Good Removal Effect Research Articles

Adsorption/desorption performance of Pb2+ and Cd2+ with super adsorption capacity of PASP/CMS hydrogel.

Super-absorbent polyaspartic acid/carboxymethyl Salix psammophila powder (PASP/CMS) hydrogel was prepared by aqueous solution polymerization. PASP/CMS hydrogel was characterized by Fourier-transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The results showed that PASP/CMS hydrogel is prepared by graft copolymerization of the -COOH of polyaspartic acid (PASP) and the -CH2OH of CMS. The surface of the hydrogel became dense from loose porosity, and Pb2+ and Cd2+ were adsorbed onto the surface of hydrogel. The crystallinity of CMS was destroyed by the addition of PASP. The initial concentration of Pb2+ and Cd2+, pH, adsorption time and adsorption temperature on the adsorption effect were studied through experiments. Results showed that hydrogel has a good removal effect on Pb(II) and Cd(II) ions. Pseudo-second-order kinetics and Langmuir isotherm models are represented in the process, which are spontaneous, exothermic and decreased in randomness, and it is a single layer chemical adsorption. At the same time, the effect of desorption experimental parameters (HNO3 initial concentration, desorption time, and desorption temperature) on the experiment was studied and optimized.

Activation of persulfate by green nano-zero-valent iron-loaded biochar for the removal of p-nitrophenol: Performance, mechanism and variables effects

In this study, with the green tea extraction solution as a reducing agent and green tea residues as a raw material of biochar, green nano zero-valent iron biochar (G-nZVI-BC) was prepared with the green synthesis method and then combined with potassium persulfate to degrade p-nitrophenol in water. Compared with zero-valent iron-loaded biochar (C-nZVI-BC) prepared by the traditional chemical liquid phase synthesis method, G-nZVI-BC containing tea polyphenols further improved dispersibility of Fe0 on biochar, prevented nZVI agglomeration on BC, and promoted PNP degradation. The system constructed by G-nZVI-BC/PDS showed the high oxidation resistance than the C-nZVI-BC/PDS system, thus endowing the synthesis material with long-term reactivity. Both the radical pathway and non-radical pathways contributed to catalytic degradation and free radicals played a key role. The G-nZVI-BC/PDS system realized the good removal effect on PNP in the pH range of 3.06–9.23. The reusability of G-nZVI-BC and the PNP removal effect in water body conditions indicated that G-nZVI-BC had a good application prospect in the field of water treatment.

Removal of extremely low concentration cobalt by intercalation composite material of carbon nitride/titanium dioxide

Due to the high toxicity and the great harm of radioactive cobalt to the human body and the environment, the removal of heavy metal cobalt ions from radioactive wastewater had attracted more and more scientific researchers. In this paper, the intercalation composite material of carbon nitride itanium dioxide (g-C3N4/TiO2) composite material which combined the advantages of the two materials was prepared and its actual effect of removing Co (Ⅱ) from wastewater was evaluated. Batch experimental method was employed for the investigation of the impact of solution pH during adsorption, adsorption kinetics, adsorption thermodynamics and adsorption isotherms. In this experiment, the saturation adsorption capacity of the composite material to Co (Ⅱ) was 91.55 mg/g, while the bulk g-C3N4 was only 13.2 mg/g. The adsorption kinetics showed that the adsorption process followed a pseudo-second-order kinetic model. The adsorption thermodynamic showed that the adsorption of Co (Ⅱ) was a spontaneous endothermic process. The Langmuir isotherm adsorption model was more consistent with the adsorption isotherm than the Freundlich model. The experimental results proved that g-C3N4/TiO2 composite material had a good adsorption and removal effect on extremely low concentration of Co (II) and was a promising adsorbent for removal radioactive Co (II) from nuclear industrial wastewater.

Study on melamine/bentonite polyurethane porous composite foam: Pb2+ adsorption and mechanical properties

AbstractIn this paper, by adding melamine and bentonite to the polyurethane (PU) foam, a porous composite material with heavy metal adsorption properties is obtained. The cell size of the PU porous composite foam was affected by the addition of melamine and bentonite particles. With the increase of particles amount, the cell size decreased. The compression performance of the composite foam increased by 54% after adding 8 wt% melamine particles. The optimal adsorption conditions such as pH, adsorption time, and initial concentration of PU porous composites were also explored. Result shows that porous composite foam had a good removal effect on Pb2+. Moreover, the Langmuir model, the Freundlich model, and the adsorption kinetic model are used to evaluate the adsorption capacity of the porous composite foam. It is of great significance to obtain porous composite with good heavy‐metal adsorption and high‐strength performance.

