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Optimization of process parameters for mature landfill leachate pretreatment using MAP precipitation

Wei LI, Xiaowen DING, Min LIU, Yuewen GUO, Lei LIU

《环境科学与工程前沿(英文)》 2012年 第6卷 第6期   页码 892-900 doi: 10.1007/s11783-012-0440-9

摘要: Chemical precipitation is a useful technology as a pretreatment to treat mature landfill leachate with high concentrations of ammonium-nitrogen ( ) and refractory organic compounds. Orthogonal experiments and factorial experiments were carried out to determine the optimal conditions enhancing the magnesium ammonium phosphate (MAP) precipitation process, and the experimental results demonstrated that the removal rate of was more than 85% when MgO and NaH PO ·2H O were applied as external sources of magnesium and phosphorous under the optimal conditions that molar ratio n(Mg)∶n(N)∶n(P) = 1.4∶1∶0.8, reaction time 60 min, original pH of leachate and settling time 30 min. In the precipitation process, pH could be maintained at the optimal range of 8–9.5 because MgO could release hydroxide ions to consume hydrogen ions. Calcium ions and carbonate ions existed in the leachate could affect the precipitation process, which resulted in the decrease of removal efficiency. The residues of MAP sediments decomposed by heating under alkaline conditions can be reused as the sources of phosphorous and magnesium for the removal of high concentrations of , and up to 90% of ammonium could be released under molar ratio of n[OH]∶n[MAP] = 2.5∶1, heating temperature 90°C and heating time 2h.

关键词: magnesium ammonium phosphate precipitation     mature landfill leachate     optimization     ammonium-nitrogen    

Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by

H. Watamura, H. Marukawa, I. Hirasawa

《化学科学与工程前沿(英文)》 2013年 第7卷 第1期   页码 55-59 doi: 10.1007/s11705-013-1312-y

摘要: Relationship between magnesium ammonium phosphate (MAP) crystal properties and the filtration ability of hollow fiber membrane (HFM) were investigated. Phosphorus recovery process by crystallization has a problem that it produces a large amount of fine crystals. So improvement of the crystallization process by combining with filtration was discussed. MAP crystals were obtained by batch reaction crystallization and the filtration characteristics were investigated. The filtration was evaluated by the specific filtration resistance ( ) on HFM. Filtered slurry was prepared with each suspension density and crystal size distribution. The solution was filtered at constant pressure of 0.02 MPa and the filtration time on each filtrated volume was recorded. As a result, decreases exponentially with suspension density increasing from 0.25 g/L to 0.5 g/L and decreases moderately with suspension density increasing from 0.5 g/L to 1.5 g/L. of large crystals decreases exponentially at less suspension density than of small crystals does. Also, increases as the ratio of the fractured crystals increases.

关键词: membrane separation     crystallization     MAP    

Experimental study on mechanical properties of a novel micro-steel fiber reinforced magnesium phosphate

《结构与土木工程前沿(英文)》 2021年 第15卷 第4期   页码 1047-1057 doi: 10.1007/s11709-021-0755-3

摘要: Magnesium phosphate cement (MPC) received increased attention in recent years, but MPC-based concrete is rarely reported. The micro-steel fibers (MSF) were added to MPC-based concrete to enhance its ductility due to the high brittleness in tensile and flexural strength properties of MPC. This paper investigates the effect of MSF volume fraction on the mechanical properties of a new pattern of MPC-based concrete. The temperature development curve, fluidity, cubic compressive strength, modulus of elastic, axial compressive strength, and four-point flexural strength were experimentally studied with 192 specimens, and a scanning electron microscopy (SEM) test was carried out after the specimens were failed. Based on the test results, the correlations between the cubic compressive strength and curing age, the axial and cubic compressive strength of MPC-based concrete were proposed. The results showed that with the increase of MSF volume fraction, the fluidity of fresh MPC-based concrete decreased gradually. MSF had no apparent influence on the compressive strength, while it enhanced the four-point flexural strength of MPC-based concrete. The four-point flexural strength of specimens with MSF volume fraction from 0.25% to 0.75% were 12.3%, 21.1%, 24.6% higher than that of the specimens without MSF, respectively.

