Siti Mariam Sumari

Removal of Amido Black Dye from Aqueous Solution by Uncalcined and Calcined Hydrotalcite

Adsorption of amido black by calcined and uncalcined hydrotalcite was investigated. The influence of contact time, pH of the dye solution and adsorbent dose has been studied. In the light of so called “memory effect,” the removal of amido black, an anionic dye from aqueous solution by calcined hydrotalcite was also investigated. The results of adsorption experiments indicate that the percentage removal of amido black increased with increased in contact time and adsorbent dose but decreased with the increased in pH of the solution. Calcined hydrotalcite showed better adsorption capacity compared with uncalcined hydrotalcite. The isotherms showed that the adsorption of amido black was well fitted with Langmuir equation. The present study showed that hydrotalcite can be used as an adsorbent for the removal of amido black from aqueous solution. Better percentage removal of amido black performed by calcined hydrotalcite is due to their reconstruction of original layer in aqueous solution with good ion exchangers.

Adsorption of arsenic (V) and phosphate onto MgAlNO 3 -LDHs

LDH with nitrate in the interlayer and Mg-Al (3:1) in the layer have been synthesized by co-precipitation method. The adsorption of arsenic and phosphate onto MgAlNO3 hydrotalcite was evaluated with respect to pH, contact time, initial concentration and adsorbent dosage. The kinetic data were fitted into the pseudo-first-order equation, and the pseudo-second-order equations, and the intra-particle diffusion model. The results indicate that the pseudo-second-order model generates the best agreement with the experimental data for both arsenic and phosphate suggesting that the adsorption process might involve chemical sorption.

A 5-Year study of inland aquatic acidification at Semenyih Dam

A 5-year inland aquatic acidification study was conducted on surface water of Semenyih Dam from 2005 to 2009. This study is part of a continous acidification monitoring programme for Malaysia as a participatory country of EANET (East Asia Acid Monitoring Network). Water samples were taken every three months at selected points of the dam. Besides pH, temperature and electrical conductivity, these samples were also analysed for soluble ions using ion chromatography. The ions analysed include SO₄^2-, NO₃^-, Cl^-, NH₄⁺, Na⁺, K⁺, Ca²⁺ and Mg²⁺. Basic pH, together with high acid neutralizing capacity (ANC) and alkalinity especially in 2005 and 2006 indicate Semenyih Dam was capable of neutralization any acidification due to anthropogenic activities. However, in 2008 and 2009, decreases in pH, alkalinity and ANC indicate surface water at Semenyih Dam was experiencing some acidification due to increases in acidifying species with respect to basic neutralizing cations.

Adsorption of Reactive Orange 16 from aqueous solutions by MgAlNO 3 -LDH: Kinetic and equilibrium studies

An anionic MgAlNO3 layered double hydroxides (MgAlNO3-LDH) with Mg/Al molar ratio 4∶1, was investigated for its ability to adsorb an anionic dye, Reactive Orange 16 (RO16), with the objective of evaluating its suitability as an adsorbent. The experimental data were analyzed by the Langmuir and Freundlich adsorption models. Equilibrium data fitted well with Langmuir model for the concentration range of 5–100 mg/L. The equilibrium adsorption capacity of MgAlNO3-LDH was determined with the Langmuir equation and found to be 111 mg dye per gram adsorbent at 25 °C. Adsorption kinetics showed that the rates of adsorption were found to conform to the pseudo-second-order rather than first order kinetics. The results also indicate that MgAlNO3-LDH was a promising adsorbent for reactive dye removal from effluents, and with the potential to be used as an alternative adsorbent to other costly materials such as activated carbon.