Mohsin Nawaz | Kyungpook National University (original) (raw)

Papers by Mohsin Nawaz

Graphene-based two-dimensional materials have been explored in a variety of applications, includi... more Graphene-based two-dimensional materials have been explored in a variety of applications, including the treatment of heavy-metal-rich water/wastewater. Ethylenediaminetetraacetic acid (EDTA)-functionalized magnetic chitosan (CS) graphene oxide (GO) nanocomposites (EDTA-MCS/GO) were synthesized using a reduction precipitation method and applied to the removal of heavy metals, such as Pb 2+ , Cu 2+ , and As 3+ , from aqueous solutions. The synthesized nanocomposite was characterized by FT-IR, XRD, SEM, MPMS, zeta-potential and BET analyses. The influence of various operating parameters, such as pH, temperature, metal ion concentration, and contact time on the removal of the metal ions, was investigated. Owing to the large specific surface area, hydrophilic behavior, and functional moieties, the magnetic nanocomposite demonstrated excellent removal ability with a maximum adsorption capacity of 206.52, 207.26, and 42.75 mg g À1 for Pb 2+ , Cu 2+ , and As 3+ , respectively. The equilibrium data was evaluated by Langmuir and Freundlich isotherms, while the heavy metal adsorption reaction kinetics was analyzed by Lagergren pseudo-first-order and pseudo-second-order kinetic models. The nanocomposite was reused in four successive adsorption–desorption cycles, revealing a good regeneration capacity of the adsorbent.

PLoS ONE, 2014

Efficiency of solar based disinfection of Pseudomonas aeruginosa (P. aeruginosa) in rooftop harve... more Efficiency of solar based disinfection of Pseudomonas aeruginosa (P. aeruginosa) in rooftop harvested rainwater was evaluated aiming the potability of rainwater. The rainwater samples were exposed to direct sunlight for about 8-9 hours and the effects of water temperature (uC), sunlight irradiance (W/m 2 ), different rear surfaces of polyethylene terephthalate bottles, variable microbial concentrations, pH and turbidity were observed on P. aeruginosa inactivation at different weathers. In simple solar disinfection (SODIS), the complete inactivation of P. aeruginosa was obtained only under sunny weather conditions (.50uC and .700 W/m 2 ) with absorptive rear surface. Solar collector disinfection (SOCODIS) system, used to improve the efficiency of simple SODIS under mild and weak weather, completely inactivated the P. aeruginosa by enhancing the disinfection efficiency of about 20% only at mild weather. Both SODIS and SOCODIS systems, however, were found inefficient at weak weather. Different initial concentrations of P. aeruginosa and/or Escherichia coli had little effects on the disinfection efficiency except for the SODIS with highest initial concentrations. The inactivation of P. aeruginosa increased by about 10-15% by lowering the initial pH values from 10 to 3. A high initial turbidity, adjusted by adding kaolin, adversely affected the efficiency of both systems and a decrease, about 15-25%; in inactivation of P. aeruginosa was observed. The kinetics of this study was investigated by Geeraerd Model for highlighting the best disinfection system based on reaction rate constant. The unique detailed investigation of P. aeruginosa disinfection with sunlight based disinfection systems under different weather conditions and variable parameters will help researchers to understand and further improve the newly invented SOCODIS system. Citation: Amin MT, Nawaz M, Amin MN, Han M (2014) Solar Disinfection of Pseudomonas aeruginosa in Harvested Rainwater: A Step towards Potability of Rainwater. PLoS ONE 9(3): e90743.

CLEAN - Soil, Air, Water, 2013

The effects of different catchment types and storage conditions on Pseudomonas aeruginosa in harv... more The effects of different catchment types and storage conditions on Pseudomonas aeruginosa in harvested rainwater under wet and dry seasons were investigated. Both horizontal (roof intercepted to outlet point) and vertical (surface to bottom) quality variation inside storage tanks of different rainwater harvesting (RWH) systems was also monitored. The numbers of P. aeruginosa varied from 30 to 400 colony forming units (CFU)/100 mL during the dry season and 200 to 1800 CFU/100 mL during the wet season. A relatively good quality of harvested rainwater was observed in dry season. The horizontal and vertical quality variation of P. aeruginosa revealed best quality at the supply point. The number of P. aeruginosa was the highest (about 1800 and 1000 CFU/100 mL during wet and dry seasons, respectively) in rainwater harvested from mountain catchment while the lowest (about 30 and 1000 CFU/100 mL during dry and wet seasons, respectively) numbers was seen from concrete roof catchment. Dark, covered storage conditions resulting low rainwater temperatures showed better microbial quality of rainwater than uncovered and open storage conditions exposed to light. The study suggests that the improvement in the quality of harvested rainwater is possible when appropriate tank designs, maintenance of catchment surfaces, and proper storage conditions are considered in RWH systems.

