PAPERmaking! g FROM THE PUBLISHERS OF PAPER TECHNOLOGY Volume 1, Number 1, 2015
Organic matter (OM) content was calculated from loss on ignition (correction factor of 1.78) by using following formula:
OM = 1000 × (mass of oven dry soil – mass of ignited soil) / mass of oven dry soil.
Total nitrogen was determined using the modified Kjeldahl method [9]. Soil CEC was determined by the NH 4 OAc (pH 7.0) method [10]. 2.3. Determination of Total Heavy Metals in Recycled Paper Mill Sludge The aqua regia method was used to extract total heavy metals in the sludge and soil [11]. Aqua regia is a mixture of concentrated hydrochloric acid (HCl) and nitric acid (HNO 3 ) in the ratio of 3:1. Evidently, aqua regia is the only extractant that can release most of the components bound in the silicate matrix (residual fraction) [12]. Total metal concentrations were determined using a PE5100 atomic absorption spectrophotometer (Perkin Elmer, Wellesley, MA, USA) except for phosphorus (P) concentration in the extract which was determined using the Quikchem FIA 8000 auto-analyser (Lachat Instruments, Loveland, CO, USA). 2.4. Analytical Procedure for Polycyclic Aromatic Hydrocarbons Determination of PAHs was carried out at the Centre of Excellence for Environmental Forensics, Faculty of Environmental Studies, Universiti Putra Malaysia (UPM). The samples were purified and fractionated according to the method for polycyclic aromatic hydrocarbons (PAHs) [13]. Glassware for the experiment were rinsed sequentially with methanol, acetone and hexane to remove any organic contaminants and kept in an oven at 60°C. About 20g dry weights of the sludge samples were homogenised with anhydrous sodium sulphate (Na 2 SO 4 ) to remove excess water. Cellulose thimbles were filled with the samples and then transferred into the glass chamber. Round-bottom flasks were filled with 300mL dichloromethane (DCM) and then set up together with the glass chamber and heater in the extraction unit. The samples were then extracted using dichloromethane for 8h. The extracts were transferred into a pear-shape vial from the round-bottom flask after volume of the extract was reduced to dryness by a rotary evaporator. Extracted samples were purified and fractioned into aromatic fraction through silica gel column chromatography. About 50 μL of the PAH surrogate internal injection standard mixture (10ppm each component; anthracene-d10 and chrysene-d12) were added to the extracts. The extracts were transferred onto the top of 5% H 2 O deactivated silica gel column. The flasks with reduced sample were rinsed with 20mL hexane: DCM (3:1v/v). The volume of sample extracts was reduced to 2mL using a rotary evaporator for the next step which was injection into the column chromatography. In the second step of sample introduction into the column chromatography, fully activated silica gel was used to pack the column. The PAHs fractions were eluted with 16mL of dichloromethane/hexane (1:3v/v). Each PAH fraction was evaporated to approximately 1mL, transferred to a 1.5mL amber ampule, and evaporated to dryness under a gentle stream of nitrogen, then re-dissolved in 50 μL of isooctane containing p-terphenyl-d14 which was used as an internal injection standard (IISTD) for PAHs analysis for quantification and to eliminate errors due to variation in
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Article 2 – Environment (sludge)
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