99 % yield biodiesel production from rapeseed oil using benzyl bromide–CaO catalyst

Biofuels are sustainable fuels produced from modern biomass such as plants and algae. Biodiesel has high lubricity and ultra-low sulfur content. Biodiesel is produced from vegetable oil by transesterification. Actually, practical biodiesel production is limited by the low reaction rate of transesterification of vegetable oil with methanol catalyzed by CaO. Here we designed an efficient catalyst: benzyl bromide-modified CaO. Using benzyl bromide-modified CaO, we obtained a 99.2 % yield of fatty acid methyl esters in 3 h, compared with 35.3 % yield using commercial CaO under the same reaction conditions. The improved catalytic activity is explained by better fat diffusion to the surface of the benzyl bromide-modified CaO. The novelty of our findings is the much higher yield of our method compared to literature data on heterogeneous catalysis. In addition, the lifetime of our catalyst is excellent.     

基于改进型AES算法汽车门禁系统的研究

汽车门禁系统已成为汽车智能与安全领域的重要一部分.车主手持智能钥匙靠近汽车,通过车载基站与钥匙的双频通信,实现车门的开与关,还可实现发动机的一键启动.同时,对信号加密采用了改进的AES算法,加入了循环扩展密钥,加大了密码的破解难度.并对整个系统进行了建模仿真,分析了信号传输的误码率.图6,表1,参5.     

高炉干法除尘系统噪声控制技术

高炉干法除尘系统主要噪声源为煤气调压阀组。在煤气调压阀组下游加装带整流栅的消声器,解决了此类消声器易被吹坏的问题,振动也得到缓解。另外采用隔声罩和局部包扎,可控制噪声。此项技术在鞍钢鲅鱼圈等厂应用,消声器下游噪声降至90 dB以下。经过进一步开发,研制成功了新型高炉煤气调压阀组与降噪减振成套装置,可在不加隔声罩的情况下,使噪声达到国家标准。     

苯胺的超临界水氧化研究1

苯胺的超临界水氧化表明,氧化剂Ｈ２Ｏ２、试验温度、压力和停留时间以及水样的起始ＴＯＣ值对ＴＯＣ的去除率有显著影响．在本试验中,选取了硫酸铜、硫酸铁、硫酸锰等金属盐进行苯胺的均相催化氧化试验研究,结果表明,这些金属盐对苯胺的氧化有不同的催化活性,筛选出硫酸锰和和硫酸亚铁进行了进一步的研究．以硫酸锰作催化剂为例,在４５０℃,２８ＭＰａ,Ｋ＝１．１,ｐＨ＝４．０的条件下,当停留时间为４６ｓ时,ＴＯＣ去除率达到１００%．     

土壤中腐殖酸对外源农用稀土生物可利用性的影响

采用盆栽实验方法,研究了腐殖酸对稀土元素在土壤-植物体系中的迁移、富集和生物可利用性的影响,结果表明,在试验土壤红壤中,稀土元素主要富集在小麦根部,加入低浓度的腐殖酸后,促进了小麦对稀土元素的吸收：而高浓度的腐殖酸则抑制小麦对稀土元素的吸收,腐殖酸浓度过高时,对小麦生长产生毒害作用,同时发现,小麦中叶绿素含量与小麦中稀土含量存在相关关系。     

快速测定水中有机磷农药方法的研究

研制出一种能快速测定水中有机磷农药的植物酯酶片和底物片。这种酶片和底物片具有价格低,易获取、稳定性好等优点,适用于野外无仪器设备条件下快速检测有机磷农药危险水平,对常用几种有机磷农药来说,其检出限在０．０４－１０．０ｍｇ．ｌ＾－１范围。     

微囊藻毒素及其与其他环境污染物的联合毒性研究进展

微囊藻毒素(microcystins,MCs)是一种蓝藻代谢产物,在全球富营养淡水生态系统中广泛分布,高浓度的MCs不仅对水生生物造成负面影响,还会与水体中共存污染物发生相互作用,影响彼此在生物体内转化代谢和毒性效应.因此,开展MCs与多种环境污染物的复合污染对不同生物的毒性研究十分必要,其对水体复合污染风险评价和防控...     

Thin-layer fine-sand capping of polluted sediments decreases nutrients in overlying water of Wuhan Donghu Lake in China

Environmental Science and Pollution Research - Capping water body sediments with a thin layer of sand is an effective technique to decrease nutrient concentrations in the water column and...     

Effects of juvenile crucian carp (Carassius carassius) removal on submerged macrophyte growth—implications for subtropical shallow lake restoration

Environmental Science and Pollution Research - Rapid expansion of juvenile fish after biomanipulation can delay the successful restoration of submerged macrophytes, leading to a turbid water status...     

Assessment of private economic benefits and positive environmental externalities of tea plantation in China

Tea plantations are rapidly expanding in China and other countries in the tropical and subtropical zones, driven by relatively high private economic benefit. However, the impact of tea plantations on the regional environment, including ecosystem services and disservices are unclear. In this study, we developed an assessment framework for determining the private economic benefits and environmental externalities (the algebraic sum of the regulating services and disservices) of tea plantations in China. Our results showed that tea plantations provided private economic benefits of 5,652 yuan ha^?1 year^?1 (7.6 yuan?=?1 USD in 2007) for tea farmers, plus positive environmental externalities of 6,054 yuan ha^?1 year^?1 for the society. The environmental externalities were calculated as the sum of the value of four regulating services, including carbon sequestration (392 yuan ha^?1 year^?1); soil retention (72 yuan ha^?1 year^?1); soil fertility protection (3,189 yuan ha^?1 year^?1) and water conservation (2,685 yuan ha^?1 year^?1), and three disservices, including CO₂ emission (?39 yuan ha^?1 year^?1), N₂O emission (?137 yuan ha^?1 year^?1) and nonpoint source pollution (?108 yuan ha^?1 year^?1). Before the private optimal level, the positive environmental externalities can be maintained by private economic benefits; if a social optimal level is required, subsidies from government are necessary.