Mechanical and Barrier Properties of Biodegradable Films Made from Chitosan and Poly (Lactic Acid) Blends

Biodegradable film blends of chitosan with poly(lactic acid) (PLA) were prepared by solution mixing and film casting. The main goal of these blends is to improve the water vapor barrier of chitosan by blending it with a hydrophobic biodegradable polymer from renewable resources. Mechanical properties of obtained films were assessed by tensile test. Thermal properties, water barrier properties, and water sensitivity were studied by differential scanning calorimeter analysis, water vapor permeability measurements, and surface-angle contact tests, respectively. The incorporation of PLA to chitosan improved the water barrier properties and decreased the water sensitivity of chitosan film. However, the tensile strength and elastic modulus of chitosan decreased with the addition of PLA. Mechanical and thermal properties revealed that chitosan and PLA blends are incompatible, consistent with the results of Fourier transform infrared (FTIR) analysis that showed the absence of specific interaction between chitosan and PLA.     

Lightweight Concrete Containing an Alkaline Resistant Starch-Based Aquagel

Starch aquagel-based lightweight concrete has properties similar to those of other lightweight concrete products. However, starch aquagels are unstable in the strongly alkaline conditions typical of Portland Cement-based concrete and may interfere with the setting process. The effect of alkali treatments on the physical, mechanical, and functional properties of starch aquagels and aquagels from starch/polymer blends was investigated. Starch was blended at 100–115°C in a twin-screw extruder with five different polymers to determine whether the blends improved alkaline resistance. Polymer blends containing 5%, 15%, and 30% of the polymer hydrated and formed aquagels when equilibrated in water for 24 h. However, equilibrium moisture content was lower for the blends compared to the starch control. Aquagels equilibrated in 0.15 N NaOH swelled, lost compressive strength and had greater than 90% moisture. The blend of starch and 30% PVOH absorbed less moisture and was more resistant to alkaline dissolution in 1 N NaOH than the other blends tested making it a more suitable material for aquagel-based concrete. The moisture content of starch-based aquagels and mixing time were critical factors in determining setting times. The size of aquagel blends had a minor effect on density and compressive strength.     

β-环糊精/醋酸纤维素纳米纤维的制备及对染料废水的处理

制备了不同β-环糊精(β-CD)含量的醋酸纤维素(CA)纳米纤维膜,并对纤维膜的结构形貌、尺寸分布、孔隙率、比表面积以及纤维膜的力学性能进行表征分析。随后研究了不同β-CD含量、初始浓度、吸附时间下,纳米纤维膜对甲基红染料的截留性能和吸附性能。结果表明:过量(≥30%)的β-环糊精会使纳米纤维产生珠节,纤维的形貌和力学性能变差;吸附试验表明,β-CD的加入提高了CA纳米纤维膜对染料的吸附,MR吸附率可达93.48%,最大平衡吸附量可达181.74 mg/g,比纯CA纳米纤维膜提高了将近40%;此外,染料的截留实验表明,纳米纤维膜对染料的截留效果较差,最大截留率为50.35%。     

地下水循环井技术处理土壤和地下水中甲基叔丁基醚研究

研究了MTBE在砂土中的静态吸附以及采用地下水循环井技术(GCW)去除砂土和地下水中MTBE的衰减规律。结果表明:MTBE在砂土中的吸附动力学符合准二级动力学方程,相关系数R2为0.99618,在砂土中的吸附平衡时间为24 h;吸附热力学符合Linear平衡吸附,吸附系数为0.00306 m3/kg。GCW运行30 h后,地下水饱和含水层中MTBE浓度由500 mg/L降至72.5 mg/L,去除率为85.5%;砂土中MTBE的吸附量由0.93 mg/g降至0.03 mg/g,去除率达96.4%。水平方向距GCW越近,MTBE的去除效率越快,垂直方向位于GCW上部的MTBE优先会被去除,最佳修复时间为运行15 h。GCW对砂土和地下水中高浓度MTBE具有良好的修复效果。     

气相色谱法测定大气中乙酸乙酯和甲基丙烯酸甲酯

建立了用气相色谱法测定大气中乙酸乙酯和甲基丙烯酸甲酯的方法。大气中乙酸乙酯和甲基丙烯酸甲酯活性炭吸附,二硫化碳解吸,DB-200毛细管柱分离,直接进样分析,氢火焰离子化检测器检测,时间定性,峰面积定量。本方法前处理简便,分离度好,分析灵敏度高,满足环境分析要求。     

TiO2/硅藻土光催化氧化降解甲基橙的研究

使用经过预处理的硅藻土做载体,采用溶胶-凝胶法制备硅藻土负载二氧化钛光催化剂,利用XRD和EDS对其进行表征.通过分析光催化反应的主要影响因素,研究了硅藻土负载二氧化钛光催化剂对甲基橙的催化降解效果.结果表明：负载3次,在550℃焙烧2h,制备出的负载型催化剂催化活性较高,催化剂上的TiO2为锐钛矿结构.当催化剂投加量为lg/L,溶液初始浓度为15 mg/L,pH为3,H2O2为2 mmol/L时,对甲基橙的降解效果达到最佳.     

