Comparison of quartz sand, anthracite, shale and biological ceramsite for adsorptive removal of phosphorus from aqueous solution

The choice of substrates with high phosphorus adsorption capacity is vital for sustainable phosphorus removal from waste water in constructed wetlands. In this study, four substrates were used： quartz sand, anthracite, shale and biological ceramsite. These substrate samples were characterized by X- ray diffractometry and scanning electron microscopy studies for their mineral components （chemical components） and surface characteristics. The dynamic experimental results revealed the following ranking order for total phosphorus （TP） removal efficiency： anthracite 〉 biological ceramsite 〉 shale 〉 quartz sand. The adsorptive removal capacities for TP using anthracite, biological ceramsite, shale and quartz sand were 85.87, 81.44, 59.65, and 55.98 mg/kg, respectively. Phosphorus desorption was also studied to analyze the substrates＇ adsorption efficiency in wastewater treatment as well as the substrates＇ ability to be reused for treatment. It was noted that the removal performance for the different forms of phosphorus was dependent on the nature of the substrate and the adsorption mechanism. A comparative analysis showed that the removal of particulate phosphorus was much easier using shale. Whereas anthracite had the highest soluble reactive phosphorus （SRP） adsorptive capacity, biological ceramsite had the highest dissolved organic phosphorus （DOP） removal capacity. Phosphorus removal by shale and biological ceramsite was mainly through chemical adsorption, precipitation or biological adsorption. On the other hand, phosphorus removal through physical adsorption （electrostatic attraction or ion exchange） was dominant in anthracite and quartz sand.     

Adsorption mechanism of phenolic compounds from aqueous solution on hypercrosslinked polymeric adsorbent

The adsorption of two phenols, namely, phenol and salicylic acid(SA) onto a water-compatible hypercrosslinked polymeric resin (NJ-8) were studied in terms of pseudo-second-order and first order mechanisms for chemical sorption as well as an intraparticle diffusion mechanism process. Kinetic analysis showed that the intraparticle diffusion process was the essential rate-controlling step. The activation energies of sorption have also been evaluated with the pseudo-second-order and intraparticle diffusion constants, respectively. Adsorption equilibrium data were well fitted by the Langmuir, Freundlich and Redlich-Peterson isotherms. Adsorption was exothermic and basically of a type of transition between physical and chemical character. The sorption capacity was higher for SA due to its more hydrophobic. Phenol has a higher adsorption enthalpy since it could form stronger hydrogen bonding on NJ-8.     

Photocatalytic degradation of dye effluent by titanium dioxide pillar pellets in aqueous solution

Photocatalytic oxidation (PCO) process is an effective way to deal with organic pollutants in wastewater which could be difficult to be degraded by conventional biological treatment methods. Normally the TiO2 powder in nanometre size range was directly used as photocatalyst for dye degradation in wastewater. However the titanium dioxide powder was arduous to be recovered from the solution after treatment. In this application, a new form of TiO2(i. e. pillar pellets ranging from 2.5 to 5.3 mm long and with a diameter of 3.7 mm) was used and investigated for photocatalytic degradation of textile dye effluent. A test system was built with a flat plate reactor(FPR) and UV light source(blacklight and solar simulator as light source respectively) for investigating the effectiveness of the new form of TiO2. It was found that the photocatalytic process under this configuration could efficiently remove colours from textile dyeing effluent. Comparing with the TiO2 powder, the pellet was very easy to recovered from the treated solution and can be reused in multiple times without the significant change on the photocatalytic property. The results also showed that to achieve the same photocatalytic performance, the FPR area by pellets was about 91% smaller than required by TiO2 powder. At least TiO2 pellet could be used as an alternative form of photocatalyst in applications for textile effluent treatment process, also other wastewater treatment processes.     

