Rana, HK, Akhtar, R, Ahmed, MB, Lio, P, Quinn, JMW, Huq, F & Moni, MA 2019, 'Genetic effects of welding fumes on the progression of neurodegenerative diseases', NEUROTOXICOLOGY, vol. 71, pp. 93-101.View/Download from: UTS OPUS or Publisher's site
Rana, HK, Akhtar, R, Islam, MB, Ahmed, MB, Lio, P, Quinn, JMW, Huq, F & Moni, MA 2019, 'Genetic effects of welding fumes on the development of respiratory system diseases', COMPUTERS IN BIOLOGY AND MEDICINE, vol. 108, pp. 142-149.View/Download from: UTS OPUS or Publisher's site
Ahmed, MB, Hasan Johir, MA, Zhou, JL, Ngo, HH, Nghiem, LD, Richardson, C, Moni, MA & Bryant, MR 2019, 'Activated carbon preparation from biomass feedstock: Clean production and carbon dioxide adsorption', Journal of Cleaner Production, vol. 225, pp. 405-413.View/Download from: UTS OPUS or Publisher's site
© 2019 Elsevier Ltd The current methods used for the production of activated carbon (AC) are often chemical and energy intensive and produce significant amount of chemical waste. Thus, clean production of AC is important to reduce its overall production cost and to limit the adverse effect on the environment. Therefore, the main aim of this study is to develop a clean method for AC production from woody biomass with low chemical consumption. Herein, this study reports a facile strategy for reducing chemical usages in the production of high-performance AC, by introducing a crucial pre-pyrolysis step before chemical activation of biomass. The ACs prepared were characterised using scanning electron microscopy, Fourier transform infrared spectroscopy, nitrogen and carbon dioxide gas adsorption measurements. All these characterisations indicated that produced ACs have similar physicochemical properties. The strategy reduced chemical use by 70% and produced high-performance ultra-microporous ACs with excellent carbon dioxide adsorption capacity (4.22–5.44 mmol m −2 ). The facile pre-pyrolysis method is recommended for further research as a cleaner activated carbon preparation method from biomass feedstock.
Nguyen, KT, Nguyen, HM, Truong, CK, Ahmed, MB, Huang, Y & Zhou, JL 2019, 'Chemical and microbiological risk assessment of urban river water quality in Vietnam', Environmental Geochemistry and Health.View/Download from: Publisher's site
© 2019, Springer Nature B.V. Abstract: The contamination and risk by nutrients (NH 4+ , NO 2− , NO 3− and PO 43− ), COD, BOD 5 , coliform and potentially toxic elements (PTEs) of As, Cd, Ni, Hg, Cu, Pb, Zn and Cr were investigated in urban river (Nhue River), Vietnam during 2010–2017. The extensive results demonstrated that concentrations of these contaminants showed significant spatial and temporal variations. The Nhue River was seriously polluted by NH 4+ (0.025–11.28 mg/L), PO 43− (0.17–1.72 mg/L), BOD 5 (5.8–179.6 mg/L), COD (1.4–239.8 mg/L) and coliform (1540–326,470 CFU/100 mL); moderately polluted by As (0.2–131.15 μg/L) and Hg (0.11–4.1 μg/L); and slightly polluted by NO 2− (0.003–0.33 mg/L) and Cd (2.1–18.2 μg/L). The concentrations of NH 4+ , PO 43− , COD, BOD 5 and coliform frequently exceeded both drinking water guidelines and irrigation water standards. Regarding PTEs, As, Cd and Hg concentrations were frequently higher than the regulatory limits. Human health risks of PTEs were evaluated by estimating hazard index (HI) and cancer risk through ingestion and dermal contacts for adults and children. The findings indicated that As was the most important pollutant causing both non-carcinogenic and carcinogenic concerns. The non-carcinogenic risks of As were higher than 1.0 at all sites for both adults (HI = 1.83–7.4) and children (HI = 2.6–10.5), while As posed significant carcinogenic risks for adults (1 × 10 −4 −4.96 × 10 −4 ). A management strategy for controlling wastewater discharge and protecting human health is urgently needed. Graphical abstract: [Figure not available: see fulltext.].
