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Experimental determination of Cd^2＋ adsorption mechanism on low-cost biological waste

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Frontiers of Environmental Science & Engineering 2013年第3期7卷 356-364页

作者： Farhah Amalya ismail ahmad Zaharin ARIS Environmental Forensics Research Centre Faculty of Environmental Studies Universiti Putra Malaysia UPM Serdang 43400 Malaysia

Carbonate shells have an astonishing ability in the removal of Cd^2＋ in a short time period with emphasis on being a low cost adsorbent. In the present study, the sorption capacity of carbonate shells was studied for Cd^2＋ in batch experiments. The influence of different carbonate shell sizes and physico-chemical factors were evaluated and the results were analyzed for its correlation matrices by using Predictive Analytics Software （PASW）. The miner- alogy state of aqueous solution regarding the saturation index was simulated using PHREEQC to identify the Cd^2＋ uptake mechanism. The Cd uptake rates were calculated as well as Ca^2＋, HCO3- concentration, pH, ambient humidity and temperature were measured. Cd2＋ removal of 91.52% was achieved after 5 h adsorption. The adsorption efficiencies were significantly influenced by pH as they increased with the increase of pH from acidic solution （5.50±0.02） to slightly alkaline （7.60±0.05）. In addition, the mineralogy state of aqueous solution calculated from PHREEQC confirmed that the increment of Ca^2＋ and HCO3- concentrations in solution was attributed to the dissolution of carbonate shells. Moreover, the ion exchange adsorption mechanism of Cd^2＋ toward Ca^2＋ was identified as the process involved in Cd^2＋ uptake.

关键词： carbonate shell cadmium heavy metal,adsorption mechanism saturation state

Synthesis of linear low-density polyethylene-g-poly(acrylic acid)-co-starch/organo-montmorillonite hydrogel composite as an adsorbent for removal of Pb(Ⅱ) from aqueous solutions

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Journal of Environmental Sciences 2015年第1期27卷 9-20页

作者： Maryam Irani Hanafi ismail Zulkifli ahmad Maohong Fan School of Materials and Mineral Resources Engineering USM Engineering Campus Universiti Sains Malaysia Department of Chemical and Petroleum Engineering University of Wyoming

The purpose of this work is to remove Pb（II） from the aqueous solution using a type of hydrogel composite. A hydrogel composite consisting of waste linear low density polyethylene, acrylic acid, starch, and organo-montmorillonite was prepared through emulsion polymerization method. Fourier transform infrared spectroscopy（FTIR）, Solid carbon nuclear magnetic resonance spectroscopy（CNMR））, silicon-29 nuclear magnetic resonance spectroscopy（Si NMR））, and X-ray diffraction spectroscope（（XRD） were applied to characterize the hydrogel composite. The hydrogel composite was then employed as an adsorbent for the removal of Pb（II） from the aqueous solution. The Pb（II）-loaded hydrogel composite was characterized using Fourier transform infrared spectroscopy（FTIR））,scanning electron microscopy（SEM））, and X-ray photoelectron spectroscopy（（XPS））. From XPS results, it was found that the carboxyl and hydroxyl groups of the hydrogel composite participated in the removal of Pb（II）. Kinetic studies indicated that the adsorption of Pb（II）followed the pseudo-second-order equation. It was also found that the Langmuir model described the adsorption isotherm better than the Freundlich isotherm. The maximum removal capacity of the hydrogel composite for Pb（II） ions was 430 mg/g. Thus, the waste linear low-density polyethylene-g-poly（acrylic acid）-co-starch/organo-montmorillonite hydrogel composite could be a promising Pb（II） adsorbent.

关键词： Hydrogel Waste polymers Organo clay Heavy metal ions Adsorption mechanism

Spatial Distribution and Anthropogenic Assessment of Heavy Metals in the Surface Sediments of Klang River

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湿地科学 2011年第1期9卷 8-18页

作者： Abolfazl Naji ahmad ismail Department of Biology Faculty of science University Putra Malaysia

The study was conducted to quantify the concentration and distribution of metals (Cd, Zn, Ni, Cu, Pb, and Fe) in the surface sediments and to assess the status of metal contaminations in the Klang River, Malaysia. The concentrations of metals (μg∕g, Fe%, dry weight) were as follows: 0.57-2.19 μg∕g Cd; 31.89-272.33 μg∕g Zn; 5.96-24.47 μg∕g Ni; 10.57-52.87 μg∕g Cu; 24.23-64.11 μg∕g Pb and 1.56%-3.03% Fe. Sequential extraction technique (SET) showed that mean anthropogenic portions of metals were in the order of Zn (60.22%), Cu (56.01%), Cd (45.63%), Ni (42.08%), Pb (33.22%) and Fe (10.26%). The highest concentrations of metals ( p<0.05) were found in the stations located close to industrial parks and highly populated areas. The results of the present study showed that the effectiveness of total organic carbon (TOC) contents in controlling the distribution and enrichment of metals was a more important factor compared to grain size. The study also indicated that the control of metals pollution from direct influx of domestic wastes and insufficiently treated industrial wastes in the Klang River was an important and desirable way to minimize the detrimental effects of metals.

