the surface of PPCs have shown specific change laws of decreasing hydroxyl groups and increasing phosphate ester groups occurring as the pyrolysis temperature rises. Both reaction models (PFO and PSO models) and diffusion models (intra-particle diffusion models) have been applied to simulate the adsorption experimental data to verify the hypothesis deduced from the Elovich model. PPC-300 exhibits the highest adsorption capacity of MB (423 mg/g) under given conditions. Due to its large quantities of active sites on the external and internal surfaces (1274.577 m2/g), a fast adsorption equilibrium can be achieved within 60 min (with an initial MB concentration of 100 ppm). PPC-300 and PPC-350 also exhibit an intra-particle-diffusion-controlled adsorption kinetic process with a low initial MB concentration (100 ppm) or at the very beginning and final stage of adsorption with a high initial MB concentration (300 ppm) at 40 °C, considering that the diffusion is likely hindered by adsorbate molecules through internal pore channels at the middle stage of adsorption in these cases.

As(III) removal of aqueous solutions using zerovalent iron nanoparticles: The role of the UVA-Vis irradiation wavelength

Arsenic contamination in drinking water is dramatic in many countries, particularly in Asia and Latin America. Arsenic removal from water can be achieved through some conventional technologies but some of them have drawbacks or are very expensive, especially in developing countries, where the population uses groundwater for drinking purposes. Therefore, the need of searching for new and low-cost methodologies for As removal from water is mandatory. Because As(V) is removed more easily than As(III), oxidation of this species, when present, is needed as the first step. The use of zerovalent iron nanoparticles (nZVI), particularly reactive due to their extremely small particle size and large surface area can be proposed at a household scale and in isolated regions. The effect of UV–Vis irradiation on the removal of arsenical species using nZVI presents scarce reports in the literature. In the present work, experiments of As(III) removal with commercial nZVI under UVA-Vis irradiation (λem = 300–800 nm) are described. The effect of the As(III) concentration, the As:nZVI molar ratio (MR = [As(III)]:[FeTOTAL]), and the irradiation wavelength on the As(III) removal were analyzed. Two initial As(III) concentrations, 1 and 10 mg L−1, and different MR in the range 1:10–1:100 were tested at pH 6–6.8. The increase of the nZVI amount and the use of UV–Vis irradiation enhanced the As removal under all conditions. The optimal MR for the As(III) removal after 60 min of irradiation at both initial concentrations was 1:30, being 85% for [As(III)]0 = 10 mg L−1, and 92% for [As(III)]0 = 1 mg L−1. By the use of chemical optical filters, it was determined that the most efficient wavelengths to improve the As(III) removal were those lower than 450 nm. All experimental data were adjusted to a biexponential decay suggesting the occurrence of two removal processes, one faster than the other. It was proposed that the main mechanisms under UVA-Vis irradiation were the action of oxides and oxyhydroxides already present or formed on the surface of nZVI during the reaction as semiconductors originating oxidative species and a ligand-to-metal charge-transfer reaction on As(III)-Fe(III) complexes formed in the system with simultaneous As(III) oxidation and Fe(III) reduction. It was concluded that the effect of the light depends on the pollutant and not on the iron material.

Kidney replacement therapy: Pros and Cons

Kidney replacement therapy (KRT) is a term used to encompass life-supporting treatments for kidney failure. Kidney replacement therapy except kidney transplantation replaces nonendocrine kidney functions in patients with kidney failure. Researchers have noted that dialysis, which is one of the most common KRT used, cannot compensate for all the tasks performed by a kidney, and thus the term ‘Kidney support therapy’ has been suggested to be a better name. Support of kidney function in modern times encompasses a wide array of methods and clinical scenarios, from the ambulatory patient to the critically ill. The ability to safely and routinely deliver ongoing organ support in the outpatient setting has, until recently, separated kidney replacement therapy from other organ support. Kidney replacement therapy (KRT) can be applied intermittently or continuously using extracorporeal (hemodialysis) or Para corporeal (peritoneal dialysis) methods. All modalities exchange solute and remove fluid from the blood, using dialysis and filtration across permeable membranes. Nearly 4 million people in the world are living on kidney replacement therapy(KRT),and haemodialysis (HD) remains the commonest form of KRT, accounting forapproximately 69% of all KRT and 89% of all dialysis. Continuous therapy although costly is used mainly for hemodynamically unstable patients; benefits over intermittent therapy are improved tolerability as a result of slower removal of solute and water. Kidney transplantation is the ultimate step for end stage kidney failure management, as it replaces native kidney function completely. The main disadvantages of KRT relate to: Catheter related complications – blood loss, disconnection, infection or failure of access, mechanical complications of the extracorporeal circuit, fluctuations in the salt-water balance, activation of the coagulation cascade. Specific complications of peritoneal dialysis include: peritonitis, catheter- associated infections, hyperglycemia, protein loss etc. Current trends in artificial kidney research are ongoing with the lofty goal of a small device, preferably implanted with little or no maintenance required by the wearer that would deliver safe and highly effective renal replacement therapy including metabolic and endocrine functions. Bangladesh J Medicine 2023; Vol. 34, No. 2(1) Supplement: 181

Application of Adsorption Thermodynamics and Column Studies for Pb2+, Cd2+ and Mn2+ Ions Removal in Multicomponents Model Solution Using Low-Cost Bentonite Clay Adsorbent

The presence of heavy metal contaminants in wastewater effluents has become a great threat to living creatures and the environment. In this study, the application of thermodynamics and column studies for Pb2+, Cd2+ and Mn2+ metal ions removal in multicomponent aqueous solution using low-cost bentonite clay was investigated. Evaluation of enthalpy (∆Ho), entropy (∆So) and Gibbs free energy (∆Go) revealed that heavy metals adsorption was endothermic and spontaneous as temperature increased from 30 to 65 oC. The column performance was determined at 0.05m adsorbent bed depth, 0.023 and 0.04 mL/s flow rates. The influent concentration was 10 and 50 ppm while the breakthrough time was between 0.83 and 8 hr. The maximum uptake of metal ions was 2.2 mg/g for Pb(II), Mn(II) was 0.4 mg/g and 1.7 mg/g for Cd(II). The result showed the potential of bentonite clay as a candidate for toxic metal ions adsorption in wastewater.

