Viscosity Of Coal Water Slurry Research Articles

Preparation of an additive using tannic acid for enhancing rheological properties of coal-water slurry

ABSTRACT Low-rank coal is an ideal future development coal for coal-water slurry (CWS) due to its abundant resource, but low-rank coal is tougher to produce slurry than high-rank coal. Herein, a new-type macromolecular additive, tannic acid grafted carboxymethyl cellulose sodium (TAC), was designed and prepared to enhance the rheological properties of CWS using Hongshaquan coal in Xinjiang (Coal-HSQ). This work shows that trace amounts of TAC can effectively improve the fluidity of CWS in comparison with calcium lignosulfonate (CLS). Through contact angle and a novel surface characterization method in this field called microscopic infrared imaging, the analyses reveal the hydrophobicity of the Coal-HSQ surface modified by TAC is improved, which is beneficial for enhancing the fluidity of CWS. The apparent viscosity of CWS can be reduced to the lowest point (674.8 mpa·s), as CWS slurry concentration is 55 wt% and TAC addition is only 0.2 wt%. Finally, the highest slurry concentration of CWS prepared with 0.2 wt% TAC can be increased to 56.3 wt%.

The effect of inorganic salt modification of sludge on the performance of sludge-coal water slurry

Coal water slurry (CWS) is a coal-based liquid fuel with the characteristics of high efficiency and low pollution. Municipal sludge, as a substantial solid waste, is of increasing attention due to the severe environmental pollution and difficult disposal. In this study, sludge is modified by inorganic salt solution and then used to prepare salt-modified sludge coal water slurry (SSCWS). The results showed that the sludge modified by KCl and AlCl3 can reduce the viscosity of CWS. While low concentration of CaCl2 tends to slightly increase the viscosity of CWS and higher concentration of CaCl2 can reduce the viscosity. It was found that among the three salts used in the experiment, the higher the cation valence state is, the easier and more the dispersant molecules are adsorbed on the surface of coal or sludge particles to improve the dispersion of coal and sludge particles, which was the main reason for improving the slurryability of SSCWS.

Synthesis and Performance of a Novel Cotton Linter Based Cellulose Derivatives Dispersant for Coal-Water Slurries.

A novel sulfonic-cellulose succinate half ester (S-CSHE) dispersant for coal–water slurry (CWS) was successfully synthesized using cotton linters, sulfamic acid and succinic anhydride in DMF by a one-pot synthesis. The effects of the synthetic condition of S-CSHE as a dispersant for CWS were studied. An S-CSHE with a maximum degree of substitution of 0.98 was obtained under these optimized conditions. The synthesized samples were characterized by GPC, FT-IR spectroscopy, 13C-NMR, and SEM. The molecular weight was from 2.2 × 103 to 1.2 × 104, revealed by GPC; FT-IR spectra analysis revealed characteristic absorptions of the sulfonic-cellulose succinate half ester; SEM images showed smooth cellulose structures, while the S-CSHE had a compact surface. Effects of S-CSHE on the fluidity of application as the dispersants for the CWS prepared from Chinese Zhundong coal were studied further. The CWS application performance investigations showed that S-CSHE can most effectively reduce CWS viscosity, and perform excellent dispersity and stability. When the dosage of S-CSHE was up to 0.5 wt.%, the maximum coal content of CWS may reach 70 wt.%, and the apparent viscosity of CWS was 487 mPa·s. The CWS prepared using S-CSHE (0.38 wt.%) for Zhundong coal showed the rheological characteristics of shear-thinning, and is consistent with the Herschel–Bulkley model. This work found a new route for utilizing cotton linters cellulose and enlarged the selecting range of the dispersant for CWS. It has a positive significance for efficient and clean utilization of Xinjiang Zhundong coal.

