Solute Removal Efficiency Research Articles

Effect of manganese(II) and magnesiumg(II) in zinc acid leaching solution on iron precipitation via the hematite process

Abstract Iron (Fe) removal is a critical step in the hydrometallurgical zinc (Zn) extraction process. Hematite, a stable Fe precipitate, offers an environmentally friendly option that complies with environmental protection standards. While existing research primarily focuses on hematite process technology, there is a lack of studies on how ions in ZnSO4 leaching solutions affect Fe removal efficiency and hematite particle size distribution. This study investigated the influence of manganese II (Mn(II)) and magnesium II (Mg(II)) concentrations and temperature on both Fe removal efficiency and hematite particle size distribution in ZnSO4 leaching solution. The results indicated that at various temperatures, the highest Fe removal efficiency occurred with an initial Mn(II) concentration of 10 g/L and an Mg(II) concentration of 15 g/L. As the concentrations of Mn(II) and Mg(II) as well as temperature increased, FeSO₄ crystallization also increased, which adversely affected hematite precipitation. The average particle size of hematite decreases from 300 to 100 nm, resulting in a more uniform particle size distribution, which correlated with the homogeneous solution saturation precipitation mechanism. However, the number of rod-shaped, regular small particles decreases, while the number of irregular, blocky particles increased.

Can one long peritoneal dwell with icodextrin replace two short dwells with glucose?

Due to the slower dissipation of the osmotic gradient, icodextrin-based solutions, compared to glucose-based solutions, can improve water removal. We investigated scenarios where one icodextrin-based long dwell (Extraneal) replaced two glucose-based exchanges. The three-pore model with icodextrin hydrolysis was used for numerical simulations of a single exchange to investigate the impact of different peritoneal dialysis schedules on fluid and solute removal in patients with different peritoneal solute transfer rates (PSTRs). We evaluated water removal (ultrafiltration, UF), absorbed mass of glucose (AbsGluc) and carbohydrates (AbsCHO, for glucose and glucose polymers), ultrafiltration efficiency (UFE = UF/AbsCHO) per exchange, and specified dwell time, and removed solute mass for sodium (ReNa), urea (ReU), and creatinine (ReCr) for a single peritoneal exchange with 7.5% icodextrin (Extraneal®) and glucose-based solutions (1.36% and 2.27%) and various dwell durations in patients with fast and average PSTRs. Introducing 7.5% icodextrin for the long dwell to replace one of three or four glucose-based exchanges per day leads to increased fluid and solute removal and higher UF efficiency for studied transport groups. Replacing two glucose-based exchanges with one icodextrin exchange provides higher or similar water removal and higher daily sodium removal but slightly lower daily removal of urea and creatinine, irrespective of the transport type present in the case of reference prescription with three and four daily exchanges. One 7.5% icodextrin can replace two glucose solutions. Unlike glucose-based solutions, it resulted only in minor differences between PSTR groups in terms of water and solute removal with UFE remaining stable up to 16h.

Application of therapeutic ultrasonic waves across the dialyzer membrane: A pilot study on the impact on dialyzer clearance and safety.

