Characterization of mixed plastic wastes as a potential renewable energy resource

The management of waste materials is a problem worldwide. Incineration technology to burn all kind of wastes and reduce them to much smaller volume i.e. ashes and gas emission is not accepted in Malaysia due to public concern on dioxin and furan emission to the environment. In this study, the characteristics of flue gas emission from various kinds of plastic wastes as well as the calorific value were investigated. HDPE, LDPE, PS, PVC, PP and PET were incinerated in a furnace at temperature 850- 900°C to imitate the thermal incineration process, and the emission from the burning process was found to contain CO 2 , CO, SO 2 , NO, NO 2 , NO x and Cl 2 . Then, each plastic wastes were combusted in a bomb calorimeter to analyze the calorific value. However, when the plastic wastes were mixed with the ratio of 1:1:1:1:1:1 and combusted in the bomb calorimeter, the calorific value was found to be 45.54 MJ/kg, much higher than biomass fuels with the range of 14.0 - 18.4 MJ/kg and similar range with LPG, gasoline and fuel oil. Therefore, a new technology should be invented to recover this waste and convert them into value-added energy

Controlled-release fertilizers: advances and challenges

Controlled- release fertilizers (CRFs) offer an excellent option to improve nutrients uptake by plants and reduce the environmental hazards due to excess release of chemicals. Polymer-coated fertilizers, compared to the other types of CRF, are by far the most intensively researched topic because of their great characteristics. Polymer-coated fertilizers, which are less sensitive to the soil and environmental factors, offer superior control over nutrients release for plants uptake. In recent years, the art has mainly focused on the design of biodegradable polymer-based coating for fertilizers considering the effective control on nutrient release. This review covers the basic information about CRFs with an emphasis on the development of polymer-coated fertilizers. Topics that are discussed herewith include materials and methods utilized for coated fertilizer, particularly polymer-coated fertilizers, manufacturing and related issues. The large market potential for fertilizer using necessitates more studies for development and commercial production of polymer-coated fertilizers

Catalytic pyrolysis and a pyrolysis kinetic study of shredded printed circuit board for fuel recovery

Scrap printed circuit boards (PCBs) are the most abundant wastes that can be found in the landfills in Malaysia and this disposal certainly poses serious detrimental to the environment. This research aims to investigate optimum temperature for pyrolyzing waste PCBs, find out the best catalyst to be used in accelerating PCBs’ pyrolysis, select suitable ratio of catalyst to PCBs for higher oil yield and examine kinetics pyrolysis of the waste PCBs’ decomposition. Operating temperatures ranged from 200 to 350 ˚C of PCB’s pyrolysis were conducted with the optimum temperature obtained was 275 ˚C. Fluid cata-lytic cracking (FCC) catalyst, zeolite socony mobil-5 (ZSM-5), H-Y-type zeolite and dolomite were used to accelerate PCB’s pyrolysis at 275 ˚C and FCC was identified as the best catalyst to be used. Differ-ent ratios of FCC to waste PCBs such as 10:90, 20:80, 30:70, 40:60 and 50:50 were applied in the pyro-lysis at 275 ˚C and ratio of 10:90 was selected as the suitable ratio to be utilized for maximum yield. The kinetic study was done through thermogravimetric analysis on waste PCBs under various heating rates and different particle sizes. The GC-MS analysis revealed that compounds detected in the pyro-oil have the potential to be used as fuel

Recovery of heavy metals from spent etching waste solution of printed circuit board (PCB) manufacturing

The process of etching is the most crucial part of the work of manufacturing printed circuit boards (PCB). In the etching process by nitric acid, a spent etching waste solution of composition 250 g/L HNO3, 30-40 g/L Cu, 30-40 g/L Sn, 30-40 g/L Pb and 20-25 g/L Fe is produced. High metal concentrations in the spent etching waste solution make it a viable candidate for the recovery of metals. Recovery of metals from spent etching waste solution is a significant concern as the recent growth in production of printed circuit boards has generated a drastic increase of spent etching waste solution each year. This study concerns itself with the recovery of metals from spent etching waste. In this study a dilution was made in order to increase the pH of the solution as spent etching waste solution has high acidity, and the electrowinning method was performed to recover metals from the spent etching waste solution. Glassy carbon and platinum were used as cathode and anode in order to investigate the electrodeposition of metals and cyclic voltammetry investigation suggests that the deposition of metals on glassy carbon electrodes occurs at four different overpotentials mainly at -0.15 V, -0.35 V, -0.45 V and -0.75 V. Microscopy observation demonstrates that there is a deposition of metals by applying the potentials in a set of current-time transient study for a duration of 60 seconds and the metals recovered formed as aggregates

Toxicity immobilization of refinery sludge containing heavy metals via vitrification process

Heavy metals are known to be toxic to human and the environment. Despite the growing of petrochemical and refinery industries, the world is facing problems with the heavy metals contamination from the sludge by the industries. Many methods have been applied to address these issues from the refinery sludge. In this study, stabilization and solidification of refinery sludge containing heavy metals using vitrification method was utilized to solve this problem. The ashing temperature of 550oC was selected in preparing the ash of the dried sludge prior to the vitrification process at 1110oC to 1400oC. After vitrification, all samples were morphologically, thermally and toxically analyzed using Scanning Electron Microscopy, Thermogravimetric Analysis and Toxicity Characteristic Leaching Procedure. The sludge contained high amount of iron and aluminum, followed by some amount of magnesium, gold, arsenic and zinc with some traces of nickel and lead. Results showed that at maximum vitrified temperature of 1400oC, no magnesium, nickel and lead were detected in the sludge and only some traces of other heavy metals with less than 1 ppm. The vitrification method exhibits excellent output in immobilizing the transition metals leading to a reduction in environmental pollution caused by petrochemical and refinery sludge containing heavy metals

Health Effects Associated with Fluoridated Water Sources - A Review of Central Asia.