The use of modified coal gangue for the remediation and removal of phosphorus in an enclosed water area

Thermally activated coal gangue and lanthanum-modified coal gangue were prepared by thermal activation and hydrothermal methods, respectively. Their structures and properties were characterized by X-ray diffraction (XRD), attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR) and transmission electron microscopy (TEM). Thermally activated coal gangue and coal gangue modified by lanthanum were used in a closed water body and compared to polymeric ferric sulfate. The results show that gangue modified by lanthanum exhibits stronger chemical oxygen demand by chromium method (CODcr), total phosphorus (TP) and ammonia nitrogen (NH4-N) removal capacities in overlying water than thermally activated coal gangue. The concentrations of CODcr, TP and NH4-N in overlying water during the stable period reached 11–14 mg/L, 0.023–0.028 mg/L and 0.16–0.20 mg/L, respectively. Thermally activated coal gangue had a good removal effect on CODcr but a poor inhibition effect on the TP. Compared to the thermally activated coal gangue and polymerized ferric sulfate, the lanthanum-modified coal gangue exhibited a better capacity to fix phosphorus in sediment, and the phosphorus extracted by hydrochloric acid (HCL-P) and residual phosphorus (Res-P) levels in the sediment increased, where HCL-P accounted for 57.40% of the TP, exceeding the control group’s value by 34.15%. Thermally activated coal gangue showed a limited capacity to fix phosphorus in sediment, while polymeric ferric sulfate improved phosphorus extracted by bicarbonate dithionite (BD-P) content in the sediment.

Water model study of the removal effect of soluble gas floatation technology (SGFT) on inclusions with different characteristics

In this study, the removal effects of soluble gas floatation technology (SGFT) on inclusions with different characteristics were studied by using a self-made water model experimental device and Coulter counter. The water/CO2 system was used to simulate the molten steel/(H2, N2) system, and PP, PE and ABS particles were used to simulate the inclusions in molten steel. The experimental results show that this technology has good removal effects on particles with different characteristics. A large amount of fine bubbles can be formed when adding particles via heterogeneous nucleation, while no bubbles were formed without adding particles due to lack of nucleation cores. The removal rate of the particles increases with the increase of particle number. The size of the particles has a significant impact on its removal effect that the removal rate increases with the increase of particle size. The Ostwald ripening may appear on the bubble nucleation process on the surface of large particles, which can promote floating behavior and removal effect of the particles. The particles with different contact angles can be removed effectively by soluble gas floatation technology (SGFT), while the removal effect of particles with large contact angles is better.

Study on the effect of Fe and N co-doped supported TiO2/GF photocatalytic oxidation of nitrobenzene wastewater

This research aims to treat the refractory nitrobenzene wastewater in the industrial water treatment industry with modified supported TiO2, and to study its influence on the treatment effect.Experiments have found that by preparing Fe and N co-doped TiO2/GF supported catalysts, it has better catalytic performance. Under the same conditions, Fe and N co-doped TiO2/GF can degrade nitrobenzene wastewater better than single Doped with Fe-TiO2/GF and N-TiO2/GF, the removal rates of nitrobenzene and COD are as high as 97.2% and 92.5%, respectively.The Fe and N co-doped TiO2/GF catalyst overcomes the agglomeration of traditional powdered TiO2 in solution, and has a good removal effect on nitrobenzene wastewater.

Study on water purification effects and microbial community compositions of the estuarine wetland buffer zones during a low-temperature period

The estuarine wetland buffer zone of the Fuhe river plays an important role in terms of improving water quality of Baiyangdian lake. In this study, the water purification effect and microbial community composition of an estuarine wetland buffer zone during a low-temperature period were investigated (March, 2021). The results indicated that the pre-sedimentation ecological pond (Pep), the subsurface flow wetland (Sfw), and the aquatic plant pond (App) exhibited good removal effects on total phosphorus (TP) and NH3-N. In contrast, the removal effects on chemical oxygen demand (COD) and total nitrogen (TN) was unsatisfied. Various phosphorus removal bacteria were detected in the water samples from the Pep and the Sfw, such as Arthrobacter, Flavobacterium, and Planococcus. These findings indicated the water purification performance and the microbial community composition in an estuarine wetland buffer zone during a low-temperature period.