关键词: magnesium phosphate cement-based concrete     micro-steel fibers     four-point flexural strength     compressive strength    

料浆法磷铵生产工艺发展与五大磷肥工程改造

钟本和

《中国工程科学》 2004年 第6卷 第6期   页码 22-25

摘要:

针对引进磷酸浓缩工艺生产磷铵的技术不适应我国矿产资源具体情况的难题,开发了料浆法磷铵生产工艺技术,已在21个省区布点推广建设了87套装置,形成生产能力279×104 t/a的规模,占全国磷铵生产能力的60%。最近在贵州瓮福实施料浆法磷铵与引进的传统磷酸浓缩工艺联产的成功,为五大磷肥工程的改造提供了一条新的途径。

关键词: 磷肥     磷铵     料浆法磷铵    

Synthesis and characterization of magnesium hydroxide by batch reaction crystallization

Xingfu SONG, Shuying SUN, Dengke ZHANG, Jin WANG, Jianguo YU

《化学科学与工程前沿(英文)》 2011年 第5卷 第4期   页码 416-421 doi: 10.1007/s11705-011-1125-9

摘要: Magnesium hydroxide with high purity and uniform particle size distribution was synthesized by the direct precipitation method using MgCl and NaOH as reactive materials and NaCl as additive to improve the crystallization behavior of the product. The particle size distribution, crystal phase, morphology, and surface area of magnesium hydroxide were characterized by Malvern laser particle size analyzer, X-ray diffraction (XRD), scanning electron microscope (SEM) and Branauer-Emmett-Teller (BET) method, respectively. The purity of products was analyzed by the chemical method. The effects of synthesis conditions on the particle size distribution and water content (filtration cake) of magnesium hydroxide were investigated. The results indicated that feeding mode and rate, and reaction temperature had important effects on water content and the particle size distribution of the product, and sodium chloride improved the crystallization behavior of magnesium hydroxide. The ball-like magnesium hydroxides with the particle size distribution of 6.0–30.0 μm and purity higher than 99.0% were obtained. This simple and mild synthesis method was promising to be scaled up for the industrial production of magnesium hydroxide.

关键词: magnesium hydroxide     direct precipitation method     industrial crystallization     particle size distribution    

Use of zeolitized coal fly ash in the simultaneous removal of ammonium and phosphate from aqueous solution

WU Deyi, HU Zhanbo, WANG Xinze, HE Shengbing, KONG Hainan

《环境科学与工程前沿(英文)》 2007年 第1卷 第2期   页码 213-220 doi: 10.1007/s11783-007-0037-x

摘要: Discharge of wastewater containing nitrogen and phosphate can cause eutrophication. Therefore, the development of an efficient material for the immobilization of the nutrients is important. In this study, a low calcium fly ash and high calcium fly ash were converted into zeolite using the hydrothermal method. The removal of ammonium and phosphate that coexist in aqueous solution by the synthesized zeolites were studied. The results showed that zeolitized fly ash could efficiently eliminate ammonium and phosphate at the same time. Saturation of zeolite with Ca rather than N favored the removal of both ammonium and phosphate because the cation exchange reaction by the NH resulted in the release of Ca into the solution and precipitation of Ca with PO followed. An increase in the temperature elevated the immobilization of phosphate whereas it abated the removal of ammonium. Nearly 60% removal efficiency for ammonium was achieved in the neutral pH range from 5.5 to 10.5, while the increase or decrease in pH out of the neutral range lowered the adsorption. In contrast, the removal of phosphate approached 100% at a pH lower than 5.0 or higher than 9.0, and less phosphate was immobilized at neutral pH. However, there was still a narrow pH range from 9.0 to 10.5 favoring the removal of both ammonium and phosphate. It was concluded that the removal of ammonium was caused by cation exchange; the contribution of NH volatilization to immobilization at alkaline conditions (up to pH level of 11.4) was limited. With respect to phosphate immobilization, the mechanism was mainly the formation of precipitate as Ca(PO) within the basic pH range or as FePO and AlPO within acidic pH range.