Xu, J, Cao, Z, Wang, Y, Zhang, Y, Gao, X, Ahmed, MB, Zhang, J, Yang, Y, Zhou, JL & Lowry, GV 2019, 'Distributing sulfidized nanoscale zerovalent iron onto phosphorus-functionalized biochar for enhanced removal of antibiotic florfenicol', CHEMICAL ENGINEERING JOURNAL, vol. 359, pp. 713-722.View/Download from: UTS OPUS or Publisher's site
Nur, T, Loganathan, P, Ahmed, MB, Johir, MAH, Tien, VN & Vigneswaran, S 2019, 'Removing arsenic from water by coprecipitation with iron: Effect of arsenic and iron concentrations and adsorbent incorporation', CHEMOSPHERE, vol. 226, pp. 431-438.View/Download from: UTS OPUS or Publisher's site
Ahmed, M, Johir, MAH, Khourshed, C, Zhou, J, Ngo, HH, Nghiem, D, Moni, M & Sun, L 2018, 'Sorptive removal of dissolved organic matter in biologically-treated effluent by functionalized biochar and carbon nanotubes: importance of sorbent functionality', Bioresource Technology.View/Download from: UTS OPUS or Publisher's site
The sorptive removal of dissolved organic matter (DOM) in biologically-treated effluent was studied by using multi-walled carbon nanotube (MWCNT), carboxylic functionalised MWCNT (MWCNT-COOH), hydroxyl functionalized MWCNT (MWCNT-OH) and functionalized biochar (fBC). DOM was dominated by hydrophilic fraction (79.6%) with a significantly lower hydrophobic fraction (20.4%). The sorption of hydrophobic DOM was not significantly affected by the sorbent functionality (∼10.4% variation) and sorption capacity followed the order of MWCNT > MWCNT-COOH > MWCNT-OH > fBC. In comparison, the sorption of hydrophilic fraction of DOM changed significantly (∼37.35% variation) with the change of sorbent functionality with adsorption capacity decreasing as MWCNT-OH > MWCNT-COOH > MWCNT > fBC. Furthermore, the affinity of adsorbents toward a hydrophilic compound (dinitrobenzene), a hydrophobic compound (pyrene) and humic acid was also evaluated to validate the proposed mechanisms. The results provided important insights on the type of sorbents which are most effective to remove different DOM fractions.
Ahmed, M, Zhou, J, Ngo, H, Johir, MAH & Kireesan, S 2018, 'Sorptive removal of phenolic endocrine disruptors by functionalized biochar:competitive interaction mechanism, removal efficacy and application in wastewater', Chemical Engineering Journal, vol. 335, pp. 801-811.View/Download from: UTS OPUS or Publisher's site
Sorptive removal of six phenolic endocrine disrupting chemicals (EDCs) estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2), bisphenol A (BPA) and 4-tert-butylphenol (4tBP) by functionalized biochar (fBC) through competitive interactions was investigated. EDC sorption was pH dependent with the maximum sorption at pH 3.0-3.5 due to hydrogen bonds and π-π interactions as the principal sorptive mechanism. Sorption isotherm of the EDCs was fitted to the Langmuir model. Sorption capacities and distribution coefficient values followed the order E1 > E2 ≥ EE2 > BPA > 4tBP > E3. The findings suggested that EDC sorption occurred mainly through pseudo-second order and external mass transfer diffusion processes, by forming H-bonds along with π-π electron-donor-acceptor (EDA) interactions at different pH. The complete removal of ∼500 μg L-1 of each EDC from different water decreased in the order: deionised water > membrane bioreactor (MBR) sewage effluent > synthetic wastewater. The presence of sodium lauryl sulphonate and acacia gum in synthetic wastewater significantly suppressed sorption affinity of EDCs by 38-50%, hence requiring more fBC to maintain removal efficacy.
