Effects of Slow-Mixing on the Coagulation Performance of Polyaluminum Chloride (PACI)

Conventional jar tests and on-line size monitoring were used to investigate the effects of slow-mixing intensity and duration on residual turbidity and floc size during charge neutralization coagulation and sweep flocculation with polyaluminum chloride. The compensatory effect of slow-mixing on coagulation performance following inadequate or excessive rapid-mixing was also examined. It is found that slow-mixing intensity has a more marked positive effect on charge neutralization coagulation than on sweep flocculation. The optimal root-mean- square velocity gradient, G, for slow-mixing is 15 s^-1 for both coagulation mechanisms, and charge neutralization coagulation requires a longer slow-mixing duration. The optimal slow-mixing duration, based on residual turbidity, is longer than the time to form the largest mean flocs. The optimal product of G and mixing duration, GT, for slow-mixing during charge neutralization coagulation (13500) are higher than that during sweep flocculation (4500) and both are less than the range of values recommended by the American Water Works Association (24000-84000). The optimal GT value under various slow-mixing conditions increases with G. Appropriate extension of slow-mixing duration during charge neutralization coagulation can improve coagulation performance after an inadequate or excessive rapid-mixing duration, but during sweep flocculation, appropriate shortening of slow-mixing duration after an excessive rapid-mixing or appropriate extension of slow-mixing duration after an inadequate rapid-mixing is favorable.     

超细材料强化混凝去除海水中腐殖酸的研究

采用纳米SiO2超细粉末、FeCl3和聚合氯化铝(PAC)强化混凝去除海水中的腐殖酸。结果表明,FeCl3和PAC复配,使铝系絮凝剂良好的分散性与铁系絮凝剂优良的沉降性得到了较好协同效果,浊度和腐殖酸的去除率均好于两者单独使用。两者最适宜配比为:m(Fe)/m(Al2O3)=2,投加超细粉末强化混凝,浊度和腐殖酸的去除率分别可以达到94%和95%,并可以有效地改善絮体的沉降性能,缩短沉淀时间,使絮体和水体分离的更为彻底,水体上部几乎无悬浮物,对进水温度和pH值的适用范围广。     

止血性壳聚糖的制备及其凝血效果的研究

在温和均相条件下,对较高脱乙酰度的壳聚糖进行乙酰化,制备不同脱乙酰度的壳聚糖;测试不同脱乙酰度和分子量的壳聚糖醋酸溶液的凝血效果。中药—壳聚糖复合止血材料的制备及其止血功能的研究。     

甲壳胺纤维和含银甲壳胺纤维的抗菌性能比较

从定性、定量的角度探讨了甲壳胺纤维和含银甲壳胺纤维对大肠杆菌、金黄色葡萄球菌、枯草芽孢杆菌三种常见的、具有代表性的细菌的抑制作用,并把这两种纤维和粘胶纤维的抗菌性能作了比较。实验结果表明:含银甲壳胺纤维比普通的甲壳胺纤维具有更好的抗菌性能。     

颖壳不闭合水稻专用肥的生产与应用

颖壳不闭合水稻专用肥是一种生物有机-无机复合肥料,采用腐殖酸(粉状风化煤)包膜,轻质碳酸钙、骨粉进行扑粉,同时喷淋微生物菌液进行吸附,从而完成微生物与颗粒肥料的复合一体化处理。经大田试验验证,颖壳不闭合水稻专用肥可以大幅降低水稻的颖壳不闭合现象,与普通复合肥(15-15-15)相比,水稻可增产13.8%,具有显著的经济和社会效益。     

Comparative Coagulant Demand of Polyferric Chloride and Ferric Chloride for the Removal of Humic Acid

Abstract

This paper is concerned with the potential advantages of the use of polyferric chloride as a coagulant for the removal of natural organic matter (e.g., humic acid) in water treatment. In particular, this paper assesses the effects of the basic nature of polyferric chloride, the type of water, and the coagulation pH on the humic acid removal performance. The comparative dose demand of polyferric chloride and ferric chloride was assessed in terms of a good humic acid removal efficiency (> 50%) achieved. It was found that a polyferric chloride with a basic ratio of 0.3 can achieve the best humic acid removal. The water having both humic acid and colloidal particles was favorable to the floc development and a better humic acid removal. For the same coagulation conditions, the dose demand of polyferric chloride was 50% less than that of FeCl₃ for a > 50% humic acid removal.     