Effectively enhanced piezocatalytic activity in flower-like 2H-MoS2 with tunable S vacancy towards organic pollutant degradation

Piezocatalysis technology is emerging as a promising strategy for removing organic pollutants from water by harvesting mechanical energy from the surrounding environment. Herein, 2H-MoS2 flower-like nanosheets with tunable S vacancies was synthesized via a hydrothermal method by adjusting pH of the precursor solution, Mo and S molar ratio, reaction time and temperature. The results showed that the presence of S vacancy leads to significantly enhanced piezoelectric response in the MoS2 nanosheets, as confirmed by both theoretical calculation using first-principle based density functional theory and probe force microscopy (PFM) measurements. As a result, the as-obtained MoS2 nanoflower piezocatalyst exhibited excellent degradation efficiency for Orange Ⅱ solution (removal rate > 95 % in 1 h) under ultrasonic vibration (40 kHz and 110 W). Importantly, we demonstrated for the first time that the piezocatalytic performance was tightly related with the water level in ultrasonic cleaner. The present work not only reports a simple and effective strategy for improving the piezocatalytic degradation activity of MoS2 by introducing vacancy, but also provides new insights and deeper understanding on the underlying mechanism.

Evaluation of the performance and feasibility of a pseudo-catalytic solution in the biogas purification process

Biogas is a valuable renewable energy source used as a fuel or feedstock to produce hydrogen, syngas, and chemicals. In addition to the main constituents, CH4 and CO2, biogas also contains several undesirable contaminants. Although it is in small amounts in biogas, hydrogen sulfide must be removed because it is a toxic and corrosive gas pollutant to the air. Thus, the objective of this study was to investigate the operating conditions of a process for the purification of biogas by removing H2S through a pseudo-catalyst solution based on a fertilizer containing FeEDTA. Then, the operating conditions were optimized to obtain maximum H2S removal and minimum degradation of the pseudo-catalyst solution. Operating at the optimum conditions, a maximum H2S absorption capacity and a minimum pseudo-catalyst solution degradation rate achieved were 0.83 molH2S/molPCS and 0.020%/min, respectively. Therefore, oxidative absorption using a pseudo-catalyst solution based on a fertilizer containing FeEDTA is a potential route for biogas purification.

Case report: therapeutic monitoring of vancomycin in an acute liver failure patient with anuria under high-flow continuous hemodiafiltration

BackgroundHigh-flow continuous hemodiafiltration (HF-CHDF) combines diffusive and convective solute removal and is employed for artificial liver adjuvant therapy. However, there is no report on dosage planning of vancomycin (VCM) in patients with acute liver failure under HF-CHDF.Case presentationA 20-year-old woman (154 cm tall, weighing 50 kg) was transferred to the intensive care unit (ICU) with acute liver failure associated with autoimmune liver disease. On the following day, HF-CHDF was started due to elevated plasma ammonia concentration. On ICU day 8, VCM was started for suspected pneumonia and meningitis (30 mg/kg loading dose, then 20 mg/kg every 12 hrs). However, on ICU day 10, VCM blood concentration was under the limit of detection (< 3.0 μg/mL) and the patient developed anuria. The VCM dose was increased to 20 mg/kg every 6 hrs. Calculation with a one-compartment model using the HF-CHDF blood flow rate as a surrogate for VCM clearance, together with hematocrit and protein binding ratio, predicted a trough VCM blood concentration of 15 μg/mL. The observed concentration was about 12 μg/mL. The difference may represent non-HF-CHDF clearance. Finally, living donor liver transplantation was performed.ConclusionWe report an acute liver failure patient with anuria under HF-CHDF in whom VCM administration failed to produce an effective blood concentration, likely due to HF-CHDF-enhanced clearance. VCM dosage adjustment proved successful, and was confirmed by calculation using a one-compartment model.

Low temperature synthesis of MCM-48 and its adsorbent capacity for the removal of basic red 29 dye from model solutions

The low temperature synthesis of MCM-48 was performed and its adsorptive properties were investigated for the first time in literature by studying Basic Red 29 (BR29) dye adsorption from model solutions. The modification of the surface properties and pore structure of silica-based material MCM-48 induced by BR29 adsorption were characterized using XRD, nitrogen physisorption, and SEM methods before and after dye adsorption.The effects of contact time, solution pH, dye concentration, and temperature on the adsorption capacity of MCM-48 were investigated. Different adsorption models and different kinetic models were used, respectively to define the equilibrium data and the kinetics of adsorption. Adsorption data was seen to fit the Langmuir isotherm and the pseudo-second-order kinetic model. In addition, MCM-48 was found to be very successful for the removal of the BR29 dye model solutions, even at an initial dye concentration of 500 mg/L for which the removal efficiency was above 97%.