The sources and ecological risk assessment of elemental pollution in sediment of Linggi estuary, Malaysia.

In this study, concentrations of heavy metals, rare earth elements (REEs), Uranium (U) and Thorium (Th) of the actinide group were determined from Linggi estuary sediment samples by neutron activation analysis (NAA) and inductive coupled plasma - mass spectrometry techniques. The geo-accumulation (Igeo) and ecological risk index (Ri) values were calculated to identify the quality status of Linggi estuary sediments. Results indicated Linggi estuary was polluted by arsenic (As), lead (Pb) and antimony (Sb). REEs, U and Th showed significant increase of concentration in Linggi estuary sediments. Ri of Linggi estuary was categorised as low to considerable ecological risk, which indicates no significant to moderate effect on the majority of the sediment-dwelling organisms. Correlation matrix and principal component analysis assessed pollution sources to be both natural and anthropogenic.

Removal of emulsified food and mineral oils from wastewater using surfactant modified barley straw.

Barley straw, an agricultural waste, was chemically modified and evaluated for the removal of emulsified oils from aqueous solution. The chemical modification was performed using NaOH and a cationic surfactant, hexadecylpyridinium chloride monohydrate (CPC). The surface textural and chemical properties of the surfactant modified barley straw (BMBS) were characterized by N(2) adsorption, FT-IR, SEM and water soluble mineral content. The adsorption tests were carried out in batch adsorption system for removal of standard mineral oil (SMO) and canola oil (CO) from water. For both emulsified oils in wastewater, adsorption was found to be strongly related with solution pH. The isotherm study indicated that emulsified oil adsorption on BMBS could be fitted well with the Langmuir model other than Freundlich model. The maximum adsorption capacity for CO and SMO at 25 degrees C determined from the Langmuir isotherm is 613.3 and 584.2 mg g(-1), respectively. Desorption tests in water solution show that oil is strongly bonded with adsorbent and desorption is only about 1-2% in 24 h.