In this study, the three-dimensional (3D) reduced graphene oxide/TiO 2 (RGOT) aerogel was synthes... more In this study, the three-dimensional (3D) reduced graphene oxide/TiO 2 (RGOT) aerogel was synthesized by a facile one-step hydrothermal treatment, and its photocatalytic efficiency was evaluated in the pho-todegradation of recalcitrant carbamazepine (CBZ) in aqueous solution. RGOT exhibited high adsorption and an almost twofold higher photodegradation ability than bare TiO 2 as more than 99% CBZ removal was observed within 90 min in 10 ppm aqueous solution of the latter. The mass ratio of TiO 2 in the RGOT aerogel substantially affected CBZ adsorption and photocatalytic degradation, with the optimal TiO 2 /GO ratio in RGOT found to be 2:1. The chemical bonding between TiO 2 and GO and the effective reduction of the latter during RGOT synthesis were also considered to achieve high photocatalytic efficiency, because the physical mixture of GO and TiO 2 showed a lower photocatalytic CBZ degradation ability than bare TiO 2. The macroporous 3D structure, abundant surface sites for anchoring the catalyst, effective charge separation, and mass transportation of CBZ near the photocatalyst surface are the attractive features of RGOT aerogels, promoting their use in resolving environmental issues.

The use of engineered nanomaterials is continuously increasing in commercial products and industr... more The use of engineered nanomaterials is continuously increasing in commercial products and industrial applications, and a significant portion of these materials may enter domestic and industrial wastewater streams and subsequently, wastewater treatment plants. Microbial fuel cells (MFCs) represent a new emerging technology for simultaneously generating bioenergy and treating wastewater. In this work, the performance of a MFC with wastewater containing multi-walled carbon nanotubes (MWCNTs) was evaluated. No significant negative effect on power generation was observed for MWCNT concentrations from 10 mg L À1 to 200 mg L À1. In fact, there was a stimulating effect due to the increased conductivity resulting from the MWCNTs, therefore slightly enhancing voltage generation (linked to enhanced electron transfer rate). The maximum voltage generation was increased from 0.61 V to 0.68 V (at 1000 U external resistance). Low lactate dehydrogenase release at all concentrations of MWCNTs showed that no adverse cell piercing took place and the wrapping of cells by MWCNTs most likely occurred. Chemical oxygen demand (COD) removal efficiency was also enhanced from 74.2% to 84.7%. The experimental results demonstrated that wastewater containing MWCNTs can be applied to MFCs for generating bioelectricity and treating wastewater without any significant adverse effect on performance.

Microorganisms have the potential to become a game-changer in sustainable energy production in th... more Microorganisms have the potential to become a game-changer in sustainable energy production in the coming
generations. Microbial fuel cells (MFCs) as an alternative renewable technology can capture bioenergy (electricity)
from carbon-based sources by utilizing microorganisms as biocatalysts. This study demonstrated that MFC
technology can be explored for bioelectricity production from orange peel waste (OPW), an agricultural
byproduct and an organic substrate, without any chemical pretreatment or the addition of extra mediators. A
maximum voltage generation of 0.59 ± 0.02 V (at 500 Ω) was achieved in a dual chamber MFC during stable voltage
generation stages. The maximum power density and current density obtained were 358.8 ± 15.6 mW/m2
and 847 ± 18.4 mA/m2
, respectively. Key components of OPW, namely pectin and cellulose, were also tested
in their pure form, with pectin giving a stable current, while no significant current generation was achieved
using cellulose alone as the substrate, thus demonstrating the absence of cellulose-degrading bacteria. Maximum
pectinase and polygalacturonase enzyme activities of 18.55 U/g and 9.04 U/g (per gram of substrate), respectively
were achieved during orange peel degradation in MFCs. Bacterial identification using 16S rRNA analysis of the initial
inoculum fed to the MFC, the biofilm attached to the anode, and the anode suspension, showed significant
diversity in community composition. A well-known exoelectrogen, Pseudomonas, was present among the predominant
genera in the anode biofilm.

Microbial fuel cells (MFCs) are envisaged as an emerging cost effective technology for organic wa... more Microbial fuel cells (MFCs) are envisaged as an emerging cost effective technology for organic waste
treatment and simultaneous bioelectricity generation. In this work, the potential use of lemon peel waste
for bioenergy generation was investigated in a dual chamber MFC. A stable voltage generation of
0.58 ± 0.02 V (500 U external resistor) at peel waste concentrations of 0.5e1.5 g l1 was achieved. A
maximum power density of 371 ± 30 mW m2
, corresponding to a current density of 994 ± 41 mA m2
,
was obtained at an initial peel waste concentration of 1.0 g l1
. Performance characteristics in terms of
coulombic efficiency and internal resistance obtained by the MFC at this initial concentration were 32.3%
and 143 U, respectively. The effect of sonication time, temperature, and external resistance were also
studied to determine the maximum level of cumulative power generation. These preliminary results
clearly indicate that the carbon source present in lemon peel waste can be utilized by exoelectrogens
present in the anodic chamber, and that it ultimately releases electrons, which results in the generation
of cell voltage.

