Amnorzahira Amir

Enhanced reductive dechlorination of tetrachloroethene during reduction of cobalamin (III) by nano-mackinawite

We demonstrated adsorption and reduction of cobalamin(III) (Co(III)) on nano-mackinawite (nFeS) surface and their impact on reductive dechlorination of tetrachloroethene (PCE). The adsorption of Co(III) on the nFeS surface followed Langmuir isotherm and the reduction of Co(III) provided different reactive surface chemical species on nFeS surface. Content of Fe(2+)S on nFeS surface decreased (45.9-14.5%) as Fe(2+)S was oxidized to Fe(3+)S and Fe(3+)O coupled with the surface reduction of Co(III) to cobalamin(II) (Co(II)). S(2-) and S(n)(2-) contents on the nFeS surface also decreased by 48.5% and 82.3%, respectively during the formation of sulfidecobalamin(II) (≡S(2-)Co(II)) by the reactive surface sulfur. PCE was fully degraded in nFeSCo(III) suspension at pH 8.3 in 120 h. The dechlorination kinetic rate constant of PCE in the nFeSCo(III) suspension (k(FeSCo(III))=0.188±0.003 h(-1)) was 145 times greater than that in nFeS suspension, showing a potential role of ≡S(2-)Co(II) as an electron transfer mediator to shuttle electrons for the enhanced reductive dechlorination. PCE was transformed to acetylene and 1,3-butadiene as major products via reductive β-elimination and isomerization reactions, respectively. The experimental findings can provide basic knowledge to identify a reaction mechanism for the enhanced reductive dechlorination of chlorinated organic by biogeochemical reactions possibly observed in natural reducing environments.

Removal of Zinc by Nano-scale Zero Valent Iron in Groundwater

Groundwater has long been identified as potential alternative of clean water supply due to its reliable quantity. However, pollution of groundwater due to anthropogenic factor still remains a challenging issue. To date, nanoscale zero valent iron (nZVI) has received great attention for its capability to treat various contaminants including chlorinated organics and metals. This study investigate Zinc (Zn) removal in aqueous solution by nanoscale zerovalent iron (nZVI). The characteristics study of the synthesized nZVI particles were investigated by its particle size and surface morphology using Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). SEM and TEM analyses verified that the particles size of synthesized nZVI were 71nm (< 100 nm). Structure of nZVI congragate to each other and a thin layer of oxide layer formed on the outer part of the nZVI particle. In the batch study, removal kinetic of Zn increased from 0.14 to 0.18 mins-1 as the concentration of Zn increased from 0.1 to 0.5 ppm. However, the removal kinetic decreased from 0.162 to 0.148 mins-1 as the amount of nZVI was increased from 0.25 mg/L to 2.50 mg/L. At pH 7, removal kinetic reached 0.157 mins-1. However as the pH suspension decreases to pH 6.5, the removal kinetics decreased significantly to 0.144 mins-1. The same behaviour was observed at pH 9 where the removal kinetics was decreased to 0.117 mins-1. Removal kinetic of Zn significantly decreased at basic condition due to the formation of passivation layer which decreased the density of reactive surface area (e.g., Fe0 and Fe2+) on the surface of nZVI. Experimental results from this study can provide basic knowledge of effectiveness of Zn removal mechanisms by nZVI at different environment conditions and provide potential remediation technology for the treatment of toxic heavy metals in groundwater.

Removal of Lead by Nanoscale Zerovalent Iron in Surfacewater

This study investigates removal of Lead (Pb2+) by nanoscale zerovalent iron (nZVI) in surface water under various environmental conditions. Particles size of synthesized nZVI was in the range of 35.57–49.62 nm (<100 nm) and congregated to each other. Remarkable removal of Pb2+ (k = 0.30 min−1) was observed in nZVI suspension (0.32 g/L) in 10 min, while no significant of Pb2+ removal was observed in suspension alone at neutral pH. The removal of Pb2+ was significantly dependent on the suspension pH and concentrations of Pb2+ and nZVI. Percent removal of Pb2+ significantly decreased as the concentrations of Pb2+ increased. Removal efficiency of Pb2+ decreased (49–25 %) as the pH increased from neutral to basic conditions (pH 7–9). As concentration of nZVI increased (0.06–0.10 g/L), the removal efficiency increased approximately 1.67 times (42–70 %). Experimental results from this study provide basic knowledge on the role of nZVI as a reductant to remove Pb2+ in surface water at different environment conditions.

Mn(II) Ions Biosorption from Aqueous Solution using Pleurotus Spent Mushroom Compost under Batch Experiment

The Pleurotus spent mushroom compost was selected as biosorbent to sorption Mn(II) ions. The Mn(II) ions biosorption was investigated under batch experiments. The influences of pH, contact time and initial Mn(II) concentration were also investigated. The optimum Mn(II) ions biosorption was achieved at pH 6, 20 minutes of contact time and 10 mg/L of initial Mn(II) concentration using 1.0 g biosorbent dosage. The Mn(II) ions biosorption experimental data were best described by the Langmuir isotherm model and pseudo-second order kinetic model. As conclusion, the Pleurotus spent mushroom compost can be used to sorption the Mn(II) ions from the aqueous solution.