Ahmed, MB, Zhou, J, Ngo, HH, Johir, MAH, Sun, L, Asadullah, M & Belhaj, D 2018, 'Sorption of hydrophobic organic contaminants on functionalized biochar: protagonist role of π-π electron-donor-acceptor interactions and hydrogen bonds', Journal of Hazardous Materials.View/Download from: UTS OPUS or Publisher's site
The sorption of five potent endocrine disruptors as representative hydrophobic organic contaminants (HOCs) namely estrone (E1), 17β-estradiol (E2), estriol (E3), 17α-ethynylestradiol (EE2) and bisphenol A (BPA) on functionalized biochar (fBC) was systematically examined, with a particular focus on the importance of π-electron-donor (phenanthrene: PHEN) and π-electron-acceptors (1,3-dinitrobenzene: DNB, p-amino benzoic acid: PABA) on sorption. Experimental results suggested that hydrogen-bond formation and π-π-electron-donor-acceptor (EDA) interactions were the dominant sorption mechanisms. The sorption of HOCs decreased as E1 > E2 > EE2 > E3 > BPA based on the Freundlich and Polanyi-Mane-models. The comparison of adsorption coefficient (Kd) normalized against hexadecane-water partition coefficient (KHW) between HOCs and PHEN indicated strong π-π-EDA interactions. π-π interactions among DNB, PHEN and HOCs were verified by the observed upfield frequency (Hz) shifts using proton nuclear magnetic resonance (1H NMR) which identified the specific direction of π-π interactions. UV-vis spectra showed charge-transfer bands for π-donors (PHEN and HOCs) with the model π-acceptor (DNB) also demonstrating the role of π-π EDA interactions. The role of π-electron-donor and π-electron-acceptor domains in fBC was identified at different solution pH.
Altaee, A, Xu, B, Ahmed, MB, Zhou, JL, Xu, G & Wu, M 2018, 'Graphitic carbon nitride based nanocomposites for the photocatalysis of organic contaminants under visible irradiation: Progress, limitations and future directions', Science of the Total Environment, vol. 633, pp. 546-559.View/Download from: UTS OPUS or Publisher's site
Graphitic carbon nitride (g-C3N4) has drawn great attention recently because of its visible light response, suitable energy band gap, good redox ability, and metal-free nature. g-C3N4 can absorb visible light directly, therefore has better photocatalytic ability under solar irradiation and is more energy-efficient than TiO2. However, pure g-C3N4 still has the drawbacks of insufficient light absorption, small surface area and fast recombination of photogenerated electron and hole pairs. This review summarizes the recent progress in the development of g- C3N4 nanocomposites to photodegrade organic contaminants in water. Element doping especially by potassium has been reported to be an efficient method to promote the degradation efficacy. In addition, compound doping improves photodegradation performance of g-C3N4, especially Ag3PO4-g-C3N4 which can completely degrade 10 mg L−1 of methyl orange under visible light irradiation in 5 min, with the rate constant (k) as high as 0.236 min−1. Moreover, co-doping enhances the photodegradation rate of multiple contaminants while immobilization significantly improves catalyst stability. Most of g-C3N4 composites possess high reusability enabling their practical applications in wastewater treatment. Furthermore, environmental conditions such as solution pH, reaction temperature, dissolved oxygen, and dissolved organic matter all have important effects on the photocatalytic ability of g-C3N4 photocatalyst. Future work should focus on the synthesis of innovative g-C3N4 nanocomposites for the efficient removal of organic contaminants in water and wastewater.
