Effect of in-situ formed Al hydrates through long-term aging on enhanced particle destabilization by PACl coagulation

Aging of polyaluminum chloride (PACl) coagulants could significantly influence hydrolyzed Al speciation ruling coagulation performance. The goal of this study was to investigate Al species transformation through long-term aging and its impact on coagulation performance. Two kinds of commercial coagulants (PACl-1 and PACl-2) were stored for in-situ aging tests in six months to evaluate Al species variation with time and the performance of coagulation with natural turbid waters. The results showed that CaSO₄ precipitation easily occur in a commercial PACl coagulant with time as it contains SO₄^2? and Ca²⁺. It also activates the precipitation of gibbsite Al(OH)₃ in PACl with aging. Through 180 days aging, both monomeric Al (Al_a) and polymeric Al (Al_b) substantially transform into colloidal Al (Al_c) and precipitated for both PACl coagulants. At low turbidity (10 NTU), PACl-1 has a superior turbidity reduction rate than PACl-2, while PACl-2 performs a little better turbidity reduction at high turbidity (1000 NTU) regardless of aging time. With aging time, an obvious decrease in turbidity reduction for PACl-1 coagulation is observed at low turbidity of 10 NTU, while the improvement in turbidity reduction for PACl-2 coagulation by enhanced sweep flocculation can be achieved as Al_b mostly transform into Al_c after 150 days aging. It is concluded that dominant in-situ formed Al_c after a long time hydrolysis can improve PACl coagulation efficiency in turbidity reduction by enhanced sweep flocculation, especially for low turbidity water, but the increase in preformed Al_c in PACl would worsen particle destabilization after aging.     

聚合氯化铝镁钛的制备及结构表征

为提高铝基复合混凝剂的混凝效果,以AlCl₃、MgCl₂、TiCl₄为原料,通过共聚反应制备出无机复合高分子混凝剂PCAMT（聚合氯化铝镁钛）,并探究其混凝机理.采用Ferron（高铁试剂）逐时络合比色法、红外光谱、X-射线衍射谱图、扫描电镜与能谱分析（SEM-EDS）、Zeta电位对产物的Al形态、结构形貌、组成及混凝机理进行分析.结果表明:①采用单因素试验法获得最佳合成条件,即反应温度为60 ℃,Mg/Al（摩尔比,下同）为0.5,Ti/Al（摩尔比,下同）为0.5,OH/（Al+Mg+Ti）（摩尔比,下同）为0.6.②形态分析表明,反应温度、Mg/Al、Ti/Al,OH/（Al+Mg+Ti）对Al的形态分布均存在影响.随着反应温度的升高,n（Ala）（Ala在Al的水解聚合形态中所占摩尔分数,下同）先减后增,n（Alb）（Alb在Al的水解聚合形态中所占摩尔分数,下同）先增后减,n（Alc）（Alc在Al的水解聚合形态中所占摩尔分数,下同）逐渐减小;随着Mg/Al的增大,n（Ala）先减后增,n（Alb）、n（Alc）为先增后减的趋势;随着Ti/Al的增大,n（Ala）逐渐增加,n（Alb）逐渐减少,n（Alc）先增后减;随着OH/（Al+Mg+Ti）的增大,n（Ala）逐渐减少,n（Alb）、n（Alc）逐渐增加.③通过红外光谱、X-射线衍射,确定了PCAMT的结构组成,表明PCAMT是一种—OH桥联的铝镁钛复杂无定型聚合物,含有Al—OH—Mg与Ti—O—Ti新基团以及形成了Mg_1.5Ti_1.25O₄、Mg_1.2Ti_1.8O₅、Al₃Ti₅O₂等共聚物.④扫描电镜与能谱结果表明,PCAMT呈紧凑的空间立体网状形貌结构,利于发挥吸附架桥、网捕卷扫作用.⑤由PCAMT投加量对Zeta电位的影响分析可知,低投药量的混凝过程中起主导作用的是电中和作用,高投药量PCAMT处理原水的混凝机制以吸附架桥和网捕卷扫作用为主.研究显示,AlCl₃、MgCl₂和TiCl₄通过共聚反应,可生成具有更高聚合度的无定型共聚物PCAMT,利于电中和、吸附架桥和网捕卷扫,具有较好的混凝效果.      

产品设计中的人性化因素

通过对工业产品人性化设计中人的因素的分析和研究,阐明了人性化各因素之间的关系,提出了产品人性化设计的核心是人,只有把人对工业产品的多元需求、特别是人的精神与文化需求提升到一定高度的设计才是好的设计.     

