A field remediation treatment was carried out to examine the long-term effect of biochar on the immobilisation of metals and the revegetation of a contaminated site in Castleford, UK. The extracted concentrations of nickel (Ni) (II) and zinc (Zn) (II) in the carbonic acid leaching tests were reduced by 83-98% over three years. The extracted Ni (II) and Zn (II) concentrations three years after the treatment were comparable to a cement-based treatment study carried out in a parallel manner on the same site. The sequential extraction results indicated that biochar addition (0.5-2%) increased the residue fractions of Ni (II) (from 51% to 61-66%) and Zn (II) (from 7% to 27-35%) in the soils through competitive sorption, which may have resulted in the reduction of leachabilities of Ni (II) (from 0.35% to 0.12-0.15%) and Zn (II) (from 0.12% to 0.01%) in the plots with biochar compared with that without biochar three years after the treatment. The germination of grass in the plots on site failed. Further laboratory pot study suggested that larger amounts of biochar (5% or more) and compost (5% or more) were needed for the success of revegetation on this site. This study suggests the effectiveness and potential of biochar application in immobilising heavy metals in contaminated site in the long term.
It has become a great challenge in the modern radiation treatment to ensure the accuracy of treatment delivery in electron beam therapy. Tissue inhomogeneity has become one of the factors for accurate dose calculation, and this requires complex algorithm calculation like Monte Carlo (MC). On the other hand, computed tomography (CT) images used in treatment planning system need to be trustful as they are the input in radiotherapy treatment. However, with the presence of metal amalgam in treatment volume, the CT images input showed prominent streak artefact, thus, contributed sources of error. Hence, metal amalgam phantom often creates streak artifacts, which cause an error in the dose calculation. Thus, a streak artifact reduction technique was applied to correct the images, and as a result, better images were observed in terms of structure delineation and density assigning. Furthermore, the amalgam density data were corrected to provide amalgam voxel with accurate density value. As for the errors of dose uncertainties due to metal amalgam, they were reduced from 46% to as low as 2% at d80 (depth of the 80% dose beyond Zmax) using the presented strategies. Considering the number of vital and radiosensitive organs in the head and the neck regions, this correction strategy is suggested in reducing calculation uncertainties through MC calculation.
A highly active and stable nano structured Pt/Mg1-xNixO catalysts was developed by a simple co-precipitation method. The obtained Pt/Mg1-xNixO catalyst exhibited cubic structure nanocatalyst with a size of 50-80 nm and realized CH4 and CO2 conversions as high as 98% at 900°C with excellent stability in the dry reforming of methane. The characterization of catalyst was performed using various kinds of analytical techniques including XRD, BET, XRF, TPR-H2, TGA, TEM, FESEM, FT-IR, and XPS analyses. Characterization of spent catalyst further confirms that Pt/Mg1-xNixO catalyst has high coke-resistance for dry reforming. Thus, the catalyst demonstrated in this study, offers a promising catalyst for resolving the dilemma between dispersion and reducibility of supported metal, as well as activity and stability during high temperature reactions.
Phaseonium is a three-level Λ quantum system, in which a coherent microwave and an optical control (pump) beams can be used to actively modulate the dielectric response. Here we propose a new metamaterial structure comprising of a periodic array of triangular phaseonium metamolecules arranged as a trefoil. We present a computational study of the spatial distribution of magnetic and electric fields of the probe light and the corresponding transmission and reflection, for various parameters of the optical and microwave beams. For specific values of the probing frequencies and control fields, the phaseonium can display either metallic or dielectric optical response. We find that, in the metallic regime, the phaseonium metamaterial structure supports extremely large transmission, with optical amplification at large enough intensity of the microwave thanks to strong surface plasmon coupling; while, in the dielectric regime without microwave excitation, the transmission bandwidth can be tuned by varying the control beam intensity. Implementation of such phaseonium metamaterial structure in solid-state systems, such as patterned crystals doped with rare-earth elements or dielectric matrices embedded with quantum dots, could enable a new class of actively tunable quantum metamaterials.
Chemical forms of copper and lead in river water of the Linggi River Basin have been fractionated into ASV labile, moderately labile, slowly labile, and inert metal species, based on a previously proposed scheme. Free (hydrated) metal ions were identified by a potentiometric method using an ion selective electrode. Speciation results showed that the soluble copper and lead species occurred mainly in the moderately labile and slowly labile fractions. The speciation results are primarily interpreted in terms of organic interaction due to agricultural based and light industries, and urban discharges. The measured metal complexing capacity (MCC) of the samples reveals consistency of the results with the nature of the discharge. MCC correlates reasonably well with the value from the permanganate test on the river water. In general, the speciation pattern was found to be consistent with the findings of other workers.