Study of Fe(II) Biosorption Using Pleurotus Spent Mushroom Compost in a Fixed-Bed Column

The potential use of Pleurotus spent mushroom compost as a biosorbent for Fe (II) removal from aqueous solutions was investigated. The experiments were conducted in a fixed-bed column to investigate the influence of various parameters such as flow rate, bed depth and initial concentration on the biosorption of Fe (II). The results of breakthrough time, exhaustion time as well as the Fe (II) uptake and percentage of removal are highly influenced by the flow rate, bed depth and the initial Fe (II) concentration. The results demonstrated that the breakthrough time and exhaustion time increased with decreases in flow rate and initial Fe (II) concentration. Conversely, the breakthrough and exhaustion time decreased as the bed depth decreases.

Detection of Polycyclic Aromatic Hydrocarbons (PAHs) in Municipal Wastewater Treatment Plant at Klang Valley

Two different types of wastewater treatments are explained in this chapter. All the six parameters were under the standards A and B compared to EQA 1974. However, it does not confirm that PAHs were treated and not exist in the effluent. The possibilities of a low-ring of polycyclic aromatic hydrocarbons (PAHs) exist in both municipal wastewater were analyzed using gas chromatography–mass spectrometry (GC-MS). The main PAHs exist are naphthalene, phenanthrene, and anthracene. 9,9′-Biphenanthrene, octacosahydro, phenanthrene, 4,5-dimethyl, anthracene, anthracene, 9-cyclohexyltetradecaydro, 2-ethyl, phenanthrene, 9-ethyl, phenanthrene, 9,10-bis (chloromethyl) were detected. Municipal wastewater sample B contained 9,9′-Biphenanthrene, octacosahydro, anthracene and phenanthrene, 4,5-dimethyl, 2(3H)-Naphthalenone and 1,8,9-trihydroxyanthracene. The sources of these compounds may come from tobacco smoke and ingestion of food contaminated with combustion products, dandruff shampoo, detergents, and mothballs. This toxic compound may cause skin irritation and lower body’s system for fighting disease after both short- and long-term exposure. ​Wastewater that contains PAHs required an effective technology in order to completely remove in the system. This study also provides baseline assessment on the existence PAHs in the municipal wastewater treatment plan and possible activities that released PAHs into wastewater.

Removal of Hexavalent Chromium by Magnetite in Groundwater

Hexavalent chromium (Cr6+) is a toxic contaminant that contaminates soil and groundwater and is listed as a priority contaminant. This study investigates removal of Cr6+ by magnetite (Fe3O4) in groundwater. The removal of Cr+6 is significantly dependent on the amount of reactive surface area on the surface of Fe3O4. Approximately 20 % of Cr+6 was removed by Fe3O4 in 20 min of reaction time. The removal of Cr+6 increases by 2 times as the concentration of Fe3O4 increases from 0.1 to 0.5 g. Results from this study provide a basic understanding of Cr6+ by Fe3O4 and can be suggested to be implemented at the real site contaminated with Cr+6.

Study of Heavy Metals Concentration from Different Steel-Based Industries Effluents

A study was conducted to identify and analyze heavy metals concentration in the steel industries effluents. The industrial effluents were collected from three different steel based factories in Shah Alam, Selangor, Malaysia. For each factory, the effluent samples were collected at two different points for determination of heavy metals concentration. Heavy metal concentrations were analyzed using Inductively Coupled Plasma Atomic Emission Spectroscopy. The results showed heavy metals (Cr, Fe, Mn, Ni and Zn) in the untreated effluent at Factory C have the highest concentrations compared with other steel-based factories. Also, the concentration of Fe, Mn and Ni in the treated effluent from Factory C were found above the permissible limits.

Pollutants Removal in Storm Water Pond

Storm water ponds are a common feature of the urban landscape in many countries with storm water management. Built to control the impacts of urbanisation in the form of increased runoff flows, volumes and pollution loads, storm water ponds are exposed to strong anthropogenic pressures. This paper presents the ability of storm water pond to self-purify the runoff water. In this study, selected chemical parameters (pH, BOD5, COD, zinc and lead) and physical parameters (turbidity, colour and suspended solid) of the inlet and outlet runoff waters were measured. From this study, the percentage of reduction in BOD5, COD, zinc and lead were 15, 16, 15 and 8 % respectively. The percentage of reduction in turbidity, colour and suspended solid was 11, 19 and 11 % respectively. Storm water pond has a greater capacity to remove soluble nutrients and biochemical compounds from storm water runoff. Overall, storm water pond has the ability to purify water contained.

Removal of Nitrate by Eichhornia crassipes sp. in Landfill Leachate

Removal of nitrate (NO3 −) by Eichhornia crassipes sp. in landfill leachate was investigated in this study. Characterization study on the leachates collected from Jeram Sanitary Landfill (young landfill) and Ayer Hitam Sanitary Landfill (old landfill) show interesting pattern in concentration of NO3 − . This study shows that concentration of NO3 − was higher in young landfill (27 mg/L) than that in old landfill (9 mg/L) at neutral pH. Finding of these results indicate that Eichhornia crassipes sp. has the ability to remove NO3 − at different concentrations in three days. Approximately 69 and 64 % of NO3 − that present in leachate from young landfill was removed in sample without dilution and 50 % dilution, respectively. While approximately 28 and 33.6 % of NO3 − present in leachate collected from old landfill was removed in similar dilution samples. This study is very significant to identify the capability of Eichhornia crassipes sp. to remove NO3 − in landfill leachate.