Assessment of heavy metal attenuation and mobility in compacted soil columns

Groundwater pollution from unlined landfill is a worrying problem nowadays. In order to reduce the pollution, a good soil liner is very important. Natural compacted soil is used to prevent leachate from reaching the groundwater. The soil column study was performed to investigate the retention capability of three soil types in Malaysia, namely marine clay (SBMC), weathered metasediments (HMS) and river alluvium soil (ARA). All soil columns were tested against four types of heavy metals, i.e. lead (Pb), copper (Cu), nickel (Ni) and zinc (Zn). The breakthrough curves show that the SBMC has better retention capability on heavy metals compared to other soils; indicating less migration of heavy metals through SBMC soil column. The affinity of heavy metals for adsorption were also varied with soil types and can be ranked as follow: SBMC (Pb>Cu>Ni ≈ Zn) and HMS/ARA: Zn ≈ Cu>Pb>N. Soil SBMC showed very high resistance to acidic test solution (i.e. high buffering capacity), where the pH values throughout the test were in an alkaline region with the values of pH 8 to 7. The study also discovered that heavy metals entered the soil columns were retained predominantly at the top 30 mm. Engineering applications of these findings show that soil SBMC has a very good potential to function as soil liner material compared to two other soils (ARA and HMS)

Adsorption of acid blue 25 from aqueous solution using zeolite and surfactant modified zeolite

In the present study, we have demonstrated the Indonesian natural zeolite and modified zeolite was used to remove the acid blue 25 (AB25) from wastewater. The adsorption capacity of AB25 on zeolite and modified zeolite (zeolite-CTAB) were investigated by various batch adsorption experiments. The modification effect on the surface of zeolite was analyzed using Fourier transforms infrared spectra, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray fluorescence, and X-ray diffraction, respectively. The maximum removal of AB25 was obtained under acidic conditions at pH 2. The kinetic experimental results imply that the adsorption of AB25 onto these adsorbents well followed the second-order kinetic model. The maximum adsorption capacity of 64.2 mg/g was found in Zeolite at 30°C and 112.44 mg/g for zeolite-CTAB at 60°C. The results revealed that the adsorption of AB25 onto zeolite-CTAB fitted better to Langmuir model and Zeolite fitted better with Freundlich model. The AB25 adsorption on zeolite-CTAB increases with an increasing temperature indicates that the preferential adsorption may occur at a higher temperature. The positive value of ∆H° in zeolite-CTAB material thermodynamic parameters indicates that the process was an endothermic process. These results indicate that zeolite-CTAB has high adsorbent efficiency and it is promising adsorbents for removing the dye AB25