Synthesis and characterization of agricultural controllable humic acid superabsorbent

Humic acid superabsorbent polymer (P(AA/AM-HA)) and superabsorbent polymer (P(AA/AM)) were synthesized by aqueous solution polymerization method using acrylic acid (AA), acrylamide (AM) and humic acid (HA) as raw material. The effects of N,N'-methylenebisacrylamide (MBA) crosslinking agent, potassium peroxydisulfate (KPS) initiator, reaction temperature, HA content, ratio of AA to AM, concentration of monomer and neutralization of AA on water absorption were investigated. Absorption and desorption ratios of nitrogen fertilizer and phosphate fertilizer were also investigated by determination of absorption and desorption ratio of NH₄⁺, PO₄^3? on P(AA/AM-HA) and P(AA/AM). The P(AA/AM-HA) and P(AA/AM) were characterized by Fourier translation infrared spectroscopy, biological photomicroscope and scanning electron microscopy (SEM). The optimal conditions obtained were as follows: the weight ratio of MBA to AA and AM was 0.003; the weight ratio of KPS to AA and AM was 0.008; the weight ratio of HA to AA was 0.1; the mole ratio of AM to AA is 0.1; the mole ratio of NaOH to AA is 0.9; the reaction temperature was 60°C. P(AA/AM-HA) synthesized under optimal conditions, has a good saline tolerance, its water absorbency in distilled water and 0.9 wt.% saline solution is 1180 g/g and 110 g/g, respectively. P(AA/AM-HA) achieves half saturation in 6.5 min. P(AA/AM-HA) is superior to P(AA/AM) on absorption of NH₄⁺, PO₄^3?. The SEM micrograph of P(AA/AM-HA) shows a fine alveolate structure. The biological optical microscope micrograph of P(AA/AM-HA) shows a network structure. Graft polymerization between P(AA/AM) and HA was demonstrated by infrared spectrum. The P(AA/AM-HA) superabsorbent has better absorbing ability of water and fertilizer, electrolytic tolerance and fewer cost than P(AA/AM) superabsorbent.     

矿区土地复垦措施选择分析

在全面分析文献及前人研究的基础上,通过理论分析,提出了矿区土地复垦模式的分类体系和确定的理论方法,总结了矿区土地复垦措施的特点。对矿区土地复垦模式的合理选择,实现矿区的可持续发展具有一定的指导意义。     

Zero-valent iron doped carbons readily developed from sewage sludge for lead removal from aqueous solution

Low-cost but high-efficiency composites of iron-containing porous carbons were prepared using sewage sludge and ferric salts as raw materials. Unlike previous time- and energy-consuming manufacturing procedures, this study shows that pyrolyzing a mixture of sludge and ferric salt can produce suitable composites for lead adsorption. The specific surface area, the total pore volume and the average pore width of the optimal composite were 321 m²/g, 0.25 cm³/g, and 3.17 nm, respectively. X-ray diffraction analysis indicated that ferric salt favored the formation of metallic iron, while Fourier transform infrared spectroscopy revealed the formation of hydroxyl and carboxylic groups. The result of batch tests indicated that the adsorption capacity of carbons activated with ferric salt could be as high as 128.9 mg/g, while that of carbons without activation was 79.1 mg/g. The new manufacturing procedure used in this study could save at least 19.5 kJ of energy per gram of activated carbon.     

兰州市西固区蔬菜重金属污染现状及健康风险评价研究

针对西北地区典型的工业区-兰州市西固工业区内种植的蔬菜进行重金属含量状况调查分析,对购自当地市场的8种蔬菜中Cu、Cd、Pb、Zn 4种重金属元素的含量进行分析,通过污染指数法和经蔬菜途径重金属暴露接触对人体的健康风险进行了系统评价.结果表明,蔬菜中均不含有Pb元素或Pb元素在蔬菜中的含量比较少,低于分析方法检测限;Cu元素含量最高的是茄子为0.067 mg/kg,含量最低的是菜花为0.015 mg/kg;Cd元素含量最高的是芹菜为0.067 mg/kg,含量最低的是白菜为0.023 mg/kg;Zn元素含量最高的是菠菜为1.001 mg/kg,含量最低的是辣椒为0.274 mg/kg.美国环境健康风险评估方法评价所得THQ值均小于1,表明实验所采集的大多数蔬菜样品的重金属含量符合农产品安全质量要求.     

