Adsorption of Organic Micropollutants to Biosolids-Derived Biochar: Estimation of Thermodynamic Parameters

This research quantified thermodynamic parameters to better understand the use of wastewater biosolids-derived biochar as an adsorbent to remove micropollutants. The objective of this research was to quantify adsorption capacity; isosteric heat; and change of enthalpy, entropy, and free energy characterizing adsorption reactions between biochar and micropollutants. Adsorption isotherms were developed using a range of temperatures for the micropollutants benzyldimethyldecylammonium chloride (BAC-C10) Carbamazepine (CBZ), 17β-estradiol (E2), 17α-ethynylestradiol (EE2), and triclosan (TCS). The thermodynamic parameters derived from the isotherm data were used to assist in characterizing binding affinity, spontaneity, and mechanisms of adsorption. More polar compounds such as BAC-C10 and CBZ exhibited linear adsorption, indicating weak interactions with more polar amorphous moieties on the biochar surface. For the micropollutants that were present predominantly in the neutral form at pH 7 (CBZ, E2, EE2, and TCS), increasing hydrophobicity increased the extent of adsorption. The enthalpy change of adsorption and the positive correlation between hydrophobicity and change of entropy (R2=0.8) both suggest that hydrophobic interaction was the dominant adsorption mechanism for neutral compounds. Increases in adsorption with increasing temperature, together with the estimated thermodynamic parameters, indicated that the reactions were endothermic, meaning that higher temperatures should offer improved removal via adsorption. The negative free energy changes observed suggested that adsorption was spontaneous and that adsorption rates outcompete desorption rates. Under multi-solute conditions, the adsorption capacities for all compounds were suppressed to varying extents; however, the magnitude of changes in enthalpy and entropy were not affected by competitive multi-solute adsorption

Time Reversal and n-qubit Canonical Decompositions

For n an even number of qubits and v a unitary evolution, a matrix decomposition v=k1 a k2 of the unitary group is explicitly computable and allows for study of the dynamics of the concurrence entanglement monotone. The side factors k1 and k2 of this Concurrence Canonical Decomposition (CCD) are concurrence symmetries, so the dynamics reduce to consideration of the a factor. In this work, we provide an explicit numerical algorithm computing v=k1 a k2 for n odd. Further, in the odd case we lift the monotone to a two-argument function, allowing for a theory of concurrence dynamics in odd qubits. The generalization may also be studied using the CCD, leading again to maximal concurrence capacity for most unitaries. The key technique is to consider the spin-flip as a time reversal symmetry operator in Wigner's axiomatization; the original CCD derivation may be restated entirely in terms of this time reversal. En route, we observe a Kramers' nondegeneracy: the existence of a nondegenerate eigenstate of any time reversal symmetric n-qubit Hamiltonian demands (i) n even and (ii) maximal concurrence of said eigenstate. We provide examples of how to apply this work to study the kinematics and dynamics of entanglement in spin chain Hamiltonians.Comment: 20 pages, 3 figures; v2 (17pp.): major revision, new abstract, introduction, expanded bibliograph

Quantum Indeterminacy, Polar Duality, and Symplectic Capacities

The notion of polarity between sets, well-known from convex geometry, is a geometric version of the Fourier transform. We exploit this analogy to propose a new simple definition of quantum indeterminacy, using what we call "hbar-polar quantum pairs", which can be viewed as pairs of position-momentum indeterminacy with minimum spread. The existence of such pairs is guaranteed by the usual uncertainty principle, but is at the same time more general. We use recent advances in symplectic topology to show that this quantum indeterminacy can be measured using a particular symplectic capacity related to action and which reduces to area in the case of one degree of freedom. We show in addition that polar quantum pairs are closely related to Hardy's uncertainty principle about the localization of a function and its Fourier transform.Comment: Revised improved versio

Comparison of FDMA and CDMA for second generation land-mobile satellite communications

Code Division Multiple Access (CDMA) and Frequency Division Multiple Access (FDMA) (both analog and digital) systems capacities are compared on the basis of identical link availabilities and physical propagation models. Parameters are optimized for a bandwidth limited, multibeam environment. For CDMA, the benefits of voice activated carriers, antenna discrimination, polarization reuse, return link power control and multipath suppression are included in the analysis. For FDMA, the advantages of bandwidth efficient modulation/coding combinations, voice activated carriers, polarization reuse, beam placement, and frequency staggering were taken into account