ABSTRACT
The recovery of rare earth elements (REEs) including neodymium (Nd) and dysprosium (Dy) from NdFeB permanent magnets has become one of the main ways to solve the increased demand for rare earth. Herein, n-dodecyl phosphate (DPPA) was used for the first time as the adsorption functional group donor, sodium alginate as the substrate, and calcium chloride solution as the reactive solvent, a hybrid hydrogel adsorbent DPPA/CaALG was synthesized by sol-gel method for application in the adsorption and separation of Nd and Dy from the Co-Nd-Dy ternary system. SEM-EDS, and N2 adsorption-desorption analysis showed the successful preparation of DDPA/CaALG with mesoporous structure. Batch experiments showed the superiority of the hybrid hydrogel for the good selective adsorption of Nd and Dy, such as large adsorption capacity (Nd: 162.5 mg/g, Dy: 183.5 mg/g), and no adsorption for Co. FT-IR, XPS showed that PO and P-O groups are involved in the adsorption process of Nd and Dy as electron acceptors, where the ion exchange of P-OH is dominant. Furthermore, the chemical properties of ligands and complexes were analyzed by Density Functional Theory (DFT) calculations and revealed their adsorption behaviors as well as the competition between different metal ions.
Subject(s)
Metals, Rare Earth , Neodymium , Dysprosium , Hydrogels , Adsorption , Alginates , Spectroscopy, Fourier Transform Infrared , PhosphatesABSTRACT
Cobalt carbides are emerging as promising materials for various magnetic and catalytic applications. However, exploring dedicated cobalt carbides with optimal catalytic properties via adjusting phase compositions remains a significant challenge. Herein, three different cobalt carbides, CoxC (Co2C-Co3C), Co2C-Co, and Co3C, were successfully prepared using a facile one-pot green method. The phase compositions of cobalt carbides could be easily controlled by varying the cobalt-based precursors and carbon sources. More remarkably, three different cobalt carbides could serve as reduction cocatalysts decorated CdS for improved hydrogen production under visible light. Intriguingly, the obtained Co3C/CdS nanocomposite displayed the highest photocatalytic hydrogen evolution activity among the three composites and superior photocatalytic stability. This work provides a fundamental approach to tuning the photocatalytic properties of cobalt carbides for energy conversion fields.
ABSTRACT
Arsenic (As) is a toxic non-essential metal. Its accumulation in rice has not only seriously affected the growth of rice, but also poses a significant threat to human health. Many reports have been published to decrease the arsenic accumulation in the rice plant by various additives such as chemicals, fertilizers, adsorbents, microorganisms and analyzing the mechanism. Nanobubble is a new technology widely used in agriculture because of its long existence time and high mass transfer efficiency. However, a few studies have investigated the effect of nanobubbles on arsenic uptake in rice. This study investigated the effect of oxygen nanobubbles on the growth and uptake of As in rice. The oxygen nanobubbles could rupture the salinity of nutrients and produce the hydroxyl radical. The hydroxyl radical caused the oxidation of arsenic As(III) to As (V) and the oxidation of ferrous ions. At the same time, the oxidized iron adsorbing As (V) created the iron plaque on the rice roots to stop arsenic introduction into the rice plant. The results indicated that the treatment of oxygen nanobubbles increased rice biomass under As stress, while they increased the chlorophyll content and promoted plant photosynthesis. Oxygen nanobubbles reduced the As content in rice roots to 12.5% and shoots to 46.4%. In other words, it significantly decreased As accumulation in rice. Overall, oxygen nanobubbles mitigated the toxic effects of arsenic on rice and had the potential to reduce the accumulation of arsenic in rice.
Subject(s)
Arsenic , Oryza , Soil Pollutants , Humans , Seedlings , Arsenic/analysis , Hydroponics , Oxygen , Hydroxyl Radical , Plant Roots , Iron/analysis , Soil Pollutants/pharmacologyABSTRACT
The effective removal of radioactive strontium (especially 90Sr) from nuclear wastewater is crucial to environmental safety. Nevertheless, materials with excellent selectivity in Sr removal remain a challenge since the similarity with alkaline earth metal ions in the liquid phase. In this work, a novel titanium phosphate (TiP) aerogel was investigated for Sr(II) removal from the radioactive wastewater based on the sol-gel method and supercritical drying technique. The TiP aerogel has amorphous, three-dimensional and mesoporous structures with abundant phosphate groups, which was confirmed by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS), atomic force microscope (AFM) and Fourier transform infrared spectroscopy (FT-IR). The adsorbent exhibited high efficiency and selectivity for the removal of Sr(II) with an extensive distribution coefficient up to 4740.03 mL/g. The adsorption equilibrium reached within 10 min and the maximum adsorption capacity was 373.6 mg/g at pH 5. And the kinetics and thermodynamics data fitted well with the pseudo-second-order model and Langmuir model respectively. It can be attributed to the rapid trapping and slow intraparticle diffusion of Sr(II) inside the mesoporous channels of the TiP aerogel. Furthermore, TiP aerogel exhibited over 80% removal for 50 mg/L Sr2+ in real water systems (seawater, lake water and tap water). X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy revealed that strong ionic bonding formed during Sr(II) adsorption with the phosphate group on TiP aerogel. These results indicated that TiP aerogel is a promising high-capacity adsorbent for the effective and selective capture of Sr(II) from radioactive wastewater.
Subject(s)
Strontium , Water Pollutants, Chemical , Strontium/analysis , Wastewater/chemistry , Spectroscopy, Fourier Transform Infrared , Adsorption , Water Pollutants, Chemical/chemistry , Water/chemistry , Kinetics , Phosphates , Hydrogen-Ion ConcentrationABSTRACT
The electron-rich squarate ion (C4O42-, SA2-) possesses electronic delocalization over the entire molecule and good redox activity, and the functionalization of metal-organic complexes with the SA2- group is desirable. In this work, a mixed-ligand method is used to construct novel uranyl squarate coordination polymers utilizing 4,4'-bipyridine (bpy), 4,4'-bipyridine-N,N'-dioxide (bpydo), 1,10-phenanthroline (phen), 4,4'-vinylenedipyridine (vidpy), and in situ formed oxalate (OA2-) as ancillary ligands. Seven mixed-ligand uranyl compounds, [(UO2)(OH)(SA)](Hbpy) (1), [(UO2)(H2O)(SA)2](H2bpy) (2), (UO2)(H2O)(SA)(bpydo)·2H2O (3), (UO2)(H2O)(SA)(phen)·H2O (4), (UO2)(OH)(SA)0.5(phen)·H2O (5), [(UO2)(SA)(OA)0.5](Hphen) (6), and [(UO2)(SA)(OA)0.5](Hvidpy) (7), with varying crystal structures were synthesized under hydrothermal conditions. Compound 1, together with bpy molecules filling in the interlayer space as template agents, has a two-dimensional (2D) network structure, while 2 gives a one-dimensional (1D) chain based on mononuclear uranium units. Compound 3 shows a neutral 2D network through the combined linkage of SA2- and bpydo. Both 4 and 5 have a similar chain-like structure due to the capping effect of phen motifs, while phen molecules in 6 act as templating agents after protonation. Similar to 6, compound 7 has a "sandwich-like" structure in which the Hvidpy motifs locate in the voids of layers of 2D uranyl-squarate networks. The redox properties of typical mixed-ligand uranyl-squarate compounds, 1, 4, and 5 with high phase purity, are characterized using cyclic voltammetry. All three of these uranyl coordination compounds show anode peaks (Ea) at 0.777, 0.804, and 0.760 V, respectively, which correspond to the oxidation process of SA2- â SA. Meanwhile, cathodic peaks (Ec) at -0.328, -0.315, and -0.323 V corresponding to the reduction process of U(VI) â U(V) are also observed. The results reveal that all three of these uranyl coordination compounds show good redox activity and, most importantly, the interplay between two different redox-active motifs of SA2- organic linker and uranyl node. This work enriches the library of redox-active uranyl compounds and provides a feasible mixed-ligand method for regulating the synthesis of functional actinide compounds.
