Comparative study of pb(II) and cr(VI) removal using Cassava peel (Manihot Esculenta Crantz).

The present study investigated the capability of cassava peel (Manihot Esculenta Crantz) in Pb(II) and Cr(VI) removal. The comparative study was conducted using batch method observing some parameters. The results indicated that the optimum adsorption of Pb(II) occurred at pH 5, initial concentration of 1000 mg/L, and contact time of 50 min. On the other hand, the optimal adsorption of Cr(VI) was achieved at pH 2, initial concentration of 1200 mg/L, and contact time of 70 min. The adsorption isotherms of both metals tended to follow the Langmuir model, while the adsorption kinetics suited to pseudo-second-order model. Thermodynamic parameters indicated that the adsorption process was spontaneous (ΔG° negative), endothermic (ΔH° positive), and exhibited surface dispersion on the biosorbent (ΔS° positive). Characterization using Fourier Transform Infrared (FTIR), X-Ray Fluorescence (XRF), Scanning Electron Microscopy (SEM), and Thermogravimetry (TGA) provided evidence of both physical and chemical adsorption. The adsorption capacity of cassava peel was also tested on samples collected approximately 30 m from the bay shoreline, resulting in a removal percentage of 94.67% for Pb(II) and 82.28% for Cr(VI) under optimal pH and contact time conditions.

A facile-treated sago bark (Metroxylon sagu) as a biosorbent for Cd(II) ions removal in aqueous solution by using the batch method.

The performance of sago bark for Cd(II) ions removal in the aqueous solution has been investigated using the batch method. The sago bark was facile-treated using HNO3 0.01 M and its ability on Cd(II) removal was evaluated under specific parameters such as pH, contact time, agitation speed, temperature, initial concentration, and adsorbent mass. The adsorption capacity of sago bark was found to be 2.473 mg/g. The Langmuir isotherm model corresponding to the monolayer adsorption process described the adsorption data well. The kinetic and thermodynamic evaluation confirmed that the Cd(II) ion sorption followed a pseudo-second-order model and endothermic. The adsorption capacity decreased after three times adsorption-desorption cycles. This result showed that the treated sago bark could be a good candidate as an adsorbent for Cd(II) removal.

Effect of Phaleria Macrocarpa Flesh Fruits Extract on MDA Level, SGOT and SGPT Activity in Serum of Experimental Rats Contaminated by Cd (II) Ion.

BACKGROUND: Cd (II) ion is a heavy metal that has a toxic ability in the human body. P. macrocarpa has been used as anticancer, Diabetes Mellitus and antimicrobe because it consists of flavonoid, steroid, and tannin. AIM: The purpose of this study was to investigate the effectiveness of P. macrocarpa fruits extract as an antidote for the toxicity of Cd (II) in the liver of experimental rats. METHODS: The experimental laboratory was done by using 9 female of Wistar rats (Rattus novergicus) that divided into 3 groups with the age between 2.5-3 months and weight between 133-160 grams. The first group was a control given distilled water and a normal diet. The second group was given antidote 5 mL of P. macrocarpa fruit extract x BW/200 g dosage for 7 days and induced by 1000 mg/L of Cd (II) ion with dosage of 1 mL x BW/200 g. The third group was given 1000 mg/L Cd (II) ion only of 1 mL x BW/200 g. After 5 hours, the blood sample was taken for analysis of MDA, SGOT, and SGPT. RESULTS: As the result of experimental rats exposed with Cd (II) ion, there are significant decreasing of all the observed parameters including MAD, SGOT and SGPT with percentage 71.5%, 72.1%, and 93.6% respectively. CONCLUSION: The rats given with the antidote of Phaleria macrocarpa flesh fruit were able to protect the liver from damage due to exposure to Cd (II) as seen from the decrease in liver function enzyme parameters namely SGOT and SGPT.

Electrochemical Determination of Chromium(VI) in River Water with Gold Nanoparticles-Graphene Nanocomposites Modified Electrodes.

In this study, nanocomposites of ligand-free gold nanoparticles that are anchored onto the graphene surface (Graphene/AuNPs) were synthesized by a sonochemical method in a single reaction step. A highly sensitive amperometric sensor using Graphene/AuNPs is proposed for the determination of trace hexavalent chromium Cr(VI) in environmental water samples. Compared with a gold electrode, a glassy carbon electrode and a AuNPs modified glassy carbon electrode, the Graphene/AuNPs modified glassy carbon electrode exhibits the highest electrocatalytic activity and stability towards the reduction of Cr(VI), based on the results by cyclic voltammetry and electrochemical AC impedance studies. This study shows that the Graphene/AuNPs-based sensor can detect Cr(VI) with a low detection limit of 10 nM (∼0.5 µg/L), a wide dynamic range of 0 to 20 µM (R = 0.999) and very good selectivity and reproducibility. The electrode is applied to the determination of Cr(VI) in river samples with satisfactory recovery values.

Anodic Stripping Voltammetry for the Determination of Trace Cr(VI) with Graphite/Styrene-Acrylonitrile Copolymer Composite Electrodes.

A square-wave anodic stripping voltammetry (SWASV) for the determination of trace amounts of hexavalent chromium Cr(VI) at a graphite/styrene-acrylonitrile (Graphite-SAN) copolymer composite electrode is described. This method involves a preconcentration step whereby the trace Cr(VI) was cathodically reduced to Cr(III) on an electrode surface in an acetate buffer (pH 5), followed by an anodic stripping technique with a square-wave voltammetric mode. It has been shown that the analytical sensitivity is significantly improved at the Graphite-SAN copolymer composite electrode in comparison with the conventional glassy carbon electrode, due to the strong interaction between Cr(III) and the nitrile end group of the SAN copolymer. The SWASV response was characterized with respect to the pH, deposition potential, possible interferences, etc. Under the optimal conditions, the stripping peak height linearly increased with the concentration of Cr(VI) in a range from 0 to 150 ng mL-1 with a correlation coefficient of 0.997, and a detection limit of 4.2 ng mL-1 was achieved based on signal-to-noise ratio of about 3. The Graphite-SAN composite electrode exhibited some interesting advantages, such as high mechanical rigid, easy surface renewable, higher sensitivity and better peak resolution in comparison with the results at conventional glassy carbon electrodes. They have been applied to the determination of Cr(VI) in real water samples with satisfactory recoveries.

Liquid chromatographic determination of alcohols in food and beverages with indirect polarimetric detection using a beta-cyclodextrin mobile phase.

An indirect polarimetric detection method for the determination of alcohols has been proposed in liquid chromatography (LC). Optically active mobile-phase additives, such as beta-cyclodextrin (beta-CD), could be used to visualize optically inactive alcohols in reversed-phase LC. The visualization of alcohols is based on a perturbation of the partition of beta-CD caused by the alcohols. The detection limits of the present system at a signal-to-noise ratio of 3 were 0.031, 0.019, 0.018, 0.013, 0.011, 0.008 and 0.008% (v/v) for ethanol, 2-propanol, 1-propanol, 2-methyl-2-propanol, 2-butanol, 2-methyl-1-propanol and 1-butanol, respectively. The method was successfully applied to the determination of ethanol present in food and beverage samples.