Progressive clogging of the dialyzer membrane during hemodialysis can compromise solute removal efficiency. Existing solutions fall short in addressing intradialytic reduction of dialyzer clearance. This pilot study aims to assess the impact and safety of applying therapeutic ultrasonic waves to dialyzers for mitigating intradialytic clogging. In this pilot study, 15 stable maintenance hemodialysis patients (12 males and 3 females) were enrolled. Each patient served as their own control. They underwent one session of hemodialysis with the application of therapeutic ultrasonic waves (Ultrasonic session) and were crossed-over to a second session without the use of ultrasonic waves (Control session). All the study sessions operated at a fixed dialysate flow rate of 500 mL/min and a blood flow rate of 250 or 300 mL/min. The adequacy of dialysis achieved during each session was monitored using Online Clearance Monitoring of the dialysis machines, and clearance K values, varying between 135 and 209 mL/min, were recorded, and plotted. A direct comparison between Control and Ultrasonic sessions was performed to assess the impact and safety of using ultrasonic waves during hemodialysis. The mean percentage decline in dialyzer clearance values was 4.41% for Ultrasonic sessions (SD: 5.3) and 12.69% for Control sessions (SD: 6.35) (p-value <0.001). This indicates that the application of ultrasonic waves reduced the decline in clearance values. The mean differences of the blood component parameters were comparable between both Ultrasonic sessions and Control sessions, suggesting the safety of utilizing ultrasonic waves during dialysis. Microscopic membrane analysis corroborated the safety. Intradialytic clogging of dialyzer membranes is a significant problem that can cause dialysis inadequacy. Our study tackles this issue by introducing therapeutic ultrasonic waves to improve dialyzer clearance during hemodialysis sessions in patients.

Unprecedented formation of reactive BrO– ions and their role as mediators for organic compounds degradation: The fate of bromide ions released during the anodic oxidation of Bromophenol blue dye

AbstractBased on the existing literature, active chlorine‐mediated electrochemical oxidation has been extensively studied when Cl‒ is added or Cl‒ is already present in the water matrices, as well as when Cl‒ is released from the target organic pollutants during their degradation. However, no attempts have been published concerning the fate and role of bromide (Br‒) ions released during the anodic oxidation (AO) of organobromine compounds. Therefore, the AO of bromophenol blue dye (BPB) was investigated in a parallel plate flow reactor using a boron‐doped diamond (BDD) anode. The effect of the applied current on the color removal efficiency and mineralization of BPB solution was examined and compared with AO of phenol red (PR) which has a similar molecular structure to BPB (but without Br) in order to understand the role of Br heteroatoms on the mineralization of BPB. Faster and higher mineralization and discoloration were achieved when treated with BPB solution compared to PR under similar experimental conditions. This behavior was associated with the electrogeneration of BrO‒, from the heteroatom Br which is released as the bromide ion (Br‒), during the degradation of BPB. The active bromine species are formed via direct and indirect oxidation approaches which were proposed based on ion chromatography and linear scanning voltammetry analysis.

Facile synthesis of rod-like TiO2-based composite loaded with g-C3N4 for efficient removal of high-chroma organic pollutants based on adsorption-photocatalysis mechanism

• Rod-like TiO 2 -based composite loaded with g-C 3 N 4 (denoted as RT/CN) is fabricated by alkaline hydrothermal method. • The removal efficiency of high-chroma methylene blue solution by RT/CN is regulated by controlling the amount of g-C 3 N 4 . • RT/CN-10 (10 mg g-C 3 N 4 loading) has a significant removal rate upgrade under adsorption-photocatalysis mechanism. • The formation of RT/CN heterojunction with the large specific surface area is the key reason for the improved performance. In this study, a simple alkaline hydrothermal method for synthesizing the rod-like TiO 2 -based composite loaded with g-C 3 N 4 (denoted as RT/CN) to efficiently remove the high-chroma organic pollutants is presented. The removal efficiency of high-chroma methylene blue (MB) solution by RT/CN is regulated by controlling the amount of g-C 3 N 4 . The results show that RT/CN-10 (10 mg g-C 3 N 4 loading) has a significant removal rate upgrade, i.e., 22.7 times than that of TiO 2 , and 20.6 times than that of g-C 3 N 4 under adsorption-photocatalysis mechanism. The key reason for the improved performance is related to the large specific surface area, which accounts for the adsorption of pollutants and the utilization of visible light. Moreover, the formation of RT/CN heterojunction contributes to the rapid separation and transfer of photogenerated electron-hole pairs under visible light. In brief, the facile synthesis strategy for heterojunction based on adsorption-photocatalysis mechanism displays high potential of practical application in the removal of high-chroma organic pollutants.