Water fluoridation is a common practice in different parts of the world, mostly as a means of decontaminating water. It has been used in developed, as well as in developing countries. In recent years however, other countries have minimized, even eliminated its use due to health issues. In Central Asia, usage of fluoride is profoundly extant, thus occasioning the citizens’ exposure to various health risks. An excessive level of fluoride causes various health issues, mostly on dental and skeletal fluorosis which often leads to vulnerabilities in the bones and teeth. Studies also indicate that excessive levels of fluoride have been known to contribute to poor neurological development among children, hip fractures to older adults, as well as osterosclerosis. Moreover, the review has concluded that fluoride contamination in groundwater is very high in India, Pakistan and Sri Lanka. In contrast, fluoride levels are below threshold value of 1.5 mg/L in Bangladesh. Fluorosis cases have been observed in Nepal but available data is quite unsystematic and incomplete, thus rendering them of no statistical significance. In India, districts such as Kerala, Gujrat, Bakresh (West Bengal), Khudra (Orissa), Manikaran (Hima Pradesh), Unkeeher (Mahar) and Tattapani (Chattisgarh) are currently facing a high level of fluoride. In Pakistan, fluoride data of 29 major cities are reviewed and 34% of the cities show fluoride levels with mean value greater than 1.5 mg/L where Lahore and Quetta are having the maximum values of 23.60 mg/L and 24.48 mg/L, respectively. Sri Lankan dry zone is polluted with fluoride having maximum value of 8.00 mg/L. Considering these verities, health authorities urgently need to establish alternative means of water decontamination in order to prevent associated health problems

Supercritical water gasification of empty fruit bunches from oil palm for hydrogen production

Empty fruit bunches (EFBs) from the palm plantation sector are abundant agricultural waste products in Malaysia. Supercritical water gasification (SCWG) is a prominent way to convert high-moisture-content biomass such as EFBs into valuable end products. This investigation is focused on EFB conversion into hydrogen-rich products using SCWG (temperature = 380 °C and pressure ≈ 240 bar). Lignocellulosic model compounds (xylan, cellulose, and lignin) were used to study the degradation patterns and gas compositions under similar reaction conditions. The effect of the EFB/water ratio and the SCWG reaction time on the composition of the product gas was examined. Carbon gasification does not improve with increasing EFB/water ratio as well as with increasing reaction time caused by the thermally stable tar formation during reaction. The hydrogen concentration was found to be increased with reaction time along with raising the EFB/water ratio to 0.3 g (3.75 wt%). In addition, the possibility of using palm oil mill effluent as a reaction medium in comparison to deionized water was analyzed

Multiple use of waste catalysts with and without regeneration for waste polymer cracking

Waste plastics contain a substantial number of valuable chemicals. The wastes from post-consumer as well as from industrial production can be recycled to valuable chemical feedstock, which can be used in refineries and/or petrochemical industries. This chemical recycling process is an ideal approach in recycling the waste for a better environment. Polymer cracking using a laboratory fluidised bed reactor concentrated on the used highly contaminated catalyst, E-Cat 2. Even though E-Cat 2 had low activity due to fewer acid sites, the products yielded were similar with amorphous ASA and were far better than thermal cracking. The high levels of heavy metals, namely nickel and vanadium, deposited during their lifetime as an FCC catalyst, did not greatly affect on the catalyst activity. It was also shown that E-Cat 2 could be used with and without regeneration. Although there was more deactivation when there was no regeneration step, the yield of gases (C2–C7) remained fairly constant. For the first time, these results indicate that “waste” FCC catalyst (E-Cat) is a good candidate for future feedstock recycling of polymer waste. The major benefits of using E-Cat are a low market price, the ability to tolerate reuse and regeneration capacity

Particulate matter dispersion and haze occurrence potential studies at a local palm oil mill.

The emissions from palm oil industry through incineration and open burning are the major sources of air pollutions contribution in Malaysia. The consequence of increasing the particulate concentration, the particulate matter dissolves with vapour and grows into droplets when the humidity exceeds approximately 70% and causing opaque situation known as haze. This work focuses on the dispersion particulate matter from palm oil mill. Gaussian Plume Model from a point source, subject to various atmospheric conditions is used to calculate particulate matter concentration then display the distribution of plume dispersion using geographic information system. Atmospheric Stability, mixing height, wind direction, wind speed, natural and artificial features play an important role in dispersion process. Study on the dispersion of particulate matters and the haze potential are presented as a case study in this paper. The data obtained will be served as the purpose of modeling the transport of particulate matter for obtaining permits and prevention of significant deterioration to the environment

Recent developments in purification of single wall carbon nanotubes

The status of SWNT purification sciences within the last two decades are reviewed. Over the years, the aggressive search for effective and efficient post-synthetic purification technique has given rise to the development of numerous methods. Unfortunately, most of these methods do not possess the potentials of being selective, scalable, nor effective. On the other hand, the mechanisms behind the promising separation methods are yet to be fully understood. For such techniques, it is recommended that interest should now lie more on investigating the underpinning mass transfer kinetics and equilibrium thermodynamics with a view to making them more efficient