The Effects of Several Paper Characteristics and Application Methods on the Sublimation Rate of Cyclododecane

Cyclododecane (CDD) is a waxy, solid cyclic hydrocarbon (C12H24) that sublimes at room temperature and possesses strong hydrophobicity. In paper conservation CDD is used principally as a temporary fixative of water-soluble media during aqueous treatments. Hydrophobicity, ease of reversibility, low toxicity, and absence of residues are reasons often cited for its use over alternative materials although the latter two claims continue to be debated in the literature. The sublimation rate has important implications for treatment planning as well as health and safety considerations given the dearth of reliable information on its toxicity and exposure limits. This study examined how the rate of sublimation is affected by fiber type, sizing, and surface finish as well as delivery in the molten phase and as a saturated solution in low boiling petroleum ether. The effect of warming the paper prior to application was also evaluated. Sublimation was monitored using gravimetric analysis after which samples were tested for residues with gas chromatography-flame ionization detection (GC-FID) to confirm complete sublimation. Water absorbency tests were conducted to determine whether this property is fully reestablished. Results suggested that the sublimation rate of CDD is affected minimally by all of the paper characteristics and application methods examined in this study. The main factors influencing the rate appear to be the thickness and mass of the CDD over a given surface area as well as temperature and ventilation. The GC-FID results showed that most of the CDD sublimed within several days of its disappearance from the paper surface regardless of the application method. Minimal changes occurred in the water absorbency of the samples following complete sublimation.

Preparation and evaluation of Fuller's Earth Beads for removal of Cesium from waste streams

This work deals with removal of Cesium (radioactive waste) in dilute aqueous phase by adsorption. Fullers earth was used as an adsorbent. The adsorption capacity of Fullers earth with respect to Cesium was found to be high, 26.3 mg / g of adsorbent.

Dilute acid hydrolysis of cellulose and cellulosic bio-waste using a microwave reactor system

The dilute acid hydrolysis of grass and cellulose with phosphoric acid was undertaken in a microwave reactor system. The experimental data and reaction kinetic analysis indicate that this is a potential process for cellulose and hemi-cellulose hydrolysis, due to a rapid hydrolysis reaction at moderate temperatures. The optimum conditions for grass hydrolysis were found to be 2.5% phosphoric acid at a temperature of 175 degrees C. It was found that sugar degradation occurred at acid concentrations greater than 2.5% (v/v) and temperatures greater than 175 degrees C. In a further series of experiments, the kinetics of dilute acid hydrolysis of cellulose was investigated varying phosphoric acid concentration and reaction temperatures. The experimental data indicate that the use of microwave technology can successfully facilitate dilute acid hydrolysis of cellulose allowing high yields of glucose in short reaction times. The optimum conditions gave a yield of 90% glucose. A pseudo-homogeneous consecutive first order reaction was assumed and the reaction rate constants were calculated as: k(1) = 0.0813 s(-1); k(2) = 0.0075 s(-1), which compare favourably with reaction rate constants found in conventional non-microwave reaction systems. The kinetic analysis would indicate that the primary advantages of employing microwave heating were to: achieve a high rate constant at moderate temperatures: and to prevent 'hot spot' formation within the reactor, which would have cause localised degradation of glucose.

Mineralogy of selected geological deposits from the United Kingdom and the Republic of Ireland as possible capping materials for low-level radioactive waste disposal facilities

Solid low-level radioactive waste (LLW) is currently being disposed at a number of facilities in the United Kingdom (UK). The safety of these facilities relies to some extent on the use of engineered barriers, such as a cap, to isolate the waste and protect the environment. Generally, the material used as the barrier layer within such a cap should be of low permeability and it should retain this property over long timescales (beyond a few decades normally required for facilities containing non-radioactive wastes). The objective of this research is to determine the mineralogy of selected geological deposits from the UK and Ireland as part of a larger project to examine their suitability as a capping material, particularly on LLW sites. Mineral transformations, as a result of future climate change, may impact on the long-term performance of the cap and even the disposal facility. X-ray diffraction (XRD) was carried-out on the sand, silt and clay fractions of the London Clay, Belfast Upper Boulder Clay, Irish Glacial Till, Belfast Sleech, and Ampthill Clay geological deposits. Minerals were present that could pose both positive and negative effects on the long-term performance of the cap. Smectite, which has a high shrink swell potential, may produce cracks in London Clay, Belfast Upper Boulder Clay and Ampthill Clay capping material during dry, hotter periods as a possible consequence of future climate change; thus, resulting in higher permeability. Ampthill Clay and Belfast Sleech had elevated amounts of organic matter (OM) at 5.93% and 5.88%, respectively, which may also contribute to cracking. Over time, this OM may decompose and result in increased permeability. Gypsum (CaSO4) in the silt and sand fractions of Ampthill Clay may reduce the impact of erosion during wetter periods if it is incorporated into the upper portion of the cap. There are potential negative effects from the acidity created by the weathering of pyrite (FeS2) present in the silt and sand fractions of Belfast Sleech and Ampthill Clay that could impede the growth of grasses used to stabilize the surface of the capping material if this material is used as part of the vegetative soil layer. Additionally, acidic waters generated from pyrite weathering could negatively impact the lower lying capping layers and the disposal facility in general. However, the calcium carbonate (CaCO3) present in the silt and sand fractions of these deposits, and dolomite (CaMg(CO3)2) in Belfast Sleech, may counter act the acidity.