The prepared nanocomposites
exhibiting river sand-like properties were easy to prepare in
water itself and constantly release Ag ions. Such composites
can effectively remove E. coli, Fe2+, Pb2+, and As5+ from water,
and they have been used to manufacture an affordable water
purifier providing clean drinking water at US $2.5 year per
family. Besides, cellulose materials have been extensively
used as low cost support materials to Ag nanoparticles for
water purification. For instance, Dankovich et al. designed
low-cost bactericidal paper embedded with Ag nanoparticles
for point-of-use water purification (Fig. 6c).294 Such paper
was used as a water filter and it was able to remove bacteria
completely, while the silver release from the Ag nanoparticles
was below 0.1 ppm. Similarly, woven fabric microfiltration
membranes embedded with Ag nanoparticles have also been
used as water filters.287 As shown in Fig. 6d, the membranes
turn into brown-yellow after the incorporation of Ag nanoparticles.
The coated membranes were more hydrophilic
showing higher water permeability and 100% removal of bacterial
load from drinking water. Besides, Ag nanoparticles
could be incorporated into cellulose paper by microwave irradiation
(Fig. 6e).290 Such paper sheets could be fixed to containers
of different models to filter the contaminated water
providing excellent antibacterial activity against Escherichia
coli and Enterococcus faecalis bacteria in deionized water or