Thermal stability and oil absorption of aluminum hydroxide treated by dry modification with phosphoric acid

The dry modification of aluminum hydroxide powders with phosphoric acid and the effects of modification of technological conditions on thermal stability, morphology and oil absorption of aluminum hydroxide powders were investigated. The results show that the increase of mass ratio of phosphoric acid to aluminum hydroxide, the decrease of mass concentration of phosphoric acid and prolongation of mixing time are favorable to the improvement of thermal stability of aluminum hydroxide; when the mass ratio of phosphoric acid to aluminum hydroxide is 5:100, the mass concentration of phosphoric acid is 200 g/L and the mixing time is 10 min, the initial temperature of loss of crystal water in aluminum hydroxide rises from about 192.10 to 208.66 ℃, but the dry modification results in the appearance of agglomeration and macro-aggregate in the modified powders, and the oil absorption of modified powders becomes higher than that of original aluminum hydroxide.

Study on reactions of gaseous P_2O_5 with Ca_3(PO_4)_2 and SiO_2 during a rotary kiln process for phosphoric acid production

In a rotary kiln process for phosphoric acid production,the reaction between gaseous phosphorus pentoxide(P_2O_5)and phosphate ore and silica contained in feed balls(the so-called P_2O_5"absorption")not only reduces phosphorous recovery but also generates a large amount of low melting-point side products.The products may give rise to formation of kiln ring,which interferes with kiln operation performance.In this study,the reactions of gaseous P_2O_5with solid calcium phosphate(Ca_3(PO_4)_2),silica(SiO_2)and their mixture,respectively,were investigated via combined chemical analysis and various characterizations comprised of X-ray diffraction(XRD),Fourier-transform infrared(FT-IR)spectroscopy,thermogravimetric analysis and differential scanning calorimeter(TG&DSC),and scanning electron microscopy and energy dispersive spectrometer(SEM&EDS).Attentions were focused on apparent morphology,phase transformation and thermal stability of the products of the P_2O_5"absorption"at different temperatures.The results show that the temperature significantly affected the"absorption".The reaction between pure Ca_3(PO_4)_2 and P_2O_5 occurred at 500°C.Calcium metaphosphate(Ca(PO_3)_2)was the primary product at the temperatures≤900°C with its melting point≤900°C while calcium pyrophosphate(Ca_2P_2O_7)was obtained over 1000°C,which has a melting point≤1200°C.The"absorption"by pure SiO_2 started at 800°C and the most significant reaction occurred at 1000°C with formation of silicon pyrophosphate(SiP_2O_7)product of melting point≤1000°C.Using mixed Ca_3(PO_4)_2and SiO_2as raw material,the"absorption"by Ca_3(PO_4)_2 was enhanced due to existence of silica.At 600–700°C,silica was inert to P_2O_5and thus formed a porous structure in the raw material,which accelerated diffusion of gaseous P_2O_5inside the mixture.At higher temperatures,the combined"absorption"by calcium phosphate and reaction between silicon dioxide and the"absorption"product calcium pyrophosphate,reinforced the"absorption"by the mixture.Besides,it was found that both Ca(PO_3)_2and SiP_2O_7were unstable at high temperatures and would decompose to Ca_2P_2O_7and SiO_2,respectively,at over 1000°C and 1100°C with the release of gaseous P_2O_5at the same time.

Performance Optimization of a Phosphoric Acid Fuel Cell/Absorption Refrigerator Hybrid System

A hybrid system that consists of a phosphoric acid fuel cell(PAFC),an absorption refrigerator and a refrigeration-space is proposed.The four-heat-source absorption refrigerator,which is driven by the waste heat produced from PAFC,provides cooling for a refrigeration-space.A numerical model is set up to analyze both the steady-state performance and transient performance considering the influences of the electrochemical and thermodynamic irreversibilities.Expressions of the equivalent power output and efficiency of the hybrid system are determined.Moreover,the transient behavior of cold-space temperature is performed and the time to reach a prescribed cold-space temperature is displayed.Thus,the operation regions of the current are optimized at different operating conditions.The results showthat in an appropriate current range,the overall power output and efficiencies of the hybrid system are enhanced.

