Mechanism and kinetics study on removal of Iron from phosphoric acid by cation exchange resin

Iron element is one of the main impurities in wet-process phosphoric acid and it has a significant impact on the subsequent phosphorus chemical products. This paper studied the feasibility of using Sinco-430 cation exchange resin for iron removal from phosphoric acid. The specific surface area and the total exchange capacity of resin were 8.91 m2·g-1 and 5.18 mmol·g-1, respectively. The sorption mechanism was determined by FTIR and XPS and the results indicated that iron was combined with-SO3 H in resin. The removal process was studied as a function of temperature, H3 PO4 content and mass ratio between resin and solution. The unit mass of resin to remove iron was 0.058 g·g-1 resin when the operating parameters were T = 50 ℃, H3 PO4 content = 27.61 wt%and S/L = 0.1, respectively. Kinetics study demonstrated that pseudo-second-order reaction model fits this study best and the calculated activation energy of overall reaction is 29.10 kJ·mol-1. The overall reaction process was mainly controlled by pore diffusion.

Adsorption equilibrium and kinetics studies of divalent manganese from phosphoric acid solution by using cationic exchange resin

There are numerous impurities in wet-process phosphoric acid,among which manganese is one of detrimental metallic impurities,and it causes striking negative effects on the industrial phosphoric acid production and downstream commodity.This article investigated the adsorption behavior of manganese from phosphoric acid employing Sinco-430 cationic ion-exchange resin.Resorting FT-IR and XPS characterizations,the adsorption mechanism was proved to be that manganese was combined with sulfonic acid group.Several crucial parameters such as temperature,phosphoric acid content and resin dose were studied to optimize adsorption efficiency.Through optimization,removal percentage and sorption capacity of manganese reached 53.12 wt%,28.34 mg·g^-1,respectively.Pseudo-2nd-order kinetic model simulated kinetics data best and the activation energy was evaluated as 6.34 kJ·mol^-1 for the sorption reaction of manganese.In addition,the global adsorption rate was first controlled by film diffusion process and second determined by pore diffusion process.It was found that the resin could adsorb up to 50.24 mg·g^-1 for manganese.Equilibrium studies showed that Toth adsorption isotherm model fitted best,followed by Temkin and Langmuir adsorption isotherm models.Thermodynamic analysis showed that manganese adsorption was an endothermic process with enhanced randomness and spontaneity.

The development road of ammonium phosphate fertilizer in China

Ammonium phosphate fertilizer is the compounds containing nitrogen and phosphorus that are usually produced through the neutralization reaction of phosphoric acid and ammonia.At present,there are a variety of products,such as slurry monoammonium phosphate(MAP),diammonium phosphate(DAP),industrial grade MAP,water soluble MAP,water soluble ammonium polyphosphate(APP)and so on.After more than 60 years of development,China’s ammonium phosphate fertilizer industry has experienced the road of from scratch and from weak to strong.The successful development of the slurry MAP technology ended the history that the high concentration phosphate fertilizer cannot be produced by using the medium and low grade phosphate ore.The continuous,stable and large-scale production of DAP plant provides sufficient guarantee for DAP products in China.The development of new ammonium phosphate fertilizer products,such as industrial grade MAP,water soluble MAP,water soluble APP,provides technical support for the transformation and upgrading of phosphorus chemical enterprises.In this paper,the production methods,the development history and the latest research progress of ammonium phosphate fertilizers were reviewed.

Leaching calcium from phosphogypsum desulfurization slag by using ammonium chloride solution: Thermodynamics and kinetics study

Phosphogypsum(PG) desulfurization slag is a calcium-rich residue from reductive decomposition of PG using sulfur as the reductant. We proposed a technology of preparation light calcium carbonate with PG desulfurization slag, which mainly contains two steps: leaching and carbonizing. In this work, we concentrated on the former, in which ammonium chloride aqueous solution was utilized as leaching agent to extract calcium from the slag, and conducted thermodynamics and kinetics study on it. Fact Sage software was employed to do thermodynamic and phase equilibrium diagram calculations. The influence of leaching conditions including agitation speed, initial concentration of leaching solution, reaction temperature, and liquid/solid ratio on the calcium leaching rate was discussed in detail by means of experiment optimal design. A kinetic model developed from the shrinking core model was given to describe the leaching process. The apparent kinetic activation energy(Ea) of the leaching reaction was calculated to be 10.58 kJ·mol^-1.

