Surface Modification Effects on CNTs Adsorption of Methylene Blue and Phenol

This study compares the adsorption capacity of modified CNTs using acid and heat treatment. The CNTs were synthesized from acetone and ethanol as carbon sources, using floating catalyst chemical vapor deposition (FC-CVD) method. energy-dispersive X-ray spectroscopy (EDX) and Boehm method revealed the existence of oxygen functional group on the surface of CNTs. Heat modification increases the adsorption capacity of as-synthesized CNTs for methylene blue (MB) and phenol by approximately 76% and 50%, respectively. However, acid modification decreases the adsorption capacity. The equilibrium adsorption data fitted the Redlich-Peterson isotherm. For the adsorption kinetic study, the experimental data obeyed the pseudo-second-order model. Both modifications methods reduced the surface area and pore volume. The studies show that the adsorption of MB and phenol onto modified CNTs is much more influenced by their surface functional group than their surface area and pore volume

The influences of melt-compounding parameters on the tensile properties of low filler loading of untreated-MWCNTs polypropylene (PP) nanocomposites.

This study is to investigate the effects of addition self synthesised multi-walled carbon nanotubes (MWCNTs), to the final properties of polypropylene (PP) matrix nanocomposites. The influences of melt blending parameters were evaluated, where the interrelationship between the temperatures of compounding and roller rotor speed of sh earing blade parameter, to the tensile properties of fabricated composites were studied. MWCNT was synthesised in the laboratory scale; by using the floating catalyst chemical vapour deposition(FC-CVD) method. Pre-compounding work is begun with de-agglomeration of MWCNT which carried out by combining the ultrasonication and mechanical stirrer means simultaneously. Carbon nanotubes produced was first verified by using SEM and TEM imaging microscopy t echniques. It was later integrated with the thermoplastic PP matrix, via melt blending process through internally mixing approach. Very low weight percentage of chemically untreated MWCNT (0, 0.25, 0.50, 0.75 & 1.00 wt. %) was added into PP and later was compression moulded to the thin sheet of composites film. Composites were prepared by varying the compounding temperature into three processing temperature namely 165, 175 & 185°C and also into three shearing speed of roller rotor blade, 40, 60 & 80 rpm respectively. Later, it was mechanically tested via tensile testing following the ASTM D-638 standard method. The interrelationship between each parameter of compounding to the mechanical tensile properties was tested. It was shown that, the additional of very low loading of untreated-MWCNT filler content, does give moderate effects on reinforcement to the tensile properties of composite. Different compounding parameter gives significant difference to the pattern of plot which was comparable between each other

Fed batch production of hydrogen from palm oil mill effluent using anaerobic microflora

Anaerobic production of hydrogen from palm oil mill effluent (POME) by microflora was investigated in 5-l bioreactor at 60 °C and pH 5.5. POME sludge was collected from the anaerobic pond of a POME treatment plant at a palm oil mill and used as a source of inocula. A batch reactor was found to yield a total of 4708 ml H2H2/(l POME) and the maximum evolution rate was 454 ml-H2H2/(l POME h). A fed batch process was conducted after 50 h. Two liters of reaction medium was removed and 2 l of fresh POME was added to the reactor every 24 h (15 times). The reproducibility of the fed batch process checked by changing the feeding time every 8 h (10 times). A yield of 2382 ml H2H2/(l POME) and 2419 ml H2H2/(l POME) at maximum evolution rate of 313 ml H2H2/(l POME h) and 436 ml H2H2/(l POME h) were obtained, respectively. Throughout the study, methane gas was not observed in the evolved gas mixture

