Phosphate recovery through struvite precipitation by CO2 removal: effect of magnesium, phosphate and ammonium concentrations

In the present study, the precipitation of struvite (MgNH(4)PO(4)·6H(2)O) using the CO(2) degasification technique is investigated. The precipitation of struvite was done from supersaturated solutions in which precipitation was induced by the increase of the solution supersaturation concomitant with the removal of dissolved carbon dioxide. The effect of magnesium, phosphate and ammonium concentrations on the kinetics and the efficiency of struvite precipitation was measured monitoring the respective concentrations in solution. In all cases struvite precipitated exclusively and the solid was characterized by powder XRD and FTIR. The morphology of the precipitated crystals was examined by scanning electronic microscopy and it was found that it exhibited the typical prismatic pattern of the struvite crystals with sizes in the range between 100 and 300 μm. The increase of magnesium concentration in the supersaturated solutions, resulted for all phosphate concentration tested, in significantly higher phosphate removal efficiency. Moreover, it is interesting to note that in this case the adhesion of the suspended struvite crystals to the reactor walls was reduced suggesting changes in the particle characteristics. The increase of phosphate concentration in the supersaturated solutions, for the magnesium concentrations tested resulted to the reduction of struvite suppression which reached complete suppression of the precipitate formation. Excess of ammonium in solution was found favour struvite precipitation. Contrary to the results found with increasing the magnesium concentration in solution, higher ammonium concentrations resulted to higher adhesion of the precipitated crystallites to the reactor walls. The results of the present work showed that it is possible to recover phosphorus in the form of struvite from wastewater reducing water pollution and at the same time saving valuable resources.     

Multivariate analysis of anionic, cationic and nonionic textile surfactant degradation with the H(2)O(2)/UV-C process by using the capabilities of response surface methodology

Anionic, cationic and nonionic surfactants being frequently employed in the textile preparation process were subjected to H(2)O(2)/UV-C treatment. As a consequence of the considerable number of parameters affecting the H(2)O(2)/UV-C process, an experimental design methodology was used to mathematically describe and optimize the single and combined influences of the critical process variables treatment time, initial H(2)O(2)concentration and chemical oxygen demand (COD) on parent pollutant (surfactant) as well as organic carbon (COD and total organic carbon (TOC)) removal efficiencies. Multivariate analysis was based on two different photochemical treatment targets; (i) full oxidation/complete treatment of the surfactants or, alternatively, (ii) partial oxidation/pretreatment of the surfactants to comply with the legislative discharge requirements. According to the established polynomial regression models, the process independent variables "treatment time" (exerting a positive effect) and "initial COD content" (exerting a negative effect) played more significant roles in surfactant photodegradation than the process variable "initial H(2)O(2) concentration" under the studied experimental conditions.     

A new approach for preparation of oil-soluble bimetallic dispersed catalyst from layered ammonium nickel molybdate

A new route via the coating of layered ammonium nickel molybdate with oleic acid was developed to prepare an oil-soluble bimetallic dispersed catalyst for the hydrocracking reaction of heavy oil. The layered ammonium nickel molybdate, termed Ni-LTM precursor, was synthesized by precipitation, and the NiMo oleate complex was prepared with the oleic acid serving as an organic ligand. The prepared materials were characterized with X-ray diffraction, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. It was found that the oleic acid is chemisorbed as a carboxylate onto the Ni-LTM nanoparticles, specifically on Ni-O bond. Also, the catalytic activities were compared between the NiMo oleate complex and other ordinary monometallic dispersed catalysts. The NiMo oleate complex showed excellent catalytic activity, demonstrating its potential to be applied as a novel dispersed catalyst.     

提高改性铵油炸药流散性的研究

在试验的基础上,研究了固态块状复合油相、不同比例松香和固态块状复合油相混合物取代液态复合油相对改性铵油炸药流散性的影响,并对用两种油相制造的改性铵油炸药的爆炸性能进行了测试。结果表明两种可燃剂取代液态复合油相后能够大幅提高改性铵油炸药的流散性,而且爆炸性能、生产安全性和贮存稳定性优良,适用于露天深孔岩石爆破。     

液体硝酸铵直接应用于工业炸药生产的效益分析

随着技术进步,液体硝酸铵直接应用于工业炸药生产的工艺是今后技术发展主流。文章分析了该项技术在简化生产工艺、优化生产设备、提高安全性、改善生产环境、避免环境污染等方面的社会效益,以及在降低人工成本、节约包装成本、降低能耗、减少资金占用等方面的经济效益。     

