新型固化单宁大孔吸附树脂的合成

应用曼尼希反应将植物单宁固定在苯乙烯-二乙烯苯共聚物上,制备一种新型固化单宁大孔吸附树脂.系统研究了胺基树脂的合成及其与单宁固化的工艺合成试验,得出最佳工艺条件为:胺基树脂:甲醛:单宁(质量比)=2:0.74:1,反应温度99～100℃,反应时间7 h.制备的固化单宁大孔吸附树脂具有较好亲水性,对水溶液中苯酚的吸附容量可达90 mg/g.该树脂易洗脱再生,重复使用效果好,对实际含酚废水的富集回收均获得了令人满意的结果.     

螯合剂诱导下污染土壤溶液中TOC和重金属的动态变化及其相关性

采用土培盆栽试验研究了EDTA,NTA(氨三乙酸)和EDDS(乙二胺二琥珀酸)三种螯合剂诱导下,土壤溶液中总有机碳(TOC)含量和重金属浓度的动态变化以及二者之间的关系.结果表明,施用5 mmol·kg-1螯合剂能极显著地增加土壤溶液中TOC的含量和Cu,Zn,Cd,Pb的浓度.土壤溶液TOC含量从第2天达最大后就随时间呈一阶指数衰减函数y=y0 Ae(x-x0)/t变化,衰减因子大小顺序为tEDTA>tNTA>tEDDS.土壤溶液中Cu,Zn,Cd和Pb浓度的动态变化也有与TOC相似的规律,并且两者呈显著线性正相关.结果还表明,螯合剂对重金属的活化能力与其相应金属螯合物的稳定常数lgKMe基本一致,为EDTA>EDDS>NTA,因此,在螯合诱导强化植物提取中NTA和EDDS的潜在环境风险比EDTA要小.     

纳米Pd／Fe双金属颗粒对单氯酚及二氯酚的还原脱氯

采用改进液相化学还原法制备纳米Pd／Fe双金属颗粒,研究其钯化率为0．045％和0．135％的条件下分别对3种单氯酚（2-CP、3-CP和4-CP）和3种二氯酚（2,3-DCP、2,4-DCP和2,6-DCP）的脱氯反应。结果表明,合成的纳米Pd／Fe颗粒分散性良好,粒径分布介于25～40nm。纳米Pd／Fe双金属颗粒对单氯酚及二氯酚具有良好的去除效果,3种单氯酚和3种二氯酚的脱氯难易程度分别为2-CP〉4-CP〉3-CP和2,6-DCP〉2,4-DCP〉2,3-DCP,脱氯反应均符合拟一级反应动力学方程。通过还原脱氯实验揭示了分子中氯原子的化学环境对还原脱氯过程具有明显影响。     

Pd/Fe催化脱氯水中PCE的动力学研究

以GC-MS为分析方法,采用Pd／Fe双金属对水溶液中四氯乙烯（PCE）进行了催化还原脱氯处理,考察了PCE初始浓度、钯含量、Pd／Fe用量和溶液初始pH值等各因素对脱氯效果影响及还原动力学规律。结果表明,Pd／Fe双金属对PCE有较好的还原脱氯效率,反应遵循准一级反应动力学规律,以反应物PCE浓度为参照的反应速率常数K变化范围为0．019min^-1～0．16min^-1,对应的PCE半衰期从6min到36min,揭示反应有可能是在过量的Pd／Fe双金属表面进行。当PCE溶液初始浓度为1mmol／L,投加1．2g钯含量为0．03％的Pd／Fe双金属,在25℃下反应60min,PCE的脱氯率达到95％以上。增大钯含量和Pd／Fe用量可有效提高脱氯率,在初始pH值为弱酸性条件下有利于还原脱氯反应进行。     

Reduction of nitrate from groundwater: powder catalysts and catalytic membrane

The reduction of nitrate contaminant in groundwater has gained renewed and intensive attention due to the environmental problems and health risks. Catalytic denetrification presents one of the most promising approaches for the removal of nitrate from water. Catalytic nitrate reduction from water by powder catalysts and catalytic membrane in a batch reactor was studied. And the effects of the initial concentration, the amounts of catalyst, and the flux H2 on the nitrate reduction were also discussed. The results demonstrated that nitrate reduction activity and the selectivity to nitrogen gas were mainly controlled by diffusion limitations and the mass transfer of the reactants. The selectivity can improved while retaining a high catalytic activity under controlled diffusion condition or the intensification of the mass transfer, and a good reaction condition. The total nitrogen removal efficiency reached above 80%. Moreover, catalytic membrane can create a high effective gas/liquid/solid interface, and show a good selectivity to nitrogen in comparative with the powder catalyst, the selectivity to nitrogen was improved from 73.4 % to 89.4%.     

