生物炭负载纳米羟基磷灰石复合材料的制备及对铅离子的吸附特性

以玉米秸秆为前体,在高温限氧条件下,将纳米羟基磷灰石(nano-HAP)负载于生物炭(BC)表面制备出了生物炭负载纳米羟基磷灰石(n HAP/BC)复合材料,并利用SEM、XRD和FTIR对其进行表征。批量吸附实验考察其对Pb^(2+)的吸附特性,研究pH、投加量、吸附时间、初始浓度及吸附温度等因素对吸附的影响。通过吸附动力学、吸附等温线和吸附热力学分析了吸附特性,通过解吸实验考察了解吸再生效应,并对吸附机制进行了探讨。结果表明:与BC相比,n HAP/BC复合材料具备更好的吸附效果,25℃时理论最大吸附量为383.75mg/g。n HAP/BC对Pb^(2+)的吸附符合拟二级动力学方程和Langmuir等温吸附模型,表明n HAP/BC对Pb^(2+)的吸附为单分子层化学吸附。热力学参数ΔG<0、ΔH>0,表明吸附是一个自发的吸热过程。n HAP/BC对Pb^(2+)的吸附机制主要包括nano-HAP的溶解-沉淀作用以及生物炭表面—OH和—COOH等含氧官能团的络合作用。n HAP/BC具有良好的循环利用能力,是一种潜在的Pb^(2+)高效吸附材料。

Fluorescent Labeling of Nanometer Hydroxyapatite

A novel surface treatment method using 3-aminopropyltriethoxysilane （AMPTES）, was developed to immobilize the fluorescein molecule on nano-HAP （nanometer hydroxyapatite） powders. By pretreating the nano-HAP powders surface with AMPTES, fluorescein, chosen on the basis of the chemical structure of the nano- HAP powders, could be bound to the nano-HAP powders surface. The chemical compositions of nano-HAP before and after being labeled were characterized by Fourier transform infrared spectroscopy （FTIR） and X-ray photoelectron spectroscopy （XPS）. The morphology, phase composition, and the fluorescence characteristics of the nano-HAP powders with and without staining were also investigated. The FTIR and XPS results revealed that fluorescein had been successfully immobilized on the surface of AMPTES-bound nano-HAP powders via the acylamide bond formation between the -COOH of fluorescein and the -NH2 of AMPTES. The labeled nano-HAP powders possessed strong fluorescent intensity with a little deviation from the maximum emission wavelength of fluorescein. But the morphology and phase composition had no obvious alteration. Under fluorescence microscopy, the labeled nano-HAP powders, even after 24 h cell incubation, exhibited strong fluorescence.

不同环境因子对纳米羟基磷灰石在饱和填充柱中迁移规律的影响

选用石英砂填充柱模拟土壤体系,通过测量纳米羟基磷灰石(Nano-HAP)ζ电位、出流比等来考察不同环境因素(腐殖酸浓度、pH和离子强度)对其在饱和石英砂柱中迁移规律的影响.结果表明,随着腐殖酸浓度的增加,Nano-HAP胶体的ζ电位相应增加(绝对值增加),吸附效率(α)相应降低,当溶液中腐殖酸浓度由0增加为10 mg/L时,Nano-HAP胶体的ζ电位由-15mV增加至-55 mV,吸附效率由1.0减小为0.012,迁移能力增加;此外,随着本体溶液pH增加,Nano-HAP胶体的ζ电位亦随之增加,吸附效率相应降低,因此有利于其在饱和体系中的迁移.然而,随着本体溶液离子强度增加,Nano-HAP胶体的双电层被压缩,ζ电位逐渐减小,吸附效率相应增加,且二价阳离子对Nano-HAP迁移能力的影响要远大于单价阳离子的影响.当本体溶液离子强度(支持电解质为单价阳离子Na+)由1 mmol/L增加至100 mmol/L时,吸附效率由0.030增加至0.13,而当本体溶液离子强度(支持电解质为二价阳离子Ca2+)由0.2 mmol/L增加至10 mmol/L时,吸附效率由0.030增加至1.0,更多的Nano-HAP胶体被滞留在多孔介质中,阻碍其迁移.该研究结果将有助于从机制上深入地了解纳米羟基磷灰石在土壤-地下水环境中的迁移行为及其归趋.