去除水中腐殖酸的磁性焙烧态类水滑石制备与表征

采用共沉淀法一步合成系列类水滑石负载磁性粒子的颗粒,经煅烧得到磁性焙烧产物.利用焙烧产物吸附水中腐殖酸,得到磁性焙烧态锌铝类水滑石去除腐殖酸效果较好.考察了磁性焙烧态锌铝类水滑石制备条件对腐殖酸去除效果的影响,通过正交试验优化了制备条件.静态吸附实验表明:吸附剂投加量0.2 g/L, 30 min内20 mg/L腐殖酸去除率为97.96%.X射线衍射(XRD)、红外光谱(FT-IR)、热重-差热(TG-DSC)和比表面积(SSA)表征结果表明:一定量的磁性基质掺入并没有破坏锌铝类水滑石典型的层状结构;焙烧态产物为氧化物,磁性保持良好;比表面积达80.00 m2/g.磁性焙烧态锌铝类水滑石在水中因"记忆效应"而结构重建通过表面吸附和腐殖酸结构中小尺寸的官能团插层快速去除腐殖酸.     

A Review on the Potential Use of Chitosan-Based Delivery System in Mild Facial Cleansing Formulation

The facial cleansing products segment has grown over the years and most surfactant-based systems do not retain many of the active ingredients on the skin. Development of a positively charged vesicle as the delivery vehicle for personal cleansing products is based on the negatively charged nature of the skin surface. Chitosan has the potential to be used as a vesicle to encapsulate active ingredients and can be used in facial formulations that are based on amphoteric surfactant with or without the addition of nonionic surfactant. This review briefly summarizes the potential of chitosan nanoparticles as the delivery system in facial cleansing formulations.     

2-羟基-3-萘甲酸生产工艺条件的优化研究

通过对中和及酸析过程的分析,采用改进后的参数指标进行中和及酸析得到的2-羟基-3-萘甲酸,产品为大颗粒、亮黄色,含量98.78%,收率80.13%(以消耗的2-萘酚计),并实现了在大生产中的应用。     

Preparation of Pure PLLA,Pure Chitosan,and PLLA/Chitosan Blend Porous Tissue Engineering Scaffolds by Thermally Induced Phase Separation Method and Evaluation of the Corresponding Mechanical and Biological Properties

The aim of this work was to prepare the scaffolds of pure poly (L-lactic acid) 3% (w/v), pure chitosan 3% (w/v), and PLLA/chitosan blend (1:5) 3% (w/v) using TIPS method and investigate their properties and application in tissue engineering. An in vitro degradation study of scaffolds showed the addition of chitosan to PLLA not only increased its degradation rate, but also slowed down its pH value reduction. Addition of chitosan to PLLA increased hydrophilicity, porosity, compressive properties, and cell viability of the scaffolds. The results indicate that among all scaffolds, the most appropriate candidate for tissue engineering is PLLA/chitosan blend.     

A Novel Nanocomposite Matrix Based on Silylated Chitosan and Multiwall Carban Nanotubes for the Immobilization of Urease

A nanocomposite matrix made up of silylated chitosan and multiwall carbon nanotubes (CHIT–SiO₂–MWCNTs) was fabricated to investigate the immobilization of urease (Urs). Urs enzyme was covalently immobilized with the CHIT–SiO₂–MWCNTs matrix using glutaraldehyde as a linker. The resulting Urs/CHIT–SiO₂–MWCNTs biomatrix was characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and cyclic voltammetry (CV) taking CHIT–SiO₂–MWNTs as a reference. The influence of various parameters on Urs enzyme activity within the matrix was investigated including pH, temperature, and time. The Michaelis–Menten constant and apparent activities for the Urs enzyme were calculated to be 0.51 mM and 89.02 mg/cm², respectively; indicating CHIT–SiO₂–MWCNTs nanocomposite matrix has a high affinity to immobilize Urs enzyme.     

A Study on the Effects of the Degree of Deacetylation of Chitosan Films on Physical and Antibacterial Properties

The principal aim of this research study is to discuss the influences and effects of the acetylation degree of chitosan on antibacterial properties, mechanism, and thermal properties. Various chitosan with different degrees of deacetylation (DD%) were dissolved in acetic acid solution to produce films. The basic structure of chitosan consists of different ratios of amine (?NH₂) and acetic (R-HNCO-R). The discussion in this research paper also includes bacteriostasis, sterilization antibacterial capabilities, thermal manufacturing properties, and mechanisms.     

The Effectiveness in the Removal of PAHs from Aqueous Solutions in Physical and Chemical Processes: A Review

Polycyclic aromatic hydrocarbons (PAHs) are relatively well-known organic pollutants and due to their carcinogenic and mutagenic properties, their presence in the aqueous environment still attracts a lot of attention. This article presents a critical review of the literature on the application of physical and chemical processes for removal of PAHs from aqueous solution, including water and wastewater. The effectiveness of coagulation, chemical oxidation, photodegradation, sorption, and membrane processes in the degradation or removal of these micropollutants is described. The PAHs removal efficiency (coagulation ～ 99%, chemical oxidation ～ 87%, photodegradation ～ 93%, sorption ～ 100%, and membrane ～ 100%) during the above processes is difficult to compare due to the works conducted under different conditions and using various mediums, e.g., water, wastewater, PAHs model aqueous solutions.     

