Flocculation of dilute titanium dioxide suspensions by graft cationic polyelectrolytes

The flocculation of a dilute titanium dioxide (TiO₂) suspension using homopolymers and graft copolymers of acrylamide (AM) and diallyldimethylammonium chloride (DADMAC) was investigated. The graft copolymers produced by γ-irradiating the mixtures of polyacrylamide (PAM) and polyDADMAC gave better flocculating performance than homopolymers, reflecting the higher fractions of large particles and bigger floc size. A kinetic delay in the onset of flocculation was observed after adding the copolymers in the dose range 5–30 [mg polymer]/ [g TiO₂]. Increasing dosage resulted in a longer delay period. No significant flocculation was observed when the dose was above 50 [mg polymer]/[g TiO₂]. This delay was interpreted in terms of the re-conformation of polymer chains driven by charge neutralization, between the positively charged polymer branches and the negative particle surface. Depending on the dosage used, the flocculation behavior of the graft copolymer has been suggested to be equilibrium and non-equilibrium flocculation. It was also observed that re-conformation is not affected by the ion strength of the media, but a strong shear force significantly reduces the chain reconformation time. Received: 9 April 1998 Accepted in revised form: 28 August 1998     

马铃薯深加工工艺废液化学絮凝研究

以钙盐、铝盐、铁盐及聚丙烯酰胺为絮凝剂在不同温度、不同pH等条件下对马铃薯深加工的废液进行化学絮凝。结果发现聚丙烯酰胺加聚合氯化铝絮凝的效果最好。CODCr能由15000mg/L降到5500mg/L,沉降率60%左右。SS能由9500mg/L降到1000mg/L,沉降率为90%左右。能达到进行生物絮凝的要求。     

Numerical simulation of flocculation and transport of suspended particles: Application to metered-dose inhalers

This study investigates the dynamics of flocculation and transport of solid particles suspended in a liquid propellant. Polydisperse particles with lognormal size distribution are considered. Collision of particles is presumed to be controlled by upward velocity differential and Brownian motion. These mechanisms are enhanced by the van der Waals force. Flocculation of the particles is described using the continuous form of the Smoluchowski equation. Upward transport of the particles is specified via a convection term. The general dynamics of the system is governed by a nonlinear transient partial integro-differential equation which is solved numerically. The technique employed is based on discretizing the size distribution function using orthogonal collocation on finite elements. This is combined with a finite difference discretization of the physical domain, and an explicit Runge–Kutta–Fehlberg time marching scheme. The numerical analysis is validated by comparing with a closed form analytical solution. The simulation results represent the particle size distribution as a function of time and position. The method allows prediction of the effects of the initial conditions and physical properties of the suspension on its dynamic behavior and phase separation.     

木质素胺絮凝剂的制备及其脱色性能

以造纸污泥中提取的木质素和二乙基环氧丙基胺（简称环氧胺单体）为原料,通过接枝共聚反应制备了木质素胺絮凝剂（DL）,并确定了最佳合成工艺条件,同时采用傅里叶变换红外光谱（FTIR）对产物结构进行了表征。结果表明,以1.5mo1·L^-1NaOH为催化剂,木质素和环氧胺单体的质量比为1:1,于70℃下接枝反应2h时,所得絮凝剂DL对3种模拟染料废水的脱色率分别可达89.66%、74.10%和89.84%,通过比较DL与木质素的絮凝效果以及絮体微观形貌,对DL的絮凝机理进行了初步探讨。     