A mathematic model based on eDLVO and Lifshitz theory calculating interparticle interactions in coal water slurry

The emission of CO2 can be greatly reduced by increasing the solid loading of coal water slurry (CWS) in the gasification industry. In this paper, a mathematic model based on eDLVO and Lifshitz theory is proposed to calculate the interaction between two coal particles and guide the preparation of CWS to increase the solid loading. Lifshitz theory is adopted to calculate the retardation Hamaker constant and van der Waals interaction, which has relatively wide applicability and less assumption. Equations of hydrophobic interaction and electrical double layer are properly simplified with assumptions. It is found that the low rank coal particles in dilute solution are difficult to cross the energy barrier to form aggregations, due to large electrical double layer repulsive interaction. While for bituminous coal, even in dilute solution, the particles will attract with each other. All the coal particles in high concentration CWS will naturally attract with each other to form aggregations, due to higher ion concentration that compressed the electrical double layer with lower absolute value of zeta potential. More energy is dissipated to break the aggregating structure, thus increasing the shear viscosity. Our model can be applied to explain and quantify the influence of ions and pH successfully. For SHH CWS with pH above 9.35, the viscosity of CWS is sharply reduced to 1/3 of original value, which is caused by the greatly increase of the absolute value of zeta potential, as quantified by eDLVO model.

Performance and mechanism of polyacrylamide stabilizers in coal water slurry

The stability of coal water slurry (CWS) is a significant factor affecting its storage and transportation. However, the understanding of the mechanism of high-molecular-weight polymer used as stabilizers in CWS is still limited. We experimentally studied the rheological behaviors and stability performance of coal water slurry prepared with anionic (APAM), cationic (CPAM) and nonionic (NPAM) polyacrylamide. Apparent viscosity and rheology were measured using a viscometer. The rod penetration method incorporating with the oscillation method was applied to evaluate the stability performance of CWS. The zeta potential measurement and interaction energy calculations were also conducted. The results showed that the apparent viscosity of CWS increased with the addition of all the three PAMs. CWS by adding either APAM or CPAM behaved as a pseudoplastic fluid while the CWS with the addition of NPAM behaved as a dilatant fluid. The CWS with 0.1 wt% (on the dry coal basis) APAM exhibited the best stability performance. The settling rate for this slurry was the lowest (6.67%), and the zeta potential was the highest (−22.33 mV). The CWS by adding APAM had the highest total interaction energy between coal particles among four samples. The mechanism that controls the stability of CWS may be relevant to the increased electrostatic repulsive energy between coal particles by adding APAM, which depends on the surface potential of coal particles.

Eco-friendly utilization of microplastics for preparing coal water slurry: rheological behavior and dispersion mechanism

Microplastics (MPs) are emergingly hazardous contaminants which ubiquitously exists in aquatic, terrestrial and atmospheric system, as well as in human system. Coal water slurry (CWS) is an important clean-coal-based liquid fuel with the characteristics of high-efficiency and low-pollution. This paper aims to implement the principles of clean production and prepare CWS by coblending coal particles and polyethylene terephthalate (PET) microplastics. It shows that the presence of PET particles significantly reduces the viscosity and increases the dispersion performance of CWS suspension. The apparent viscosity of CWS tends to decrease with the increase of PET content. Through the contact angle, surface morphology, and zeta potential analyses, particles with stronger hydrophobicity, more spherical shape and higher electronegativity, are more easily to form consistent and dispersed CWS suspensions. The extended DLVO theory demonstrates that the repulsion between solid particles becomes larger when PET particles are added to the slurry, which is beneficial to particle dispersion. In addition, the dispersant interfacial distribution differs between coal and PET particles, and significantly affect the rheological behavior and dispersion mechanism of CWS. This study proposes a potential approach to recycle the hazardous waste MPs and provides theoretical basis for enhancing CWS dispersion performance through coblending with PET microplastic particles.

The effect of isoamyl alcohol and sec-octyl alcohol on the viscosity of coal water slurry

In this work, the addition of isoamyl alcohol and sec-octyl alcohol on the viscosity of coal water slurry (CWS) was investigated and comprehensively analyzed. The surface tension, contact angle, dispersant absorbed amount, the microstructure of the particles as well as surface functional groups of coal powder was impacted by the addition of alcohols in the CWS. The isoamyl alcohol and sec-octyl alcohol lowers the surface tension and also partially absorbs to the coal particle surface, which would reduce the dispersant absorbed amount of the coal surface. The results show that both the isoamyl alcohol and sec-octyl alcohol can effectively reduce the viscosity of CWS under the amount of organic alcohol below to its solubility, and sec-octyl alcohol exhibits preferable performance than isoamyl alcohol. Our results anticipate to provide a convenient way to reduce CWS viscosity and could also be a reference for CWS preparation with such wastewater containing alcohol compounds.