Preparation of Acid Dye Molecule Surface-Imprinted Material for Effective Removal of Acid Dyes from Water and Study on its Molecule Recognition Performance

An acid dye molecule surface-imprinted material was prepared successfully for the dye removal from water by using a novel molecular surface-imprinting technique. The cationic monomer acryloyloxyethyl trimethyl ammonium chloride (DAC) was used as functional monomer, and sunset yellow was used as a model compound of water-soluble acid dyes. In the aqueous solution, DAC molecules were combined around sunset yellow molecules via electrostatic interaction. The graft/cross-linking copolymerization of DAC and the crosslinker on SiO₂ particles was initiated by a surface-initiating system of –NH₂/S₂O₈^2-, resulting in the sunset yellow molecule surface-imprinted material MIP-PDAC/SiO₂. MIP-PDAC/SiO₂ possesses special recognition property for sunset yellow.     

一种用腐殖酸助滤生产硝磷酸液的新方法

在以硝酸和磷矿为起始原料生产硝基肥的工艺中：在硝酸萃取磷矿过程中加入腐殖酸,过滤工段利用腐殖酸助滤,实现了固液顺利分离;滤饼简单洗涤并中和后去造有机肥,滤液经后续工序去造硝基肥,这样不外排滤渣,养分也不损失,做到了资源的循环利用。     

新型脱色絮凝剂(KD-800)处理印染废水的研究

探讨了一种新型有机高分子脱色絮凝剂(KD-800)的制备方法。KD-800与钢铁酸洗废液和聚丙烯酰胺联合使用,对以活性染料为主要成分的印染废水进行混凝脱色试验,对脱色影响因素和控制条件等进行了研究。结果表明,当K型KN型活性染料废水的pH值为6．0～11．0,KD-800用量为1．2mL/L,钢铁酸洗废液用量为2．5mL/L时．对活性染料废水的脱色率均可达到95％以上。     

A Study on the Acetylation Degree of Chitosan and Its Effects on the Physical Properties of Antibacterial Membrane in the Polyurethane Lamination Process

This article aims to explore how the thermoplastic polyurethane (TPU) affects the various conditions of chitosan. Several processes were used and two of them are the TPU film and chitosan lamination process intended to complete a membrane, and the TPU and chitosan blending process designed to manufacture a film. This research shall also probe into the acetylation degree of chitosan so as to understand how an increase in content may affect the antibacterial qualities, manufacturing process, mechanism, and thermal properties.     

Equilibrium Isotherms,Thermodynamics, and Kinetic Studies for the Adsorption of Food Azo Dyes onto Chitosan Films

The adsorption of FD&C red 2 and FD&C yellow 5 onto chitosan films (CFs) was evaluated by equilibrium isotherms, thermodynamics, and kinetic studies. The effects of temperature (298–328 K), initial dye concentration (50–300 mg L^?1), stirring rate (50–350 rpm), and contact time (0–120 min) were investigated at pH of 2.0 and 100 mg L^?1 of CFs. The dye concentration was determined by spectrophotometry. Freundlich and Langmuir models were used to represent the equilibrium data. The Langmuir model was the more adequate to represent the equilibrium data (R² > 0.99 and average relative error <2.50%) and the maximum adsorption capacities were 494.13 and 480.00 mg g^?1 for FD&C red 2 and FD&C yellow 5, respectively, obtained at 298 K. The R_L values ranged from 0.044 to 0.145. The adsorption was exothermic, spontaneous, and favorable. For the FD&C red 2, 90% of saturation was attained at 120 min and the Elovich model was the more appropriate. For the FD&C yellow 5, 95% of saturation was attained at 20 min and the pseudo first-order model was the more adequate to fit the kinetic data. CFs were easily separated from the liquid phase after the adsorption process, providing benefits for industrial applications, and its application range can be extended for azo dyes.     

偶氮染料结构与日晒牢度关系研究

本文介绍了近年来国内外对于偶氮染料光致褪色的研究进展,综述了偶氮染料光褪色与偶氮键断裂机理。利用Hammett方程,反映出取代基效应与染料褪色速率间的定量关系,并将Hammett方程引入分散、酸性偶氮染料日晒牢度的分析中,很好的阐释了取代基团吸、供电子效应对染料在不同纤维上日晒牢度的影响,并提出了获得优异日晒牢度染料的合成和应用方法。     

粉煤灰负载壳聚糖处理印染废水的最佳实验条件

对粉煤灰负载壳聚糖的制备及将其应用于印染废水处理上的情况进行了研究。研究了不同试剂的投加量,pH 和反应时间等因素对印染废水脱色效果的影响。实验结果表明,印染废水的最适处理条件是：在常温下,当pH是3.5,粉煤灰负载壳聚糖的投加量是4 g/L,反应时间为20 min,静置沉淀时间是5 h时,印染废水的脱色率可达92.6%。。