Ahmad F and Ahmad S*
Confederation of Indian Industry, India
*Corresponding author: Ahmad S, Confederation of Indian Industry, 508, BWT, Eros Garden, Charmwood Village, Faridabad, Haryana, India
Submission: October 29, 2021;Published: November 11, 2021
ISSN: 2770-6613 Volume2 Issue4
The manufacturers of cost-effective water treatment products for potable water with
lower maintenance and installation costs have been trying hard to explore state-of-the-art
water filtration technologies based on nanostructured materials and advanced membrane
systems. Five latest water purification technologies, identified recently, have been projected
as emerging alternatives to the existing ones, include photo oxidation as one of them (PR-01).
Ongoing studies of 2D-nanomaterials (2D-NMs) have already established their photocatalytic
properties. Lamellar 2D-NMs based nanocomposites appear still more promising for designing
photocatalysts with enhanced capabilities. Some of these nanocomposites, examined recently,
are being designed for their uses in the Point-Of-Use (POU) water filtration units that are
independent of the quality of input water. Such POU water filtration units are expected to
gain considerable importance once developed fully as the nanocomposites employed therein
would be capable of thoroughly removing the bacterial contaminants in water particularly [1-
3]. 2D-NMs have been explored extensively as a filler for polymer composites for enhancing
the performance even at extremely small loading. In a recent review, a number of relevant
aspects of 2D-NM-fillers for polymer composites were discussed including their dispersion
in the polymers, surface decoration of 2D materials, and interface bonding between 2D-NM
and polymers. The challenges involved in preparing 2D-NMs/polymer composites, and future
perspectives for using these novel composites were discussed .
Hydrophilic surfaces charged negatively in case of lamellar MXenes (i.e., Ti3C2) were found making intimate contact with bacterial membranes inactivated the micro-organisms. Antibacterial activity of its derivatives with Ag, Pd, Au-nanoclusters (Au-NCs) got further improved against the Gram-positive and Gram-negative strains. The bactericidal efficiency of the conjugation was enhanced >96% by damaging the bacterial DNAs resulting in improved anti-bacterial properties . In this context, a comprehensive R&D program was undertaken to study the structural and optical properties of CdO-NPs, ZnO-NPs, Cd-ZnO-NPs, g-C3N4 NSs, and g-C3N4/Cd-ZnO-NCs with the help of extensive analytical techniques (XRD, SEM, EDX, TEM, FTIR, UV-Vis, ESR, and PL spectroscopies) followed by determining their bactericidal efficacies against Gram-positive and Gram-negative bacterial strains. These experiments enabled the involved research group to prepare some novel formulations with potentials for cost-effective production at mass scale . On-site, cost-effective, and easy to maintain POU water filtration units are foreseen to prevent a number of water borne diseases specially in the rural areas of underdeveloped countries. POU-devices must, however, provide potable water without microbial contaminations independent of input water sources. These units should be reliable, simple, and recyclable. In this context, the investigations made by Jakubczak, et al. , reported a significant breakthrough in synthesizing a nanocomposite filtration material (2D-Ti3C2/Al2O3/ Ag/Cu) with future applications in POU water filters with 99.6% removal of bacterial contaminations. Antibacterial properties combined with the inhibition of biofilm formation in the presence of 2D-MXenes were examined recently after observing that MXene activated membranes eliminated the bacterial cells from the filtered water. Surface decorations with Zn, Ti, Mn, or Nb-NPs were noted to further improve their antimicrobial properties. Filtration materials based on polypropylene fabrics modified with 2D-Ti3C2, Al2O3, Ag, and Cu-NPs were found possessing self-disinfecting abilities, efficient filtration, and with almost negligible release of nanoparticulate species into the filtrate, as observed during the study of surface oxidation of MXene Ti3C2/Al2O3/Ag/Cu-NPs modified polypropylene fabric .