ABSTRACT
The strong demand for rare-earth elements (REEs) is driven by their wide use in high-tech devices. New processes have to be developed for valorizing low-grade ores or alternative metal sources (such as wastes and spent materials). The present work contributed to the development of new sorbents for the recovery of rare earth ions from aqueous solutions. Functionalized mesoporous silica composite was synthesized by grafting diethylenetriamine onto composite support. The physical and chemical properties of the new sorbent are characterized using BET, TGA, elemental analysis, titration, FTIR, and XPS spectroscopies to identify the reactive groups (amine groups: 3.25 mmol N g-1 and 3.41 by EA and titration, respectively) and their mode of interaction with Nd(III) and Gd(III). The sorption capacity at the optimum pH (i.e., 4) reaches 0.9 mmol Nd g-1 and 1 mmol Gd g-1. Uptake kinetics are modeled by the pseudo-first-order rate equation (equilibrium time: 30-40 min). At pH close to 4-5, the sorbent shows high selectivity for rare-earth elements against alkali-earth elements. This selectivity is confirmed by the efficient recovery of REEs from acidic leachates of gibbsite ore. After elution (using 0.5 M HCl solutions), selective precipitation (using oxalate solutions), and calcination, pure rare earth oxides were obtained. The sorbent shows promising perspective due to its high and fast sorption properties for REEs, good recycling, and high selectivity.
Subject(s)
Amines/chemistry , Gadolinium/chemistry , Neodymium/chemistry , Polymers/chemistry , Silicon Dioxide/chemistry , Adsorption , Hydrogen-Ion Concentration , Industrial Waste/analysis , Kinetics , Photoelectron Spectroscopy , Porosity , Solutions , Spectroscopy, Fourier Transform InfraredABSTRACT
There is a need for developing new sorbents that incorporate renewable resources for the treatment of metal-containing solutions. Algal-polyethyleneimine beads (APEI) (reinforced with alginate) are functionalized by grafting amidoxime groups (AO-APEI). Physicochemical characteristics of the new material are characterized using FTIR, XPS, TGA, SEM, SEM-EDX, and BET. AO-APEI beads are tested for the recovery of Sr(II) from synthetic solutions after pH optimization (≈ pH 6). Uptake kinetics is fast (equilibrium ≈ 60-90 min). Sorption isotherm (fitted by the Langmuir equation) shows remarkable sorption capacity (≈ 189 mg Sr g-1). Sr(II) is desorbed using 0.2 M HCl/0.5 M CaCl2 solution; sorbent recycling over five cycles shows high stability in terms of sorption/desorption performances. The presence of competitor cations is studied in relation to the pH; the selectivity for Sr(II) is correlated to the softness parameter. Finally, the recovery of Sr(II) is carried out in complex solutions (seawater samples): AO-APEI is remarkably selective over highly concentrated metal cations such as Na(I), K(I), Mg(II), and Ca(II), with weaker selectivity over B(I) and As(V). AO-APEI appears to be a promising material for selective recovery of strontium from complex solutions (including seawater).
Subject(s)
Microspheres , Oximes/chemistry , Polyethyleneimine/chemistry , Rhodophyta/chemistry , Strontium/isolation & purification , Adsorption , Hydrogen-Ion Concentration , Kinetics , Photoelectron Spectroscopy , Rheology , Seawater/chemistry , Solutions , Temperature , Water Pollutants, Chemical/isolation & purificationABSTRACT
A 59-year-old woman was admitted with to our hospital with a sudden severe headache that had lasted for 5 days. Neck stiffness was present, but no other neurological deficits were present. Subarachnoid hemorrhage and intra-tumor hemorrhage were not noted on a head computed tomography (HCT). The patient's cerebrospinal fluid was xanthochromic. Magnetic resonance imaging (MRI) demonstrated a gadolinium-enhanced tumor with hemorrhagic changes around the foramen magnum. After conservative therapy, MRI showed a decrease in tumor size and a dural tail sign. This tumor was diagnosed as a hemorrhagic meningioma, and was resected with a posterior suboccipital approach. Histology confirmed that this tumor was a benign transitional meningioma with hemorrhagic change. This is a rare case involving benign meningioma onset by hemorrhagic change. Postoperative tumor recurrence was not present.