Belhaj, D, Athmouni, K, Ahmed, MB, Aoiadni, N, El Feki, A, Zhou, JL & Ayadi, H 2018, 'Polysaccharides from Phormidium versicolor (NCC466) protecting HepG2 human hepatocellular carcinoma cells and rat liver tissues from cadmium toxicity: Evidence from in vitro and in vivo tests', INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES, vol. 113, pp. 813-820.View/Download from: UTS OPUS or Publisher's site
Mohsen, M, Ahmed, MB & Zhou, JL 2018, 'Particulate matter concentrations and heavy metal contamination levels in the railway transport system of Sydney, Australia', Transportation Research Part D: Transport and Environment, vol. 62, pp. 112-124.View/Download from: UTS OPUS or Publisher's site
© 2018 Elsevier Ltd Sampling campaign was conducted over six weeks to determine particulate matter (PM) concentrations from Sydney Trains airport line (T2) at both underground and ground levels using DustTrak. Dust samples were collected and analysed for 12 metals (Fe, Ca, Mn, Cr, Zn, Cu, Pb, Al, Co, Ni, Ba and Na) by atomic emission spectroscopy. Average underground PM10 and PM2.5 concentrations from inside the trains were 2.8 and 2.5 times greater than at ground level. Similarly, PM10 and PM2.5 concentrations on underground platforms were 2.7 and 2.5 times greater than ground level platforms. Average underground PM concentrations exceeded the national air quality standards for both PM10 (50 µg/m3) and PM2.5 (25 µg/m3). Correlation analysis showed a strong to moderate association between PM concentrations at ground level and background PM concentrations (r2 from 0.952 to 0.500). The findings suggested that underground PM concentrations were less influenced by the ambient background than at ground level. The metal concentrations decreased in the order of Fe, Cr, Ca, Al, Na, Ba, Mn, Zn, Cu, Ni, Co and Pb. The pollution index (PI) and enrichment factor (EF) values were calculated to identify the levels and sources of contamination in the underground railway microenvironments. PM was remarkably rich in Fe with a mean concentration of 73.51 mg/g and EF of 61.31, followed by Ni and Cr. These results noticeably indicated a high level of metal contamination in the underground environments, with the principal contribution from track abrasion and wear processes.
Sornalingam, K, McDonagh, A, Zhou, J, Johir, M & Ahmed, M 2018, 'Photocatalysis of estrone in water and wastewater: Comparison between Au-TiO2 nanocomposite and TiO2, and degradation by-products', Science of the Total Environment, vol. 610–611, pp. 521-530.View/Download from: UTS OPUS or Publisher's site
Gold-modified TiO2 (Au-TiO2) photocatalysts were utilised for the degradation of estrone (E1), a major endocrine disrupting chemical in water and wastewater. Au-TiO2 catalysts were synthesised by a deposition-precipitation method with gold loadings of 0–8% (wt%). The Au-TiO2 nanocomposite exhibited superior activity compared to P25 TiO2 under UVA (λ = 365 nm), cool white (λ > 420 nm) and green (λ = 523 nm) light emitting diodes (LEDs), for treating 1 mg l− 1 of E1. The 4 wt% Au loading was found to produce the best photocatalytic activity with a rate constant of 2.44 ± 0.36 h− 1, compared to 0.06 ± 0.01 h− 1 for P25 TiO2, under visible light. In total 4 by-products were identified, one from negative ionization mode (m/z = 269) and three from positive ionization mode (m/z = 287) during photocatalysis, which were also degraded with time by Au-TiO2. For different water matrices, the photodegradation rate of E1 decreased in the order: ultrapure water > synthetic wastewater ≈ wastewater effluent from membrane bio-reactor. Overall, 4 wt% Au-TiO2 demonstrated superior performance compared to P25 TiO2 in water and wastewater.