Effect of PAC on the Behavior of Dynamic Membrane Bioreactor Filtration Layer Based on the Analysis of Mixed Liquid Properties and Model Fitting.

Recently, dynamic membrane bioreactor (DMBR) has gradually gained the interest of researchers for the development of membrane technology. In this paper, we set up parallel experiments to investigate the effect of powder activated carbon (PAC) on organic matter removal, transmembrane pressure, and filter cake layer characterization to make an overall performance assessment of DMBR. The results showed that DMBR has a good removal effect on organic matter removal, and with a chemical oxygen demand removal rate over 85%. Protein was found to be the main membrane fouling substance. Due to the electric double-layer effect, membrane fouling tended to be alleviated when the PN/PS value was low. Using a filtration model under constant current conditions, the filtration process through the cake layer was observed to be consistent with cake-intermediate model.

Application of Two Kinds of Automatic Nucleic Acid Purifiers

Objective To investigate the effect of automatic nucleic acid purifiers QIAsymphony SP and QIAcube in the DNA extraction of samples of trace amount or mixed with inhibitors. Methods Different kinds of purification methods using QIAsymphony SP and QIAcube were applied to extract swabs which contained 30, 100, 150 and 300 cells and other samples which contained six types of inhibitors-heme, humic acid, lard, soil, rust and grease. PCR amplification and STR typing were performed on the extracted DNA templates to compare extracting efficiency and inhibitor removal ability of four different purification methods. Results Different purification methods showed similar extraction effects, 70.83%-100.00% of loci could be detected by amplification of DNA extracted from samples with 30, 100 and 300 cells, and the six types of inhibitors could be removed well. Conclusion The two automatic nucleic acid purifiers have a good inhibitor removal effect. For swabs with only 30 cells, after DNA extraction and amplification, the locus detection rate of samples can still be high, which can meet the requirements of local DNA laboratory work, and realize the standardization construction of the laboratory.

Modeling and experimental investigation of drilling force for low-frequency axial vibration-assisted BTA deep hole drilling

The ability to form regular chips and evacuate them smoothly is crucial for deep hole drilling. In this work, an eccentric cam mechanism is used to apply low-frequency axial vibration at the end of the drill tube for boring and trepanning association (BTA) deep hole machining, and the instantaneous cutting thickness equation of low-frequency axial vibration assisted drilling is derived, which can actively control the length of the chip and achieve a good chip removal effect. Considering the variable geometric parameters and the scale effect of teeth cutting, a new analytical model is established to obtain the instantaneous drilling force of staggered teeth BTA deep hole drill assisted by low-frequency axial vibration. The relevant parameters in drilling force model are identified, and the distribution laws of the normal friction angle, normal shear angle, and shear stress with instantaneous cutting layer thickness and drilling radius values are achieved. The influence of the vibration drilling process parameters, including feed, speed, amplitude, and frequency ratio, on the drilling force is investigated experimentally, and the validity of the drilling force model is verified. These results show that the drilling force model is reliable, and the thrust and torque of the low-frequency axial vibration assisted drilling relative to ordinary drilling are reduced by 21.63% and 13.74%, respectively.

Occurrence and fate of antibiotics, antimicrobial resistance determinants and potential human pathogens in a wastewater treatment plant and their effects on receiving waters in Nanjing, China

