The defluoridation of water by acidic alumina

Fluoride is considered as a major inorganic pollutant present in drinking water. To remove this excess fluoride, defluoridation was done by alumina. In the present study, alumina used was acidic in nature and hence considered as a good fluoride removing adsorbent. Characterization of the adsorbent was done by XRD, SEM, BET and FTIR with BET surface area of 144.27 m²/g. Systematic adsorption experiments were carried out with different process parameters such as contact time, adsorbent mass, pH, temperature and stirring speed. Fluoride adsorption by alumina was highly pH dependent. Maximum fluoride was removed from water at pH 4.4. At very low and very high pH, fluoride removal efficiency was affected. The study of thermodynamic parameters inferred that physical adsorption was dominant with activation energy of 95.13 kJ/mol and endothermic behavior of the process. The kinetics study concluded that pseudo second order kinetics was followed by the adsorption process. Adsorption equilibrium was studied with Langmuir and Freundlich isotherm models. The adsorption process followed Langmuir isotherm with an adsorption capacity of 8.4 mg/g. A regeneration study was proposed in order to reuse the adsorbent for better economy of the process. Finally, a process design calculation was reported to know the amount of adsorbent required for efficient removal of fluoride from aqueous medium.     

Adsorption of 4-chlorophenol by inexpensive sewage sludge-based adsorbents

Sewage sludge was used as precursor to develop a potential inexpensive adsorbent by both simple drying and pyrolysis. The resulting materials were evaluated as adsorbents for the removal of 4-chlorophenol (4-CP) from aqueous solution. The dried biosolids showed a BET surface area lower than 3 m²/g, which yield a maximum adsorption capacity of 0.73 mmol 4-CP/g at pH 5.0 and 15 °C. The carbonization of biosolids under relatively mild conditions allowed obtaining materials with BET surface area up to 45 m²/g, which led to a significant increase of the maximum adsorption capacity (1.36 mmol 4-CP/g). The high ash content of the starting material (23%, d.b.) limits the development of porosity on a total dry-weight basis. Adsorption data were well fitted to the Redlich–Peterson isotherm equation whereas the most commonly used Langmuir and Freundlich equations were less satisfactory probably because of the occurrence of summative adsorption phenomenon. A thermodynamic study of the adsorption showed the spontaneous and exothermic nature of the process. Thus, simple drying and carbonization provide two ways of valorization of sewage sludge through its conversion into inexpensive low-rank adsorbents potentially useful for the removal of some hazardous water pollutants, like chlorophenols and related compounds.     

耐盐耐温耐油水基微泡钻井液的制备

研究并测试了不同起泡剂、稳定剂及黏土对耐盐耐温耐油微泡钻井液的影响.实验发现耐温耐盐的微泡钻井液与起泡剂和稳定剂的结构有关,而起泡体系的耐油性与各种物质在泡沫界面的吸附状态有关.选用具有枝型结构的发泡剂和具有耐盐、耐温结构的起泡剂和稳定剂制备微泡体系,可使其具有好的耐盐、耐高温老化的性质,选择适当的无机有机物质进行复配,可在泡沫界面形成亲油但是不溶油的弱极性界面吸附层,使体系有很好的耐油性.由DM5512、甜菜碱、烷基糖苷、1631混合制备成了离子型复合起泡剂QR-1,由HPMC、SMP-Ⅱ和SP-8混合制备成了稳定剂WD-1.实验评价了由QR-1、WD-1和黏土在矿化度为10×104 mg/L的基液中配制的微泡钻井液的耐盐、耐高温老化和耐油性能,证实了以上结论并探讨了其机理.     

不同精炼工艺及条件对油脂中3-MCPD含量的影响

为了探究不同精炼工艺及其条件对油脂中3-MCPD含量的影响规律,本文较系统地探讨了溶剂和水相萃取、吸附剂吸附以及高温加热等条件对油脂中3-MCPD含量的影响。结果表明：甲醇、乙醇和异丙醇萃取对降低油脂中3-MCPD的含量效果显著,且萃取次数越多油脂中3-MCPD含量越低,可将其降至11μg/kg;3-MCPD的含量随着水洗次数与加水量的增加会逐渐降低;NaCl溶液水洗也能降低3-MCPD含量,但与NaCl浓度有关;活性炭和活性白土等吸附剂对3-MCPD均有一定吸附效果,但活性炭效果较佳,并且吸附效果与加入量和温度有关;温度高于100℃时,随着温度的增加油脂中3-MCPD含量会逐渐增加,但温度达到240℃以上时能将油脂中3-MCPD降至一定程度。     