Preparation of ultrafine α-AlO using precipitation-azeotropic distillation method

XIAO Jin, QIN Qi, ZHOU Feng, CHEN Yanbin, WAN Ye

《机械工程前沿(英文)》 2008年 第3卷 第2期   页码 226-231 doi: 10.1007/s11465-008-0029-y

摘要: Ammonium aluminum carbonate hydroxide (AACH) was prepared by a precipitation-azeotropic distillation method, which uses aluminum sulfate as the Al source and ammonium carbonate as the precipitant. Then, AACH was calcined into ultrafine ?-AlO powder. The factors that influence the dispersion property of ultrafine ?-AlO powder are discussed in this paper, such as the methods of adding materials, surfactant, and drying methods. The changes of the structure and property of ultrafine alumina in the thermal treatment process are also studied. The morphological structure and properties of AACH are characterized by DTA/TGA, SEM, XRD, and ICP measurements. The results show that ultrafine ?-AlO powder with a uniform particle size and well-distributed property can be synthesized only after aluminum sulfate atomizes into ammonium carbonate, proper amount of PEG1000 is added as the dispersant, and the product is treated by azeotropic distillation. The phase transformation of alumina during the calcination process can be described as amorphous AlO → ?-AlO → ?-AlO → ?-AlO. The crystal grain size and density of ultrafine alumina powder increase with the increase of the calcination temperature. After AACH has been calcined at 1200°C for 2 h, the ultrafine ?-AlO with uniform particle size, spherical shape, and more than 99.97% purity is obtained and its powder is well dispersed.

关键词: calcination temperature     spherical     AACH     carbonate hydroxide     ammonium carbonate    

EFFICIENT CONTAMINANT REMOVAL FROM LIQUID DIGESTATE OF PIG MANURE BY CHEMICAL PRECIPITATION AND CO MINERALIZATION

《农业科学与工程前沿(英文)》 2023年 第10卷 第3期   页码 479-491 doi: 10.15302/J-FASE-2023480

摘要:

● LFD was treated by fly ash-based chemical precipitation and CO2 mineralization.

关键词: anaerobic digestion     chemical oxygen demand     fly ash     ion removal     total phosphate    

Preparation and crystallization kinetics of micron-sized Mg(OH)

Xingfu SONG, Kefeng TONG, Shuying SUN, Ze SUN, Jianguo YU

《化学科学与工程前沿(英文)》 2013年 第7卷 第2期   页码 130-138 doi: 10.1007/s11705-013-1332-7

摘要: Magnesium hydroxide is an important chemical, and is usually obtained from seawater or brine via precipitation process. The particle size distribution of magnesium hydroxide has great effects on the subsequent filtration and drying processes. In this paper, micron-sized magnesium hydroxide with high purity, large particle size and low water content in filter cake was synthesized via simple wet precipitation in a mixed suspension mixed product removal (MSMPR) crystallizer. The effects of reactant concentration, residence time and impurities on the properties of magnesium hydroxide were investigated by X-Ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Malvern laser particle size analyzer. The results show that NaOH concentration and residence time have great effects on the water content and particle size of Mg(OH) . The spherical Mg(OH) with uniform diameter of about 30 μm was obtained with purity higher than 99% and water content less than 31%. Furthermore, the crystallization kinetics based on the population balance theory was studied to provide the theoretical data for industrial enlargement, and the simulation coefficients ( ) based on ASL model and C-R model are 0.9962 and 0.9972, respectively, indicating that the crystal growth rate of magnesium hydroxide can be well simulated by the size-dependent growth models.

关键词: magnesium hydroxide     precipitation     micron-sized     crystallization kinetics    

消光法测定磷酸铵盐微粒灭火剂灭火浓度研究

殷志平,刘爱华,潘仁明

《中国工程科学》 2008年 第10卷 第7期   页码 90-95

摘要:

采用过滤称重法配合激光消光法对两种粒度的磷酸铵盐微粒灭火剂在杯式燃烧器中的灭火浓度进行了研究,得出了激光测定磷酸铵盐微粒灭火剂的质量浓度标定曲线和微粒灭火剂的灭火浓度。结果表明,在该实验条件下,平均粒度分别为6.0 μm和13.7 μm的磷酸铵盐微粒灭火剂其激光吸收发散系数K值分别为0.353 0 m2/g和0.257 3 m2/g,平均灭火质量浓度分别为32.9 g/m3和41.6 g/m3,前者的灭火效能比后者高出25 % ~ 30 %,且前者采用激光消光法测定时相对误差较小。