Biological production of hydrogen from glucose by natural anaerobic microflora

Palm oil mill effluent (POME) sludge, sludge compost from Malaysia and CREST compost from Philippines were collected for the study. The capability of these microflora to produce hydrogen was examined with 500 ml artificial wastewater containing 1% glucose, 0.2% yeast extract and 0.018% magnesium chloride hexahydrate under anaerobic fermentation in a batch culture. The microflora in POME sludge, sludge compost and CREST compost were found to produce significant amounts of hydrogen. The maximum production yield of hydrogen per decomposed glucose was 2.1 mol/mol-glucose at a conversion rate of 0.137 L/(L-medh) at 50°C obtained by sludge compost. All fermentations were carried out without pH control. It was also found that the addition of nitrogen source in the medium caused a change in hydrogen produced. There was no methane gas in the evolved gas

Microfiltration of oxidation pond effluent using single flexible tubular fabric membrane and polyelectrolyte dosage

Membrane separation is an effective wastewater treatment alternative. However, as with all membrane processes, the fouling effect has always been one of the major limiting factors for their usage. Of the current available membrane modules, the tubular configuration is the least affected with fouling because of the relatively large passage. A novel approach of using tubular woven fabric membranes, naturally cheaper to produce, has been studied in treating secondary oxidation pond effluent. The membrane was prepared by sewing two strips of fabric, on both sides. Its tubular configuration is obtained by the flow of aqueous solution through, at an appropriate pressure and flow rate. Thus, there is no need for housing, as with most available tubular membranes in the market. Its flexible character also facilitates external mechanical cleansing. The fabric has pore sizes ranging between 20 and 40 μm. The effects of batch dosing the secondary pond effluent with Nalco Ultrion 8109W polyelectrolytes. with the main objective of improving filtrate flux, was investigated. The batch polyelectrolyte pretreatment, at three times the optimal dosage of floe jar test, showed a tremendous increase (five fold) on filtrate pseudo-steady-state flux. The pseudo-steady-state flux was 70 l/m2.h at 0.65 ml/1 dosage

Low-temperature synthesis of carbon nanotubes via floating catalyst chemical vapor deposition method

Carbon nanotubes (CNTs) are widely synthesized at high temperatures via floating catalyst chemical vapor deposition (FC-CVD) method. It is important to reduce the synthesis temperature of CNTs to allow better control of the reactor's conditions and to eliminate the formation of carbon by-products. The main objective of this work was to synthesize carbon nanotubes at low temperatures. Temperature in-situ monitoring unit was used to monitor the temperature profile in the reactor. Benzene and ferrocene were used as the carbon source and catalyst precursor, respectively. The minimum pyrolysis temperature of benzene was successfully estimated, and the investigation of temperature profile in the reactor was achieved. In this work, multi-walled CNTs were successfully synthesized for synthesis temperatures between 540°C and 600°C. Based on the analyses, the qualities of CNTs produced were profoundly improved with the increase of synthesis temperatures

Optimization of process parameters for pilot-scale liquid-state bioconversion of sewage sludge by mixed fungal inoculation

Liquid-state bioconversion (LSB) technique has great potential for application in bioremediation of sewage sludge. The purpose of this study is to determine the optimum level of LSB process of sewage sludge treatment by mixed fungal (Aspergillus niger and Penicillium corylophilum) inoculation in a pilot-scale bioreactor. The optimization of process factors was investigated using response surface methodology based on Box–Behnken design considering hydraulic retention time (HRT) and substrate influent concentration (S0) on nine responses for optimizing and fitted to the regression model. The optimum region was successfully depicted by optimized conditions, which was identified as the best fit for convenient multiple responses. The results from process verification were in close agreement with those obtained through predictions. Considering five runs of different conditions of HRT (low, medium and high 3.62, 6.13 and 8.27 days, respectively) with the range of S0 value (the highest 12.56 and the lowest 7.85 g L−1), it was monitored as the lower HRT was considered as the best option because it required minimum days of treatment than the others with influent concentration around 10 g L−1. Therefore, optimum process factors of 3.62 days for HRT and 10.12 g L−1 for S0 were identified as the best fit for LSB process and its performance was deviated by less than 5% in most of the cases compared to the predicted values. The recorded optimized results address a dynamic development in commercial-scale biological treatment of wastewater for safe and environment-friendly disposal in near future

New trends on microbiological water treatment.