层状复合金属氢氧化物-聚丙烯酸钠水分散体系的双絮凝现象及机理探讨

研究了聚丙烯酸钠(PAAS)对镁铝型层状复合金属氢氧化物(MgAl-LDH)的胶体水分散体系稳定性的影响. 利用总有机碳(TOC)分析技术测定了PAAS在LDH颗粒上的吸附量, 并利用ζ电位表征了LDH颗粒的电性质. 实验结果表明, 在质量分数为1%的LDH水分散体系中加入0.006~2.400 mmol/L PAAS, 随着PAAS浓度的增加, LDH-PAAS混合体系出现了絮凝-分散-再絮凝变化. 同时, 随着PAAS浓度的增加, PAAS在LDH颗粒上的吸附导致颗粒ζ电位由正减至0, 并进一步负向增加, 颗粒间静电斥力先减小后增加, 因此体系先絮凝再分散. 随着LDH颗粒负电性的进一步增强, 未吸附的PAAS引发颗粒间产生的空缺引力成为体系再次絮凝的主要原因. 对吸附PAAS的LDH颗粒的红外光谱分析表明, PAAS主要通过-COO-与LDH的相互作用而吸附在颗粒上.     

Effect of pH on the Flocculation of SDS Micelles by Al3+

SDS micelles flocculate in the presence of Al³⁺, creating an aggregate with pollutant-removing properties. The fraction of SDS micelles flocculating depends on the concentrations of SDS and Al³⁺. This paper describes how this fraction also changes with pH. There are two reasons for this dependence: a change in pH has a strong effect in the solution chemistry of Al³⁺, converting it into the compound [Al₁₃O₄(OH)₂₄]⁷⁺, a strong flocculant, or precipitating it as Al(OH)₃; and at low pH protons may compete with Al³⁺ as binding counter-ions for micelles. An increase in pH allows flocculation of SDS at high concentrations of Al³⁺, which under unmodified pH does not occur. Micelle flocculates are reported in this work to exist between pH 5 and pH 8, suggesting the potential use of Adsorptive Micellar Flocculation for the removal of anionic pollutants from waste waters not necessarily limited to acidic solutions. Received: 18 August 2000 Accepted: 5 October 2000     

粉末活性炭与碱式氯化铝混凝处理微污染水源水的研究

用粉末活性炭吸附与碱式氯化铝混凝相结合的工艺处理微污染生活水源水,研究活性炭种类、加入量和加入先后等因素对原水嗅味、色度和有机物等去除效率的影响。结果显示,投加40mg/L200mesh活性炭以后再进行混凝,对各种污染物的去除效果较好,对原水异嗅味、色度、浊度、矿物油和苯酚的去除率分别达到71%~90%,对CODMn、TOC和氨氮的去除率分别在47%~53%、26%~27%和10%~18%范围。     

壳聚糖对药液絮凝作用的研究

以壳聚糖为絮凝剂，研究了它对丹参水提液的絮凝情况。比较了絮凝剂加入量不同和分子量不同时，絮凝物的沉降速率，从而考察了它们对絮凝效果的影响以及所得产品的质量。     

魔芋葡甘聚糖磷酸酯对高岭土悬浊液的絮凝研究（Ⅰ）

魔芋葡甘聚糖磷酸酯对高岭土悬浊液的絮凝研究（Ⅰ）奉平陈旭东（西南师范大学环境化学研究所重庆，６３０７１５）（华南理工大学高分子系广州，５１０６４１）杨大成，付英姿（西南师范大学化学系重庆，６３０７１５）关键词：魔芋葡甘聚糖磷酸酯（ＫＧＭＰ），高岭土，...     

丙烯酰胺与4-乙烯基吡啶共聚物的季胺化及其若干性能

将丙烯酰胺 (AM)与 4 乙烯基吡啶 (4VP)的共聚物 (P(AM co 4VP) )用硫酸二甲酯季铵化 ,制备了系列吡啶季铵盐型阳离子丙烯酰胺共聚物 ,用FTIR、1 H NMR和紫外分光光度法表征了其分子结构与组成 ,并重点研究了其絮凝与缓蚀性 ,考察了阳离子度与分子量对其各种功能的影响 .研究结果表明 ,吡啶季铵盐型阳离子丙烯酰胺共聚物具有优良的絮凝 缓蚀等功能 ,且阳离子度越高 ,性能越好 ,而分子量对其性能亦有显著的影响 .