In another set of experiments, Sher, et al, demonstrated that Cddoped ZnO nanocomposites involving g-C3N4 (Cd-ZnO/g-C3N4-NCs) were found effective against Gram-positive and Gram-negative bacterial strains by eliminating them during applications. The in situ growth of well-dispersed Cd-doped ZnO-NPs (Cd-ZnO-NPs) onto g-C3N4-NSs was realized through the co-precipitation forming Cd-doped ZnO-nanocomposites with g-C3N4 (Cd-ZnO/g-C3N4 NCs). Study of composition specific photocatalytic properties of the ternary nanocomposites (Cd-ZnO/g-C3N4-NCs) exhibited optimum performance in case of composition with 60% g-C3N4 hybridized with 7% Cd-doped ZnO (g-C3N4/Cd-ZnO) NCs for visible-lightdriven photocatalytic degradation of methylene blue dye mainly due to the increase in the generation of photogenerated charge carriers resulting in creation of reactive oxygen species (ROS), O2−, and ˙OH radicals. Superoxide and hydroxyl radicals (ESR) were found degrading MB with enhanced stability observed in high degradation rates for 10 successive catalytic cycles . Based on these studies, Qamar, et al, reported another efficient and costeffective photocatalyst termed as NiZG (Ni/ZnO/g-C3N4), using Nidoped ZnO-NPs with g-C3N4 by chemical co-precipitation method. The catalytic efficiencies of NiZG composites were evaluated by determining the UV-vis absorption spectra for methylene blue and testing the bactericidal effects against Gram-positive and Gramnegative microbes. The NiZG-70 composite (i.e., 3% Ni/ZnO and 70% g-C3N4) demonstrated superior bactericidal and photocatalytic properties under solar irradiation compared to Ni/ZnO, g-C3N4 alone. Reduced electron-hole recombination in the composite enabling the Ni-atoms to function as electron transmitters at the interfaces. The recycling measurement of the NiZG exhibited it as a practical candidate for environmental remediation applications .
Market growth of POU water filtration units
Market research forecast of global POU water treatment
systems, expected to grow from USD 15.0 billion in 2020 to USD 23.4
billion by 2025, at a CAGR of 9.29% (2020 to 2025), is a fairly clear
indicator of this emerging technology. The POU water treatment
systems market is expected to witness significant future growth
due to its increased demands in residential and non-residential
points of use. Various factors like better awareness of using quality
potable water, increasing demands at affordable cost, technology
development in water treatment industry, combined with
increasing income of the consumers in the emerging economies,
are likely to support the growth of the POU water treatment
systems market during the forecast period (MRR-01). Out of many
water treatment technologies developed so far, those deploying
low-cost POU treatment systems must deploy mature technology of
removing waterborne pathogens using techniques like flocculation
and coagulation, filtration, and disinfection . Here, the process of
flocculation and coagulation remove not only the water turbidity
but also reduce the support for microbial growth in addition to
finally removing all of them larger in size than the pore size of the
membrane. Disinfection in the form of inactivation and destruction
of microorganisms makes it appropriate for regular usage.
Despite having made considerable efforts by the manufacturers World over, there are still challenges to address to as indicated below. The major concern is expensive installation of POU water treatment systems in general. In addition, operating and maintenance costs of the POU water treatment systems is also high. In underdeveloped countries the lack of basic infrastructure for the distribution and storage of potable water could prove to be another challenge in the installation of POU water treatment system. Developing and underdeveloped countries lacking in financial stability are unable to provide clean drinking water to their whole population. WHO noted diarrhoea as a major disease responsible for 8.5% and 7.7% of all deaths in Asia and Africa, respectively (MRR-01). A major challenge influencing the POU water treatment systems market came from the bottled water manufacturers who succeeded in solving the problem of unpotable water by offering convenient solutions. The increasing demand of counter-top units dominated the market in 2019 due to their convenient usage at low maintenance, and installation costs. Moreover, these units also helped in reducing the contamination like dirt, chlorine, particulates, rust, lead, mercury, sediment, copper, benzene, cadmium, cysts including bacteria (MRR-01). The demand of residential segment accounting for a larger share in 2019 was projected to grow at a higher CAGR from 2020 to 2025 [8,9]. The increasing demand for clean water across the globe and limited freshwater resources makes it crucial to treat water for residential and non-residential applications at affordable costs. Factors like improving global economy, expanding working population, rapid urbanization, growing awareness about water purification technologies, growth in the middle-class population, and rise in income are projected to drive the demand for the POU treatment systems in the Asia Pacific during the forecast period. Europe is projected to follow the Asia Pacific (MRR-01).
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