Nur, T, Loganathan, P, Ahmed, MB, Johir, M, Kandasamy, J & Vigneswaran, S 2018, 'Struvite production using membrane-bioreactor wastewater effluent and seawater', Desalination, vol. 444, pp. 1-5.View/Download from: UTS OPUS or Publisher's site
© 2018 Elsevier B.V. Wastewater phosphorus (P) released into natural water bodies such as lakes and rivers, can cause water pollution as a result of eutrophication. If this P is effectively removed from wastewaters and economically recovered for use as fertilisers, not only can the water pollution be controlled, but also reduce the anticipated global shortage of P. This scarcity will result from the natural phosphate rock reserve being exhausted. Three experiments were conducted using membrane-bioreactor effluent (MBR, 35 mg PO 4 /L) and reverse osmosis concentrate (ROC, 10 mg PO 4 /L) waters to supply phosphate, and sea water (1530 mg Mg/L) to supply Mg for the production of struvite. The phosphate in the MBR and ROC was concentrated approximately 15 times by adsorption onto an ion exchange resin column followed by desorption. Struvite was precipitated by mixing the desorbed solution with seawater and NH 4 Cl. The chemical composition and mineral structure of the precipitates agreed with those of the reference struvite. When Ca in seawater (300 mg Ca/L) was removed before mixing the water with MBR or ROC, the purity of the struvite improved.
Ahmed, M, Guo, W, Zhou, J, Johir, M & Ngo, H 2017, 'Competitive sorption affinity of sulfonamides and chloramphenicol antibiotics toward functionalized biochar for water and wastewater treatment', Bioresource Technology.View/Download from: UTS OPUS or Publisher's site
Competitive sorption of sulfamethazine (SMT), sulfamethoxazole (SMX), sulfathiazole (STZ) and chloramphenicol (CP) toward functionalized biochar (fBC) was highly pH dependent with maximum sorption at pH ∼4.0-4.25. Equilibrium data were well represented by the Langmuir and Freundlich models in the order STZ > SMX > CP > SMT. Kinetics data were slightly better fitted by the pseudo second-order model than pseudo first-order and intra-particle-diffusion models. Maximum sorptive interactions occurred at pH 4.0-4.25 through H-bonds formations for neutral sulfonamides species and through negative charge assisted H-bond (CAHB) formation for CP, in addition to π-π electron-donor-acceptor (EDA) interactions. EDA was the main mechanism for the sorption of positive sulfonamides species and CP at pH < 2.0. Sorption of negative sulfonamides species and CP at pH > 7.0 was regulated by H-bond formation and proton exchange with water by forming CAHB, respectively. The results suggested fBC to be highly efficient in removing antibiotics mixture.
Ahmed, M, zhou, J, Ngo, H, Guo, W, Johir, M & Kiressan, S 2017, 'Nano-Fe0 Immobilized onto Functionalized Biochar Gaining Excellent Stability during Sorption and Reduction of Chloramphenicol via Transforming to Reusable Magnetic Composite', Chemical Engineering Journal, vol. 322, pp. 571-581.View/Download from: UTS OPUS or Publisher's site
The widely used nanosized zero-valent iron (nZVI or nFe0) particles and their composite material lose reductive nature during application, and the stability of transformed composite material for repeatable application is not addressed to date. To shed light on this, nZVI was synthesized from scrap material and immobilized on functionalized biochar (fBC) to prepare nZVI-fBC composite. Comparative study between nZVI and nZVI-fBC composite on the removal of chlorinated antibiotic chloramphenicol from different water types was conducted. The results suggested that nZVI was solely responsible for reduction of chloramphenicol. Whereas nZVI-fBC could be applied once, within a few hours, for the reduction of chloramphenico (29–32.5%) and subsequently sorption (67.5–70.5%) by transforming to a fully magnetic composite (nFe3O4-fBC) gaining stability with synergistic sorption performance. In both cases, two reduction by-products were identified namely 2-chloro-N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 257) and dechlorinated N-[1,3-dihydroxy-1-(4-aminophenyl)propan-2-yl]acetamide (m/z 223). The complete removal of 3.1 µM L−1 of chloramphenicol in different water was faster by nZVI-fBC (∼12–15 h) than by stable nFe3O4-fBC composite (∼18 h). Both nZVI-fBC and nFe3O4-fBC composites removed chloramphenicol in the order: deionized water > lake water > synthetic wastewater. nFe3O4-fBC showed excellent reusability after regeneration, with the regenerated nFe3O4-fBC composite (after 6 cycles of application) showing significant performance for methylene blue removal (∼287 mg g−1). Therefore, the transformed nFe3O4-fBC composite is a promising and reusable sorbent for the efficient removal of organic contaminants.
