5. Water Softening:
• Water softening is achieved either by adding
chemicals that form insoluble precipitates or
by ion exchange. On a small scale, chemicals
used for softening include ammonia, borax,
calcium hydroxide (slaked lime), or trisodium
phosphate, usually in conjunction with sodium
carbonate (soda ash). The lime-soda method of
water softening must be followed by
sedimentation and filtration in order to remove
the precipitates.
6. Recent Developments
• Nanofiltration Membranes are the core elements for
nanofiltration process. The chemical structures
and physical properties of nanofiltration
membranes determine water permeability, solute
selectivity, mechanical/thermal stability, and
antifouling properties, which greatly influence
the separation efficiency and operation cost in
nanofiltration applications. In recent years, a
great progress has been made in the development of
high performance nanofiltration membranes based on
nanomaterials. Considering the increasing interest
in this field, this paper reviews the recent
studies on the nanofiltration membranes comprising
various nanomaterials, including the metal and
metal oxide nanoparticles, carbon-based
nanomaterials, metal–organic frameworks (MOFs),
water channel proteins, and organic
micro/nanoparticles. Finally, a perspective is
7. References:
1.Roy, Yagnaseni; Warsinger, David M.; Lienhard,
John H. (2017). “Effect of temperature on ion
transport in nanofiltration membranes:
Diffusion, convection and electromigration”.
Desalination. 420: 241–257.
2.Baker, L.A.; Martin (2007). “Nanotechnology in
Biology and Medicine: Methods, Devices and
Applications”. Nanomedicine: Nanotechnology,
Biology and Medicine. 9: 1–24.