The mechanical properties of electrospun polyacrylonitrile (PAN)-based membranes for ultrafiltration, such as oil-water separation and heavy metals from water, are often characterised in the dry state but little is known about the membrane properties in the hydrated state. This dataset comprised mechanical properties and structure-related properties of electrospun PAN-based membranes. The mechanical dataset described the yield strength and strain, stiffness, resilience energy, fracture strength, strain at fracture and fracture toughness of electrospun neat PAN and halloysite nanotube (HNT) reinforced PAN membranes in both hydrated and dry states. The data related to the hydrated state were derived from direct measurements of the mechanical properties of the PAN-based membrane using a novel environmental micromechanical tester. The structure-related dataset comprised electron micrographs and quantitative measurements (fibre diameter and pore diameter) derived from the micrographs. For further interpretation and discussion of the dataset, the reader is referred to the research data article, "Direct measurement of the elasticity and fracture properties of electrospun polyacrylonitrile/halloysite fibrous mesh in water" (Govindasamy et al., 2014).
It is important to monitor the concentration of toxic metals in the Sungai Kuantan as it serves many communities in terms of domestic, fisheries and agriculture purpose. In order to determine the distributions of dissolved and particulate As and Hg in Sungai Kuantan and evaluate its changes temporally and spatially, water samples were collected from the surface and bottom layers in a grid of 9 stations from estuary towards the upstream of Sungai Kuantan from May 2012 till October 2012. The dissolved metals were pre-concentrated using Chelex-100 while particulate metals were digested using Teflon bomb and subsequently were analyzed using ICP-MS. Dissolved As ranging from 4.650 to 36.894 µg L-1 while dissolved Hg ranging from BDL to 0.011 µg L-1. Particulate As and Hg varied from 0.650 to 86.087 mg L-1 and BDL to 5.873 mg L-1, respectively. Higher concentration of the dissolved elements were found mainly in October 2012 and particulate elements concentration mostly higher in May 2012. The source of the studied metals in the river may be the run-off from the effluent discharges and other natural sources. The toxic elements studied in Sungai Kuantan waters were still below the Interim Marine Water Quality Standard (INWQS) permissible limits.
Increased disposal of heavy metals, including lead (II) (Pb(II)) into the environment calls for a reliable and sustainable solution. In this study, nano-sized biochar from sago activated sludge was proposed for the removal of Pb(II). Sago activated sludge was pyrolysed in a tube furnace followed by a chemical activation to yield nano-sized particles ranging from 45 to 75 nm. The nano-sized biochar obtained was characterised and the influence of pH (2 – 10), initial Pb(II) concentration (1 – 5 mg/L), contact time (30 – 90 mins) and adsorbent dosage (0.1 – 0.5 g) was investigated in a batch adsorption study. Response surface methodology (RSM) approach with central composite design (CCD) was used as statistical tools to optimize the adsorption process by relating the mutual interactions among all studied variables. Characterisation of the prepared adsorbent showed that large surface area was observed on sludge activated carbon (78.863 m2 /g) compared with sludge biochar (8.044 m2 /g) and sludge biomass (1.303 m2 /g). The batch adsorption best fitted the Langmuir isotherm (maximum adsorption capacity, Q0 = 3.202 × 10-3 mg/g, R-squared value = 0.9308). The RSM indicated that the optimum Pb(II) removal (99.87%) was at 0.5 g of adsorbent, 5 mg/L initial concentration and 30 min contact time. This study is significant because utilisation of sago effluent will reduce sago manufacturing waste by conversion into a value-added product as adsorbent to adsorb Pb(II) in wastewater.
Reinforced aluminum composites are the basic class of materials for aviation and transport industries. The machinability of these composites is still an issue due to the presence of hard fillers. The current research is aimed to investigate the drilling topographies of AA7075/TiB2 composites. The samples were prepared with 0, 3, 6, 9 and 12 wt.% of fillers and experiments were conducted by varying the cutting speed, feed, depth of cut and tool nose radius. The machining forces and surface topographies, the structure of the cutting tool and chip patterns were examined. The maximum cutting force was recorded upon increase in cutting speed because of thermal softening, loss of strength discontinuity and reduction of the built-up-edge. The increased plastic deformation with higher cutting speed resulted in the excess metal chip. In addition, the increase in cutting speed improved the surface roughness due to decrease in material movement. The cutting force was decreased upon high loading of TiB2 due to the deterioration of chips caused by fillers. Further introduction of TiB2 particles above 12 wt.% weakened the composite; however, due to the impact of the microcutting action of the fillers, the surface roughness was improved.