关键词: 激光消光法     过滤称重法     微粒灭火剂     灭火浓度    

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

《机械工程前沿(英文)》 2010年 第5卷 第1期   页码 98-105 doi: 10.1007/s11465-009-0088-8

摘要: To study the requirements of the power supply in micro-arc oxidation (MAO) of magnesium alloy, many experiments were performed under the DC, unipolar, and ambipolar pulse output modes. Based on the experimental results and electric arc theory, the separate local arc discharge mechanism was put forward. It is considered that magnesium MAO process consists of three stages including anodic oxidation, micro-arc oxidation, and large-arc discharge in turn with increasing source voltage. The MAO film is composed of metal oxides that resulted from numerous discrete local arc discharges, which accumulate the non-equilibrium structure after undergoing sudden heating and cooling cycles. Separate local arc discharge is caused by the process in which the oxygen-based gas is ionized in the conduct channel bearing electric field intensity, changed from insulator to conductor that presents sharp negative resistance effect, and produced partially high temperature to ignite locally metal oxidation. The local arc discharge model is described as four courses: gas created from electrolysis, arc discharge, metals oxidization, and cooling and shrinking of oxides. The purpose of pulse supply is to inhibit the large-arc discharge by intervening proper cooling time, which cannot be actualized by a unipolar pulse mode because of the strong capacitive load characteristics but can be reached by an ambipolar pulse supply because the negative pulse period acts as cooling time. Using a discharge loop to remove the influence of load capacitive, a new type of pulse power supply for MAO is developed, so that the large-arc problem is resolved effectively, the film-forming efficiency is improved, and the pollution of the film and electrolyte caused by negative voltage is avoided.

关键词: micro-arc oxidation     local arc discharge     pulse power supply     magnesium alloy    

Enhanced adsorption of phosphate by loading nanosized ferric oxyhydroxide on anion resin

Jing REN,Nan LI,Lin ZHAO,Nanqi REN

《环境科学与工程前沿(英文)》 2014年 第8卷 第4期   页码 531-538 doi: 10.1007/s11783-014-0629-1

摘要: Ferric oxyhydroxide loaded anion exchanger (FOAE) hybrid adsorbent was prepared by loading nanosized ferric oxyhydroxide (FO) on anion exchanger resin for the removal of phosphate from wastewater. TEM and XRD analysis confirmed the existence of FO on FOAE. After FO loading, the adsorption capacity of the hybrid adsorbent increased from 38.70 to 51.52 mg·g . Adsorption processes for both FOAE and anion resin were better fit to the pseudo first order model. Batch adsorption experiments revealed that higher temperature (313K), higher initial phosphate concentration (50 mg·L ) and lower solution pH (pH value of 2) would be more propitious to phosphate adsorption. Competition effect of coexisting anions on phosphate removal can be concluded as sulfate>nitrate>chloride. Freundlich isotherm model can describe the adsorption of phosphate on FOAE more accurately, which indicated the heterogeneous adsorption occurred on the inner-surface of FOAE.

关键词: phosphate removal     adsorption     nanosized ferric oxyhydroxide     anion exchanger    

Effects of operational and structural parameters on cell voltage of industrial magnesium electrolysis

Ze Sun,Chenglin Liu,Guimin Lu,Xingfu Song,Jianguo Yu

《化学科学与工程前沿(英文)》 2015年 第9卷 第4期   页码 522-531 doi: 10.1007/s11705-015-1539-x

摘要: Electric field is the energy foundation of the electrolysis process and the source of the multiphysical fields in a magnesium electrolysis cell. In this study, a three-dimensional numerical model was developed and used to calculate electric field at the steady state through the finite element analysis. Based on the simulation of the electric field, the operational and structural parameters, such as the current intensity, anode thickness, cathode thickness, and anode-cathode distance (ACD), were investigated to obtain the minimum cell voltage. The optimization is to obtain the minimum resistance voltage which has a significant effect on the energy consumption in the magnesium electrolysis process. The results indicate that the effect of the current intensity on the voltage could be ignored and the effect of the ACD is obvious. Moreover, there is a linear decrease between the voltage and the thicknesses of the anode and cathode; and the anode-cathode working height also has a significant effect on the voltage.

关键词: finite element method     magnesium electrolysis cell     electric field    

Green process to recover magnesium chloride from residue solution of potassium chloride production plant

WANG Lin, HE Yunliang, WANG Yanfei, BAO Ying, WANG Jingkang

《化学科学与工程前沿(英文)》 2008年 第2卷 第4期   页码 385-389 doi: 10.1007/s11705-008-0079-z

摘要: The green process to recover magnesium chloride from the residue solution of a potassium chloride production plant, which comes from the leach solution of a potash mine in Laos, is designed and optimized. The residue solution contains magnesium chloride above 25 wt-%, potassium chloride and sodium chloride together below 5 wt-% and a few other ions such as Br, SO and Ca. The recovery process contains two steps: the previous impurity removal operation and the two-stage evaporation-cooling crystallization procedure to produce magnesium chloride. The crystallized impurity carnallite obtained from the first step is recycled to the potassium chloride plant to recover the potassium salt. The developed process is a zero discharge one and thus fulfills the requirements for green chemical industrial production. The produced magnesium chloride is up to industrial criteria.