Antibiotics, antimicrobial resistance determinants and human pathogens are new types of environmental pollutants that pose a great threat to human health. Wastewater treatment plants (WWTPs) are important sources of novel pollutants; however, few studies have investigated their impact on surrounding natural water. Therefore, this study used a WWTP as the entry point to explore WWTP removal efficiency of antibiotics, antimicrobial resistance determinants and human pathogens and further analyze the impact of WWTP effluent on receiving waters. The investigated WWTP had a good removal effect on fluoroquinolones, macrolides, lincomycin, sulfanilamide, tetracycline and chloramphenicol antibiotics in wastewater, and the concentration of antibiotics in the WWTP's effluent was reduced by >80% relative to the influent. In addition to cmlA, the effect of the WWTP on antimicrobial resistance determinants removal was poor, although the effluent from the WWTP had no effect on the abundance of antimicrobial resistance determinants in the receiving water. However, with the dilution of receiving water, the abundance of antimicrobial resistance determinants gradually decreased. The WWTP could reduce the abundance of bacteria by 1000 times from influent water to effluent water. The major bacteria in the influent and effluent were Bacteroidetes and Proteobacteria. After effluent is discharged into receiving water, Cyanobacteria proliferate in large quantities, which can affect the microbial structure in the environment.The abundance of Acinetobacter, which was the predominant potential human pathogen in local wastewater, decreased dramatically after wastewater treatment. We also conducted an ecological risk assessment of the antibiotics identified and found that the ecological risk AZM and CLR posed to aquatic organisms was high. Overall, we identified the efficiency of WWTP control of antibiotics, antimicrobial resistance determinants and potential human pathogens and the impact of WWTP effluent on receiving water and provided data to support the control of the investigated pollutants.

Distribution Characteristics of Inorganic Solids in Biochemical Treatment System

This paper studies the accumulation mechanism of different types of inorganic solids in activated sludge system by taking two main kinds of inorganic solids-chemical sludge and sediment as the research object. In the chemical phosphorus removal experiment, self-made calcium silicate hydrate was used as the chemical phosphorus removal agent and added to the end of the biochemical system of domestic sewage for phosphorus removal experiment, while the fine sediment was simulated by quartz sand of 26, 73, 106, 165 and 210 μm respectively, and a complete mixture model of inorganic solid accumulation was established as Xiss =Ciss, inf × (SRT/HRT + 1) × (1 – e–t/SRT). The results showed that the self-made hydrated calcium silicate had good phosphorus removal effect, and the TP of domestic sewage could be removed from 7 mg/L to 0.5 mg/L. The chemical sludge accumulation in the phosphorus removal process conforms to the complete mixing model, and the relative errors of measured and predicted values of MLVSS/MLSS and MLISS were 1% and 3%, respectively. The sediment accumulation process does not conform to the completely mixed model. The relative error of MLVSS/MLSS is between 56% and 77%, and that of MLISS is between –45% and –80%. The accumulation forms of inorganic solids in different forms of activated sludge systems are also different. Chemical sludge is mainly suspended in the mixture, reducing the proportion of MLVSS/MLSS. In activated sludge system, sediment is accumulated in various forms such as suspension and deposition.

Deep-Learning Steganalysis for Removing Document Images on the Basis of Geometric Median Pruning

The deep-learning steganography of current hotspots can conceal an image secret message in a cover image of the same size. While the steganography secret message is primarily removed via active steganalysis. The document image as the secret message in deep-learning steganography can deliver a considerable amount of effective information in a secret communication process. This study builds and implements deep-learning steganography removal models of document image secret messages based on the idea of adversarial perturbation removal: feed-forward denoising convolutional neural networks (DnCNN) and high-level representation guided denoiser (HGD). Further—considering the large computation cost and storage overheads of the above model—we use the document image-quality assessment (DIQA) as threshold, calculate the importance of filters using geometric median and prune redundant filters as extensively as possible through the overall iterative pruning and artificial bee colony (ABC) automatic pruning algorithms to reduce the size of the network structure of the existing vast and over-parameterized deep-learning steganography removal model, while maintaining the good removal effects of the model in the pruning process. Experiment results showed that the model generated by this method has better adaptability and scalability. Compared with the original deep-learning steganography removal model without pruning in this paper, the classic indicators params and flops are reduced by more than 75%.

Efficient Picosecond Laser for Tattoo Removal in Rat Models.