Silver nanoparticle-decorated porous polypropylene filter is prepared by physical vapor deposition method using a modified Balzers 760 coating machine. Silver nanoparticles were generated by electron beam bombardment of the silver metal. A 45nm layer of the silver nanoparticles were subsequently deposited on the polypropylene filter homogenously. The nano silver-coated filters were characterized using scanning electron microscopy, transmission electron microscopy and atomic force microscopy. The antibacterial efficiency of the nano silver-coated filters was evaluated using a custom- made experimental set up and the membrane filter method. A zone of inhibition test was also performed to compare the bactericidal effect of coated versus non-coated filters. At a flow rate of 3L/hr, the output count of Escherichia coli was zero after 6.5 hours filtration when the input water had a bacterial load of 103 colony-forming units (cfu) per milliliter. The inductively coupled plasma/mass spectrometry (ICP/MS) results showed that the 45nm layer of the silver nanoparticles are stable on the water filter and are not washed away by water flow even after 6.5h filtration

A kinetic study of a membrane anaerobic reactor (MAR) for treatment of sewage sludge

The application of kinetic models (Monod, Contois and Chen & Hashimoto) and overall microbial kinetic on the membrane anaerobic reactor (MAR) for treatment of sewage sludge was investigated. The system consists of a cross-flow ultrafiltration membrane and six steady states were attained over a range of mixed liquor suspended solids of 12,760-21,800 mg/l. The results of all six steady states were successfully fitted above 98% for three known kinetics. The growth yield coefficient, Y, was found to be 0.74 gVSS/gCOD while the specific microorganism decay rate was 0.20 d-1. The k values were in the range of 0.350-0.519 gCOD/gVSS.d and μmax values were between 0.259 and 0.384 d-1. The COD removal efficiency was 96.5-99% with HRT of 7.8 days. The methane gas yield was between 0.19 l/g COD/d to 0.54 l/g COD/d when the organic loading rate increased from 0.1 kg COD/m3/d to 10 kg COD/m3/d. The system efficiency was greatly influenced by SRT and OLRs. Membrane flux rate deterioration was observed from 62.1 l/m2/h to 6.9 l/m2/h due to membrane fouling

Air gasification of empty fruit bunch for hydrogen-rich gas production in a fluidized-bed reactor

A study on gasification of empty fruit bunch (EFB), a waste of the palm oil industry, was investigated. The composition and particle size distribution of feedstock were determined and the thermal degradation behaviour was analysed by a thermogravimetric analysis (TGA). Then fluidized bed bench scale gasification unit was used to investigate the effect of the operating parameters on EFB air gasification namely reactor temperature in the range of 700–1000 °C, feedstock particle size in the range of 0.3–1.0 mm and equivalence ratio (ER) in the range of 0.15–0.35. The main gas species generated, as identified by a gas chromatography (GC), were H2, CO, CO2 and CH4. With temperature increasing from 700 °C to 1000 °C, the total gas yield was enhanced greatly and reached the maximum value (∼92 wt.%, on the raw biomass sample basis) at 1000 °C with big portions of H2 (38.02 vol.%) and CO (36.36 vol.%). Feedstock particle size showed an influence on the upgrading of H2, CO and CH4 yields. The feedstock particle size of 0.3–0.5 mm, was found to obtain a higher H2 yield (33.93 vol.%), and higher LHV of gas product (15.26 MJ/m3). Equivalence ratio (ER) showed a significant influence on the upgrading of hydrogen production and product distribution. The optimum ER (0.25) was found to attain a higher H2 yield (27.31 vol.%) at 850 °C. Due to the low efficiency of bench scale gasification unit the system needs to be scaling-up. The cost analysis for scale-up EFB gasification unit showed that the hydrogen supply cost is RM 6.70/kg EFB ($2.11/kg =$0.18/Nm3)