全连续生产线上膨化硝铵炸药防结块研究

文章分别研究了表面活性剂、油相材料和木粉水分对连续生产线上膨化硝铵炸药结块性影响。研究发现,表面活性剂、高熔点油相、低水分木粉可以降低炸药结块性,尤其以表面活性剂的防结块效果最佳;同时采用表面活性剂、高熔点油相和低水分木粉能有效解决夏季高湿环境下全连续生产线上膨化硝铵炸药结块问题,以保证产品爆炸和贮存性能稳定。     

爆炸焊接专用炸药的研究与应用

为满足金属爆炸焊接的要求,以岩石膨化硝铵炸药为主体,配以适量的添加剂制得一种爆炸焊接专用炸药.试验结果表明:通过改变添加剂的含量,可以得到不同爆速的爆炸焊接炸药,爆炸焊接效果理想,且该炸药具有优良的安全性能和可靠的爆炸性能.     

喹啉型季铵盐缓蚀性能评价

本文采用季铵化试剂与喹啉反应,合成了6种季铵盐型缓蚀剂.通过失重法对它们的缓蚀性能进行了评价,分析了缓蚀剂浓度、腐蚀温度对缓蚀性能的影响,并通过Tafel曲线争EIS谱研究了这些缓蚀剂的缓蚀机理.实验结果表明,6种合成缓释剂的缓蚀效果按从小到大顺序排列为:1,3-二氯化喹啉-2-羟基丙烷＜环氧丙烷基氯化喹啉＜1,2-二溴化喹啉乙烷＜烯丙基氯化喹啉＜(4-乙烯基)-苄基氯化喹啉＜苄基氯化喹啉;当苄基氯化喹啉质量分数为0.1％时,腐蚀电流密度由空白时的222.80μA/cm2降为17.28μA/cm2,缓蚀效率迭92.24％;随缓蚀剂浓度增加,缓蚀效果增强;随温度增加,缓蚀效果减弱.合成缓蚀剂的缓蚀机理均属于“负催化效应”,均为以抑制阳极反应为主的混合型缓蚀剂.对于季铵盐型缓蚀剂,缓蚀剂分子的空间位阻越小,分子中能与Fe原子形成配位键的基团越多,且形成配位键的基团亲水性越差,则缓蚀性能越好.图6表3参7     

新型酸化液体系在复杂水井中的研究与应用

针对长庆油田开发现状,建立了分步解堵思路,开发了一套酸化解堵液体系。结果表明,采用预处理液体系（3%盐酸＋3%琥珀酸＋0.5%柠檬酸＋1%缓速剂HSJ＋2%渗透剂STJ＋5%有机分解剂YFJ）处理4 h后,胍胶和聚合物破胶液残渣的分解率分别为82.3%和96.0%,岩屑溶蚀率为11.3%;采用前置液体系（4%已二胺四乙酸＋5%溶垢剂RGJ＋2%渗透剂STJ）处理16 h后,硫酸钙的溶解率达86.5%,硅胶和氟硅酸钠的溶解率分别为100%和97.5%;采用主体液体系（20%复合酸＋3%缓速剂HSJ＋0.3%柠檬酸＋5%渗透剂STJ＋6%分子成膜剂CMJ）处理4 h后,岩屑的溶蚀率为38.9%。此外,预处理液和主体酸体系还具有很好的缓速性能,预处理液与CaCO3反应0.5 h时H＋浓度是5%HCl体系H＋浓度的9.1倍,主体酸体系与CaCO3反应0.5 h时H＋浓度是土酸体系H＋浓度的12.2倍。该技术已在现场成功实施15井次,改造后平均降压6.9 MPa,日增注9.6 m3,目前累计增注31060 m3,取得了较好的试验效果。图3表5参4     

粉浆法制备平面荧光粉涂层白光LED的技术改进

基于粉浆法制备白光LED能得到厚度可控的荧光粉层,改善了白光LED的均匀性.由于芯片长时间工作时表面的发热以及回流焊时的瞬间高温环境,聚乙烯醇(PVA)感光胶的颜色容易发生改变,影响了白光LED光效的稳定性.本文采用等离子体去胶,实验结果表明,通过该方法能有效去除感光胶,处理后的LED不会因为长时间工作荧光粉表面涂层的...