Ahmed, MB, Johir, MAH, Zhou, JL, Ngo, HH, Guo, W & Sornalingam, K 2017, 'Photolytic and Photocatalytic Degradation of Organic UV Filters in Contaminated Water', Current Opinion in Green and Sustainable Chemistry, vol. 6, pp. 85-92.View/Download from: UTS OPUS or Publisher's site
UV filters as emerging contaminants are of great concern and their wide detection in aquatic environments indicates their chemical stability and persistence. This review summarized the photolytic and photocatalytic degradation of UV filters in contaminated water. The findings indicated that limited research has been conducted on the photolysis and photocatalysis of UV filters. Photolysis of UV filters through UV irradiation in natural water was a slow process, which was accelerated by the presence of photosensitisers e.g. triplet state of chromaphoric dissolved organic matter (3CDOM*) and nutrients but reduced by salinity, dissolved organic matter (DOM) and divalent cations. UV Photocatalysis of 4-methylbenzylidene camphor and 2-phenylbenzimidazole-5-sulfonic acid was very effective with 100% removal within 30 min and 90 min using medicated TiO2/H2O2 and TiO2, respectively. The radiation source, type of catalyst and oxygen content were key factors. Future research should focus on improved understanding of photodegradation pathways and by-products of UV filters.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Johir, MAH & Sornalingam, K 2017, 'Single and competitive sorption properties and mechanism of functionalized biochar for removing sulfonamide antibiotics from water', Chemical Engineering Journal, vol. 311, pp. 348-358.View/Download from: UTS OPUS or Publisher's site
© 2016 Elsevier B.V.Single and competitive sorption of ionisable sulphonamides sulfamethazine, sulfamethoxazole and sulfathiazole on functionalized biochar was highly pH dependent. The equilibrium data were well represented by both Langmuir and Freundlich models for single solutes, and by the Langmuir model for competitive solutes. Sorption capacity and distribution coefficient values decreased as sulfathiazole > sulfamethoxazole > sulfamethazine. The sorption capacity of each antibiotic in competitive mode is about three times lower than in single solute sorption. The kinetics data were best described by the pseudo second-order (PSO) model for single solutes, and by PSO and intra-particle diffusion models for competitive solutes. Adsorption mechanism was governed by pore filling through diffusion process. The findings from pH shift, FTIR spectra and Raman band shift showed that sorption of neutral sulfonamide species occurred mainly due to strong H-bonds followed by π+-π electron-donor-acceptor (EDA), and by Lewis acid-base interaction. Moreover, EDA was the main mechanism for the sorption of positive sulfonamides species. The sorption of negative species was mainly regulated by proton exchange with water forming negative charge assisted H-bond (CAHB), followed by the neutralization of –OH groups by H+ released from functionalized biochar surface; in addition π-π electron-acceptor-acceptor (EAA) interaction played an important role.
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W, Thomaidis, NS & Xu, J 2017, 'Progress in the biological and chemical treatment technologies for emerging contaminant removal from wastewater: A critical review.', Journal of Hazardous Materials, vol. 323, pp. 274-298.View/Download from: UTS OPUS or Publisher's site
This review focuses on the removal of emerging contaminants (ECs) by biological, chemical and hybrid technologies in effluents from wastewater treatment plants (WWTPs). Results showed that endocrine disruption chemicals (EDCs) were better removed by membrane bioreactor (MBR), activated sludge and aeration processes among different biological processes. Surfactants, EDCs and personal care products (PCPs) can be well removed by activated sludge process. Pesticides and pharmaceuticals showed good removal efficiencies by biological activated carbon. Microalgae treatment processes can remove almost all types of ECs to some extent. Other biological processes were found less effective in ECs removal from wastewater. Chemical oxidation processes such as ozonation/H2O2, UV photolysis/H2O2 and photo-Fenton processes can successfully remove up to 100% of pesticides, beta blockers and pharmaceuticals, while EDCs can be better removed by ozonation and UV photocatalysis. Fenton process was found less effective in the removal of any types of ECs. A hybrid system based on ozonation followed by biological activated carbon was found highly efficient in the removal of pesticides, beta blockers and pharmaceuticals. A hybrid ozonation-ultrasound system can remove up to 100% of many pharmaceuticals. Future research directions to enhance the removal of ECs have been elaborated.