Prescription of online hemodiafiltration (ol-HDF).

HDF prescription should be able to satisfy the delivery of an optimal dialytic convective dose. Several factors are implicated in this endeavor. High blood flow rate is crucial to warranty processing an adequate blood volume and to ensure the highest shear rate per fiber needed to cleanse and prevent membrane fouling. A highly permeable dialyzer is needed with a surface area aligned to blood flow and performance needs. Anticoagulation requires specific adaptation in case of low molecular weight heparin use. By default, HDF prescription modality should ideally start by postdilution mode with a stepwise increment of convective dose by probing patient tolerance and efficacy. Alternative substitution modality should be considered if dialytic convective dose could not be achieved in the usual time frame. Convective dose prescription relies either on a manual mode (pressure control or volume control) or on automated mode (ultrafiltration control) depending on the technical options of the HDF machines. Dialysate flow rate is regulated by the HDF machine but should preferably keep constant dialysis fluid flowing the dialyzer with a Qb:Qd ratio of 1.4. Treatment time should not be reduced with HDF prescription. Treatment time should fit with patient tolerance (hemodynamic, osmotic, and solute shifts) and overall solute removal efficiency. Electrolytic prescription does not require specific adjustments as compared with conventional dialysis, but the patient needs to be monitored regularly and dialysate electrolyte adjusted to lab tests. A stepwise approach for implementing ol-HDF is preferable depending on the initial condition of the patient. Three particular cases may be considered: late-stage chronic kidney disease patient transitioning to renal replacement therapy, stable dialysis patient switching to HDF, and unstable or fragile patient or specific treatment schedule. Optimal dosing of HDF and personalized care to ensure treatment adequacy is the main goal for renal replacement therapy to improve patient outcomes. That should be ensured with HDF treatment.

Enhancement of solute removal efficiency of polyamide reverse osmosis membrane without water permeability loss

This study investigates the enhancement of the solute removal efficiency of reverse osmosis (RO) membranes without water permeability loss during the treatment of secondary wastewater effluent (SWE). First, filtration experiments were performed using a synthetic SWE containing three types of solutes with different membrane transport properties, namely arsenious acid (H3AsO3), electrolyte, and rhodamine-WT (R-WT), and alginate as a representative biopolymer foulant. The flux of R-WT at 2.0 MPa decreased by up to 45% in the presence of alginate without decreasing water permeability; this trend was not observed for H3AsO3 and the electrolyte, indicating that nanoscale imperfections that allow unselective solute transport were plugged by alginate. Second, H3AsO3 and R-WT were spiked into a real SWE that was pretreated using 0.1 µm microfiltration, and the enhancement of solute removal efficiency was investigated. Membrane performance after 14 days of operation revealed that the flux of R-WT at 2.0 MPa decreased by up to 44% in the presence of the biopolymer. These results demonstrated that nanoscale imperfections in the RO membrane were plugged by the biopolymer contained in SWE and that the removal of large solutes was enhanced without forfeiting water permeability.

Performance prediction of suspension freeze crystallization for the treatment of liquid hazardous wastes via machine learning methods

The experimental method for determining treatment efficiency of suspension freeze crystallization (SFC) on liquid hazardous wastes (LHWs) is accurate but complex, costly and time-consuming. In the present study, artificial neural works (ANN) and random forest (RF), two machine learning methods, were utilized to develop models that were capable of predicting the treatment performance of SFC based on 8 typical LHWs. The targeted solutes in the chosen LHWs were characterized by COD, TOC, TDS, sulfide, conductivity, etc. The models were induced and tested to predict solute removal efficiency in accordance with freezing conditions and solution characteristics of 328 pieces of data collected from previous publications. Although both models have comparable predictive power, RF model presented better prediction accuracy and power (R2 = 0.9811, RMSE = 0.0323) than ANN model (R2 = 0.9615, RMSE = 0.0481). At the same time, the RF models showed better generalization ability than ANN models regardless different LHWs. The variable importance measurement indicated that ice phase fraction was the most important factor for solute removal efficiency in SFC process. The accurate predictability of developed models could be used before actual experiment to predict the removal efficiency of SFC according to various independent variables, so as to significantly reduce experiment workload of searching for the optimum freezing conditions. The variable importance measurement could provide a right direction for adjust the higher treatment efficiency of SFC on LHWs in the real situation.