Synthesis of a novel amphoteric copolymer and its application as a dispersant for coal water slurry preparation.

In this work, a novel amphoteric copolymer named Poly(sodium p-styrenesulfonate–co-acrylic acid-co-diallyldimethylammonium chloride) (P(SS-co-AA-co-DMDAAC)) was synthesized via free radical polymerization. Afterwards, P(SS-co-AA-co-DMDAAC) was explored for use as a dispersant in coal water slurry (CWS) preparation. The structure of P(SS-co-AA-co-DMDAAC) was verified by Fourier transform infrared spectroscopy and nuclear magnetic resonance. The synthetic conditions were optimized as the feed ratio of AA to SS was 1 : 1 (for Yulin coal) or 1.5 : 1 (for Yili coal), and DMDAAC dosage was 4.0 wt% (for Yulin coal) and 6.0 wt% (for Yili coal) toward total monomers. The performances of P(SS-co-AA-co-DMDAAC) as a dispersant for CWS were evaluated by various technologies, such as apparent viscosity, zeta potential, static stability and contact angle measurements. The results revealed that the optimized dosage of P(SS-co-AA-co-DMDAAC) in CWS preparation was 0.3 and 0.4 wt% for Yulin coal and Yili coal respectively. In this optimum condition, CWS prepared using P(SS-co-AA-co-DMDAAC) as dispersant showed a typical shear thinning behaviour and excellent stability, which are desired in industries. The rheological models also confirmed the pseudo-plastic characteristics of CWS. Finally, compared with the widely used anionic dispersant naphthalene sulphonate formaldehyde condensate (NSF) and poly(sodium p-styrenesulfonate) (PSS), P(SS-co-AA-co-DMDAAC) developed in this work exhibited better slurry making performance. The introduction of cationic functional groups promoted the adsorption of the dispersant, which further enhanced the electrostatic repulsion and steric hindrance among coal particles. Accordingly, the viscosity of CWS decreased and static stability enhanced.

Preparation of semicokes by medium–low temperature pyrolysis of long flame coal and their adsorption performance on sodium lignin sulfonate dispersant for high concentration coal water slurry

To get a high concentration of coal water slurry (CWS) for gasification application, semicokes were prepared by pyrolysis of Dongrong long flame coal (DRC) at medium–low temperature. The obtained semicokes were characterized by thermogravimetry, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, X-ray diffraction, scanning electron microscope, and nitrogen adsorption-desorption methods. After preparation, the adsorption experiment of sodium lignin sulfonate (NaLS) on these semicokes was also carried out. It was found that medium–low temperature pyrolysis have changed the pore structure, surface properties, and molecular structure of DRC, which increased the saturated adsorption capacity of semicokes for NaLS dispersant. The enhanced adsorption capacity for dispersant can significantly reduce the apparent viscosity of CWS and increase its concentration. Under the optimized pyrolysis conditions, the maximum solid concentration of CWS prepared with as-prepared semicokes reached up to 68.09% when the dosage of NaLS disperdant was 1%, which met the gasification application of CWS. Such medium–low temperature pyrolysis method is an effective way to large-scale development and utilization of low rank coal through modifying their physicochemical properties.

Experimental studies on coal-water slurry fuel prepared from pretreated low-grade coal

ABSTRACT Low-grade coal is characterized by high ash content and low calorific value. However, gaseous emissions from coal power plants are a serious environmental issue. In this regard, coal-water slurry fuel is a potential substitute for solid fuels used in power plants, which can reduce harmful gaseous emission. In this work, coal-water slurry fuel is prepared from precleaned coal. Prior to its use in the preparation of coal-water slurry, coal was subjected to float and sink followed by froth flotation (pretreatment) to reduce its ash content (from 33.5% to 17.4%). The rheological properties of coal-water slurry were examined and effects of stabilizing agents, dispersion agent, and temperature on viscosity were studied. According to analysis results, increasing concentration of coal increases its viscosity. The viscosity also increases if the particle size of coal decreases. Furthermore, the concentration of stabilizing agent and viscosity of coal-water slurry are directly proportional to each other. Combustion of coal-water slurry was performed under controlled conditions, which showed that the burning efficiency of CWS is fairly larger (around 21% more than that of dry coal), with hydrogen (6% by volume) generated as a by-product.