The crystal and mol-ecular structures of the two title organotin di-thio-carbamate compounds, [Sn(C4H9)2(C7H14NO2S2)2], (I), and [Sn(C6H5)3(C5H10NOS2)], (II), are described. Both structures feature asymmetrically bound di-thio-carbamate ligands leading to a skew-trapezoidal bipyramidal geometry for the metal atom in (I) and a distorted tetra-hedral geometry in (II). The complete mol-ecule of (I) is generated by a crystallographic twofold axis (Sn site symmetry 2). In the crystal of (I), mol-ecules self-assemble into a supra-molecular array parallel to (10-1) via methyl-ene-C-H⋯O(meth-oxy) inter-actions. In the crystal of (II), supra-molecular dimers are formed via pairs of weak phenyl-C-H⋯π(phen-yl) contacts. In each of (I) and (II), the specified assemblies connect into a three-dimensional architecture without directional inter-actions between them. Hirshfeld surface analyses confirm the importance of H⋯H contacts in the mol-ecular packing of each of (I) and (II), and in the case of (I), highlight the importance of short meth-oxy-H⋯H(but-yl) contacts between layers.
Heavy metals with high chemical activity from sludge and waste release, agriculture, and
mining activity are a major concern. They should be carefully managed before reaching the
main water bodies. Excessive exposure to heavy metal may cause toxic effect to any types of
organism from the biomolecular to the physiological level, and ultimately cause death. Monitoring is the best technique to ensure the safety of our environment before a rehabilitation is
needed. Nowadays, enzyme-based biosensors are utilised in biomonitoring programmes as
this technique allows for a real-time detection and rapid result. It is also inexpensive and easy
to handle. Enzyme-based biosensors are an alternative for the preliminary screening of
contamination before a secondary screening is performed using high-performance technology.
This review highlights the current knowledge on enzyme-based biosensors, focusing on
cholinesterase for toxic metal detection in the environment.
A simple and low-cost Fiber Optic Displacement Sensor (FODS) using reflective intensity modulation technique was developed to analyze various concentrations of Pb2+, a compound classified under heavy metal ions. Lead is harmful to the environment including to human but is used in the cosmetic field for beauty without realizing and considering the hazardousness of lead as it would cause a long-term effect. Therefore, a feasible way has been identified in this study to demonstrate the level of Pb2+ concentration in cosmetics field by employing the theory of modulation of intensity as a function of displacement sensor. The permissible limit according to Malaysian Cosmetics Guidelines and ASEAN Cosmetic Directive was 20 ppm. The concentration sensor’s system exhibits 0.0018 V/ppm sensitivity with a linearity of 96% and 94% respectively, for both peaks. Meanwhile, the sensitivity was 0.034 V/ppm for the first peak and 27.72 V/ppm for the second peak, with slope linearity of more than 96% for surface tension parameter. The credibility of these optical response curves data might be useful, especially in the cosmetic’s industrial application.
Carbon monoxide (CO) is the most harmful pollutant in the air, causing environmental issues and adversely affecting humans and the vegetation and then raises global warming indirectly. CO oxidation is one of the most effective methods of reducing CO by converting it into carbon dioxide (CO2) using a suitable catalytic system, due to its simplicity and great value for pollution control. The CO oxidation reaction has been widely studied in various applications, including proton-exchange membrane fuel cell technology and catalytic converters. CO oxidation has also been of great academic interest over the last few decades as a model reaction. Many review studies have been produced on catalysts development for CO oxidation, emphasizing noble metal catalysts, the configuration of catalysts, process parameter influence, and the deactivation of catalysts. Nevertheless, there is still some gap in a state of the art knowledge devoted exclusively to synergistic interactions between catalytic activity and physicochemical properties. In an effort to fill this gap, this analysis updates and clarifies innovations for various latest developed catalytic CO oxidation systems with contemporary evaluation and the synergistic relationship between oxygen vacancies, strong metal-support interaction, particle size, metal dispersion, chemical composition acidity/basicity, reducibility, porosity, and surface area. This review study is useful for environmentalists, scientists, and experts working on mitigating the harmful effects of CO on both academic and commercial levels in the research and development sectors.
In the recent decades, development of new and innovative technology resulted in a very high amount of effluents. Industrial wastewaters originating from various industries contribute as a major source of water pollution. The pollutants in the wastewater include organic and inorganic pollutants, heavy metals, and non-disintegrating materials. This pollutant poses a severe threat to the environment. Therefore, novel and innovative methods and technologies need to adapt for their removal. Recent years saw nanomaterials as a potential candidate for pollutants removal. Nowadays, a range of cost-effective nanomaterials are available with unique properties. In this context, nano-absorbents are excellent materials. Heavy metal contamination is widespread in underground and surface waters. Recently, various studies focused on the removal of heavy metals. The presented review article here focused on removal of contaminants originated from industrial wastewater utilizing nanomaterials.