Journal of Nanoelectronics and Optoelectronics, 2015

ABSTRACT Microbial fuel cells (MFCs) are attaining great interests for simultaneous current gener... more ABSTRACT Microbial fuel cells (MFCs) are attaining great interests for simultaneous current generation and recalcitrant organic pollutants treatment. Earlier investigations have revealed barley brewery wastewater as a cheap carbon source for simultaneous electricity generation, chemical oxygen demand (COD) removal, and poly azo dye (Sirius Red) degradation in a dual chamber microbial fuel cell. The experimental results showed a stable voltage production of 0.39 ± 0.02 V (220 Ω external resistor) using brewery wastewater as a sole carbon source. The maximum power density achieved was 271 ± 21 mW/m2 at an initial brewery wastewater concentration of 1000 mg/L COD, with the addition of dye (100 mg/L). A decolorization efficiency of 67% was attained in the anode chamber, and COD removal was 90% and 78% for brewery wastewater before and after the addition of dye, respectively, in a 48-h batch studies. UV-vis, Fourier transform infrared confirmed that the azo bonds in the dye were cleaved during dye degradation. Gas chromatography-mass spectrometry showed sodium-4-aminoazobenzene-4′-sulfonate and 1-3-bis(2-aminonapthalen-6-yl) urea as the main metabolites after the decolorization of Sirius Red.

Surface modification of titanium dioxide (TiO 2) was carried out with salicylic acid (SA) to gene... more Surface modification of titanium dioxide (TiO 2) was carried out with salicylic acid (SA) to generate an efficient Pickering emulsion (PE)-based photocatalytic system. The PE was stabilized with 0.5 and 1.0 mg mL −1 of TiO 2 and SA-TiO 2 by using cyclohexane and a synthetic aqueous Direct Red 80 (DR 80) solution (0.4:1) as the oil and water phases, respectively. The photocatalytic activity of solution-dispersed TiO 2 was compared with that of the PE-based photocatalytic system for DR 80 degradation. In almost all PE-based photocatalytic systems, 100% color removal of DR 80 was observed within 15–60 min, compared to 76% and 100% color removal, achieved after 120 min, using 0.5 and 1.0 mg mL −1 solution-dispersed TiO 2 , respectively. The estimated reaction rates of the PE-based photocatalytic system, as calculated using the Langmuir–Hinshelwood kinetics model, were almost double to those obtained for solution-dispersed TiO 2. However, the addition of a free oil phase adversely affected the photocatalytic activity, and the lowest DR 80 degradation percentage was observed using 0.5 or 1.0 mg mL −1 TiO 2. The results demonstrated that a functional PE was successfully stabilized with SA-TiO 2 , and enhanced photocatalytic degradation of the azo dye was achieved in an effective and novel way.

Microbial fuel cells (MFCs) are gaining tremendous interests for achieving simultaneous power pro... more Microbial fuel cells (MFCs) are gaining tremendous interests for achieving simultaneous power production and recalcitrant wastewaters treatment. In this study, simultaneous electricity generation and tetra-azo dye (Direct Red 80) decolorization was examined in a dual chamber MFC. In addition, glucose and various volatile fatty acids were separately examined as co-substrates for anaerobic dye degradation and bioelectricity generation. Maximum power of 477.8 and 455.7 mW/m 2 were attained with glucose (1,000 mg/L) as a sole carbon source and glucose (1,000 mg/L) coupled with dye (200 mg/L), respectively. At this glucose and dye initial concentration, 85.8% color and 74.9% COD removal were resulted in 48 h batch studies. Color removal without any co-substrate's addition was 23%, indicating dye was degraded mainly in the presence of carbon sources. There was no substantial negative effect in electricity generation was observed with the dye degradation. Dye removal was decreased with the increase in dye initial concentration (25-800 mg/L) and increases notably with the increase in initial glucose concentration between 0 and 1,000 mg/L, while afterward insignificant effect up to 2,000 mg/L was observed. Glucose was determined as better co-substrate followed by acetic, propionic, and lactic acid in terms of dye removal and maximum power production. Gas chromatography-mass spectrometry showed sodium 4-aminoazobenzene-4´-sulfonate to be the subsequent metabolites formed during the decolorization of dye. This work demonstrated that MFC could be applied to achieve electricity generation and simultaneous azo dye degradation using glucose as the preferred co-substrate.

