Hexadecyltrimetyl ammonium bromide and alkyldimethylbenzyl ammonium chloride-modified sericite samples were obtained by wet cation exchange process. The solid materials were then characterized by the FT-IR and XRD data whereas the surface morphology was obtained by the scanning electron microscopic images. Further, the suitability of these solids was assessed for the decontamination of phenol-contaminated waters under the batch reactor operations. Batch reactor data showed that an increase in sorbate concentration (from 1.0 to 20.0 mg/L) favoured the uptake of phenol from aqueous solution whereas an increase in pH (from 2.0 to 10.0) caused for significant decrease in percent uptake of phenol. The equilibrium state concentration dependence data were well modelled with the Freundlich adsorption isotherm.

Sand which is a good filter medium and widely used in wastewater treatments possesses a very insignificant sorption capacity for several heavy metal toxic ions. However, surface-modified sand as impregnated with manganese is supposed to possess fair removal capacity at least for the low level removal of several heavy metal toxic ions from aqueous solutions since manganese is likely to be aggregated onto the sand surface as manganese dioxide which is a good adsorbing material. The present investigation intends to exploit the use of sand obtained from the river Tlawng, Sairang site, Aizawl, Mizoram, India. The sand sample was impregnated with Mn(II) by a wet method. Further, the surface morphology of this manganese-impregnated sand (MIS) was obtained using scanning electron microscopy, which showed that the manganese oxide occupied the surface of the sand and clustered on it. The particle size of coated manganese oxide was found to be in the nanoscale range. Moreover, the specific surface area of the sand was also increased with this impregnation. Further, the removal efficiency of MIS was assessed for two important heavy metal toxic ions, that is, Cr(VI) and Cd(II). The study was carried out for the pH and concentration dependence of sorptive solutions. Results obtained for the concentration dependence were further analyzed by the Freundlich and Langmuir adsorption isotherms.

The objective of the present investigation was to explore the sorption behaviour of manganese-coated samples of calcined starfish (MCCSF) (i.e. the impregnation of calcined starfish with manganese) for the removal of low levels of an important heavy metal toxic ion, Mn(II), from aqueous solutions. The suitability of this solid was further compared with two different samples of manganese-coated sands (MCS): MCS4 and MCS9 impregnated at pH 4.0 and pH 9.0, respectively. These comparative studies were performed in both batch and column experiments. Batch data indicated that a fairly good stability of the coating was obtained for these three samples in the pH region 2.5 to 10.0. The removal efficiency of MCCSF was fairly good in comparison with the MCS4 and MCS9 samples. These last two samples possessed similar Mn(II) removal capacities. Moreover, a small dose of sodium hypochlorite further enhanced the uptake of Mn(II) by these solids. The sorbate concentration dependence data fitted reasonably well to the Freundlich adsorption isotherm. The column data indicated that MCCSF possessed a relatively higher adsorption capacity compared with the MCS4 and MCS9 samples. The breakthrough curves obtained were then used to evaluate the apparent removal capacity of these solids under the dynamic conditions using the Thomas equation. The SEM images obtained for these manganese-coated solids along with the virgin base materials, i.e. sand and calcined starfish, showed that manganese oxides occupied the surfaces or pores of the base materials and formed clusters on the base surface.

Iron coated media (activated carbon, sand and starfish) were prepared at pH 4 and applied for the treatment of landfill leachate containing organic compounds and soluble metal ions such as in batch and column experiment. The amount of iron coated in media was analyzed with EPA 3050B method. The removal efficiency of metal ions and phenol was compared with iron coated media. The amount of iron coated in Fe-AC and ICS(iron coated sand) were 1,612 mg/kg and 1,609 mg/kg, respectively, while it was higher with 1,768 mg/kg in ICSF(iron coated starfish). The result of batch study represent the highest removal efficiency in the treatment of wastewater using iron coated starfish. In column study, the removal efficiency of phenol and metal ions was higher in multi-layered system of ICS, Fe-AC and ICSF compared to single layered system. Breakthrough time in the effluent was relatively enhanced for and in multi-layered system while the removal efficiency of were not varied much. Therefore, multi-layered system was identified as the better system for the treatment of wastewater containing of metal ions and organic compound.

The bone of spinal animals has a hydroxylapatite (, HAp) structure which is well known as an excellent inorganic ion exchanger for various heavy metal ions in solutions. In this study, the reusability of cow-bone, pig-bone and fish-bone as a potential material for the removal of heavy metals in solutions was evaluated from the removal of Cu(II) ion in batch tests. The surface properties of three bones, calcined at different temperatures, were measured with SEM, XRD, FT-IR analyses. From the SEM analysis, a clear development of heterogeneity as well as pores having small diameter was observed as the calcination temperature increased. The results of X-ray diffraction analysis showed well developed crystallinity on the surface of calcined bones obtained at higher temperatures, suggesting a transform of amorphous type to crystalline type. Fourier transform infrared (FT-IR) analysis showed disappearance of water molecule on the surface of HAp and organic functional groups of the HAp with increasing the calcination temperatures. Cu(II) removal in the control test was below 15%. By the way, additional 40% increase of Cu(II) removal was observed in the presence of calcined bones. For three bones, Cu(II) removal was decreased as the calcined temperature increased. Cu(II) removal was increased as the solution pH increased due to a favorable condition for the cation exchange as well as precipitation.

The occurrence of ciprofloxacin (CIP), sulfamethoxazole (SMX), and azithromycin (AZI) was evaluated in various aqueous streams of four municipal wastewater treatment plants (WWTPs) in the Midwestern United States. Aqueous phase grab samples were collected from different locations in the WWTPs at four different times of the year. The target compounds were extracted using solid phase extraction, separated with high-performance liquid chromatography, and identified/quantified using ultraviolet and fluorescence spectroscopy (CIP and SMX) or mass spectrometry (AZI). Aqueous phase concentrations for CIP and AZI were similar to literature values while SMX concentrations were generally higher than those reported in the literature. The average aqueous phase concentrations for CIP, AZI, and SMX in the raw wastewater were 1.44, 1.11, and 18.3μg∕L, respectively, while the concentrations in the WWTP effluent were 0.59, 1.23, and 3.25μg∕L, respectively. AZI concentration was consistently lower in the winter. While some CIP and SMX removal from the aqueous phase was observed in the WWTP, such reductions were not seen for AZI. Composite sampling data indicated that CIP and SMX concentrations were significantly higher in summer than in winter.