Subject(s)
Foramen Magnum/pathology , Meningeal Neoplasms/pathology , Meningioma/pathology , Subarachnoid Hemorrhage/pathology , Female , Foramen Magnum/surgery , Humans , Magnetic Resonance Imaging , Meningeal Neoplasms/complications , Meningeal Neoplasms/surgery , Meningioma/complications , Meningioma/surgery , Middle Aged , Multimodal Imaging , Subarachnoid Hemorrhage/etiology , Subarachnoid Hemorrhage/surgery , Tomography, X-Ray ComputedABSTRACT
Understanding the interaction mechanism between polymeric flocculants and solid particles in two oppositely charged solutions: bentonite and calcium fluoride, is of great practical and fundamental importance. In this work, inorganic flocculants based on aluminum(III) or iron(III); cationic, anionic and non-ionic organic flocculants were used. The solution pH, which highly influenced the flocculation performance of the system, has been used as a function of turbidity removal, sediment volume and velocity. Results show that the flocculation of inorganic polymers does not depend on the zeta potential but on the solution pH, contrary for cationic and anionic polymers. Non-ionic polymer was independent on both. By varying the final pH of the heterogeneous solution formed of flocs-liquid, it was found for inorganic polymers, the optimum condition of pH < 3 to separate inorganic flocculant particles from flocs. Inductively coupled plasma atomic emission spectrometer and X-ray fluorescence analysis proved the reversibility of flocculation process by indicating the concentration of flocculant representative atom (Al or Fe) in the flocs and in the emerging solutions when the flocculation was optimized and the reversibility was effective. As results, weak forces were suggested as responsible for inorganic polymers flocculation where electrostatic interaction and hydrogen bonds may enroll the mechanism of organic flocculants.
Subject(s)
Flocculation , Polymers/chemistry , Bentonite/chemistry , Calcium Fluoride/chemistry , Microscopy, Electron, Scanning , Nephelometry and TurbidimetryABSTRACT
A 51 year old male was admitted to our hospital with sudden consciousness disturbance, global aphagia and right hemiparesis. Magnetic resonance imaging (MRI) revealed fresh infarctions in the territory of the left middle cerebral artery, and MR angiography (MRA) showed occlusion of the left carotid artery and the left middle cerebral artery. We started conservative therapy, including antiplatelet drug and blood pressure control. Three days later, cervical MRA revealed hematoma in the intracranial carotid wall of the petrous portion, leading to a diagnosis of spontaneous intracranial carotid artery dissection of the petrous portion. Two weeks after admission, MRA and angiography showed recanalization and pearl and string sign in the left petrous internal carotid artery. After that, the patient's neurological deficit improved, and the dissection also improved. Four months later, MR-angiography revealed an almost normalized condition.
Subject(s)
Carotid Artery, Internal, Dissection/diagnosis , Carotid Artery, Internal, Dissection/etiology , Infarction, Middle Cerebral Artery/diagnosis , Infarction, Middle Cerebral Artery/etiology , Stress, Psychological/complications , Workload/psychology , Workplace/psychology , Antipyrine/analogs & derivatives , Antipyrine/therapeutic use , Arginine/analogs & derivatives , Carotid Artery, Internal, Dissection/drug therapy , Carotid Artery, Internal, Dissection/pathology , Diagnosis, Differential , Edaravone , Humans , Infarction, Middle Cerebral Artery/drug therapy , Infarction, Middle Cerebral Artery/pathology , Intracranial Embolism/complications , Magnetic Resonance Angiography , Magnetic Resonance Imaging , Male , Middle Aged , Personnel Turnover , Pipecolic Acids/therapeutic use , Platelet Aggregation Inhibitors/therapeutic use , Stroke/complications , SulfonamidesABSTRACT
Carbon dioxide (CO2) emissions are a leading contributor to the negative effects of global warming. Globally, research has focused on effective means of reducing and mitigating CO2 emissions. In this study, we examined the efficacy of eco-industrial parks (EIPs) and accelerated mineral carbonation techniques in reducing CO2 emissions in South Korea. First, we used Logarithmic Mean Divisia Index (LMDI) analysis to determine the trends in carbon production and mitigation at the existing EIPs. We found that, although CO2 was generated as byproducts and wastes of production at these EIPs, improved energy intensity effects occurred at all EIPs, and we strongly believe that EIPs are a strong alternative to traditional industrial complexes for reducing net carbon emissions. We also examined the optimal conditions for using accelerated mineral carbonation to dispose of hazardous fly ash produced through the incineration of municipal solid wastes at these EIPs. We determined that this technique most efficiently sequestered CO2 when micro-bubbling, low flow rate inlet gas, and ammonia additives were employed.
Subject(s)
Carbon Dioxide/analysis , Carbon/chemistry , Industry , Minerals/chemistry , Coal Ash , Incineration/methods , Refuse Disposal/methods , Republic of KoreaABSTRACT
To promote the environmentally friendly and sustainable development of nuclear energy, it is imperative to address the treatment of wastewater generated by the nuclear industry. This necessitates the enhancement of fission product reclamation efficiency post-treatment. This study aims to combine defect control and confined self-assembly strategies for the precise design of interlayer spacing (14.6 Å to 15.1 Å), leading to the fabrication of conditional natroxalate-functionalized vanadosilicate, and its potential application in the efficient adsorption and reclamation of 90Sr. Na0.03Natroxalate2.47Si1.44Nb0.08V1.92O5·1.2 H2O (Nb4-NxSiVO), with a layer spacing of 14.9 Å, exhibits the highest Sr(II) adsorption capacity (248.76 mg/g), enabling effective separation with Cs+. The natroxalate embedded within the confined interlayers demonstrates excellent stability, offering rapid (within 10 min) and stable adsorption sites for Sr(II). Furthermore, Nb4-NxSiVO exhibits a wide band gap and exceptional thermal stability before and after adsorption, rendering hard desorption of 90Sr. The findings highlight the potential of Nb4-NxSiVO as a promising adsorbent for rapid and selective purification of 90Sr-containing wastewater and further application in nuclear batteries.
ABSTRACT
Zirconium is recognized as one of the main impurities of the rare earth element scandium during purification. It presents significant challenges due to its similar chemical properties, making separating it difficult. This study used trialkyl phosphine oxide (TRPO) as a functional ligand, and the effects of carrier type and acidity on adsorption performance were first investigated. Among these, the novel extraction resin SiO2-P as a carrier for TRPO demonstrated more prominent separation performance in 0.2 M H2SO4 and 5 M HCl solutions. The kinetic and isotherm data were consistent with the pseudo-secondary kinetics and Langmuir model, respectively, and the adsorption process could be regarded as homogeneous monolayer adsorption subject to the dual effects of chemisorption and internal diffusion. In addition, thermodynamic analysis showed that the adsorption process of zirconium under the experimental conditions was a spontaneous endothermic process. Combined with the results of SEM-EDS, FT-IR, and XPS analyses, scandium and zirconium were successfully adsorbed by the resin and uniformly distributed on its surface, and the greater affinity of the P=O groups on the resin for zirconium was the critical factor contributing to the separation of scandium and zirconium. Finally, scandium and zirconium in sulfuric acid and hydrochloric acid media were extracted and separated by column experiments, and the purity of scandium could reach 99.8% and 99.99%, respectively.
ABSTRACT
A MOF-on-MOF composite derivative material named ZIF-67@Ce-MOF-600 was designed and synthesized. The preparation of ZIF-67@Ce-MOF-600 was optimized from the aspects of the ratio of metal and ligand, heat-treatment temperature. It was demonstrated by XRD, FT-IR, SEM-EDS and TEM. The optimum conditions for the activation of PMS by ZIF-67@Ce-MOF-600 for the degradation of tetracycline (TC) were investigated by adjusting the catalyst dosage, TC, pH, peoxymonosulfate (PMS) concentration, and different kinds of water, co-existing anions and pollution. Under optimal conditions (20 mg catalysts and 50 mg PMS added) in 100 mL of tetracyclines (TC) solvent (20 mg TC/L), the removal rate could reach up to 99.2% and after five cycles was 70.5%. The EPR results indicated the presence of free radicals and non-free radical, among which free radicals intended to play a major role in the degradation process. Its possible degradation pathways and attack sites were analyzed by liquid-phase mass spectrometry and DFT analysis.
Subject(s)
Metal-Organic Frameworks , Peroxides , Tetracycline , Water Pollutants, Chemical , Metal-Organic Frameworks/chemistry , Water Pollutants, Chemical/chemistry , Tetracycline/chemistry , Peroxides/chemistry , Water Purification/methods , Catalysis , Water/chemistryABSTRACT
Efficient recognition, separation and recovery of palladium from high-level liquid waste (HLLW) not only helps the safe, green and environmentally friendly disposal of nuclear waste, but also is an essential important supplement to overcome the growing shortage of natural palladium resources. Herein, a novel silica-based functional adsorbent named 2AT-SiAaC was prepared by a two-step method, i.e., grafting of 2-aminothiazole (2AT) via the amidated reaction after in-situ polymerization of acrylic monomers on porous silica. SEM, EDS, TG-DSC, BET and PXRD all proved the successful preparation of 2AT-SiAaC, and it exhibited ultrahigh adsorption selectivity for Pd(II) (Kd (distribution coefficient) ≥ 10,344.2 mL/g, SFPd/M (separation factor) ≥ 613.7), fast adsorption kinetics with short equilibrium time (t ≤ 1 h) and good adsorption capacity (Q ≥ 62.1 mg Pd/g). The dynamic column experiments shows that 2AT-SiAaC achieved efficiently separation of Pd(II) from simulated HLLW, and the enrichment coefficients (C/C0) of Pd(II) was as high as about 14 with the recovery rate nearly 99.9% and basically kept the same performance in three adsorption-desorption column cycle experiments. The adsorption mechanism was analyzed by FT-IR, XPS and DFT calculations, and the ultrahigh selectivity of 2AT-SiAaC was attributed to the preferred affinity of the soft N-donor atoms in 2AT for Pd(II). NO3- ions participated in the adsorption reaction to keep charge balance, and the frontier orbital electron density distribution diagram shows the charge transfer in the process of material preparation and adsorption. To sum up, 2AT-SiAaC adsorbent provided a new insight for precise recognition and efficient separation of Pd(II) from HLLW.
Subject(s)
Palladium , Thiazoles , Water Pollutants, Chemical , Palladium/analysis , Silicon Dioxide , Spectroscopy, Fourier Transform Infrared , Adsorption , KineticsABSTRACT
Accurate separation and efficient recovery of platinum group metals (PGMs, mainly Ru, Rh and Pd) from high level liquid waste (HLLW) is a good choice for clean production and sustainable development of nuclear energy. Herein a novel SDB polymer modified silica-based amine-functionalized composite (dNbpy/SiO2-P) was synthesized for the separation and recovery of PGMs. Laser particle size analysis and BET results clarified the regular spherical and highly interconnected mesoporous structure of dNbpy/SiO2-P which is critical for the separation of PGMs. The removal percent of PGMs were over 99% on the optimized conditions. In addition, dNbpy/SiO2-P showed excellent selectivity (SFPd/M > 3805, SFRu/M > 1705, SFRh/M > 336) and repeatability (≥5). Interestingly, based on the different adsorption and desorption kinetics of PGMs, a double-column strategy is designed to solve the challenge of separating and recovering PGMs from HLLW. The enrichment factors of Pd(II), Ru(III) and Rh(III) reached 36.7, 8.2, and 1.2. The adsorption of PGMs was coordination mechanism and required the involvement of NO3- to maintain charge balance. The specific distribution of elements within the adsorbents and the changes in valence state were analyzed using depth-profiling XPS. Both depth-profiling XPS results and slope analysis revealed that the complex of dNbpy and PGMs is a 1 : 1 coordination structure. Overall, this work fills the gap that PGMs cannot be effectively separated and enriched from HLLW.