BiOCl/ZnMgAl-HTLCs复合材料光催化去除水中的甲基橙

以Mg(NO3)2·6H2O、Al(NO3)3·9H2O、Zn(NO3)2·6H2O、Bi(NO3)3·5H2O为主要原料,采用水热合成法,制备了Bi OCl/Zn Mg Al-HTLCs光催化剂,对其进行XRD、EDS、SEM、FT-IR、UV-Vis、TGA表征,并通过降解甲基橙(MO)实验,探究催化剂水热合成的p H、溶剂、温度对其光催化性能的影响.结果表明:Zn Mg Al-HTLCs改善了Bi OCl的分散性,Bi OCl/Zn Mg Al-HTLCs能够有效地催化去除水中的甲基橙,在p H=7.5、溶剂为水、T=140℃条件下,可见光催化活性最佳,光照60 min后对10 mg·L-1的甲基橙溶液(MO)的降解率均达到85%以上.综合表明,Bi OCl/Zn Mg Al-HTLCs是一种具有潜在应用前景的光催化剂.     

Characterisation of PM10, PM2.5 and Benzene Soluble Organic Fraction of Particulate Matter in an Urban Area of Kolkata, India

In this study, the relationship between inhalable particulate (PM₁₀), fine particulate (PM_2.5), coarse particles (PM_{2.5 – 10}) and meteorological parameters such as temperature, relative humidity, solar radiation, wind speed were statistically analyzed and modelled for urban area of Kolkata during winter months of 2003–2004. Ambient air quality was monitored with a sampling frequency of twenty-four hours at three monitoring sites located near traffic intersections and in an industrial area. The monitoring sites were located 3–5 m above ground near highly trafficked and congested areas. The 24 h average PM₁₀ and PM_2.5 samples were collected using Thermo-Andersen high volume samplers and exposed filter papers were extracted and analysed for benzene soluble organic fraction. The ratios between PM_2.5 and PM₁₀ were found to be in the range of 0.6 to 0.92 and the highest ratio was found in the most polluted urban site. Statistical analysis has shown a strong positive correlation between PM₁₀ and PM_2.5 and inverse correlation was observed between particulate matter (PM₁₀ and PM_2.5) and wind speed. Statistical analysis of air quality data shows that PM₁₀ and PM_2.5 are showing poor correlation with temperature, relative humidity and solar radiation. Regression equations for PM₁₀ and PM_2.5 and meteorological parameters were developed. The organic fraction of particulate matter soluble in benzene is an indication of poly aromatic hydrocarbon (PAH) concentration present in particulate matter. The relationship between the benzene soluble organic fraction (BSOF) of inhalable particulate (PM₁₀) and fine particulate (PM_2.5) were analysed for urban area of Kolkata. Significant positive correlation was observed between benzene soluble organic fraction of PM₁₀ (BSM10) and benzene soluble organic fraction of PM_2.5 (BSM2.5). Regression equations for BSM10 and BSM2.5 were developed.     

新型聚硅氯化铁铝絮凝剂的制备及性能

以二甲基二氯硅烷为硅源,与氯化铁、氯化铝聚合制得新型的聚硅氯化铁铝（PSFAC）絮凝剂,考察了制备条件及PSFAC对含油废水和药厂废水的絮凝效果。制备PSFAC的最佳条件：nFc：nAl为0．4,nSi：n（Al＋Fe）为0．1,碱化度为2．0,C（Al,Fe）、为0．1mol／L,熟化时间为1-2d。当PSFAC加入量为10mg／L时,对含油废水、药厂废水的浊度去除率分别为84％和86％。PSFAC具有加入量少、沉降速度快、适用的pH范围较宽等优点。     

含氮生物降解促进剂对土壤吸附正十六烷的影响

选用正十六烷模拟润滑油,通过振荡平衡实验,考察了两种含氮脂肪酸型生物降解促进剂（甲基二乙醇胺油酸酯（MDEAO）和油酸二乙醇酰胺（ODEA））对水土体系中正十六烷吸附行为的影响。实验结果表明：正十六烷在水土体系中的有机质标化分配系数与土壤种类无关,与生物降解促进剂种类有关;土壤对正十六烷的吸附过程更符合Freundlich等温吸附模型;MDEAO的临界胶束浓度为2.0 mg/L,对土壤吸附正十六烷有一定的促进作用,ODEA的临界胶束浓度为0.7 mg/L,形成的胶束对正十六烷的增溶效果明显,促进了正十六烷在土壤中的解吸。