Recent Industrial Applications of Lignin: A Sustainable Alternative to Nonrenewable Materials

Lignin represents a vastly under-utilized natural polymer co-generated during papermaking and biomass fractionation. Different types of lignin exist, and these differ with regard to isolation protocol and plant resource (i.e., wood type or agricultural harvesting residue). The incorporation of lignin into polymeric systems has been demonstrated, and this depends on solubility and reactivity characteristics. Several industrial utilization examples are presented for sulfur-free, water-insoluble lignins. These include materials for automotive brakes, wood panel products, biodispersants, polyurethane foams, and epoxy resins for printed circuit boards.     

Electroreductive dechlorination of chlorophenols with Pd catalyst supported on solid electrode

Electroreductive dechlorination of chlorophenols with Pd catalyst supported on solidelectrode was studied. As solid electrodes, carbon cloth (CC), carbon felt (CF) and titanium mesh were used, and palladium was plated on solid electrodes by either electrolytic or electroless method. On each electrode with Pd, chlorophenols were qualitatively dechlorinated to phenol, while they were entirely intact on electrodes without Pd. Moreover, neither base electrode nor plating method significantly affected the activity of Pd as far as it was sufficiently loaded on the electrode. Based on the results in the experiments using one electrode repeatedly, Pd catalyst proved to possess a satisfactory duarability under the present condition. It was suggested that the reactive species responsinble for the dechlorination of chlorophenols could be formed during preliminary electrolysis. Thus, (Pd)_x-H resulting from the adsorption of electrogenerated hydrogen on metallic Pd might be assumed most probable.     

负载型纳米Pd/Fe对氯代烃脱氯机理研究

采用实验室制备的负载型纳米Pd/Fe对几种常见的挥发性氯代烃:四氯乙烯(ICE)、三氯乙烯(TCE)、1,1-二氯乙烯(1,1-DCE)、氯乙烯(VC)和林丹(γ-HCH)进行了还原脱氯研究.负载型纳米Pd/Fe对PCE、TCE、1,1-DCE、VC和γ-HCH的还原脱氯符合准一级反应动力学方程,其反应速率常数分别为2.79 h-1、2.35 h-1、1.12 h-1、2.14 h-1和4.02 h-1.氯代烃降解过程中几乎没有中间产物生成,终产物主要为C2 H6和C2 H4,如对TCE进行降解时,生成的C2H6和C2 H4分别占总碳质量比的70%和10%.采用暴露在空气中24 h的负载型纳米Pd/Fe对PCE进行脱氯,8次循环后仍能对PCE快速完全降解,表明负载型纳米Pd/Fe的稳定性能良好.以γ-HCH为目标污染物对负载型纳米Pd/Fe的反应持久性进行了研究,200 h后负载型纳米Pd/Fe的反应性没有明显降低,表明负载型纳米Pd/Fe反应持久性能良好.温度对负载型纳米Pd/Fe的脱氯反应影响较大,测得各氯代烃脱氯反应的活化能均高于29 kJ·mol-1.对PCE、TCE进行了脱氯动力学模拟,模拟结果与试验数据基本吻合,表明负载型纳米Pd/Fe对氯代烃的脱氯,是连串、平行及多步骤反应的结合.     

Copper biosorption on immobilized seaweed biomass： Column breakthrough characteristics

The biosorption of copper by the brown seaweed Sargassum baccularia,immobilized onto polyvinyl alcohol(PVA)gel beads, was investigated with fixed-bed experiments.Laboratory-scale column tests were performed to determine breakthrough curves with varying flow rates and feed concentrations.A theoretical fixed-bed model,known as the Bohart-Adams equation,was evaluated in simulating the experimental breakthrough curves.The Bohart-Adams model qualitatively predicted the breakthrough trends.PVA- immobilized seaweed biomass beads were amenable to efficient regeneration with aqueous solution containing the chelating agent ethylenediaminetetraacetic acid(EDTA).The biosorbent retained most of its original uptake capacity over three cycles of use.The excellent reusability of the biosorbent could lead to the development of a viable metal remediation technology.