BackgroundTattoos are popular in modern times. Due to the occurance of adverse effects such as poor aesthetic value, scar hyperplasia, and abnormal pigments, there is a high demand for uniform operation standards as well as standards for tattoo technologies. In the present study we used Sprague-Dawley rats to assess the tattoo removal efficacy of use of a picosecond laser at various energy values.Material/MethodsTattoos were made on the backs of rats, then we used a picosecond laser set at various energy parameters to remove the tattoos. After performing the removal procedure in multiple groups, we selected the most suitable energy levels with corresponding parameters for the tattoo removal. We recruited human volunteers who wanted their tattoos removed and used the energy level found to perform best during tattoo removal experiments. The tattoo removal effects were evaluated and verified. Four tattoo volunteers were treated by using the optimal energy parameters for picosecond laser technology.ResultsThrough characterization observation and pathological staining results, it was demonstrated that the 1.9 mJ/μbeam energy laser had the best hollowing effect and the most complete pigment particle crushing effect in the rat skin, and had the best tattoo removal effect.ConclusionsWe leveraged the evaluation standard to choose the most suitable energy value of the picosecond laser, which had a good tattoo removal effect and could be employed as a reference for clinical removal of tattoos. This process provides criteria for tattoo removal evaluations as well as alternatives for tattoo removal in clinical practice.

Effect of carbon source on pollutant removal and microbial community dynamics in treatment of swine wastewater containing antibiotics by aerobic granular sludge

Aerobic granular sludge sequencing batch reactor (AGSBR) is a promising approach for wastewater treatment. In the paper, the effects of methanol, starch and sucrose as carbon sources on the treatment of swine wastewater (SW) containing antibiotics by aerobic granular sludge (AGS) were studied. The results revealed that the carbon sources could affect the morphology, biomass, and settleability of AGS, and AGS could maintain a better sludge performance when sucrose was used as carbon source. The pollutants (ammonium nitrogen (NH+ 4-N), organic matter and total phosphorus (TP)) in SW also had a good removal effect, and the removal rates reached 81.14%, 96.83% and 97.37% respectively. The removal efficiencies of tetracycline (TC) and oxytetracycline (OTC) from SW were the best when sucrose as co-metabolic matrix by microorganisms. The analysis of miseq pyrosequencing demonstrated that carbon sources with methanol, starch and sucrose improved the diversity of microbial community in AGS, and the dominant bacteria also changed. The dominant groups involved in TC and OTC, removal at different classification levels suggested that the formation of bacterial communities was determined by carbon sources.

Abundance and removal characteristics of microplastics at a wastewater treatment plant in Zhengzhou.

The widespread use of synthetic polymers has made microplastic (MP) a new type of contaminant that has attracted worldwide attention. Studies have shown that wastewater treatment plants (WWTPs) are an important source of MP collection in the natural environment. This study investigated the removal efficiency and migration characteristics of MPs by sampling the sewage from each treatment section of a WWTP in Zhengzhou, China. The results showed that the abundance of MPs in the influent water and primary, secondary, and tertiary treatment discharges was 16.0, 10.3, 4.5, and 2.9 MP/L, respectively, and the total removal rate of MPs from the influent to the final effluent reached 81.9%. The MPs in the WWTP were mainly small-sized (0.08-0.55 mm), followed by medium-sized (0.55-1.7 mm). Fibers were the dominant MP shape in both the water and sediment samples. Black (36%) and red (23%) were the dominant MP colors. Six different polymer types of MPs were detected, which were mainly polypropylene followed by polyethylene. In general, for the MPs in the WWTP, the removal rate of fragments can reach 97.08%, which is better than that of fibers (70.50%); the removal rate of small-sized can reach 95.86%, which is better than that of medium-sized (83.53%) and large-sized (70.00%). In this study, primary treatment has better effects in eliminating fragments and large-sized MPs; secondary treatment has better effects in eliminating fibers and small-sized MPs. Although WWTPs have a very good removal effect on MPs, 870 million MP/d are still discharged into nearby rivers from WWTPs with a treatment scale of 300,000 m3/day. Graphical Abstract.