The expansion in knowledge of the microbial community structure can play a vital role in the elec... more The expansion in knowledge of the microbial community structure can play a vital role in the electrochemical features and operation of microbial fuel cells (MFCs). In this study, bacterial community composition in a dual chamber MFC fed with brewery waste was investigated for simultaneous electricity generation and azo dye degradation. A stable voltage was generated with a maximum power density of 305 and 269 mW m −2 for brewery waste alone (2000 mg L −1 ) and after the azo dye (200 mg L −1 ) addition, respectively. Azo dye degradation was confirmed by Fourier transform infrared spectroscopy (FT-IR) as peak corresponding to -N=N-(azo) bond disappeared in the dye metabolites. Microbial communities attached to the anode were analyzed by high-throughput 454 pyrosequencing of the 16S rRNA gene. Microbial community composition analysis revealed that Proteobacteria (67.3 %), Betaproteobacteria (30.8 %), and Desulfovibrio (18.3 %) were the most dominant communities at phylum, class, and genus level, respectively. Among the classified genera, Desulfovibrio most likely plays a major role in electron transfer to the anode since its outer membrane contains c-type cytochromes. At the genus level, 62.3 % of all sequences belonged to the unclassified category indicating a high level of diversity of microbial groups in MFCs fed with brewery waste and azo dye.

1. Addition of toluene affects DR80 degradation 2. Toluene continuous layer form has adverse effe... more 1. Addition of toluene affects DR80 degradation 2. Toluene continuous layer form has adverse effect but PE form has supportive effect 3. Highly hydrophilic and large TiO 2 particles do not provide a stable PE 4. A stable PE is better than an unstable PE for DR80 degradation 5. Separation of nanomaterials/catalysts from the effluent is essential

Rainwater harvesting being an alternate source in water scarce areas is becoming a common practic... more Rainwater harvesting being an alternate source in water scarce areas is becoming a common practice. Catchment contact, however, deteriorates the quality of rainwater making it unfit for potable purposes. To improve the quality of harvested rainwater, silver was used as antimicrobial agent in this study. Rainwater samples were taken from underground storage tank of a rooftop rainwater harvesting system installed in one of the buildings at Seoul National University, Seoul, South Korea. The target microorganisms (MOs) were Pseudomonas aeruginosa and Escherichia coli which were measured by using plate count method and standard MPN method, respectively. The efficiency of silver disinfection was evaluated at concentrations, ranging from 0.01 to 0.1 mg/l; the safe limit approved by WHO. The experiments were performed for 168 h with different time intervals to evaluate the parameters including inactivation rate, residual effect of silver and re-growth in both MOs at lower (i.e. 0.01-0.04 mg/l) as well as the higher concentrations of silver (i.e. 0.08-0.1 mg/l). Results showed the re-growth in both MOs was only in the case of lower concentrations of silver. The possible reason of re-growth at these concentrations of silver may be the halting of bacterial cell replication process for some time without permanent damage. The kinetics of this study suggest that higher inactivation and long term residual effect towards both MOs can be achieved with the application of silver at 0.08 mg/l or higher under safe limit.

Hill torrents is special kind of Rainwater Harvesting in which water is harvested from the mounta... more Hill torrents is special kind of Rainwater Harvesting in which water is harvested from the mountains and diverted to the agricultural fields by locally made earthen diversion weirs across the torrent with large channels. Hill torrents encompass 65% of the total agricultural area of Pakistan and almost entire Balochistan province. Rainwater is particularly used for Agriculture and usually spate irrigation, traditionally called Rod Kohi, method is common. In these areas the major constraint is the use of flood flow which is highly variable in quantity and distribution, both in time and space. Annual rainfall is low and uncertain but brings large amount of water with each rainfall event. The agriculture in these areas is totally dependent on rainfall, although affected by flood with rainfall but most of the times remain without water. It is unfortunate that in spite of scarcity of water, major part of flood flows is lost due to mismanagement. The major problem is the unavailability of any kind of storage and modernized engineering structures, though lot of efforts and money were spent in order to control the torrents flow floods but storage is never considered important which might be considered the main drawback of the previous studies. PARC (Pakistan Agriculture Research Council) made interventions in conveyance and distribution systems in some areas but storage facility is still unattended. If the proper storage facility and modernized structures are provided in these areas then not only the flood is controlled but also the drought conditions can be mitigated and the crops which have very less yield due to the unavailability of water can be enhanced.

PLoS ONE, 2014

CLEAN - Soil, Air, Water, 2013

Journal of Nanoelectronics and Optoelectronics, 2015