H. Sattar

Improvements to the Hartmann Dust Explosion Equipment for MEC Measurements that Are Compatible with Gas Lean Limit Measurements

Literature results for the MEC of dusts show that the MECs in g/m3 convert to lean equivalence ratios of 0.2–0.3 for many HCO dusts, compared with 0.45 for hydrocarbons and alcohols. This indicates that HCO dusts are more reactive than hydrocarbons, but it could be that it is the measurements of MEC for dusts that are suspect. The measurement of the minimum explosible concentration of dusts is reviewed together with measurement methods for the lean flammability limit of gases. There is considerable uncertainty over the concentration of dusts at the lean limit in the 1 m3 MEC method, as most of the dust injected in the 1 m3 does not burn. It is shown for gases that a vertical tube equipment operated as a closed vessel will give the same lean limit of 0.46O for methane/air as the European standard method, but large spheres will not, and thus, the use of the 1 m3 dust explosion vessel is unlikely to give MEC data that is compatible with lean limits for gases. A study of the MEC of polyethylene dusts was carried out at various ignition delays in the Hartmann, and an ignition delay of 50 ms was recommended for polyethylene dust to give reliable MEC measurements.

Improved phenol adsorption from aqueous solution using electrically conducting adsorbents

The electrically conducting and partially porous graphite based adsorbent (called NyexTM 2000) was tested for its adsorption capacity and electrochemical regeneration ability for the removal of phenol from aqueous solution. Nyex™ 2000 was tested in comparison with Nyex™ 1000, which is currently being used for a number of industrial waste water treatment applications. Nyex™ 1000 exhibited small adsorption capacity of 0.1 mg g−1 for phenol because of having small specific surface area of 1 m2 g−1. In contrast, Nyex™ 2000 with specific surface area of 17 m2 g−1 delivered an adsorption capacity of 0.8 mg g−1, which was eight-fold higher than that of Nyex™ 1000. Nyex™ 2000 was successfully electrochemically regenerated by passing a current of 0.5 A, charge passed of 31 C g−1 for a treatment time of 45 minutes. These electrochemical parameters were comparable to Nyex™ 1000 for which a current of 0.5 A, charge passed of 5 C g−1 for a treatment time of 20 minutes were applied for complete oxidation of adsorbed phenol. The comparatively high charge density was found to be required for Nyex™ 2000, which is justified with its higher adsorption capacity. The FTIR results validated the mineralization of adsorbed phenol into CO2 and H2O except the formation of few by-products, which were in traces when compared with the concentration of phenol removed from aqueous solution. The electrical energy as required for electrochemical oxidation of phenol adsorbed onto Nyex™ 1000 & 2000 was found to be 214 and 196 J mg−1, respectively. The comparatively low energy requirement for electrochemical oxidation using Nyex™ 2000 is consistent with its higher bed electrical conductivity, which is twice that of Nyex™ 1000.

Agricultural Waste Biomass Energy Potential In Pakistan

Pakistan has a major electricity supply problem with urban areas having a very intermittent supply of electricity. The supply gap at periods of high demand is 6 GW. Pakistan has a large agricultural economic sector and produces a substantial amount of waste material that has little current economic use. This work shows that these agricultural wastes are a significant energy resource that could be used to generate electricity using relatively small biomass generator sets that could take all the waste biomass from the surrounding agricultural area. Pakistan currently imports most of the oil used for electricity generation. The cost of this result in high cost electricity and it is shown that bio-electricity could be generated competitively in Pakistan. It was estimated, based on 30% thermal efficiency of electric power generation, that the annual production of crop residues have the potential to generate 76% of the annual electricity requirements of Pakistan. For this to come from agricultural wastes in farmland, transport costs would have to be minimised. It is proposed that a series of about 10MWe plants should be established (which are commercially available) with all farms in about a 10km radius delivering their agricultural solid waste to the plant at the farmers cost with direct payment by the power generator.

Removal of Tartrazine From Water by Adsorption with Electrochemical Regeneration

An innovative process has been developed at University of the Manchester in order to remove organic contaminants from wastewater using graphite intercalation compounds (GICs) as adsorbents with electrochemical regeneration. The present study has demonstrated the removal of tartrazine, from water by adsorption and electrochemical regeneration. The adsorption of tartrazine onto GIC adsorbent was shown to be a quick process, however, with extremely low adsorption capacity compared to porous adsorbents. Low adsorption capacity of the adsorbent is being compensated by rapid electrochemical regeneration associated with low energy consumption that makes the process cost-effective. Regeneration efficiency of around 100% could be obtained in an electrochemical cell by passing a charge of 18 C g−1 for 18 min through a 10-mm thick adsorbent bed. A series of adsorption and regeneration cycles showed that there was little loss in adsorbent capacity, demonstrating that tartrazine loaded GIC adsorbent could be effectively regenerated electrochemically.