多菌灵在水体系中的光化学降解研究

系统研究了高压汞灯和天然日光照射下多菌灵在天然海水、人工海水和蒸馏水中的光降解情况.天然日光照射下,多菌灵在三种介质中光稳定性均很强,几乎不降解.高压汞灯较天然日光更能有效地激发多菌灵降解.在高压汞灯照射下,多菌灵在蒸馏水中的半寿期为23.42 min.多菌灵在蒸馏水中的光降解速率大于其在人工海水和天然海水的光降解速率,这主要是由于天然海水中存在的阴、阳离子和其它特殊的物质所引起的.同蒸馏水中的光反应相比,人工海水中的离子抑制了多菌灵的光降解反应.实验发现溶液中加入重金属离子会改变多菌灵的光降解速率.     

水溶液中残留四环素的光催化降解的实验研究

由于抗菌素具有抑制微生物生存的作用，因此，通常处理工业废水最有效的“生物氧化降解法”却无法用来有效处理四环素废液。本文简述了半导体光催化剂在紫外光照射下降解难溶或难分解有机物的基本原理，以半导体ＴｉＯ２和ＺｎＯ粉粒为光催化剂进行催化降解四环素废液的实验，其结果表明；半导体ＴｉＯ２光催化降解效果比较好；另外，Ｈ２Ｏ２可以作为ＴｉＯ２光催化剂的助氧化剂来加快四环素的降解。总之，该实验结果有助于光催化剂的深入研究和太阳能光催化反应装置的设计，为今后在中小型制药厂和印染厂的废水处理奠定基础。     

有机蒙脱石填充PDMS膜分离水相有机物的渗透汽化研究

以乙醇、乙酸的水溶液为渗透汽化分离对象，将CTAB柱撑蒙脱石作为填充剂，制备了填充型PDMS(聚二甲基硅氧烷)膜，研究填充膜对乙醇／水及乙酸／水体系的渗透汽化分离，结果表明，蒙脱石的吸附特性及其层间柱撑通道可以明显改善PDMS膜的选择性和通量，填充膜分离乙醇或乙酸的分离效果明显不同，对可能存在的渗透汽化分离机理进行了探讨。     

17种多环芳烃在水溶液中的光解

本文以国产高压汞灯及太阳光为光源,系统地研究了常见的17种多环芳烃(下简称PAH)在甲醇-水、乙腈-水溶液中的光化学降解。结果表明,大多数PAH的光解速率常数(k)与它们的极谱氧化半波电位(E_(1/2)~(ox)有关:E_(1/2)~(ox)值低(易氧化),则k值大(反应快)。黑暗条件下的对照试验未发现PAH降解。还测得了萘的光解产物为邻苯二甲酸,并发现溶液中的溶解氧除去后萘不能光解。这些都表明大部分PAH光解为光氧化反应。另外,用电荷转移复合物(CTC)的形成、解离和单重态氧(~1O_2)的氧化机理,讨论了温度高、助溶剂极性强会加快光解速率的效应。     

鉴定水溶液中主要污染物——酚的固相提取方法

酚类化合物是造成环境污染的重要工业比学品.酚类化合物不仅是聚合物、药物、农业化学品和染料工业的中间体,而且其本身也可用作杀菌剂和农药.五氯酚是常用的木材防腐剂,天然有机物质氯比(如木浆漂白)或水消毒剂也能产牛卤代酚副产物.酚有毒,它可使水带有讨厌的气味、味道和颜色.由干酚类对环境的危害性,EPA目前要求分析城市和工业流出物中的十一种酚.本文方法适于用EPA方法604分析样品中的酚.     

混凝剂的水溶液形态与流动电流的相关特性分析

混凝剂具有多种溶液形态，每种形态对混凝过程的作用不同，因而对流动电流的影响也不同，本通过实验及理论分析，阐述了一般水处理条件下的流动电流检测器（ＳＣＤ）对混凝剂的检测原理，分析了水中混凝剂形态改变过程中流动电流的变化特征，探讨了ＳＣＤ对不同形态混凝剂的响应灵敏度，结果表明，中性条件下铝盐的混凝过程以及三价铁阳离子对流流具有较为灵敏的正增值效果。