Effect of Dynamic Circuit Pressures Monitoring on the Lifespan of Extracorporeal Circuit and the Efficiency of Solute Removal During Continuous Renal Replacement Therapy.

Objective: To observe the effects of dynamic pressure monitoring on the lifespan of the extracorporeal circuit and the efficiency of solute removal during continuous renal replacement therapy (CRRT).Materials and Methods: A prospective observational study was performed at the West China Hospital of Sichuan University in the ICU. Analyses of the downloaded pressure data recorded by CRRT machines and the solute removal efficiencies, calculated by 2*Ce/(Cpre+Cpost), where Ce, Cpre, and Cpost are the concentrations of the effluent, pre-filter blood, and post-filter blood, respectively, were performed. Samples were collected at 0, 2, 6, 12, and 24 h when continuous veno-venous hemodiafiltration (CVVHDF) was used after the initiation of CRRT. Measurements in concentrations of creatinine, blood urea nitrogen, and β2-microglobulin in the plasma and effluent were recorded.Results: Extracorporeal circuits characterized by moderate-to-severe (M–S) access outflow dysfunction (AOD) events, defined as access outflow pressure less than or equal to −200 mmHg for more than 5 min, had shorter median lifespans with no anticoagulation (32.3 vs. 10.90 h, P = 0.001) compared with the no M–S AOD events group. The significant outcome also existed in regional citrate anticoagulation (RCA) (72 vs. 42.47 h, P = 0.02). Moreover, Cox regression analysis revealed that the lack of M–S AOD events, RCA, or CVVHDF independently prolonged the circuit lifespan. All tested solutes removal efficiencies started to decline at 12 h. Furthermore, efficiencies of all solutes removal dropped obviously at 24 h when TMP ≥ 150 mmHg.Conclusion: RCA and CVVHDF predicted a longer circuit lifespan. M–S AOD events were associated with a shorter circuit lifespan when RCA or no anticoagulant was used. Replacement of extracorporeal circuit could be considered when running time of filter lasted up to 24 h with TMP ≥ 150 mmHg.

Construction of N-CQDs/InNbO4 composites for the removal of ipronidazole: Performance and degradation mechanism

Development of visible-light photocatalysts for the removal of nitroimidazoles pharmaceutical residues in the environment has attracted widespread attention. In this respect, a series of nitrogen-containing carbon quantum dots N-CQDs/InNbO4 composites were hydrothermally synthesized for the disposal of ipronidazole. N-CQDs coupled with irregular square shaped InNbO4 was confirmed by XRD, FTIR, TEM and XPS. The as-prepared N-CQDs/InNbO4 composites displayed stronger visible-light absorption from 400 ​nm to 800 ​nm. Owing to photosensitization and electron transfer ability of N-CQDs, the photocatalytic performance of N-CQDs/InNbO4 composites was better than that of InNbO4. The highest removal efficiency of ipronidazole solution was obtained in the presence of 3 ​wt % N-CQDs/InNbO4 composite. Reactive species ●O2−, hole, ●OH and electron all took part in the reaction process, while the removal of ipronidazole was most affected by ●O2−. Moreover, six new transformation products of ipronidazole were found during photocatalytic process.