关键词： heavy metals spatial distribution surface sediment anthropogenic assessment

Effect of Synthesis Technique and Carbonate Content on the Crystallinity and Morphology of Carbonated Hydroxyapatite

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Journal of Materials Science & Technology 2013年第8期29卷 761-764页

作者： Chia Ching Kee Hanafi ismail ahmad Fauzi Mohd Noor School of Materials and Mineral Resources Engineering Engineering CampusUniversiti Sains Malaysia14300 Nibong TebalPenangMalaysia

The syntheses of nanosized carbonated hydroxyapatite （CHA） were performed by comparing dropwise and direct pouring of acetone solution of Ca（NO3）2·4H2O into mixture of （NH4）2HPO4 and NH4HCO3 at room temperature controlled at pH 11. Direct pouring method was later applied to study the increment of carbonate content in syntheses. The as-synthesized powders were characterized by various characterization techniques. The crystallographic results of the produced powders were obtained from X-ray diffraction analysis, whilst the carbonate content in the produced powders was determined by the CHNS/O elemental analyzer. Fourier transform infrared analysis confirmed that the CHA powders formed were B-type. Field emission scanning electron microscopy revealed that the powders were highly agglomerated in nanosized range and hence energy filtered transmission electron microscopy was employed to show elongated particles which decreased with increasing carbonate content.

关键词： Bioceramic Carbonated hydroxyapatite Dropwise Direct pouring

Antimonene-based saturable absorber for a soliton mode-locked and Q-switched fiber laser in the 2 μm wavelength region

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Chinese Physics B 2023年第6期32卷 259-269页

作者： H ahmad B Nizamani M Z Samion N Yusoff M F ismail Photonics Research Centre Universiti Malaya50603 Kuala LumpurMalaysia Physics Department Faculty of ScienceUniversiti Malaya50603 Kuala LumpurMalaysia Distinguished Visiting Professor Universiti Kuala Lumpur British Malaysian Institute(UniKL BMI)Batu 8Jln Sungai Pusu53100SelangorMalaysia

We demonstrate antimonene as a saturable absorber(SA) to generate an ultrafast mode-locked and Q-switched laser in the 2 μm wavelength region. The two antimonene-based SAs were prepared and inserted separately in a thulium–holmiumdoped fiber laser to produce the pulsed laser. Antimonene was coated onto a tapered fiber to generate soliton mode-locked pulses and used in thin-film form for the generation of Q-switched pulses. The mode-locking was stable within a pump power of 267 m W–511 m W, and the laser operated at a central wavelength of 1897.4 nm. The mode-locked laser had a pulse width of 1.3 ps and a repetition rate of 12.6 MHz, with a signal-to-noise ratio of 64 d B. Q-switched laser operation was stable at a wavelength of 1890.1 nm within a pump power of 312 m W–381 m W. With the increase in pump power from 312 m W to 381 m W, the repetition rate increased to a maximum of 56.63 k Hz and the pulse width decreased to a minimum value of 2.85 μs. Wide-range tunability of the Q-switched laser was also realized within the wavelength range of1882 nm–1936 nm.

关键词： mode-locking Q-switched fiber laser optical saturable absorber

Surface-tailoring chlorine resistant materials and strategies for polyamide thin film composite reverse osmosis membranes

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Frontiers of Chemical Science and Engineering 2022年第5期16卷 564-591页

作者： Pei Sean Goh Kar Chun Wong Tuck Whye Wong ahmad Fauzi ismail Advanced Membrane Technology Research Centre(AMTEC) School of Chemical and Energy EngineeringFaculty of EngineeringUniversiti Teknologi Malaysia81310 Johor BahruMalaysia

Polyamide thin film composite membranes have dominated current reverse osmosis market on account of their excellent separation performances compared to the integrally skinned *** their very promising separation performance,chlorine-induced degradation resulted from the susceptibility of polyamide toward chlorine attack has been regarded as the Achilles’s heel of polyamide thin film *** free chlorine species present during chlorine treatment can impair membrane performance through chlorination and depolymerization of the polyamide selective *** material point of view,a chemically stable membrane is crucial for the sustainable application of membrane separation process as it warrants a longer membrane lifespan and reduces the cost involved in membrane *** strategies,particularly those involved membrane material optimization and surface modifications,have been established to address this *** review discusses membrane degradation by free chlorine attack and its correlation with the surface chemistry of *** advancement in the development of chlorine resistant polyamide thin film composite membranes is reviewed based on the state-of-the-art surface modifications and tailoring approaches which include the in situ and postfabrication membrane modifications using a broad range of functional *** challenges and future directions in this field are also highlighted.