Relationship between the incidence of non-hepatic hyperammonemia and the prognosis of patients in the intensive care unit

BACKGROUND Ammonia is a normal constituent of body fluids and is found mainly through the formation of urea in the liver.Blood levels of ammonia must remain low as even slightly elevated concentrations(hyperammonemia)are toxic to the central nervous system.AIM To examine the relationship between the incidence of non-hepatic hyperammonemia(NHH)and the prognosis of patients who were admitted to the intensive care unit(ICU).METHODS This is a prospective,observational and single-center study.A total of 364 patients who were admitted to the ICU from November 2019 to February 2020 were initially enrolled.Changes in the levels of blood ammonia at the time of ICU admission and after ICU admission were continuously monitored.In addition,factors influencing the prognosis of NHH patients were analyzed.RESULTS A total of 204 patients who met the inclusion criteria were enrolled in this study,including 155 NHH patients and 44 severe-NHH patients.The incidence of NHH and severe-NHH was 75.98% and 21.57%,respectively.Patients with severe-NHH exhibited longer length of ICU stay and higher Acute Physiologic Assessment and Chronic Health Evaluation and Sequential Organ Failure Assessment scores compared to those with mild-NHH and non-NHH.Glasgow Coma Scale scores of patients with severe-NHH were than those of non-NHH patients.In addition,the mean and initial levels of ammonia in the blood might be helpful in predicting the prognosis of NHH.CONCLUSION High blood ammonia level is frequent among NHH patients admitted to the ICU,which is related to the clinical characteristics of patients.Furthermore,the level of blood ammonia may be helpful for prognosis prediction.

磷酸吸氨法生产氨水和磷酸铵的可行性研究

在我国焦化行业,磷酸吸氨法生产氨水存在磷氨资源浪费、设备管道易结垢堵塞、磷酸铵溶液处置不够环保等问题。介绍了磷酸吸氨法生产氨水的工艺原理及优缺点,研究了利用高浓度磷酸吸收氨废气后,用于生产高端水溶性、工业级磷酸铵产品的可行性,并提出相应的技改措施和建议。

磷酸法替代硫酸法处理含氨废气的可行性研究及建议

介绍了硫酸法和磷酸法处理含氨废气的技术原理和工艺流程,其中硫酸法是以硫酸为脱除剂,在饱和器或酸洗塔内洗涤吸收氨后生产硫酸铵;磷酸法是以磷酸为脱除剂,在吸收塔内与氨反应生成磷酸一铵,再继续吸收氨生成磷酸二铵,磷酸二铵在解吸塔内解吸出氨后,又转化为磷酸一铵返回吸收塔循环套用,解吸出的氨经冷凝生产氨水。分析评价了二者的经济性、安全性和环保性,得出磷酸法优于硫酸法的结论;从原料、工艺和设备等三方面的适应性,探讨了用磷酸法替代硫酸法处理含氨废气的可行性,并提出了相应的技改措施及建议。

Phelipanche aegyptiaca Management with Glyphosate in Potato

Two years field and greenhouse studies were carried out to evaluate the efficacy of sub-lethal doses of glyphosate (Round upR), ammonia gas, phosphoric acid and sulfuric acid against Phelipanche aegyptiaca in potato. Results showed that sequential application of sub-lethal doses of glyphosate at all tested rates significantly reduced P. aegyptiaca shoot number and shoot dry weight. While, the use of ammonia gas, phosphoric acid and sulfuric acid had no significant effect on the total level of P. aegyptiaca infection as compared to the control. The best results considering both P. aegyptiaca control and selectivity in potato were obtained by sequential application of sub-lethal doses of glyphosate at 60 and 80 g·ai·ha-1. Sequential application of glyphosate at 60 g·ai·ha-1 reduced P. aegyptiaca infection by 100% after 100 days after potato emergence (DAPE). Except for sequential application of glyphosate at 60 and 80 g·ai·ha-1, all tested rates enhanced the maturity rate of potato plants and decreased the number of marketable potato tubers.

乙酸对土壤累积态磷活化及棉花磷素吸收的影响

为探究乙酸对土壤累积态磷活化及棉花磷素吸收的影响,以新农大棉4号为材料,通过施用乙酸的盆栽试验方法,设置土壤中不施磷肥和乙酸溶液(对照)、仅施用磷肥、分次施入150 L/hm^(2)乙酸溶液、分次施入300 L/hm^(2)乙酸溶液、一次性施入150 L/hm^(2)乙酸溶液和一次性施入300 L/hm^(2)乙酸溶液6个处理。结果表明,4种乙酸施用方式均可提高土壤中有效磷含量和棉花磷素吸收,施用乙酸处理的棉花磷素吸收量均显著高于对照(P<0.05),与对照比棉花磷素吸收提高了37.3%~101.7%,且一次性施入300 L/hm^(2)乙酸溶液处理的磷素吸收量最高。在0~5 cm、5~10 cm和10~20 cm土层中,乙酸溶液用量为150 L/hm^(2)时,土壤有效磷含量较仅施用磷肥处理分别增加了16.3%~35.4%、1.1%~10.4%和0.9%~8.8%,乙酸溶液用量为300 L/hm^(2)时,0~5 cm、5~10 cm和10~20 cm土层中有效磷含量分别增加了18.3%~38.8%、2.4%~20.1%和2.0%~11.6%。乙酸施用可提高土壤中磷素的有效性,促进棉株磷的积累,从而提高棉花的生物量和产量,并以一次性施入300 L/hm^(2)乙酸溶液处理对棉花的磷素吸收效果最好,土壤中有效磷的含量随乙酸的用量增加而增加。