Sizable iodine uptake of porous copolymer networks bearing Tröger's base units

Copolymer networks containing Tröger's base units TBP1-3 were synthesized in very good yields from a Sonogashira cross-coupling reaction of a specially designed diethynyl Tröger's base synthon TB with various tetrabrominated aryl derivatives. Thermogravimetric analysis (TGA) of TBP1-3 discloses high 10% weight loss temperature values reaching up to 443 °C. Nitrogen adsorption measurements of the target copolymers TBP1-3 reveal a strong correlation between porosity and the geometry of the aryl spacer whose inflexible rigid structure (biphenyl, TBP1), contorted configuration (spirobifluorene, TBP2), or fused aromatic structure (pyrene, TBP3) affords Brunauer-Emmett-Teller (BET) surface areas ranging from ~586 m2 g−1 to ~620 m2 g−1. Inspection of the iodine adsorption properties of TBP1-3 reveals their significant uptake of iodine vapors reaching a maximum of 440 wt% for TBP1 whereas TBP2 exhibits a very good removal efficiency of iodine solution in hexane attaining 77% (qe = 192 mg g−1). Furthermore, reusability tests disclose the possibility to regenerate the polymers even after several iodine adsorptions-desorption cycles.

Study on Preparation and Photocatalytic Performance of Two-Dimensional Carbon Nitride Nanosheet Materials

The thin g-C3N4 nanosheets were prepared by simple second-time etching approach with melamine as raw material. The microstructure, composition, thickness, specific surface area, and optical properties of the obtained materials were investigated by XRD, XPS, SEM, TEM, AFM, and BET. The results show that the specific surface area of the two-dimension ultrathin g-C3N4 nanosheets was as high as 139.42 m2/g, and the thickness was around 5nm, which improved the response range to visible light and promoted the separation of photogenerated electron-hole pairs. The photocatalytic degradation performance of g-C3N4 nanosheets for organic pollutants was studied with dye wastewater as model pollutant, the removal efficiency of RhB solution (20 mg/L) reached 91.8% with 20mg catalyst after 30min reaction. The content of total organic carbon in the solution decreased by 58.7%, and the first-order kinetic rate constant was 10 times than that of bulk-C3N4, indicating the high catalytic activity. The stability was excellent since the activity of catalyst was not significantly reduced after used for four times.

Removal of Congo Red from Aqueous Solution by Circulating Fluidized Bed(CFB)

In this study circulating fluidized bed was adopted to remove of Congo Red from wastewater using Eichhornia crassipes as a adsorbent. Solution flow rate(6,12 and 18)l/hr, bed height(2,4 and 6) cm and Congo Red initaial concentration (10,25 and 50)mg/l were examined in experiments to show their effects on breakthrough curves and time required to reach the adsorbent to fully saturated curve. The mass transfer coefficient "KL"decreased with decreasing the liquid flow rate. The minimum fluidization velocities of bed found equal to 1.6, 2, 2.5 mm/s for heights of 2, 4,6 cm respectively. The increasing of the bed height will increase the contact time of the solute in the bed, and these improve the solute removal efficiency. the increasing in flow rate and initial concentration will increase the mass transfer rate.

A composite adsorbent of ZnS nanoclusters grown in zeolite NaA synthesized from fly ash with a high mercury ion removal efficiency in solution

In this study, the nanocomposite adsorbent (ZnS-zeolite NaA) was prepared by a simple ion-exchange method, which modified the zeolite NaA synthesized from fly ash. The removal efficiency, adsorption mechanism of mercury ions by ZnS-zeolite NaA and release of zinc ion into aqueous solution during the adsorption process were determined. The results showed that ZnS nanoclusters were introduced the supercages of zeolite by ion exchange to synthesize the ZnS-zeolite NaA with high removal capacity for Hg2+ in the initial pH 2–7 of solution. Determination of the adsorption kinetics and thermodynamic parameters, in combination with X-ray diffraction, X-ray photoelectron spectroscopy and transmission electron microscopy analyses, revealed that the Hg2+ adsorption by ZnS-zeolite NaA was Hg2+ complexed and ion exchanged with ZnS in the ZnS-zeolite NaA to form stable HgS, and then, the released Zn2+ was adsorbed by the zeolite, preventing Zn2+ pollution. The Hg2+ removal rate was greater than 99.90% with the coexistence of either Zn2+ or Cu2+, Cd2+ and Pb2+. After five repetitions, the Hg2+ removal rate by the ZnS-zeolite NaA was only slightly decreased by 2%. Therefore, ZnS-zeolite NaA synthesized using fly ash has potential for broad application as a Hg2+ adsorbent.