上海环球金融中心大厦弹塑性时程分析

在材料应力-应变关系的层次上，进行了高层钢筋混凝土结构的弹塑性时程分析。采用两种非线性宏观单元——梁柱单元和墙单元，单元截面分析采用纤维模型。在计算单元刚度矩阵时，采用子结构技术，从而实现了一根柱或一根梁采用一个非线性梁柱单元来模拟。编制了高层钢筋混凝土结构弹塑性时程分析程序，且用该程序对上海环球金融中心大厦振动台模型结构进行了分析，并与试验数据进行了对比。最后对该大厦原型结构进行了弹塑性时程分析和抗震性能评价。     

絮凝剂PSPAFC中铁铝共聚物的形态表征

通过pH值、测定波长、溶液浓度、分析试剂等确定改进了经典的Fenon逐时络合比色法,使其能用于测定Fe、Al共存溶液中[Fe,A1]的含量,从而测定实际含Fe、Al共聚物的溶液中[Fe,Al]的形态分布.结果表明,在pH=5.0,波长为362 nm,铝铁总浓度在1×10-5-1×10-4mol/L范围内,Fe、Al共聚...     

两种ZSM-5沸石分子筛吸附水中氨氮的研究

考察了两种硅铝比分别为25及50的ZSM-5沸石分子筛对水中氨氮的吸附性能及影响因素.研究表明,25℃时,25H及50H型沸石的吸附平衡时间分别为10 min和35 min,吸附等温线均符合Langmuir经验模型,25 H型分子筛的饱和吸附容量较大,为7.83 mg/g,50H型分子筛为4.36 mg/g.当吸附剂投...     

Electro-assisted regeneration of ion exchange resins

Electro-assisted regeneration (EAR) for the mixed bed of strongly acidic cation and weakly basic anion exchange resins with the Al(OH)3 suspension in a three-compartment cell was investigated. The desalination experiments were carried out to evaluate the characteristic of the regenerated mixed resins. Experimental results showed that the efficiency of resin regeneration was strictly dependent on the voltage, regeneration time, and feed regenerant flow rate. The amount of the effluent reached 50 times the volume of the resins bed, and the conductivity was less than 1.0 μs/cm. Compared to the conventional ER, the total effluent volume of EAR was about 1000 mL more than that of ER under the same conditions, and the outlet conductivity was significantly lower. The desalination and regeneration reaction mechanisms of the mixed resins indicated the regeneration efficiency of resin with Al(OH)₃ as the regenerant was much higher than that with H₂O.     

ZnO-MgO/Al2O3吸附-臭氧催化氧化处理难降解有机废水

以活性氧化铝为载体,采用浸渍法制备催化剂,对甲基橙及草酸模拟废水进行处理.在中性条件下,臭氧催化氧化比单独臭氧氧化能提前30 min使得甲基橙溶液褪色,反应105 min时,臭氧催化氧化对TOC的去除率高达96.53%,比单独使用臭氧氧化对甲基橙TOC去除率提高了47.19%,在处理草酸废水时臭氧催化氧化对TOC去除率高达80.59%,比单独使用臭氧氧化对草酸TOC去除率提高了59.14%.在处理甲基橙及草酸的小试实验中催化剂对有机污染物的吸附作用起到了加快反应进行的作用.在对垃圾渗滤液超滤出水时,O₃与COD质量比为1:1时,臭氧催化氧化对COD去除率为49.09%,比单独使用臭氧氧化提高36.37%,臭氧催化氧化对TOC的去除率是单独使用臭氧氧化的2.54倍,在处理垃圾渗滤液纳滤浓水时,臭氧催化氧化对COD去除率高达88.72%,比单独使用臭氧氧化提高37.60%,并且臭氧催化氧化对TOC的去除率是单独臭氧氧化的1.6倍.臭氧催化氧化反应过程中产生的羟基自由基对有机物更快的反应速率.     

中国居民天然气消费重心迁移路径及增长动因分解

在研究2000-2014年中国居民天然气消费重心迁移路径及其变化特征的基础上,首先运用夏普利值分解八大经济区域对重心迁移的贡献率,然后采用LMDI分解方法,将天然气消费增量分解为基础设施效应、服务效率效应、需求效应,探讨各区域对重心迁移贡献大小的原因与规律。结果显示：2000-2014年居民天然气消费重心经历了向西北、东南、东北方向迁移的三个阶段;2000-2003年西北、西南和东北地区,2003-2008年东部沿海、南部沿海地区,2008-2014年北部沿海、东部沿海和长江中游地区是居民消费重心迁移的主要推力;2000-2014年,基础设施效应一直是促进中国及各区域居民天然气增长的主要动因,而未来效率效应和需求效应将会逐步成为大部分区域的主要驱动因素。     

Interaction of PACls with sulfate

IntroductionPolyaluminumchloride (PACl)asamainkindofinorganicpolymerflocculantsisanewhighereffectivewaterandwastewatertreatmentreagent.Basedonthetraditionallow molecularaluminum ,ithasbeendevelopedworldwidesincethe 196 0s(Tang,1994 ;1990 ;1987) .PAClistheintermediateproductofthehydrolysis polymerization ageingprocessofAl(III)undersuitableconditions.Atpresent,itisgenerallyknownthattherearemanypossiblespeciesexistintheAl(III)solution ,suchasmonomers,oligomers,Al13 [AlO4Al12 (OH) 2 4(H2 …