化学吸收法采集固定污染源氨气的影响因素探究

固定污染源氨气的手工监测,干扰因素较多,其中采样环节尤为关键。实验通过催化氧化-化学发光法考察不同采样管线材质对氨气的吸附效果,离子色谱法考察化学吸收法采集氨气的吸收瓶类型、采样流量、吸收液种类、吸收液浓度及体积等采样条件对氨气吸收效率的影响。实验表明,316 L不锈钢与聚四氟乙烯对氨气的吸附较小,氨气的采样流量不宜超过1.0 L/min,棕色气泡式吸收瓶更适用于氨气样品的采集,磷酸溶液作吸收液对氨气的吸收效率较好,对于低浓度的氨气样品,应采用低流量长时间采集。

资源化氨气吸收系统应用研究

结合具体应用实例,介绍了尿素热解制氰尿酸外排废氨气的吸收工艺及设备配置,通过合理的工艺配置及关键部位重点防护,在低投资的情况下实现了对废氨气、废稀硫酸液的综合治理和资源化利用。

硫酸法和磷酸法处理氨废气的生产状况分析及建议

介绍了硫酸法和磷酸法处理氨废气的工艺过程和原理,从原料(吸氨剂)、产品、工艺、设备、消耗等五个方面,对比分析了二者的生产状况,综合评价认为,磷酸法处理氨废气比硫酸法具有以下优势:①原料磷酸性质温和,对设备的腐蚀性小;②工艺运行平稳,产品质量可控,设备故障率低、运转率高;③生产氨水基本上不消耗磷酸,运行费用低、经济效益好等,并提出了将硫酸法改为磷酸法处理氨废气的相关建议。

超低排放工艺下完全抽取式二氧化硫固定源在线监测设备全系统校准

为探索超低排放改造的固定源在线监测设备二氧化硫(SO_(2))全系统校准工作的开展情况,保障其自动监测数据的质量,利用标准物质对不同测量原理的自动监测设备进行分组试验。试验结果表明,热湿法自动监测设备在完成超低排放改造的高氨、高湿测量环境中适用性更强;造成冷干法自动监测设备SO_(2)全系统校准示值误差超标的原因为冷凝器铵盐结晶的吸附干扰;当待测烟气为高氨(>2 mg/m^(3))、高湿(>12.3%)测量环境时,14 h后SO 2全系统校准示值误差开始超过±2.5%的限值要求;在11%~13%的高湿测量环境中,磷酸滴定装置的氨逃逸水平<6 mg/m^(3)、除氨器+纳分除湿管装置的氨逃逸水平<15 mg/m^(3)时,解决铵盐结晶干扰的效果最佳。

在线监测烟气预处理优化

随着宣钢焦化厂焦炉和锅炉烟气超低排放的改造完成,烟气使用氨法脱硝,烟气排放存在二氧化硫浓度低、氨逃逸的特点,易造成冷干直抽法CEMS检测二氧化硫数值偏低或为“0”,全程通二氧化硫标气响应时间和示值误差超标的问题。原因在于高温烟气冷凝水析出,溶解烟气中的二氧化硫,逃逸氨在CEMS中发生二次脱硫,且生成的铵盐能吸附烟气中的二氧化硫。以氨法脱硝装置的抽取式CEMS系统为研究对象,通过在烟气预处理中增加磷酸滴定装置,解决了二氧化硫监测数据偏低、全程通标气响应时间不达标问题,确保了在线监测数据的准确性。

乙二胺/磷酸溶液化学吸收法烟气脱硫的研究

提出了一种有机胺吸收二氧化硫的新型烟气脱硫工艺,并建立了有机胺吸收烟气中二氧化硫的气液平衡模型,首次较好预测了二氧化硫-乙二胺-磷酸水溶液体系的气液平衡.对比0.3mol·L-1乙二胺缓冲溶液的预测结果与实验结果,最大相对偏差不超过7%.同时,以乙二胺/磷酸混合溶液作为吸收剂,在φ 30mm×600mm的填料塔中进行了逆流吸收和解吸实验,确定了实验室规模下适宜的吸收工艺条件:液气比L/G=0.6～1.0 L·m-3,乙二胺浓度0.3 mol·L-1,吸收液初始SO2浓度4～6g·L·1,pH值6.0～7.5;解吸工艺条件为:预热温度60℃,塔釜温度103℃,喷淋密度0.7m3·m-2·h-1,富液中SO2浓度14～16 g·L-1.进一步的经济分析表明,乙二胺/磷酸法脱硫费用相当于石灰石法的1/3,低于氨法和新近开发的NADS法,具有较好的经济性.