Research performed in four fishing villages in the district of Semporna, Sabah revealed a total 55 species of intertidal marine organisms were being utilized as source of food. Specimens were collected during low tides by accompanying the local people. The villages involved were Kg. Panjl, Kg. Bangau-Bangau (a resettlement area for the Sea Bajaus), Kg. Air and Kg. Kebimbangan. Idenfication of species was based on illustration described in texts as well as comparing with the collections in local muziums. Local name for each species was obtained from the population living within the vicinity of coastal areas. The total number of species collected, however, differed among the villages. Chemical analysis based on A.O.A.C of several species indicated variations in nutritive values and trace metals as well as lead content.
Heavy metal accumulation and depuration may alter the effectiveness of Meretrix meretrix as a biomonitoring organism for water quality assessment. Therefore, this study was conducted to evaluate the effects of heavy metal accumulation and depuration on M. meretrix, by immersing it in Copper (Cu), Zinc (Zn), and Lead (Pb)
solutions under laboratory conditions. The results showed that M. meretrix is able to accumulate Cu, Zn, and Pb at the rate of 0.99, 21.80, and 0.57 μg/g per day, respectively, and depurates at the rate of 0.42, 23.55, and 1.01 μg/g per day, respectively. These results indicate that M. meretrix could be effectively used as a biomonitoring organism for Cu because the accumulation rate is significantly (p ≤ 0.05) higher than the depuration rate. However, this was not the case for Zn because the accumulation rate was almost similar to the depuration rate, while for Pb, accumulation or depuration did not occur in M. meretrix.
This study was carried out to compare the rate of burn wound healing with the applications of the latex of Carica papaya Linn. (papaya) or of silver sulfadiazine cream (SSD). Partial and full thickness burn wound (2 cm x 2 cm) was induced on the dorsal part of anaesthetized rats by using heated metal plates. The rats were divided into three groups, i.e. untreated group and groups treated daily with SSD and papaya latex, respectively. A digital camera was used to take photographs of the burn wounds daily to monitor their healing. It was found that there was no significant difference in the healing time of papaya latex treated group compared to the SSD treated group. Papaya latex contained digestive enzymes which might clean burn wounds but might also cause wound bleeding in a few rats of the papaya latex group.
The joining of ceramic-metal could be done through a few techniques: brazing, diffusion bonding, friction welding etc. However, the mechanism of ceramic-metal joining was still not properly understood. In this study, alumina rod was bonded to mild steel rod via friction welding technique by using Al 1100 sheet as interlayer. The diameter of the rods was 10 mm. Friction pressure of 20 MPa and forging pressure of 40 MPa were used. Rotational speeds were maintained at 900 rpm and friction times of 2 to 20 seconds were applied. The joining strength was determined through four point bending test. The maximum bending strength, 240 MPa was obtained at the friction times of 20 seconds. Under optical microscope and SEM observation, the deformation of the aluminum interface was clearly obtained. Mechanical interlocking and close contact between the aluminaaluminum and aluminum-mild steel were observed at magnifications of 3000X. The strength of alumina-steel bonding is much dependent on the wettability of the alumina surface by the molten aluminum and the existing of mechanical interlocking between interlayer and sample materials.
Self-propagating high-temperature synthesis (SHS) of powder compacts is a novel processing technique being developed as a route for the production of engineering ceramics and other advanced materials. The process, which is also referred to as combustion synthesis, provides energy- and cost-saving advantages over the more conventional processing routes for these materials. In the case of titanium or titanium alloy materials, prior researches employed powder metallurgy technology for preparing metal matrix composites, MMCs and laminated structures through the use of fine powders of an inert phase or phases (TiC, TiN, TiB and TiB2B ) dispersed in Ti or Ti alloy powders. The present research relates to manufacture of titanium-ceramic composites that are synthesized by combustion synthesis (SHS) and retains a multilayered composite microstructure comprising one or more titanium-based layers and one ceramic titanium carbide layers.
Aluminium titanate (AT) (Al2TiO5) is a promising engineering material because of its low thermal expansion coefficient, excellent thermal shock resistance, good refractoriness and non-wetting with most metals. Functionally graded material (FGM) is generally a particulate composite with continuously varying volume fractions. FGMs are alternative materials for dental implants, building materials and ballistic protection. It has been of great interest to future engines, internal combustion engines, metal cutting and other high temperature engineering application. There has been a demand for an adequate disc brake that requires less maintenance in the automotive manufacturing industry. FGM, the next evolution of layered structure, consists of graded compositions that are dispersed across the ceramic which produces a gradual improvement in the properties across the ceramic at a steady pace.