Acid resistance of methanogenic bacteria in a two-stage anaerobic process treating high concentration methanol wastewater

In this study, the two-stage upflow anaerobic sludge blanket (UASB) system and batch experiments were employed to evaluate the performance of anaerobic digestion for the treatment of high concentration methanol wastewater. The acid resistance of granular sludge and methanogenic bacteria and their metabolizing activity were investigated. The results show that the pH of the first UASB changed from 4.9 to 5.8 and 5.5 to 6.2 for the second reactor. Apparently, these were not the advisable pH levels that common methanogenic bacteria could accept. The methanogenic bacteria of the system, viz. Methanosarcina barkeri, had some acid resistance and could still degrade methanol at pH 5.0. If the methanogenic bacteria were trained further, their acid resistance would be improved somewhat. Granular sludge of the system could protect the methanogenic bacteria within its body against the impact of the acidic environment and make them degrade methanol at pH 4.5. The performance of granular sludge was attributed to its structure, bacteria species, and the distribution of bacterium inside the granule.     

Carbamazepine degradation by heterogeneous activation of peroxymonosulfate with lanthanum cobaltite perovskite: Performance, mechanism and toxicity

The widely used carbamazepine(CBZ) is one of the most persistent pharmaceuticals and suffers insufficient removal efficiency by conventional wastewater treatment.A synthesized Co-based perovskite(LaCoO_3) was used to activate peroxymonosulfate(PMS) in order to degrade CBZ.Results showed that LaCoO_3 exhibited an excellent performance in PMS activation and CBZ degradation at neutral pH,with low cobalt leaching.The results of FT-IR and XPS verified the high structurally and chemically stability of LaCoO_3 in PMS activation.Electron spin resonance(ESR) analysis suggested the generation of radical species,such as sulfate radicals(SO_4·~-) and hydroxyl radicals(·OH).Radical quenching experiments further revealed the responsibility of SO_4·~-as the dominant oxidant for CBZ oxidation.Ten products were detected via the oxidation of CBZ,with the olefinic double bond attacked by SO_4·~-as the initial step.Hydroxylation,hydrolysis,cyclization and dehydration were involved along the transformation of CBZ.The toxicity of CBZ solution was significantly reduced after treating by PMS/LaCoO_3.     

高浓度甲醇废水厌氧处理中颗粒污泥和产甲烷细菌的耐酸性

采用两段UASB处理工艺和间歇培养试验,对高浓度甲醇废水厌氧处理的运行特性进行了研究,并较深入地研究了颗粒污泥和产甲烷菌的耐酸特性及代谢活性.试验结果表明,两段UASB反应器的pH值较低,分别为4.9～5.8和5.5～6 2,显然,这不是一般产甲烷细菌适宜的pH范围.系统中的产甲烷菌即巴氏产甲烷八叠球菌,具有一定耐酸性,在pH为5.0时仍然能够降解甲醇,如果进一步培养,其耐酸性将有所提高.系统中的颗粒污泥能够保护其内部的产甲烷菌,较少地受酸性环境的影响,并在pH为4.5时仍能降解甲醇.颗粒污泥的这种性能与其结构、细菌种类和颗粒体内细菌分布情况有很大关系.     

高职计算机应用专业基于工作过程课程体系开发的探讨

介绍了基于工作过程课程体系开发的一般方法,探讨了该方法在计算机应用专业课程体系开发中的应用,并以网站开发综合课程为例,介绍了基于工作过程课程开发方法在具体课程教学设计中的应用。     

万头猪场沼气发电工程热平衡影响因素研究

在分析万头猪场沼气发电工程热平衡及其影响因素基础上,详细阐述了系统热量收支衡算方法。通过算例表明,对于万头猪场的沼气发电工程而言,物料提温占厌氧发酵系统总热量需求的80％～88％,是厌氧消化系统热量需求的主要因素,其次是消化器的热损,占10％～17％,在发电余热回收量不低于沼气总能量40％的情况下,高寒地区的进料浓度应不低于6％,干猪粪进料量应不低于1000kg／d。     

A港区海上溢油事故数值模拟预测

为研究A港区溢油事故的影响,通过MIKE21软件建模、并综合考虑风向、风速和潮流等因素设定6种不同情景进行模拟预测。结果显示,在不利风条件下,72 h油膜扩散距离为0.7~39.50 km,扫海面积可达0.03~142.97 km²,风场对油粒子的漂移和扩散起决定性作用,潮流场次之。通过模拟预测,为加强区域溢油应急联动、充分利用周边溢油应急资源,做好溢油应急防范提供参考。