Effect of mixture of natural and synthetic surfactant and particle size distribution for stabilized high-concentrated coal water slurry

ABSTRACT A medium ash coal is used for the study. Four different samples have prepared by blending fine fraction (<38 µm) with four distinct coarse fractions (212 µm – 300 µm, 90 µm – 300 µm, 150 µm – 212 µm,75 µm – 150 µm) in the ratio of 40:60 and named as sample 1, sample 2, sample 3, sample 4, respectively. These four samples mixed with mixture of natural and chemical additive solution, i.e. saponin from shikakai and SDBS (sodium dodecyl benzene sulfonate) to reduce the viscosity and increase the stability of the slurry. The flow behavior of coal water slurry were characterized at different coal loadings, pH, dispersant contents with and without presence of mixture of bio and chemical additive. The flow behavior of the slurry studied in the solid concentration range of (58–68) % by weight and the behavior is well fitted to the Bingham plastic model which indicates non-Newtonian behavior in nature. Out of four samples, sample 1 shows maximum coal loading, i.e. 68% in the presence of mixture of additive, i.e. saponin and SDBS. For the solid loading of 68% by weight the apparent viscosity is 1.3 PaS for the shear rate 147 S−1. The ratio of saponin and SDBS is optimized on the basis of surface tension measurement and apparent viscosity of coal water slurry. During surface tension measurement the value of surface tension is 14 mN/m at the point of optimization of surfactant mixture percentage, i.e. saponin:SDBS = 92:8 and the viscosity of the surfactant/additive mixture at this optimization point is 0.403 Pa.S. The rheological behavior of the slurry has been measured. Effect of zeta potential of the coal particle has been studied in the presence of mixture of additive solution (saponin and SDBS). A suitable mechanism has given to explain the interaction between additive solution and coal surface.

The effect of inorganic salt in wastewater on the viscosity of coal water slurry.

The preparation of coal water slurry (CWS) using wastewater, which contains inorganic and organic components, is one method of wastewater utilization. In this study, the effect of inorganic salts on the viscosity of CWS was examined. The results show that monovalent salts (NaCl, KCl) decreased the viscosity of CWS. The viscosity of CWS was not affected by bivalent salts (CaCl2, MgCl2). However, CWS combined with trivalent salt (AlCl3) sharply increased the viscosity. The zeta potential of CWS with inorganic salts increased which can enhance the electric repulsion and beneficial to reduce the viscosity. The content of free water in CWS with trivalent salt decreased, and the freedom of the free water in CWS with trivalent salt decreased which were all bad to the viscosity and the adsorption of the dispersant on the particles. Compared with the surface polarity of the particles without inorganic salts, the surface polarity of the particles with divalent salts was similar to those without inorganic salts. Under the comprehensive influence, divalent salt has little effect on the viscosity of CWS.

Influence of alkaline additive on viscosity of coal water slurry

This paper was mainly about the influence of alkaline additive on the viscosity of coal water slurry (CWS). The study showed that the viscosity of CWS was sensitive to the alkaline additive. Less than 1% of alkaline additive could reduce the viscosity to more than half of the viscosity of the CWS without alkaline additive. As the content of the alkaline additive increased, the viscosity of CWS increased. The change in zeta potential, the freedom and content of the water in the CWS, the microstructure of the particles in the CWS as well as the FT-TR spectrum of the coal particles was investigated. The results show that with low concentrations of the alkaline solutions, the zeta potential of the particles in the CWS decreased which mean the absolute value of the zeta potential increased and the content of the free water in the CWS were increased. Meanwhile, the nonpolar of the particle with alkaline salts strengthened. These were all benefited to reduce the viscosity.

Effects of hydrothermal dewatering of lignite on rheology of coal water slurry

AbstractMaximizing the dry‐based solid loading of coal particles in water is essential in increasing the burning efficiency of coal water slurry, which has been widely used as a liquid fuel. Understanding the rheology of coal water slurry could provide fundamental guidance on designing and optimizing coal water slurry formulation. The rheological studies have shown that coal water slurries made with lignite samples after hydrothermal dewatering (HTD) exhibit a stronger shear thinning behaviour as compared with those made with raw lignite samples. The viscosity of coal water slurry at the shear rate of 100 s−1 decreases with an increasing HTD temperature, which is probably due to the decrease of volume of lignite particles caused by the permanent reduction of both bound and non‐freezable water (inherent moisture) after the HTD process. The reduction of the inherent moisture of lignite samples after HTD treatment was elucidated by differential scanning calorimetry (DSC) under the temperature well below the freezing point. A lignite water slurry with a solid loading of 62 wt% db (dry basis) is obtained after hydrothermal dewatering at 300 °C with the addition of 1.2 wt% of polycarboxylate ether (PCE). Our findings indicated that hydrothermal dewatering of lignite has profound impacts on the inherent moisture of lignite and the rheological properties of coal water slurry.