Belhaj, D, Frikha, D, Athmouni, K, Jerbi, B, Ahmed, MB, Bouallagui, Z, Kallel, M, Maalej, S, Zhou, J & Ayadi, H 2017, 'Box-Behnken design for extraction optimization of crude polysaccharides from Tunisian Phormidium versicolor cyanobacteria (NCC 466): Partial characterization, in vitro antioxidant and antimicrobial activities', INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES, vol. 105, pp. 1501-1510.View/Download from: UTS OPUS or Publisher's site
MB Ahmed, JunLiang Zhou, Huu Hao Nog, Wenshan Guo, MAH Johir, K. Sornalingram & MS Rahman 2017, 'Chloramphenicol interaction with functionalized biochar in water: sorptive mechanism, molecular imprinting effect and repeatable application', Science of the Total Environment, vol. 609, pp. 885-895.View/Download from: UTS OPUS or Publisher's site
Biochar and functionalized biochar (fBC-1 and fBC-2) were prepared and applied to remove antibiotic chloramphenicol
from deionized water, lake water and synthetic wastewater. Results showed that chloramphenicol removal
on biochar was pH dependent and maximum sorption occurred at pH 4.0–4.5. The sorption data of
chloramphenicol fitted better with the Langmuir isotherm model than the Freundlich isotherm model with the
maximum Langmuir sorption capacity of 233 μM g−1 using fBC-2. Chloramphenicol sorption on fBC-2 followed
the trend: deionized water N lake water N synthetic wastewater. The presence of humic acid decreased the
sorption distribution coefficient (Kd) while the presence of low ionic strength and soil in solution increased Kd
value significantly. The mechanism of sorption on fBC mainly involved electron-donor-acceptor (EDA) interactions
at pH b 2.0; formation of charge assisted hydrogen bond (CAHB) and hydrogen bonds in addition to EDA
in the pH 4.0–4.5; and CAHB and EDA interactions at pH N 7.0. Additionally, solvent and thermal regeneration
of fBC-2 for repeatable applications showed excellent sorption of chloramphenicol under the same condition,
due to the creation of a molecular imprinting effect in fBC-2. Consequently, fBC-2 can be applied with excellent
reusability properties to remove chloramphenicol and other similar organic contaminants.
Narottam Saha, M. Safiur Rahman, Ahmed, M, ZHou, Ngo & Guo 2017, 'Industrial metal pollution in water and probabilistic assessment of human health risk', Journal of Environmental Management, vol. 185, pp. 70-78.View/Download from: UTS OPUS or Publisher's site
Concentration of eight heavy metals in surface and groundwater around Dhaka Export Processing Zone
(DEPZ) industrial area were investigated, and the health risk posed to local children and adult residents
via ingestion and dermal contact was evaluated using deterministic and probabilistic approaches. Metal
concentrations (except Cu, Mn, Ni, and Zn) in Bangshi River water were above the drinking water quality
guidelines, while in groundwater were less than the recommended limits. Concentration of metals in
surface water decreased as a function of distance. Estimations of non-carcinogenic health risk for surface
water revealed that mean hazard index (HI) values of As, Cr, Cu, and Pb for combined pathways (i.e.,
ingestion and dermal contact) were >1.0 for both age groups. The estimated risk mainly came from the
ingestion pathway. However, the HI values for all the examined metals in groundwater were <1.0,
indicating no possible human health hazard. Deterministically estimated total cancer risk (TCR) via
Bangshi River water exceeded the acceptable limit of 1 104 for adult and children. Although, probabilistically
estimated 95th percentile values of TCR exceeded the benchmark, mean TCR values were less
than 1 104
. Simulated results showed that 20.13% and 5.43% values of TCR for surface water were
>1 104 for adult and children, respectively. Deterministic and probabilistic estimations of cancer risk
through exposure to groundwater were well below the safety limit. Overall, the population exposed to
Bangshi River water remained at carcinogenic and non-carcinogenic health threat and the risk was
higher for adults. Sensitivity analysis identified exposure duration (ED) and ingestion rate (IR) of water as
the most relevant variables affecting the probabilistic risk estimation model outcome.