关键词： reverse osmosis polyamide thin film composite membranes chlorine resistance surface modification

Optically Modulated Tunable O-Band Praseodymium-Doped Fluoride Fiber Laser Utilizing Multi-Walled Carbon Nanotube Saturable Absorber

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Chinese Physics Letters 2019年第10期36卷 32-35页

作者： H.ahmad M.F.ismail S.N.Aidit Photonics Research Center University of MalayaKuala Lumpur 50603Malaysia Physics Department Faculty of ScienceUniversity of Malaya50603 Kuala LumpurMalaysia

A tunable and optically modulated fiber laser utilizing a multi-walled carbon nanotube based saturable absorber is demonstrated for operation in the O-band region.A praseodymium-doped fluoride fiber is used as the gain medium and the system is capable of generating modulated outputs at 1300 *** output is observed at pump powers of 511 mW and above,with repetition rates and pulse widths that can be tuned from 41 kHz and 3.4μs to 48 kHz and 2.4μs,respectively,at the maximum pump power available.A maximum average output power of 100μW with a corresponding single pulse energy of 2.1 nJ is measured,while the tunability of the proposed laser is from 1290 nm to 1308 *** output is stable,with peak power fluctuations of^4 dB from the average value.

关键词： pump fiber Optically

A Q-Switched Erbium-Doped Fiber Laser with a Carbon Nanotube Based Saturable Absorber

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Chinese Physics Letters 2012年第11期29卷 67-69页

作者： S.W.Harun M.A.ismail F.ahmad M.F.ismail R.M.Nor N.R.Zulkepely H.ahmad Department of Electrical Engineering University of Malaya 50603 Kuala LumpurMalaysia Photonics Research Center Department of PhysicsUniversity of Malaya50603 Kuala LumpurMalaysia Department of Physics University of Malaya50603 Kuala LumpurMalaysia

We demonstrate a simple,compact and low cost Q-switched erbium-doped fiber laser(EDFL)using single-wall carbon nanotubes(CNTs)as a saturable absorber for possible applications in metrology,sensing,and medical *** EDFL operates at around 1560 nm with repetition rates of 16.1 kHz and 6.4 kHz with saturable absorbers SA1 and SA2 at a pump power of 120 *** absorbers are constructed by optically driven deposition and normal deposition *** is observed that the optical deposition method produces a Q-switched EDFL with a lower threshold of 70 mW and better Q-switching performance compared to that of the normal deposition *** EDFL also has pulse energy of 90.3 nJ and pulse width of 11.6μs at 120 mW pump power.

关键词： pump switched Erbium

Heavy Metal Concentrations in Sediment and Intertidal Gastropod Nerita lineata from Two Opposing Sites in the Straits of Malacca

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湿地科学 2008年第3期6卷 411-421页

作者： Bintal Amin ahmad ismail Chee Kong Yap Department of Biology Faculty of Science University Putra Malaysia UPM43400 Serdang Selangor Malaysia Department of Marine Science Faculty of Fisheries and Marine Science University of Riau Pekanbaru 28293 Indonesia

The concentrations of Cd,Cu,Pb,Zn,Ni and Fe were determined in the surface sediment and marine gastropod Nerita lineata collected in May 2005 from the intertidal zone of Dumai,Sumatera,Indonesia and Johor,Peninsular *** results showed that metal concentrations in sediment and the soft tissue of *** varied at different sampling *** heavy metal concentrations were 0.92 μg/g(Cd);6.40 μg/g(Cu);32.77 μg/g(Pb);54.41 μg/g(Zn);11.56 μg/g(Ni) and 2.97%(Fe) in sediment from Dumai and 1.15 μg/g(Cd);26.73 μg/g(Cu);53.45 μg/g(Pb);130.77 μg/g(Zn);20.79 μg/g(Ni) and 2.72%(Fe) in sediment from *** of metals in gastropod *** were 0.71 μg/g(Cd);15.16 μg/g(Cu);9.35 μg/g(Pb);94.69 μg/g(Zn);5.08 μg/g(Ni) and 397.97 μg/g(Fe) in samples from Dumai and 1.24 μg/g(Cd);18.02 μg/g(Cu);19.75 μg/g(Pb);95.09 μg/g(Zn);5.57 μg/g(Ni) and 473.56 μg/g(Fe) in samples from *** they were not statistically significant(p>0.05),heavy metal concentrations in *** were correlated with the concentrations of respective metals in sediment in both samples from Dumai and *** general,samples of sediment and gastropod from Johor accumulated significantly higher heavy metal concentrations when compared to samples from Dumai(p<0.05).Higher concentrations of metals were recorded in samples collected from the stations close to the industrial and anthropogenic activities in both Dumai and Johor ***,most of the concentrations were still comparable to the previous reported studies from other geographical areas.

关键词：重金属腹足动物马六甲海峡沉积物