Deployment of a New CRRT/PIRRT Device during the COVID-19 Pandemic Emergency: Organizational Challenges and Implementation Results

Introduction: The coronavirus disease 2019 (COVID-19) pandemic led to increased demand nationwide for dialysis equipment, including supplies and machines. To meet the demand in our institution, our surge plan included rapid mobilization of a novel continuous renal replacement treatment (CRRT) machine named SAMI. The SAMI is a push-pull filtration enhanced dialysis machine that can conjugate extremely high single-pass solute removal efficiency with very precise fluid balance control. Material and Methods: Machine assembly was conducted on-site by local biomedical engineers with remote assistance by the vendor. One 3-h virtual training session of 3 dialysis nurses was conducted before SAMI deployment. The SAMI was deployed in prolonged intermittent replacement therapy (PIRRT) mode to maximize patients covered per machine per day. Live on-demand vendor support was provided to troubleshoot any issues for the first few cases. After 4 weeks of the SAMI implementation, data on treatments with the SAMI were collected, and a questionnaire was provided to the nurse trainees to assess device usability. Results: On-site installation of the SAMI was accomplished with remote assistance. Delivery of remote training was successfully achieved. 23 PIRRT treatments were conducted in 10 patients. 7/10 of patients had CO­VID-19. The median PIRRT dose was 50 mL/kg/h (IQR [interquartile range] 44 – 62 mL/kg/h), and duration of the treatment was 8 h (IQR 6.3 – 8 h). Solute control was adequate. The user response was favorable to the set of usability questions involving user interface, on-screen instructions, machine setup, troubleshooting, and the ease of moving the machine. Conclusion: Assembly of the SAMI and training of nurses remotely are possible when access to vendor employees is restricted during states of emergency. The successful deployment of the SAMI in our institution during the pandemic with only 3-h virtual training supports that operating the SAMI is simple and safe.

P1100IMPACT OF THE RELATIONSHIP BETWEEN LOW MOLECULAR WEIGHT PROTEINS REMOVAL EFFICIENCIES AND THE VOLUME OF ALBUMIN LEAKAGE IN HEMODIAFILTRATION THERAPY