Polycarboxylate adsorption on coal surfaces and its effect on viscosity of coal-water slurries

It is extremely important to reveal the adsorption behavior of polycarboxylate (PC) on coal to improve the performance of PC and even enhance its fabrication and preparation. In this work, three kinds of low rank coal with different ratios of oxygen to carbon (O/C) were employed to prepare coal-water slurries and analyze performances. Apparent viscosities of the slurries were tested. The contact angle and adsorption of PC dispersant on coal were measured. It is observed that the viscosity reduction of CWS is dependent on the saturated adsorption of PC on coal. The order of viscosity reduction is same with the hydrophilicity/hydrophobicity of the PC on the coal surfaces, which corresponds well with the ratio of O/C in coal. So the future dispersant should be designed to improve its adsorption on coal according to the ratio of O/C in coal. Moreover, using a Scanning Electron Microscopy-Energy Dispersive Spectrometer, and zeta potential analysis, we demonstrate the morphology of PC dispersant on coal and clarify further the mechanism of the efficient PC dispersant. Extra dosage of the PC will prevent relative movement between coal particles thus increasing the viscosity of CWSs. So, it is quite necessary to control the proper dosage of the PC dispersant on the basis of the adsorption values in the slurry processing.

Artificial neural network approach for rheological characteristics of coal-water slurry using microwave pre-treatment

Detailed experimental investigations were carried out for microwave pre-treatment of high ash Indian coal at high power level (900W) in microwave oven. The microwave exposure times were fixed at 60s and 120s. A rheology characteristic for microwave pre-treatment of coal-water slurry (CWS) was performed in an online Bohlin viscometer. The non-Newtonian character of the slurry follows the rheological model of Ostwald de Waele. The values of n and k vary from 0.31 to 0.64 and 0.19 to 0.81Pa⋅sn, respectively. This paper presents an artificial neural network (ANN) model to predict the effects of operational parameters on apparent viscosity of CWS. A 4-2-1 topology with Levenberg-Marquardt training algorithm (trainlm) was selected as the controlled ANN. Mean squared error (MSE) of 0.002 and coefficient of multiple determinations (R2) of 0.99 were obtained for the outperforming model. The promising values of correlation coefficient further confirm the robustness and satisfactory performance of the proposed ANN model.

盐水组分和碱性条件对水煤浆制浆的影响

通过选用不同浓度的NaCl、Na2SO4、Na2CO3、NaHCO3、CaSO4、MgSO4、NaOH溶液制备水煤浆，考察了不同制浆浓度下各添加物对水煤浆制浆特性的影响，添加组分对水煤浆pH值、燃烧热的影响。并测试了盐水与煤、碱水与煤的表面接触角。结果表明：盐水和碱水对水煤浆的黏度有较大影响。各盐水制浆的最佳盐水添加条件为1.0 wt% NaCl溶液，3.0 wt% Na2CO3溶液，0.50 wt% NaHCO3溶液，1.0 wt% MgSO4溶液。饱和CaSO4溶液和1 wt%浓度的NaOH溶液代替清水不利于成浆。Na2SO4的加入，不利于水煤浆的制备。各种盐水与碱水与煤的接触角都低于清水与煤的接触角。弱碱性条件有利于水煤浆黏度的降低，有利于制浆。浓度低于1 wt%盐水或碱水的加入不影响水煤浆的燃烧特性。 In this paper, through the use of different concentrations of NaCl, Na2SO4, Na2CO3, NaHCO3, CaSO4, MgSO4, NaOH solution for the preparation of coal water slurry, the effects of various additives of different pulp concentration on the pulping properties of coal water slurry, and the effects of composition of coal water slurry pH value, heat of combustion were investigated. And the surface contact angle between salt water and coal, alkali water and coal was tested. The results show that the salt water and alkaline water have influences on viscosity of coal water slurry. The best adding composition for salt water is 1.0 wt% NaCl, 3.0 wt% Na2CO3, 0.50 wt% NaHCO3, and 1.0 wt% MgSO4. Saturated CaSO4 solution and 1 wt% NaOH solution instead of water are not suitable for CWS preparation. The addition of Na2SO4 is not conducive to the preparation of coal water slurry. The contact angles of all the salts and alkali water showed a decreasing tendency compared with the contact angle of fresh water. Weak alkaline conditions are conducive to the lower viscosity of coal-water slurry and are useful for slurry preparation. Addition of less than 1 wt% saline or alkaline water does not affect the combustion characteristics of CWS.

