图  1  自然界存在的纳米矿物的透射电镜照片

a.卡林型金矿床含砷黄铁矿中浸染状分布的金纳米颗粒(Reich et al., 2005)；b.洛川黄土中的纳米棒状方解石(陈天虎等, 2005)；c.位于Miles Crossing河床中的6-线水铁矿(Hochella et al., 2005)；d.Murchison陨石中平均粒径3 nm的纳米金刚石(Dai et al., 2002)

Fig.  1.  TEM images of naturally occurring nanominerals and mineral nanoparticles

图  2  多种铁氧化物和羟基氧化物的吉布斯自由能随比表面积(或粒径)的变化

据Navrotsky et al.(2008)

Fig.  2.  Gibbs free energy of various iron oxides and oxyhydroxides as a function of specific surface area (or particle size)

图  3  纳米金(16 nm)稳定性随pH的变化

Fig.  3.  Stability of Au colloid (16 nm) as a function of pH

图  4  柠檬酸盐保护的纳米银的附着系数随不同离子浓度的变化(pH=7.0)

据Huynh and Chen(2011).a.NaCl；b.CaCl₂和MgCl₂

Fig.  4.  Attachment efficiencies of citrate-coated AgNPs as functions of NaCl (a) and CaCl₂ and MgCl₂ (b) concentrations at pH=7.0

图  5  DLVO理论示意

据Hotze et al.(2010)

Fig.  5.  Schematic of DLVO theory

图  6  CeO₂纳米粒子在过滤和未过滤的莱茵河、默兹河水样中沉降12 d后的平均剩余浓度

据Quik et al.(2012)

Fig.  6.  Residual concentrations of CeO₂ nanoparticles after 12 d of settling in filtered and unfiltered river water, average of concentration in Rhine and Meuse Rivers

图  7  Ag和TiO₂纳米粒子与蒙脱石吸附作用示意图

据Zhou et al.(2012)

Fig.  7.  Schematic diagram of sorption of AgNPs and TiO₂ NPs on montmorillonite

图  8  aSNPs和cMNPs异相共团聚的TEM照片(a)和SEM照片(b)

据Dušak et al.(2015)

Fig.  8.  TEM (a) and SEM (b) images of the heteroaggregates formed between the aSNPs and the cMNPs

图  9  原始状态ZnO纳米粒子TEM照片(a)以及在pH=6(b)和pH=8(c)的磷酸盐溶液(150 mg L^-1)中熟化72 h后TEM照片

据Rathnayake et al.(2014)

Fig.  9.  TEM images of pristine ZnO NPs (a) and MNMs aged in 150 mg L^-1 phosphate concentration for 72 h at pH=6 (b) and at pH=8 (c)

图  10  PDDA保护的CdSe/ZnS量子点在紫外光辐射3 h后溶出离子Cd和Se的浓度随腐殖酸浓度的变化

据Li et al.(2012b)

Fig.  10.  Cd and Se release of PDDA-coated QDs as a function of HA concentration after 3 h UV irradiation

图  11  废水实验中收集的AgNP的相差明场扫描透射电镜(STEM)照片(a)和EDX图谱指示S/Ag比例随空间的变化(b)

据Kaegi et al.(2013).b.蓝色图谱指示左图篮框区域，红色图谱指示左图红色区域

Fig.  11.  Phase contrast bright field scanning transmission electron microscopy (STEM) image of an AgNP collected from the sewer batch experiments (a) and EDX spectra revealing spatial variations in the S/Ag ratios (b)

图  12  纳米银与浓度递增的Na₂S反应前后溶解速率的变化

据Levard et al.(2011).在0.01 mol/L NaNO₃，pH=7溶解速率实验中初始纳米银浓度为1 000 mg·L^-1

Fig.  12.  Dissolution rate measurements of Ag-NPs before and after reaction with increasing concentrations of aqueous Na₂S