ABSTRACT
The direct measurement of fine particles size distribution of dispersions or coagulations in liquid is important for water purification, fine particles separation for recycling and mineral processing, as well as the new material production. The nano to micro particle size is usually measured by light scattering method; however, it is difficult to measure at high concentration of suspension. Here, a novel dynamical method by using the interactive force measurement between particles in liquid under electric field is used for measuring distribution of fine particle. Three types of nano to submicron particles, that is well-dispersed nano particles, coagulated nano particles and settled submicron particles, have been measured by interactive force measurement method. The particle size distributions are compered with the size distributions of dried particles measured by TEM or SEM. The well-dispersed nano particle size distribution by interactive force measurement is influenced by the nano size surfactant micelles. The size distribution of coagulated nano particles in water is larger than the result by TEM. On the other hand, the submicron nickel particle size distribution is similar with the one analyzed by SEM.
ABSTRACT
Sea material is becoming increasingly popular and widely used as an adsorbent in wastewater treatment. Snail shell, a low-cost and natural animal waste material, has been shown to have a high calcium content (>99%) and a large potential surface area for the development of sustainable adsorbents. This paper presents a novel synthesis of methods for using snail shell absorbent materials in the treatment of wastewater containing heavy metals, textile dyes, and other organic substances. Modified biochar made from snail shells has gained popularity in recent years due to its numerous benefits. This paper discusses and analyzes modification methods, including impregnating with supplements, combining other adsorbents, synthesis of hydroxyapatite, co-precipitation, and the sol-gel method. The analysis of factors influencing adsorption efficiency revealed that pH, contact time, temperature, initial concentration, and adsorbent dose all have a significant impact on the adsorption process. Future research directions are also discussed in this paper as a result of presenting challenges for current snail adsorbents.
ABSTRACT
Nanobubbles have been applied in many fields, such as environmental cleaning, material production, agriculture, and medicine. However, the measured nanobubble sizes differed among the measurement methods, such as dynamic light scattering, particle trajectory, and resonance mass methods. Additionally, the measurement methods were limited with respect to the bubble concentration, refractive index of liquid, and liquid color. Here, a novel interactive force measurement method for bulk nanobubble size measurement was developed by measuring the force between two electrodes filled with bulk nanobubble-containing liquid under an electric field when the electrode distance was changed in the nm scale with piezoelectric equipment. The nanobubble size was measured with a bubble gas diameter and also an effective water thin film layer covered with a gas bubble that was estimated to be approximately 10 nm based on the difference between the median diameter of the particle trajectory method and this method. This method could also be applied to the solid particle size distribution measurement in a solution.
ABSTRACT
The synergistic effect between transition metal active centers and the generation of multiple removal pathways has a significant impact on the catalytic activation efficiency of peroxymonosulfate. In this work, a kind of composite catalyst was prepared by growing VCo-metal-organic frameworks (VCo-MOF) in-situ on the surface of Ti3C2Tx by a solvothermal method. The morphology and structure are characterized by Transmission Electron Microscope (TEM), Energy Dispersion Spectrum (EDS), Atomic Force Microscope (AFM), etc. Response surface methodology was used to optimize the experimental conditions. Only 5 mg catalyst can be used to effectively activate PMS and remove 96.14 % ciprofloxacin (CIP, 20 mg/L) within 30 min. The removal effect of catalyst on CIP in different actual water environment was explored. In addition, the fluorescence spectrum test also verified the effective removal of ciprofloxacin. V-Co-Ti ternary system provides a wealth of active sites for CIP removal. Cyclic voltammetry (CV) and lear sweep voltammetry (LSV) tests showed the existence of the electron transfer pathway. The results of density functional theory (DFT) calculation show that VCo-MOF@Ti3C2Tx has excellent adsorption and activation ability for PMS. At the same time, the hydrophilicity of the catalyst makes PMS more inclined to react with water molecules, which promotes the formation of a unique superoxide radical path.