石墨炉原子吸收光谱法测定磷酸中铅镉

研究了使用超声振荡混匀试液，通过计算扣除试样空白的石墨炉原子吸收光谱测定磷酸中铅、镉的方法。实验发现硝酸具有与硝-磷混酸相同的基体改进效果，从而在校准曲线溶液中仅使用硝酸，而无需再使用磷酸即可以克服基体干扰。室温下，试样在硝酸中超声搅拌1h，试液可完全混匀。试液中铅和镉用石墨炉原子吸收光谱仪直接测定，检出限为0．19ng／mL（铅）和0．068ng／mL（镉），回收率为100％～113％（铅）和94％～112％（镉）。该方法适用于测定磷酸中铅镉。

吹脱-沸石吸附法处理荧光粉生产废水研究

研究了吹脱-沸石吸附法处理荧光粉生产废水。正交试验结果表明:氨吹脱工艺中影响NH3-N去除率因素的重要性顺序为:pH>温度>气液比。当pH=11、气液比(V/V)=100∶1、温度T=40℃、吹脱时间t=120 m in,吹脱工艺对荧光粉生产废水中NH3-N的去除率为74.46%。试验确定的沸石吸附单元较佳的工艺参数为:滤速0.04 m/m in、接触时间14m in、pH=7.5,吹脱-沸石吸附工艺总NH3-N去除率96.04%。试验结果表明再生沸石氨吸附性能稳定,适于高氨氮的荧光粉生产废水处理。

窑法制磷酸反应的热力学

对窑法制磷酸回转窑反应器中磷矿可能发生的反应进行了热力学分析。结果表明:多硅配料磷矿(由Ca10(PO4)6F2,C和SiO2组成,其物质的量之比为1:15:10.5)起始还原温度为1 417 K,比多钙配料(由Ca10(PO4)6F2和C组成,其物质的量之比为1:15)低211.5 K。磷矿球团中炭烧损和磷矿吸收P2O5(称为P2O5反吸)主要发生在球团预热阶段。炭烧损主要源于窑气中残余氧气对炭的氧化,而布多尔反应的影响很小;反吸生成了焦磷酸钙和低熔点的偏磷酸钙(Ca(PO3)2)。窑气中O2,CO2,H2O和P2O5均能氧化磷蒸气,其反应热力学趋势由大到小依次为O2,P2O5,CO2,H2O,其中CO2和H2O基本相同。在现有窑法磷酸工况下回转窑内P2O5不能生成磷酸,偏磷酸的出现可能是P2O5直接水合形成。

窑法磷酸中磷酸钙对P_2O_5反吸过程

窑法磷酸生产中,气体产物P_2O_5与磷矿发生副反应（俗称P_2O_5反吸）生成大量低熔点物料,导致窑内结圈堵料,造成生产装置不能稳定运行。以磷酸钙与P_2O_5的反应为研究对象,采用化学分析与SEM、XRD、IR、Raman、TG及DSC等表征手段对不同温度下该反应产物的P_2O_5含量、形貌、物相组成、结构及热稳定性能等进行研究,探讨磷矿对P_2O_5的反吸行为。研究表明,反吸过程与反应温度密切相关,磷酸钙与P_2O_5在500℃以上发生反应,在500-900℃时,磷酸钙与P_2O_5反应生成偏磷酸钙,900℃反吸产物几乎为纯偏磷酸钙;在1000-1300℃时,反吸产物偏磷酸钙分解为稳定的焦磷酸钙,同时释放出P_2O_5气体,1300℃时反吸产物几乎为纯焦磷酸钙。

混合醇沉淀法精制湿法磷酸

介绍了混合醇沉淀法净化湿法磷酸的新工艺。采用单因素法研究了溶剂、凝结剂、洗液用量及反应温度、反应时间对湿法磷酸中杂质去除率和五氧化二磷收率的影响。

复分解法生产磷酸二氢钾的新工艺

研究了以液氨、氯化钾和湿法磷酸为原料,通过复分解法生产磷酸二氢钾的工艺,确定复分解反应的最佳反应条件为:氨与磷酸物质的量比为1.05:1,氯化钾与磷酸物质的量比为1.1:1,反应时间为50 min,反应温度为70～80℃,所得磷酸二氢钾达到HG2321-1992质量标准,可作为农业高效复合肥料.该工艺简单,能耗和原料消耗低,原料综合利用率高,生产过程无三废产生.