纳米双氧水稳定剂用于棉织物漂白效果的研究

探讨纳米双氧水稳定剂在棉织物漂白中的应用效果。分析了纳米双氧水稳定剂对双氧水分解的抑制效果及对Ca2+、Mg2+的吸附效果,并以漂白后织物白度、毛效和失重率为指标,测试了纳米双氧水稳定剂用量对织物漂白效果的影响。试验结果表明:少量的纳米双氧水稳定剂类即可有效抑制双氧水的分解;纳米双氧水稳定剂对Ca2+、Mg2+等金属离子具有显著的吸附作用,且具有较好的阻垢性;在纳米双氧水稳定剂1.5 g/L,氢氧化钠9 g/L,双氧水12 g/L,温度100℃,时间60 min的条件下纯棉织物可获得较好的漂白效果。认为纳米双氧水稳定剂可用于棉织物的漂白。     

吐温-60对钢在H2SO4中的缓蚀性能

用失重法研究了非离子表面活性剂吐温-60对冷轧钢在0.5-7.0 mol/L H2SO4溶液中的缓蚀作用。结果表明：吐温-60对冷轧钢在1.0 mol/L H2SO4溶液中具有良好的缓蚀作用,且在钢表面的吸附符合校正的Langmuir吸附模型。缓蚀率随缓蚀剂浓度的增加而增大,但随温度和硫酸浓度的增加而减小。求出了相应的吸附热力学（吸附自由能ΔG^0, 吸附焓ΔH^0, 吸附熵ΔS^0）和动力学参数（腐蚀速率常数k, 腐蚀动力学常数B）,并根据这些参数讨论了缓蚀作用机理。     

Chemical versus thermal folding of graphene edges

Using molecular dynamics (MD) simulations, we have investigated the kinetics of the graphene edge folding process. The lower limit of the energy barrier is found to be ∼380 meV/? (or about 800 meV per edge atom) and ∼50 meV/? (or about 120 meV per edge atom) for folding the edges of intrinsic clean single-layer graphene (SLG) and double-layer graphene (DLG), respectively. However, the edge folding barriers can be substantially reduced by imbalanced chemical adsorption, such as of H atoms, on the two sides of graphene along the edges. Our studies indicate that thermal folding is not feasible at room temperature (RT) for clean SLG and DLG edges and is feasible at high temperature only for DLG edges, whereas chemical folding (with adsorbates) of both SLG and DLG edges can be spontaneous at RT. These findings suggest that the folded edge structures of suspended graphene observed in some experiments are possibly due to the presence of adsorbates at the edges.      

牛奶蛋白纤维与羊毛纤维吸湿性能对比分析

研究对比牛奶蛋白纤维与羊毛纤维吸放湿性能.对牛奶蛋白纤维在标准大气条件下的吸湿、放湿回潮率进行测定,描绘出吸湿放湿曲线,并与羊毛纤维进行了比较.根据吸湿放湿曲线,推导出标准状态下两种纤维的吸湿放湿速率回归方程.结果表明:牛奶蛋白纤维与羊毛纤维达到吸湿放湿平衡的时间及吸湿放湿曲线基本相似,吸湿过程中牛奶蛋白纤维和羊毛纤维达到平衡回潮率的时间几乎相同,而在放湿过程中牛奶蛋白纤维达到平衡的时间要低于羊毛.     

彩色棉纤维吸湿性能研究

分析了彩色棉的吸放湿性能.在标准状态下,对彩色棉的吸放湿特征曲线进行了测定,并与本白棉进行了比较;根据特征曲线推导出了彩色棉纤维在标准状态下达到吸放湿平衡过程中,回潮率对于时间的回归方程以及吸放湿速率方程.结果表明:棕色棉纤维的吸湿能力与本白棉相似,初始吸、放湿速率高于本白棉;绿色棉纤维的吸湿能力比较差,吸湿速率低于棕色棉和本白棉.     

木糖醇发酵液脱色条件的研究

为了优化木糖醇发酵液脱色工艺条件,研究了4种活性炭对木糖醇发酵液吸附脱色的影响。活性炭对色素的吸附率高于对木糖醇的吸附率,所试4种活性炭对色素的吸附均属于典型的“Langmuir”型等温吸附。试验结果表明,AC3活性炭具有优良的吸附脱色效果。在pH5.0、活性炭用量4%、脱色温度40℃、脱色时间40min条件下,木糖醇发酵液色素吸附率为92%,木糖醇的损失率为6.9%,显示了良好的脱色效果。该研究结果为从发酵液中分离纯化木糖醇奠定了良好的基础。