Abstract Background and Aims The purpose of hemodiafiltration (HDF) is to remove small- to large molecular weight solutes in order to prevent and treat complications and to improve the prognosis of dialysis patients. Especially, larger low molecular weight proteins (LMWPs) must be removed efficiently. β2-microglobulin (MG) (molecular weight [MW], 11.8 kDa: Stokes radius, 15.6A), is considered as an important marker of dialysis efficiency. However, MW of β2-MG is too small as a marker in HDF. Conversely, α1-MG (MW, 33 kDa: Stokes radius, 28.4A) is the most appropriate marker for evaluation of solute removal efficiency of HDF because of the following reasons: (1) optical molecular size; (2) not very low physiological blood concentration; (3) stable production rate; (4) removal by convection; and (5) accumulation in ESRD. Efficient removal of α1-MG without losing albumin (Alb) (MW,66 kDa: Stokes radius, 35.5A) is impossible even by HDF. In this study, we investigated the relationship between LMWP removal efficiencies and the volume of Alb leakage by analyzing the results of patients undergoing HDF. And we also evaluated the trend of the serum levels of patients who had received high-efficiency HDF for more than three years Method Eighty-seven patients who had received HDF in 2018–2019 were included. The results of HDF (a total of 435 sessions) were analyzed (blood flow rate, 261.5±28.5 mL/min; replacement fluid volume, 48.7 L/s pre-dilution on-line HDF and 14.2 L/s post-dilution on-line HDF). The removal efficiencies of β2-MG, prolactin (PRL), and α1-MG, and the volume of Alb leakage were examined. In addition, the relationship between the removal efficiency of each solute and the volume of Alb leakage was investigated. Changes in serum Alb level were analyzed in 13 patients who continued to receive high-efficiency HDF (the removal rate of α1-MG was 30% or more) for more than three years. Results Analysis of the results (mean ± SD) obtained from a total of 435 sessions (87 patients) showed that the removal rates of β2-MG, PRL, and α1-MG were 80.7 ± 4.5%, 75.8±9.4 and 33.8 ± 9.4%, respectively, and the Alb leakage was 3.9 ± 1.8 g/s. The equations of the approximate curve between Alb leakage and β2-MG, PRL, and α1-MG removal rates were expressed as follows: ï½™= 1.4197ln(x) + 78.972 (R2 = 0.0426), y = 9.7185ln(x) + 64.134 (R2 =0.4632), and ï½™™= 11.225ln(x) + 20.282 (R2 = 0.6191), respectively. These results indicate that the dynamics between Alb leakage and α1-MG removal are very similar. That is, although the molecular weight of Alb is twice as that of α1-MG, the difference in their Stokes radius is 20%; therefore, separate removal of Alb and α1-MG is impossible. The mean serum Alb level in 13 patients who received high-efficiency HDF for 3 years or longer was 3.59 ± 0.23 g/dL in January 2017 and 3.69 ± 0.28 g/dL in December 2019, revealing no changes. Conclusion The efficient removal of larger LMWPs leads to the leakage of Alb. However, an Alb leakage of 3 to 6 g/s has little influence on the serum Alb level of patients. Thus, α1-MG is the most appropriate marker of the solute removal efficiency of HDF.

Study on efficient removal of SOx and NOx from marine exhaust gas by wet scrubbing method using urea peroxide solution

Marine exhaust gas is seriously harmful to the environment, and only using a single pollutant treatment device is difficult to meet the emission regulations. It is imperative to study integrated and efficient marine exhaust gas pollutant removal technology. This study proposes a novel process capable of removing NOx and SOx in marine exhaust gas, and this process can achieve higher NOx and SOx removal efficiency and lower nitrate concentration by using urea peroxide (CO(NH2)2·H2O2) combined with a countercurrent scrubber. The effects of reaction temperature, urea peroxide concentration, liquid-gas ratio (L/G), SO2 concentration and urea concentration in urea peroxide solutions on NO removal were investigated. The results showed that the temperature and liquid-gas ratio played the key role at a fixed urea peroxide concentration, and the NOx removal efficiency increased with the increase of temperature (from 23 ℃ to 80 ℃) and liquid-gas ratio (from 2 L/m3 to 6 L/m3). The NO removal efficiency of urea peroxide solution was really higher than that of mixed solution of urea and hydrogen peroxide. The NO removal efficiency can reach above 90% with proper operating parameters. The larger liquid-gas ratio can make the urea peroxide concentration decrease, and the NO removal efficiency still met the emission regulation. The use of onefold urea peroxide can not only achieve higher SOx and NOx removal efficiency, but keep lower nitrate concentration. This novel process can be applied in ships combined with exhaust gas cleaning (EGC) system.

