Polyvinyl chloride used as a chlorinating and a reducing agent

Polyvinyl chloride (PVC) or vinyl is a recyclable material. It can be used as a chlorinating and a reducing agent. Two tests of chlorination and reduction of two different samples of jarosite and hematite were realized using PVC, results are presented in this paper. The chlorination test shows that the HCl gas produced from PVC and heated at ≈250°C can be used as a chlorine source to recover as chlorinated compounds the valuable metals such as Zn, Pb contained in jarosite. The XRD reveals the presence of lead and zinc chlorides in the condensates obtained. The second test of reduction was conducted using a mixture of PVC and hematite treated in a nitrogen atmosphere between 200 and 1000°C. The results show that at low temperature, PVC produces HCl and with kinetic consideration, no reactions can be observed with hematite. However, at high temperature, the weight of the hematite sample decreases by ≈15%, due to the reduction of hematite to iron metal.     

聚合铝混凝过程研究:不同形态硅酸的影响作用

研究了不同形态硅酸对聚合铝混凝过程的影响作用 .实验结果表明经预制形成的具有不同形态分布组成的硅酸与聚合铝 ,在投加后相互间发生了十分复杂的物理化学作用 ,并受溶液pH值的影响 ,从而最终决定了混凝效果 .反应过程中所生成的形态产物及其物化特征 ,很大程度上取决于聚合铝碱化度以及所投加的Si Al比 .其中碱化度越高 ,最终产物所带电荷越高 .而不同硅酸所起影响作用分别取决于聚合程度 ,在与聚合铝反应过程中表现出一定的规律性 .单体硅酸与单体铝迅速发生较强的络合作用 ,抑制了多聚水解铝阳离子的形成 .聚合硅酸则倾向于与聚合铝形态相互作用形成一定的胶状化合物 ,从而在溶液中稳定存在 .对于胶体硅酸 ,在聚合铝作用下迅速凝聚形成更大的聚集体 ,在颗粒物间架桥形成粗大的絮体 .所得结果对混凝机理的解释与复合混凝剂的发展提供了一定的参考作用     

Simulated and experimental evaluation of factors affecting the rate and extent of reductive dehalogenation of chloroethenes with glucose

Carbohydrates such as molasses are being added to aquifers to serve as electron donors for reductive dehalogenation of chloroethenes. Glucose, as a model carbohydrate, was studied to better understand the processes involved and to evaluate the effectiveness for dehalogenation of different approaches for carbohydrate addition. A simulation model was developed and calibrated with experimental data for the reductive dehalogenation of tetrachloroethene to ethene via cis-1,2-dichloroethene. The model included fermentors that convert the primary donor (glucose) into butyrate, acetate and hydrogen, methanogens, and two separate dehalogenator groups. The dehalogenation groups use the hydrogen intermediate as an electron donor and the different haloethenes as electron acceptors through competitive inhibition. Model simulations suggest first that the initial relative population size of dehalogenators and H(2)-utilizing methanogens greatly affects the degree of dehalogenation achieved. Second, the growth and decay of biomass from soluble carbohydrate plays a significant role in reductive dehalogenation. Finally, the carbohydrate delivery strategies used (periodic versus batch addition and the time interval between periodic addition) greatly affect the degree of dehalogenation that can be obtained with a given amount of added carbohydrate.     

钛白副产硫酸亚铁的综合利用研究

以钛白副产硫酸亚铁、氯化钾和氨水为原料，采用硫酸钾铵法制取硫酸钾。实验结果表明，该工艺生产的产品，其质量达到ZBG-21006-89国家标准，且此工艺流程简单、操作方便、条件易控制，无二次污染。     

Chlorination of dibenzofuran and dibenzo-p-dioxin vapor by copper (II) chloride

Dibenzofuran (DF) is formed from phenol and benzene in combustion gas exhaust streams prior to particle collection equipment. Subsequent chlorination at lower temperatures on particle surfaces is a potential source of chlorinated dibenzofuran (CDF). Gas streams containing 8% O₂ and approximately 0.1% DF vapor were passed through particle beds containing copper (II) chloride (0.5% Cu, mass) at temperatures ranging from 200 to 400 °C to investigate the potential for CDF formation during particle collection. Experiment duration was sufficient to provide an excess amount of DF (DF/Cu=3). The efficiency of DF chlorination by CuCl₂ and the distribution of CDF products were measured, with effects of temperature, gas velocity, and experiment duration assessed. Results of a more limited investigation of dibenzo-p-dioxin (DD) chlorination by CuCl₂ to form chlorinated DD (CDD) products are also presented.