Synthesis of a novel humic acid-based polycarboxylic dispersant for coal water slurry

ABSTRACTA novel humic acid-based polycarboxylic-type (HAP) dispersant for coal–water slurry (CWS) was successfully synthesized in aqueous solution from the copolymerization of HA, acrylic acid and maleic acid. The structure of HAP was characterized by Fourier transform infrared (FTIR), thermogravimetry (TG) and 1H NMR. With HAP as a dispersant for Linfen coal slurry, the effects of the mass ratio of HA and monomer, initiator concentration, reaction temperature and reaction time on the HAP dispersant performance were discussed by examining the apparent viscosity of CWS. The results showed that CWS prepared withHAP dispersant performed excellent dispersity and stability. When the dosage of HAP was up to 0.5 wt.%, the apparent viscosity of CWS was 505 mPa·s. Experiments on the stability of CWS containing 0.5 wt.% HAP demonstrated that the penetration ratio reached 85.45 % after 96 h, which was higher by 12.87 % than that of CWS prepared with HA. And the CWS produced with HAP had lower dewatering rate within the storage time, which was less 1.85 % than that of CWS with HA when the storage time was 72 h. Furthermore, the maximum coal content of CWS with 0.5 wt.% HAP may reached 70 wt.%. This work found a new route for utilizing humic acid and enlarged the selecting range of the dispersant for CWS. It has a positive significance for protection of environment.

The influence of pre-absorbing water in coal on the viscosity of coal water slurry

Coal water slurry (CWS) with high solid content and low viscosity can allow for efficient and environmentally friendly gasification. In the process of CWS preparation, water will enter pores of coal particle to form inner water, resulting in a decrease in free water among particles and an increase in viscosity. However, pre-absorption of moisture from air was found to result in a sharp decrease of suspension viscosity, since small amount of air were sealed in particle pores. Coal particles have many polar functional groups, and pre-absorbed water sealed the entrance of pores through hydrogen bonds like a “bottle stopper”, which effectively inhibited the diffusion of water from slurry into the pores of coal particles. Pre-absorption of water from air was also found to improve the efficiency of the second fluid (immiscible with water), and cause a further decrease in viscosity and yield stress.

Evaluation of modified used engine oil acting as a dispersant for concentrated coal–water slurry

In order to convert the used engine oil (UEO) to a fine chemicals, the properties of engine oil (EO) and UEO were initially compared by FTIR, 1H NMR, and thermal behavior analyses. The UEO composition was first modified by sulfonation and then separated through separating funnel. Results showed that the as-prepared product, sulfonated UEO (SUEO), exhibits the properties of a surfactant. The surface tension of the aqueous SUEO solution was 34.64mNm−1 at the critical micellar concentration of 3.02gL−1, which was one half of 72.27mNm−1 of distilled water. Up to 0.3wt.% SUEO was used as a dispersant for coal–water slurry (CWS), and the viscosity of CWS was 170mPas when the content of coal powder was 65wt.% at shear rate of 100s−1, and the rheological behavior belonged to pseudoplastic fluids. Experiments on the stability of CWS containing 0.3wt.% SUEO demonstrated that the penetration ratio reached 37.8% after 15days, which was higher by 12.1% than that of CWS without dispersant. Compared with commercial dispersants sodium lignosulfonate and sodium dodecyl sulfate, SUEO displayed a good performance for either liquidity or stability of CWS. In addition, the possible reason for the excellent behavior of CWS prepared with SUEO was discussed. Overall, this study provided a new disposal and updated way for UEO.