Drinking-Water Supply for CKDu Affected Areas of Sri Lanka, Using Nanofiltration Membrane Technology: From Laboratory to Practice

Installation of decentralized water-treatment plants is an ideal option to supply safe drinking water for rural communities. Presently in Sri Lanka, over 3.6 million villagers face acute water-quality problems, and chronic kidney disease of unknown etiology (CKDu) is also prevalent among this community. Most of the drinking water in these villages is unpalatable due to high hardness and salinity. As an interim measure, reverse-osmosis (RO) water-treatment plants are introduced to provide safe water. However, due to deficient electrolytes, RO-treated water tastes unpleasant to some consumers; hence, people refuse it after prolonged use. The operation, maintenance, and management of RO plants are other major problems. Aimed at providing safe drinking water to the rural sector in a cost-effective manner, in this study, we fabricated an automated drinking-water purification system based on nanofiltration (NF) membrane technology, which can remove divalent cations, dissolved organic carbon (DOC) and pathogens efficiently, and monovalent ions partially, and thus keep electrolytes to some degree. Ten commercial NF membranes were tested in a laboratory, for solute and DOC removal efficiency and robustness. The DF-90 membrane showed the highest removal of DOC and hardness, and it was therefore selected, to design a pilot NF drinking-water treatment plant. The adhered DOC by the membrane can be cleaned by NaOH solution (pH = 12). The pilot NF drinking-water treatment plant has been in use since September 2018, and it shows excellent performance of removing DOC, TDS, hardness, fluoride, and pathogens in groundwater, and the permeate water of the NF plant has been well-accepted by the stakeholders of the society. The dominant genus of source water, and throughout the two processes (NF and RO), is Pseudomonas, and their difference is significant in the concentrates of the NF and RO processes.

Water-in-oil-in-water (W/O/W) emulsion instability in emulsion liquid membrane: membrane breakage

Water-in-oil-in-water (W/O/W) emulsion system in Emulsion liquid Membrane (ELM) consist of three main phases which are membrane phase, internal phase and external phase. However, ELM performance is reported to be heavily affected by the emulsion stability. Instability of emulsions occurred as a result of metastable colloids that are made of two immiscible liquids, where one being dispersed in the other with the presence of surface-active agent. Membrane breakage was identified as one of the causes of emulsion instability. This research work focuses on identifying best condition that records minimal breakage hence, high efficiency of solute removal can be anticipated. Influence of homogenization time and speed, carrier concentration and surfactant concentration on membrane breakage were investigated. Data recorded shows that the emulsion needs to be homogenized at 8000 rpm for 15 mins to obtain minimal breakage of membrane. On top of that, membrane phase consists of 4 wt% of carrier (D2EHPA) and 4 wt% of surfactant (Span 80) dissolved in kerosene is needed. 0.14% of breakage was recorded at the conditions mentioned.

Cu and Co nanoparticles co-doped MIL-101 as a novel adsorbent for efficient removal of tetracycline from aqueous solutions

Chromium metal-organic framework (MIL-101(Cr)) has been widely studied for removing organic contaminants from aqueous solutions due to its excellent water stability and giant pore size, but its low adsorption capacity limits the application. In this study, a new adsorbent MIL-101 loaded with CuCo bimetallic nanoparticles (CuCo/MIL-101) was successfully fabricated and applied in removal of tetracycline (TC) from aqueous solutions. The adsorption capacity of CuCo/MIL-101 for TC increased by 140% compared with that of pure MIL-101, which may be attributed to the chemical bonding between Cu and Co BNPs in MIL-101 and TC molecules. The effects of pH, ionic strength, humic acid and contact time on the adsorption were also discussed in detail. The results showed that the removal efficiency of TC solution with high concentration (100 mg L−1) by CuCo/MIL-101 was still as high as 82.9%. The data of adsorption kinetics and isotherms could be well fitted by Elovich model and Freundlich model, respectively. According to the fitting parameters, the maximum adsorption capacity of CuCo/MIL-101 reached up to 225.179 mg g−1. Additionally, the adsorption process of TC onto CuCo/MIL-101 was spontaneous and endothermic. Electrostatic interactions could play an important role in the adsorption process. The enhanced adsorption capacity, excellent reusability and water stability demonstrated the potential of CuCo/MIL-101 composite as a novel adsorbent for the removal of TC from aqueous solutions.