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Abstract: The adsorption of 1-naphthylamine, 1-naphthol and phenol on as-prepared and oxidized multiwalled carbon nanotubes (MWCNTs) has been investigated. The results illustrated that both as-prepared and oxidized MWCNTs showed high adsorption capacity for the three ionizable aromatic compounds (IACs) studied. Oxidation of MWCNTs increased the surface area and the pore volume, and introduced oxygen-containing functional groups to the surfaces of MWCNTs, which depressed the adsorption of IACs on MWCNTs. Both Langmuir and Freundlich models described the adsorption isotherms very well and the adsorption thermodynamic parameters (ΔG°, ΔH° and ΔS°) were measured. The adsorption for 1-naphthylamine, 1-naphthol and phenol is general spontaneous and thermodynamically favorable. The adsorption of phenol is an exothermic process, whereas the adsorption of 1-naphthylamine and 1-naphthol is an endothermic process. Results of this work are of great significance for the environmental application of MWCNTs for the removal of IACs from large volume of aqueous solutions. [Copyright &y& Elsevier]

Abstract: The development of a mathematical model on the cumulative effects due to brine discharges into shallow coastal waters with a flat seabed is conducted in this study. The model incorporates the effects of tidal currents, which are commonly encountered in the natural coastal environment. The tidal currents are represented by a small constant component, V (normally referred as residual or drift current), plus a periodic part, U 0 sin ωt. Anisotropic eddy dispersivities in the alongshore and cross-shore directions are also incorporated. The convergence to the quasi-steady state for the salinity excess due to the continuous brine input has been studied for the first time. The application of the mathematical model to assess a hypothetically practical discharge is also performed. Model predictions for representative velocity ratios of ν (=V/U 0) are obtained. In general, the placement of the outfall further offshore has been shown to reduce the shoreline impact as expected. A comparison of the results between constant and time-dependent dispersivities has been conducted. [Copyright &y& Elsevier]

Abstract: Attapulgite was investigated to remove Ni2+ from aqueous solutions because of its strong sorption ability. Herein, the sample of attapulgite was modified with ammonium citrate tribasic (ACT) and used as an adsorbent to remove Ni2+ from aqueous solutions. XRD and FTIR analysis indicated that ACT was successfully grafted on attapulgite surfaces. The results indicated that ACT–attapulgite was better than bare attapulgite in the removal of Ni2+ from aqueous solutions. Sorption of Ni2+ on ACT–attapulgite was mainly dominated by ion exchange or outer-sphere complexes at low pH values, and by inner-sphere complexes or surface precipitation at high pH values. The thermodynamic data indicated that the sorption of Ni2+ to ACT–attapulgite hybrids was an endothermic process and was enhanced with increasing temperature. ACT–attapulgite is a suitable material for the preconcentration of Ni2+ from large volume of solutions and can be used in wastewater treatment because of its negative surface charge and large surface areas. [Copyright &y& Elsevier]

Estuary protection is a fundamental part of watershed management. However, land reclamation activities affect species distribution patterns and cause ecological degradation. To improve watershed management, we studied the distribution patterns of three typical salt marsh species and their interspecific interactions along groundwater table depth and salinity gradients using an index of Field Box Dimension and a Relative Interaction Index. We also simulated the groundwater gradient after two typical land reclamation activities, sea reclamation and embanking, after ten years. Our results showed that sea reclamation will change the location of the groundwater salinity peak along a land-to-sea transect and that there is no salinity peak after embanking. Vegetation distribution patterns also differed, from a zonal pattern (in salt marsh) to a mosaic pattern (after embanking). The decrease in the salinity gradient of the non-core area is an important cause for the differences we found in vegetation patterns. [ABSTRACT FROM AUTHOR]