Xu, B, Ahmed, MB, Zhou, JL, Altaee, A, Wu, M & Xu, G 2017, 'Photocatalytic removal of perfluoroalkyl substances from water and wastewater: Mechanism, kinetics and controlling factors.', Chemosphere, vol. 189, pp. 717-729.View/Download from: UTS OPUS or Publisher's site
This review focuses on heterogeneous photocatalysis of perfluoroalkyl substances (PFAS) which are of worldwide concern as emerging persistent organic contaminants. Heterogeneous photocatalysis is an effective and advanced technology for PFAS removal from water with relatively high efficacy. During photocatalysis, various short chain perfluorocarboxylic acids (PFCA) are produced as intermediates and the efficacy is related to the photo-generated hole (h+) and photo-generated electron (e-). PFAS photodegradation in water under UV irradiation is most effective by using In2O3 as the catalyst, followed by Ga2O3 and TiO2. Significantly, modifying the chemical composition or morphology of the catalyst can improve its efficacy for PFAS removal. In2O3 porous nanoplates were found to have the best performance of 100% PFAS decomposition under UV light with rate constant (kt) and half-time (τ1/2) of 0.158 min-1 and 4.4 min, respectively. Catalysts perform well in acidic solution and increasing temperature to a certain extent. The photocatalytic performance is reduced when treating wastewater due to the presence of dissolved organic matter (DOM), with the catalysts following the order: needle-like Ga2O3 > In2O3 > TiO2. Future studies should focus on the development of novel photocatalysts, and their immobilization and application for PFAS removal in wastewater.
Biochars (BCs) are widely produced and used for the remediation of environmental contaminants as bio-sorbents. In this review, statistical analysis of different BC physico–chemical properties was conducted. It was observed that woody materials are the most suitable for preparing BCs, among many other potential raw materials such as food wastes and agricultural materials. Currently BCs are produced through a variety of thermal treatment processes between 300 and 900 °C, among which slow pyrolysis is widely used due to its moderate operating conditions and optimization of BC yields. Hydrothermal carbonisation (HTC) is also an effective approach for BC production under certain conditions. As pyrolysis temperature is increased, the carbon content, ash content, surface area, and pore volume tend to be increased while the yield, hydrogen, oxygen, nitrogen content, and H/C and O/C molar ratios tend to decrease. The economic feasibility of BCs depends on a range of factors from raw material price to efficient production technologies. Thus, the overall cost equation of a pilot BC production plant together with the cost equation for BC regeneration has been proposed. The future research directions of BCs are also elaborated
Ahmed, MB, Zhou, JL, Ngo, HH, Guo, W & Chen, M 2016, 'Progress in the preparation and application of modified biochar for improved contaminant removal from water and wastewater', BIORESOURCE TECHNOLOGY, vol. 214, pp. 836-851.View/Download from: UTS OPUS or Publisher's site
Ahmed, MB, Zhou, JL, Ngo, HH & Guo, W 2015, 'Adsorptive removal of antibiotics from water and wastewater: Progress and challenges', SCIENCE OF THE TOTAL ENVIRONMENT, vol. 532, pp. 112-126.View/Download from: UTS OPUS or Publisher's site
Asadullah, M, Jahan, I, Ahmed, MB, Adawiyah, P, Malek, NH & Rahman, MS 2014, 'Preparation of microporous activated carbon and its modification for arsenic removal from water', JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY, vol. 20, no. 3, pp. 887-896.View/Download from: UTS OPUS or Publisher's site