A bioseparation process for removing heavy metals from waste water using biosorbents

of conventional adsorbents to the use of biosorbents. The presence of heavy metals in the environment is of major concern because of their toxicity, bioaccumulating tendency, and threat to human life andthe environment. In recent years, many low cost sorbents such as algae, fungi bacteria and lignocellulosic agricultural by-products have been investigated for their biosorption capacity towards heavy metals. In this comprehensive review, the emphasis is on outlining the occurrences and toxicology of heavy metals and the biosorption capacity of biosorbents compared to conventional adsorbents. A detailed description of the adsorption properties and mode of action of these biosorbents is offered in order to explain the heavy metal selectivity displayed by these biosorbents. The role of cell structure, cell wall, micropores and macropores is evaluated in terms of the potential of these biosorbents for metal sequestration. Binding mechanisms are discussed, including the key functional groups involved and the ion-exchange process. Quantification of metal-biomass interactions is fundamental to the evaluation of potential implementation strategies, hence, sorption isotherms, sorption kinetics, intraparticle diffusivities as well as models used to characterize biosorbent sorption are reviewed. The sorption behavior of some biosorbents with various heavy metals is summarized, their relative performance evaluated and a bioseperation process flow diagram for heavy metal removal from wastewater using biosorbents was propose

Lead (II) and nickel (II) adsorption kinetics from aqueous metal solutions using chemically modified and unmodified agricultural adsorbents

This paper discusses the kinetics of lead (II) and Nickel (II) ions adsorption from aqueous solutions using chemically modified and unmodified agricultural adsorbents at 28°C, pH 6.2 and 0.01M NaCl ionic strength. The removal of the two metals were found to increase with increase in chemical modification,the sequence being 1.0MOPF>0.5MOPF>UOPF. In addition Nickel (II) had a higher percentage removal than lead (II). The intraparticle diffusion rate constant (Kid) were determined to be 63.023 min-1 (Ni2+) and38.212 min-1 (Pb2+) for the 1.0MOPF adsorbent. The results show that the intraparticle diffusion model fits the sorption of lead (II) with higher coefficient of determination (r2) than Nickel (II), thereby indicating that the intra-particle diffusion may be the rate limiting step for Pb2+ sorption. The results from this study indicates that a good adsorbent for the removal of Ni2+ and Pb2+ can be obtained from both chemically modified and unmodified oil palm fruit fibr

Transfer zone behaviour of As(III), Co(II) and Mn(II) ions on sulphur-hydryl infused cellulose surface

Penetrant transport phenomenon was applied to determine the strive of As(III), Co(II) and Mn(II) ions across the adsorbate/cellulose interface. Penetrant-n and K values calculated for the metals on differentially thiolated (mercaptoacetic acid treated) cellulose surfaces were highest for As(III) at UCF-n, K (3.1278, 0.3064), 0.5MF-n, K (2.4248, 0.4716) and 1.0MF-n, K (1.9136, 0.4885). For Co(II), n and K values were UCF (2.8608, 0.3220), 0.5MF (1.6791, 0.5351), 1.0MF (0.9348, 0.6952). For Mn(II), n and K values were UCF (1.2717, 0.6268), 0.5MF (1.1114, 0.6639), 1.0MF (0.5833, 0.7707). As(III) strive depicts 30%adsorption against the non-cationic moieties it generates in a partially electrical double layered adsorption system

The role of pH in heavy metal detoxification by biosorption from aqueous solutions containing chelating agents

The high level of toxic metal pollution in the environment is a result of increased human activities. The hydrogen ion concentration of solutions has been known to affect reactions in solutions. The role of pH in As(V), Pb(II) and Hg(II) ions detoxification by bio-sorption from aqueous solutions using coconut fiber and sawdust waste biomass, containing chelating agents was studied. pH characteristically influenced adsorption. Maximum adsorption occurred at pH 2 and 12 whereas minimum adsorption occurred at pH 6-8. Modification of the adsorbent by carboxymethylation and thiolation decreased the absorption capacity. As(V) metal ion was adsorbed more than Hg(II), then followed by Pb(II) ion. A model was proposed for the action of pH on the adsorption pattern of the metal ions on the adsorbents used. Desorption studies was investigated using NaOH and H2PO4. Therefore, these results can serveas parameters for design of treatment plants for heavy metal detoxification using agricultural byproducts, such as sawdust and coconut fiber

Studies on the kinetics and intraparticle diffusivities of BOD, colour and TSS reduction from palm oil mill effluent (POME) using boiler fly ash

The palm oil industry has been identified as one of the main contributors of organic pollution. These industries generate large volumes of effluent and solid waste including boiler fly ash. The kinetics and intraparticle diffusivities of BOD, TSS and colour reduction from palm oil mill effluent (POME) using boiler fly ash was reported in this paper. The amount of BOD, colour and TSS adsorbed increased as the weight of the boiler fly ash was increased. Also, the smaller adsorbent particle size of 425 mm adsorbed more than the 850 mm size. Attempts were made to fit the experimental data with the pseudo - first order and pseudo-second order kinetic equations. The pseudo - second order model gave a better fit to the sorption process. The rate constants obtained for the pseudo-second order model are 2.26 x 10-5 mg/g-min for BOD, 6.48 x 10-4 mg/g-min for colour and 9.55 x 10-4 mg/g-min for TSS at 30°C. The mechanism of sorption was investigated by using the intraparticle diffusion model. The regression coefficient for the intraparticle diffusion model showed that BOD with a value of 0.9744 was well correlated than TSS (R2 = 0.1018) and colour (R2 = 0.1450). This means that BOD adsorption was particle diffusion controlled while colour and TSS were film diffusion controlled. Therefore, this study reveals that boiler fly ash can effectively be used as an adsorbent for POME treatment and also established the kinetic and mechanisms of the sorption process. Also, the results of this study could serve as effective design parameters for a treatment plant to further reduce BOD, colour and TSS from POME

Detoxification of copper fungicide using EDTA-modified cellulosic material

Pesticides are poisons and can be particularly dangerous when misused or carelessly disposed. The detoxification of a copper fungicide (KOCIDE 101) using maize cob, a cellulosic material, was studied. Based on copper as the active agent (after a sorption period of 1 h), the concentration of the fungicide reduced from an initial value of 2000 to 206.25 ppm for the unmodified maize cob and to 24.31 ppm for the modified maize cob. The pseudo-first and second order rate equations were used to model thedetoxification process. The intraparticle diffusivity and mechanism of the sorption was proposed. Also, equilibrium sorption isotherms were evaluated using the Freundlich, Langmuir and Dubinin-Radushkevich isotherm models. This results show that maize cob is an effective adsorbent for copper fungicide deactivation and detoxification

Search for Charged Higgs Bosons in e+e- Collisions at \sqrt{s} = 189 GeV

A search for pair-produced charged Higgs bosons is performed with the L3 detector at LEP using data collected at a centre-of-mass energy of 188.6 GeV, corresponding to an integrated luminosity of 176.4 pb^-1. Higgs decays into a charm and a strange quark or into a tau lepton and its associated neutrino are considered. The observed events are consistent with the expectations from Standard Model background processes. A lower limit of 65.5 GeV on the charged Higgs mass is derived at 95 % confidence level, independent of the decay branching ratio Br(H^{+/-} -> tau nu)

Compressed representation of a partially defined integer function over multiple arguments

In OLAP (OnLine Analitical Processing) data are analysed in an n-dimensional cube. The cube may be represented as a partially defined function over n arguments. Considering that often the function is not defined everywhere, we ask: is there a known way of representing the function or the points in which it is defined, in a more compact manner than the trivial one

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns