Utilising highly characterised peats to remove cadmium from aqueous solutions

This research investigated the biosorption of cadmium (Cd) from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after treatment with hydrochloric acid (HCl) to free up any occupied exchange sites. Other factors tested were sample dose, contact time, mixing temperature, and the concentration and pH of the Cd solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for Cd biosorption. The results indicate that all six peats biosorb Cd from aqueous solution well (36−100 % removal) and that their Cd removal capacities are affected by the various factors that were manipulated. The three factors that had the greatest effects on the Cd removal capacities of the peats were sample dose and the concentration and pH of the Cd solution. The percentage of Cd removed increased as the sample dose increased (16−31 % increase) and as the pH of the Cd solution increased (16−57 % increase). As the concentration of the Cd solution increased, the percentage of Cd removed increased slightly for two of the six peats (1−2 % increase) and decreased for three peats (19−23 % decrease). As the mixing temperature increased, the percentage of Cd removed increased slightly for three of the peats (1−12 % increase) and decreased slightly for the other three (1−5 % decrease). The desorption results showed a 34−71 % Cd recovery rate. Re-used peats were also highly effective at removing Cd, whether or not they had gone through desorption. Two of the six peats were slightly better at Cd removal after treatment with HCl (4−7 % better than untreated peats), while the other four peats worked better in their unaltered states (3−18 % better). As all of the peat types tested can be repeatedly re-used for additional Cd biosorption cycles, their disposal should not create a hazardous waste problem. On the other hand, using peat for any industrial purpose is increasingly disfavoured nowadays, for sustainability reasons. Thus, the results of this study might be used to identify and/or develop materials with properties similar to those of the most effective peats (i.e. artificial peats) for use as biosorbents of Cd. These materials could be agricultural waste products such as soybean or rice hulls, constructed wetlands with living plants similar to those found in the tested peats, or possibly biochar of these living plants

Biosorption of mercury from aqueous solutions using highly characterised peats

This research investigated the biosorption of mercury from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after being treated with hydrochloric acid (HCl) to free up any occupied exchange sites. Other variables tested were sample dose, contact time, mixing temperature, and the concentration and pH of the mercury solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for mercury biosorption. The results indicate that all six peat types biosorb mercury from aqueous solutions extremely well (92−100 % removal) and that their mercury removal capacities are not significantly affected by manipulation of the various factors tested. The factor that had the greatest impact on the mercury removal capacities of the peats was the pH of the mercury solution. The optimal mercury solution pH for mercury removal was in the range 5−7 for four of the peats and in the range 2−3 for the other two. The desorption results indicate that it may be possible to recover up to 41 % of the removed mercury. All of the peat types tested can be repeatedly re-used for additional mercury biosorption cycles. Hence, their disposal should not become a hazardous waste problem

Biosorption of hexavalent chromium from aqueous solutions using highly characterised peats

This research investigated the biosorption of hexavalent chromium (CrVI) from aqueous solutions by six highly characterised peats. Samples of the peats were tested both in unaltered condition and after being treated with hydrochloric acid (HCl) to free up any occupied exchange sites. Other variables tested were sample dose, contact time, mixing temperature, and the concentrations and pH of the CrVI solution. Desorption studies were also performed, and tests were done to determine whether the peats could be re-used for CrVI biosorption. The results indicate that all six peat types biosorb CrVI from aqueous solution well (42–100 % removal) and that their CrVI removal capacities are affected by manipulation of the various factors. The two factors that had the greatest impact on the CrVI removal capacities of the peats were the concentrations and pH of the CrVI solution. As the CrVI solution concentration and pH were increased, the percent of CrVI removed decreased dramatically (33–56 % decrease for concentration increase; 36–45 % decrease for pH increase with four of the six peat types). The desorption results indicate that it may be possible to recover up to 5 % of the removed CrVI. All of the peat types tested can be repeatedly re-used for additional CrVI biosorption cycles. Hence, their disposal should not become a hazardous waste problem

Compton scattering of quasi-real virtual photons at LEP

Compton scattering of quasi-real virtual photons, gamma e(+/-) -\u3e gamma e(+/-), is studied with 0.6 fb(-1) of data collected by the L3 detector at the LEP e(+)e(-) collider at centre-of-mass energies root s = 189-209 GeV. About 4500 events produced by the interaction of virtual photons emitted by e(+/-) of one beam with e(-/+) of the opposite beam are collected for effective centre-of-mass energies of the photon-electron and photon-positron systems in the range from root s\u27 = 35 GeV up to root s\u27 = 175 GeV, the highest energy at which Compton scattering was ever probed. The cross sections of the gamma e(+/-) -\u3e gamma e(+/-) process as a function of root s\u27 and of the rest-frame scattering angle are measured, combined with previous U measurements down to root s\u27 similar or equal to 20 GeV, and found to agree with the QED expectations. (c) 2005 Published by Elsevier B.V

Search for neutral MSSM Higgs bosons at LEP.

The four LEP collaborations, ALEPH, DELPHI, L3 and OPAL, have searched for the neutral Higgs bosons which are predicted by the Minimal Supersymmetric standard model (MSSM). The data of the four collaborations are statistically combined and examined for their consistency with the background hypothesis and with a possible Higgs boson signal. The combined LEP data show no significant excess of events which would indicate the production of Higgs bosons. The search results are used to set upper bounds on the cross-sections of various Higgs-like event topologies. The results are interpreted within the MSSM in a number of “benchmark” models, including CP-conserving and CP-violating scenarios. These interpretations lead in all cases to large exclusions in the MSSM parameter space. Absolute limits are set on the parameter cosβ and, in some scenarios, on the masses of neutral Higgs bosons

Measurement of the mass of the Z boson and the energy calibration of LEP

In 1985 the French government created a unique circuit for the dissemination of doctoral theses: References went to a national database “Téléthèses” whereas the documents were distributed to the university libraries in microform. In the era of the electronic document this French network of deposit of and access to doctoral theses is changing. How do you discover and locate a French thesis today, how do you get hold of a paper copy and how do you access the full electronic text? What are the catalogues and databases referencing theses since the disappearance of “Téléthèses”? Where are the archives, and are they open? What is the legal environment that rules the emerging structures and tools? This paper presents national plans on referencing and archiving doctoral theses coordinated by the government as well as some initiatives for creating full text archives. These initiatives come from universities as well as from research institutions and learned societies. “Téléthèses” records have been integrated in a union catalogue of French university libraries SUDOC. University of Lyon-2 and INSA Lyon developed procedures and tools covering the entire production chain from writing to the final access in an archive: “Cyberthèses” and “Cither”. The CNRS Centre for Direct Scientific Communication at Lyon (CCSD) maintains an archive (“TEL”) with about 2000 theses in all disciplines. Another repository for theses in engineering, economics and management called “Pastel” is proposed by the Paris Institute of Technology (ParisTech), a consortium of 10 engineering and commercial schools of the Paris region