Solubility and solution thermodynamics of ammonium dihydrogen phosphate in the water–methanol system

The solubility of ammonium dihydrogen phosphate(MAP)in the water–methanol system is essential for antisolvent crystallization studies.To investigate the effect of methanol on the solubility of MAP in water,the solubility of MAP in the water–methanol system was determined by dynamic method and static equilibrium method at temperatures ranging from 293.2 to 343.2 K at atmospheric pressure.Results showed that the solubility of MAP increased with the increase of temperature and the increase of water mole fraction in the water–methanol system.The experimental solubility data were correlated with the modified Apelblat equation,the combined nearly ideal binary solvent/Redlich–Kister(CNIBS/R–K)model and the Jouyban–Acree model.The calculated results based on these three models were in very good agreement with the experimental data with the average relative deviations of 0.65%,0.97%,and 5.38%,respectively.Simultaneously,the thermodynamic properties of the MAP dissolution process in the water–methanol system,including Gibbs energy change,enthalpy,and entropy were obtained by the Van’t Hoff equation,which can be used to assess the crystallization process.

An Approach towards Synthesis of Nanoarchitectured LiNi1/3Co1/3Mn1/3O2 Cathode Material for Lithium Ion Batteries

To explore advanced cathode materials for lithium ion batteries(LIBs),a nanoarchitectured LiNi_(1/3)Co_(1/3)Mn_(1/3)O_(2)(LNCM)material is developed using a modified carbonate coprecipitation method in combination with a vacuum distillation-crystallisation process.Compared with the LNCM materials produced by a traditional carbonate copre-cipitation method,the prepared LNCM material synthesized through this modified method reveals a better hexago-nal layered structure,smaller particle sizes(ca.110.5 nm),and higher specific surface areas.Because of its unique structural characteristics,the as-prepared LNCM material demonstrates excellent electrochemical properties in-cluding high rate capability and good cycleability when it is utilized as a cathode in the lithium ion battery(LIB).

尿TIMP-2×IGFBP7在脓毒症相关性AKI中早期诊断价值的Meta分析

目的采用Meta分析系统评价尿基质金属蛋白酶组织抑制剂-2(TIMP-2)×胰岛素样生长因子结合蛋白7(IGFBP7)在脓毒症相关性急性肾损伤(AKI)中的早期诊断价值。方法系统检索PubMed,Web of Science,Cochrane,Embase英文数据库以及中国知网、万方、维普、中国生物医学文献服务系统中文数据库,用RevMan5.3和Meta-Disc1.4软件进行数据处理和分析。结果共纳入6篇文献592例患者。2项研究来自欧美国家,4项来自中国。TIMP-2×IGFBP7早期预测脓毒症相关性AKI的合并敏感度、特异度、阳性似然比、阴性似然比和诊断比值比及其95%CI分别为0.82(0.76~0.87)、0.59(0.54~0.64)、3.11(1.47~6.56)、0.27(0.13~0.57)和12.92(4.23~39.41)。绘制综合受试者工作特征曲线(sROC)发现TIMP-2×IGFBP7诊断脓毒症相关性AKI的曲线下面积(AUC)为0.8497,Q*为0.7809。亚组分析显示,TIMP-2×IGFBP7在AKI 1期和中国人群中的诊断价值更高,AUC分别为0.9072和0.8920。结论TIMP-2×IGFBP7对于脓毒症相关性AKI尤其是AKI 1期及中国人群具有较好的早期诊断能力。