关键词: industrial production     chemical industrial     produced magnesium     chloride production     impurity carnallite    

Properties and printability evaluation of three-dimensional printing magnesium oxychloride cement by

《结构与土木工程前沿(英文)》 2023年 第17卷 第11期   页码 1675-1689 doi: 10.1007/s11709-023-0994-6

摘要: Three-dimensional concrete printing (3DCP) is increasingly being applied in harsh environments and isolated regions. However, the effective utilization of aeolian sand (AS) resources and by-products derived from arid zones for 3DCP is yet to be fully realized. This study developed a three-dimensional (3D) printing composite using AS and magnesium oxychloride cement (MOC) from local materials. The effects of the mole ratio of MgO/MgCl2 and sand/binder (S/B) ratio on the mechanical properties such as water resistance, drying shrinkage strain, rheology, and printability, were investigated systematically. The results indicated that the optimal mole ratio of MgO/MgCl2 was 8, which yielded the desired mechanical performance and water resistance. Furthermore, the S/B ratio can be increased to three within the desired printability to increase the AS utilization rate. The rheological recovery and buildability of the 3D-printed MOC with AS were verified. These findings provide a promising strategy for construction in remote deserts.

关键词: 3DCP     AS     magnesium oxychloride cement     mechanical behavior     drying shrinkage     rheological property    

标题 作者 时间 类型 操作

Optimization of process parameters for mature landfill leachate pretreatment using MAP precipitation

Wei LI, Xiaowen DING, Min LIU, Yuewen GUO, Lei LIU

期刊论文

Filtration ability of hollow fiber membrane for production of magnesium ammonium phosphate crystals by

H. Watamura, H. Marukawa, I. Hirasawa

期刊论文

Experimental study on mechanical properties of a novel micro-steel fiber reinforced magnesium phosphate

期刊论文

料浆法磷铵生产工艺发展与五大磷肥工程改造

钟本和

期刊论文

Synthesis and characterization of magnesium hydroxide by batch reaction crystallization

Xingfu SONG, Shuying SUN, Dengke ZHANG, Jin WANG, Jianguo YU

期刊论文

Use of zeolitized coal fly ash in the simultaneous removal of ammonium and phosphate from aqueous solution

WU Deyi, HU Zhanbo, WANG Xinze, HE Shengbing, KONG Hainan

期刊论文

Preparation of ultrafine α-AlO using precipitation-azeotropic distillation method

XIAO Jin, QIN Qi, ZHOU Feng, CHEN Yanbin, WAN Ye

期刊论文

EFFICIENT CONTAMINANT REMOVAL FROM LIQUID DIGESTATE OF PIG MANURE BY CHEMICAL PRECIPITATION AND CO MINERALIZATION

期刊论文

Preparation and crystallization kinetics of micron-sized Mg(OH)

Xingfu SONG, Kefeng TONG, Shuying SUN, Ze SUN, Jianguo YU

期刊论文

消光法测定磷酸铵盐微粒灭火剂灭火浓度研究

殷志平,刘爱华,潘仁明

期刊论文

Local arc discharge mechanism and requirements of power supply in micro-arc oxidation of magnesium alloy

Ming CHEN, Yuezhou MA, Yuan HAO,

期刊论文

Enhanced adsorption of phosphate by loading nanosized ferric oxyhydroxide on anion resin

Jing REN,Nan LI,Lin ZHAO,Nanqi REN

期刊论文

Effects of operational and structural parameters on cell voltage of industrial magnesium electrolysis

Ze Sun,Chenglin Liu,Guimin Lu,Xingfu Song,Jianguo Yu

期刊论文

Green process to recover magnesium chloride from residue solution of potassium chloride production plant

WANG Lin, HE Yunliang, WANG Yanfei, BAO Ying, WANG Jingkang

期刊论文

Properties and printability evaluation of three-dimensional printing magnesium oxychloride cement by

期刊论文