The efficiency of DF/DD chlorination by CuCl₂ was high, both in terms of CuCl₂ utilization and DF/DD conversion. Total yields of Cl on CDF/CDD products of up to 0.5 mole Cl per mole CuCl₂ were observed between 200 and 300 °C; this suggests that nearly 100% CuCl₂ was utilized, assuming a conversion of two moles of CuCl₂ to CuCl per mole Cl added to DD/DF. In a short duration experiment (DF/Cu=0.3), nearly 100% DF adsorption and conversion to CDF was achieved. The degree of CDF chlorination was strongly dependent on gas velocity. At high gas velocity, corresponding to a gas–particle contact time of 0.3 s, mono-CDF (MCDF) yield was largest, with yields decreasing with increasing CDF chlorination. At low gas velocity, corresponding to a gas–particle contact time of 5 s, octa-CDF yield was largest. DF/DD chlorination was strongly favored at lateral sites, with the predominant CDF/CDD isomers within each homologue group those containing Cl substituents at only the 2,3,7,8 positions. At the higher temperatures and lower gas velocities studied, however, broader isomer distributions, particularly of the less CDD/CDF products, were observed, likely due to preferential destruction of the 2,3,7,8 congeners.     

高铁铝矾土制备聚合氯化铝铁及其在污水处理中的应用研究

利用含铁的低品位铝矾土为主要原料,添加适量铝酸钙粉,制备出絮凝剂聚合氯化铝铁.制备方法为酸溶两步法.对影响聚合铝铁制备的因素,如盐酸浓度、盐酸用量、温度和铝酸钙粉用量等进行了系统研究,得到了制备聚合铝铁的优化条件,同时将该絮凝剂用于实际工业污水的处理.研究结果表明：制备的絮凝剂絮凝效果明显优于一些传统的絮凝剂;不仅具有去浊性能好、沉降快的优点,而且具有原料易得,制备成本低的优势.     

聚硅氯化铝混凝剂中Al(Ⅲ)水解聚合历程及铝硅作用特性研究

采用共聚与复合两种制备工艺，制备出了系列具有不同碱化度和不同Ａｌ／Ｓｉ摩尔比的聚硅氯化铝混凝剂，分析研究了ＰＡＳＣ中Ａｌ（Ⅲ）的水解－聚合历程以及聚硅酸与铝水解聚合产物的相互作用，探讨了ＰＡＳＣ溶液的酸解聚。     

铁盐和铝盐混凝对水中天然有机物的去除特性研究

以三氯化铁和硫酸铝为研究对象,探讨了2种混凝剂对水中天然有机物的去除效果及特点.结果表明,低投量下,硫酸铝对天然有机物的去除效果要好于三氯化铁,混凝剂投量高于15mg/L时,三氯化铁的效果较好.如混凝剂投量为10mg/L时,硫酸铝和三氯化铁处理水的TOC分别为4.19mg/L和9mg/L;当混凝剂投量为20mg/L时, TOC分别降至2.44mg/L和1.69mg/L.三氯化铁混凝后水的pH值降低幅度高于硫酸铝,形成的水解产物所带正电荷密度升高,水中有机物的质子化程度高,有利于对有机物的吸附去除.通过对UV254出和SUVA的考察可知,三氯化铁对共轭结构及不饱和有机物的去除能力要高于硫酸铝.2种混凝剂对水中不同性质有机物的去除效果不同,三氯化铁对亲水性有机物去除效果较好,对小分子量有机物去除高于硫酸铝,如混凝剂投量为20mg/L时,三氯化铁和硫酸铝对相对分子质量区间小于10 000的有机物去除率分别为16.4%和6.1%,而硫酸铝对大分子量有机物去除效率较高.     

垃圾焚烧中氯化物对重金属Cd迁移转化特性的影响

采用管式炉和模拟垃圾对垃圾焚烧中氯化物对重金属Cd迁移转化特性的影响进行了研究,使用ICP-AES(美国EPA消解方法)、SEM、EDS和XRD分析技术对重金属浓度、灰渣表面形貌、成分和灰渣X射线衍射物相等进行了分析.结果表明,氯化物的加入均使得97％以上的Cd分布于飞灰中,且随氯化物含量的增加在飞灰中的分布逐渐增加.有机氯PVC和无机氯NaCl含量的变化对Cd迁移分布的影响没有显著差别.PVC对Cd迁移分布影响受温度影响显著,550℃时Cd在飞灰中分布为80.51%,850℃时Cd在飞灰中的分布上升为97.91%,但在温度超过CdCl₂的熔点568℃后温度的影响较小.NaCl对Cd的迁移分布受温度影响不明显,加入NaCl后550℃时Cd在飞灰中分布为95.02%,1 000℃时在飞灰中的分布为96.58%.氯化物存在下停留时间对Cd迁移分布没有显著影响.底渣和飞灰的SEM/EDS和XRD分析表明,PVC和NaCl对Cd迁移转化作用机理不同.     

强化混凝去除微污染湖泊水浊度及TOC的研究

通过烧杯混凝试验和动态连续混凝试验,就混凝剂种类、投药量、pH值、水温等因素,研究强化混凝对水中浊度和TOC去除效果的影响。试验结果表明:PAC最佳投量为30mg/L,浊度去除率为90.19%,TOC去除率为38.2%,水温高于20℃时,聚合氯化铝对浊度和TOC去除率分别高达84.95%、33.18%以上。虽然pH值是影响有机物去除的主要参数,动态连续混凝试验表明,不改变pH值,强化混凝工艺依然能极大地改善出水水质,滤后水质浊度为0.1NTU,TOC为6.23mg/L。