Study on the Emission Characteristics of PCDD/Fs and Other Multiple Pollutants in Flue Gas from Sintering Plant in China

In China, sintering flue gas has become the most important source of air pollution rather than burning coal-fired flue gas.The emission characteristics and removal efficiencies of various gaseous pollutants were studiedon a 180 m2 sintering equipped with a semi-dry oxidative desulfurization and denitrification system in Tangshang, Hebei province. The emission concentrations of particulate matter, fluoride,NOX and SO2were measured in the flue gas whilepolychlorinated dibenzo-p-dioxins and dibenzofurans(PCDD/Fs) were tested in both flue gas and dust ash at 100% and 60% loadconditions. The collections and analyses ofpollutantswere used by smoke sampler, TESTO350 and dioxin sampleraccording to national standards of China. The results shown that the average emission concentration of particulate matter, fluoride, NOX and SO2 in the inlet of the flue gas purification system were 47.4 mg/m3, 0.12 mg/m3, 150 mg/m3 and 521 mg/m3 while the emission concentrations in the outlet were 1.2 mg/m3, 0.07 mg/m3, 24 mg/m3 and 20 mg/m3,respectively. Through the flue gas purification system, the PCDD/Fs concentrations were reduced from 23.12 ng/m3to 1.14 ng/m3at100% load and from 12.25 ng/m3 to 0.84 ng/m3at60% load. The PCDD/Fs concentrations in the dust ash were about 178.56~197.21 ng/kg. Thedesulfurization and denitrification system significant reduced effect on the emission of particulate matter, fluoride, NOX, SO2 and PCDD/Fs with the value 97.5%, 41.7%, 84.0%, 96.2% and 95.1% at 100% load, respectively.The removal affects increases along the chlorination degree of PCDD/Fs. Meanwhile,the different load influenced the emission concentrations and removal rates of PCDD/Fs in the flue gas, the removal effects increases as the load increases. Although the desulfurization and denitrification system has good removal effects on various pollutants, the dioxins were enriched in the dust ashso as to cause secondary pollution.

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism.

Active silicate materials have good adsorption and passivation effects on heavy metal pollutants. The experimental conditions for the preparation of active silicate heavy metal adsorbent (ASHMA) and the adsorption of Cu(II) by ASHMA were investigated. The optimum preparation conditions of ASHMA were as follows: 200 mesh quartz sand as the raw material, NaOH as an activating agent, NaOH/quartz sand = 0.45 (mass fraction), and calcination at 600 °C for 60 min. Under these conditions, the active silicon content of the adsorbent was 22.38% and the utilization efficiency of NaOH reached 89.11%. The adsorption mechanism of Cu(II) on the ASHMA was analyzed by the Langmuir and Freundlich isotherm models, which provided fits of 0.99 and 0.98, respectively. The separation coefficient (RL) and adsorption constant (n) showed that the adsorbent favored the adsorption of Cu(II), and the maximum adsorption capacity (Qmax) estimated by the Langmuir isotherm was higher than that of 300 mg/L. Furthermore, adsorption by ASHMA was a relatively rapid process, and adsorption equilibrium could be achieved in 1 min. The adsorbents were characterized by FT-IR and Raman spectroscopy. The results showed that the activating agent destroyed the crystal structure of the quartz sand under calcination, and formed Si-O-Na and Si-OH groups to realize activation. The experimental results revealed that the adsorption process involved the removal of Cu(II) by the formation of Si-O-Cu bonds on the surface of the adsorbent. The above results indicated that the adsorbent prepared from quartz sand had a good removal effect on Cu(II).

Comparative study on three kinds of microtube extraction devices in vitro

This study aims to compare the efficiency of three kinds of microtube extraction devices, namely, instrument removal system (IRS), micro-retrieve and repair (MR&R) system, and MR&R system using modified microtube in removing separated instruments with different exposure lengths. After a cross-section platform model was established, the IRS, MR&R, and MR&R modified microtube system with sidewall window reduced to 0.20 mm were used to retrieve various separated instrument models, and the differences in extraction effects were statistically analyzed by Chi-square test. The separated instrument models were divided into two groups: stainless steel and nickel-titanium instrument groups. In total, 23 instruments were tested for three times each. When the exposed length of separated instrument was 0.50 mm, the removal efficiency of the modified MR&R system group was significantly higher than those of the IRS and MR&R system groups (P<0.001). When the broken end of the fracture instrument was up to 1.00 mm, the success rates of the MR&R system and modified MR&R groups were significantly higher than that of the IRS group (P<0.01). No difference was observed among these three devices when the exposure length of separated instruments was 1.50 mm or higher. The MR&R and modified MR&R systems have good removal effect when the exposed length of separated instrument is small.