Catalytic hydrothermal depolymerization of nylon 6

Depolymerization of nylon 6 to produce ε-caprolactam using an environmentally friendly heteropoly acid catalyst was studied at temperatures between 553 and 603 K in water. The products of depolymerization were analyzed qualitatively and quantitatively by means of mass spectrometry and high-performance liquid chromatography. The results showed that the depolymerized product was mainly ε-caprolactam with a little 6-aminocaproic acid and oligomers. The phosphotungstic heteropoly acid used as a catalyst can improve the hydrolysis rate and yield of ε-caprolactam. The optimum hydrolysis conditions for ε-caprolactam yield were as follows: phosphotungstic heteropoly acid content, 3%; reaction temperature, 573 K; and reaction time, 85 min. Under these conditions, the yield of ε-caprolactam was 77.96%. In the temperature range 553–603 K, the activation energy of 3% phosphotungstic heteropoly acid-catalyzed depolymerization was evaluated as 77.38 kJ/mol, which is lower than the 86.64 kJ/mol value for no catalyst.     

Decomposition of simulated odors in municipal wastewater treatment plants by a wire-plate pulse corona reactor

Decomposition of simulated odors in municipal wastewater treatment plants was investigated experimentally by a wire-plate pulse corona reactor. A new type of high pulse voltage source with a thyratron switch and a Blumlein pulse forming network (BPFN) was adopted in our experiments, and the testing malodorants were ammonia, ethanethiol and tri-methyl amine, respectively. The maximum output power of the pulse voltage source and the maximum peak voltage were 1 kW and 100 kV. The experiments were conducted at the gas-flow rate of 4.0-23.0 m3 h(-1). Important parameters, including peak voltage, pulse frequency, capacitance (inductance) of the BPFN, gas-flow rate, initial concentration, which influenced on the removal efficiency, were investigated. The results show that the odors can be treated effectively. Almost 100% removal efficiency was obtained for 32 mg m(-3) ammonia at the gas-flow rate of 4.0 m(3) h(-1). The maximum removal efficiencies of 85 mg m(-3) ethanethiol and 750 mg m(-3) tri-methyl amine at 10.0 m(3) h(-1) were 98% and 91%, respectively. The energy yield of 110 mg m(-3) ammonia was 2.99 g kWh(-1) when specific energy density was 106 Jl(-1). In the cases of ammonia, ethanethiol and tri-methyl amine removal, ozone and nitrogen oxides were observed in the exit gas. The carbon and sulfur elements of ethanethiol and tri-methyl amine were mainly converted to carbon dioxide, carbon monoxide and sulfur dioxide. Moreover, the ammonium nitrates and sulfur were discovered in the reactor.     

掺Ni2+的TiO2颗粒光催化性能的研究

通过溶胶-凝胶法制备掺杂Ni2 的纳米TiO2,并用XRD和TEM进行了表征,发现Ni2 的掺杂减小了TiO2颗粒的粒径,Ni2 /TiO2晶型为锐钛型.通过对目标物罗丹明B的光催化降解实验,发现Ni2 的掺杂提高了TiO2的光催化活性,其降解罗丹明B的反应遵从一级反应动力学方程,Ni2 惨杂量为1.2%时的光催化活性最高.     

地下金属矿山安全评价体系的探讨

对矿山实行安全评价是确保安全生产的重要措施。根据地下金属矿山生产工艺的特点，分析发生事故的原因及影响因素，以定量分析的方法，从企业管理、工程设计、人员配备、环境条件等方面进行安全评价，提出评价体系，系统而直观地反映企业生产安全程度。     

金属自由镦粗的实验研究

金属的拉伸和镦粗实验是研究金属材料力学性能的2个基本实验;而金属的自由镦粗又是人们用来研究自由表面裂纹和材料可加工性能的一个方便而实用的实验。重点介绍了高-径比与摩擦系数对镦粗变形行为与可加工性能的影响,并给出了一些有价值的曲线。     

板料成形有限元分析的牛顿一致迭代算法

此文针对塑性成形有限元分析大增量加载的收敛性困难,推导了用于板料成形弹塑性有限元分析的牛顿一致迭代公式.数值算例表明,此迭代算法对于大增量步长加载,也能保证解的收敛,是无条件稳定的.     

山头郑火山——侵入杂岩的成因探讨

本文以山头郑火山侵入杂岩为例,针对火山岩一次火山岩—侵入岩“三位一体”的成因假说提出质疑和讨论。该火山—侵入杂岩的形成与演化并不遵守“三位一体”的演化规律。其证据是:①侵入岩与火山岩之间存在明显的化学成分间断;②控制稀土元素和微量元素变化的矿物相与侵入岩的矿物相并不吻合;③侵入岩的锶初始值明显小于火山岩。作者认为,导致侵入岩与火山岩存在差别的主要原因是它们的源区不同。     

铁系和铝系无机絮凝剂的性能分析

对水工业的现状，铁系和铝系无机絮凝剂的的净水机理及其优缺点作了初步的探讨，并比较了它们的絮凝特性，在此基础上，作者认为无机絮凝剂的方向应沿着低分子向高分子，铁铝离子向其它阳离子并适当考虑阴离子的影响，加强基础研究的方向健康发展。     

沙棘改善黄土高原生态环境的功能与效益

黄土高原地区严重的水土流失、脆弱的生态环境，是该地区可持续发展的主要制约因素之一。沙棘适应性强、生长快，４～５年即可形成良好的灌木－草本群落，具防风固沙，改良土壤，调节小气候，增加生物多样性，恢复重建稳定生态系统的生态功能，并具较高的生态、经济和社会效益。为加速治理黄土高原、改善黄土高原生态环境和水土流失区群众脱盆致富开辟一条新路。     

菲尔德斯半岛火山构造及其时空演化

菲尔德斯半岛火山活动有两个高峰期,相应分为两个亚族回.火山机构有二类,一类以火山颈相岩柱为标志,另一类发育着火口相、近火口相集块岩、集块熔岩.据形成时间又可分为早期和晚期火山机构.火山活动明显受区域构造控制,为典型的裂隙中心式喷发,形成本区NW向、间距约为2km的火山喷发带.早期活动遍及全区,具有自SW向NE迁移的总体演化趋势;晚期沿火山喷发带自NW向SE局部性迁移.