T. A. M. Msagati

Polyurethane composite adsorbent using solid phase extraction method for preconcentration of metal ion from aqueous solution

Polyurethane composite adsorbent polymeric material was prepared and investigated for selected solid-phase extraction for metal ions, prior to its determination by inductively coupled plasma optical emission spectrometry. The surface characterisation was done using Fourier transform infrared spectroscopy. The separation and preconcentration conditions of the analytes investigated includes influence of pH, sample loading flow rate, elution flow rate, type and concentration of eluents. The optimum pH for the highest efficient recoveries for all metal ions, which ranged from 70 to 85xa0%, is pH 7. The metal ions were quantitatively eluted with 5xa0mL of 2xa0mol/L HNO3. Common coexisting ions did not interfere with the separation. The percentage recovery of the metal ions ranged between 70 and 89xa0%, while the results for the limit of detection and limit of quantification ranged from 0.249 to 0.256 and 0.831 to 0.855, respectively. The experimental tests showed good preconcentration results of trace levels of metal ions using synthesised polyurethane polymer adsorbent composite.

Activated Carbon from Lignocellulosic Waste Residues: Effect of Activating Agent on Porosity Characteristics and Use as Adsorbents for Organic Species

This paper reports on the effect of activating agents such as the impregnation ratio of phosphoric acid (1:1–1:5) at constant activation temperature on the performance of porous activated carbon from waste residues (maize tassel). The variation in the impregnation ratio of the produced activated carbon (AC) from 1:1 to 1:5 enabled the preparation of a high surface area (1,263xa0m2/g) and a large pore volume (1.592xa0cm3/g) of AC produced from maize tassel (MT) using a convectional chemical activating agent (phosphoric acid). Impregnation ratios (IR) of the precursors were varied between 1:1 and 1:5 in which it was found that the ratio of 1:4 was optimal based on the high surface area, while 1:5 has the optimal pore volume value for the produced activated carbon.

Steam activation, characterisation and adsorption studies of activated carbon from maize tassels

In this paper, steam-produced activated carbon (STAC) from maize tassel (MT) was evaluated for its ability to remove basic dye (methylene blue MB) from aqueous solution in a batch adsorption process. The equilibrium experiments were conducted in the range of 50–300 mg/L initial MB concentrations at 30°C, for effect of pH, adsorbent dosage and contact time. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models of adsorption. Freundlich adsorption isotherm was found to have highest value of R2(R2=0.97) compared to other models of Langmuir and Temkin having (0.96 and 0.95 respectively). STAC has a high adsorptive capacity for MB dye (200 mg/g) and also showed favourable adsorption for the dye with the separation factor (RL<1) for the dye-activated carbon system. The kinetic data obtained were analysed using pseudo first-order kinetic equation and pseudo second-order kinetic equation. The experimental data fitted well into pseudo second-order kinetic equation, as demonstrated by the high value of R2.

Adsorption studies for the simultaneous removal of arsenic and selenium using naturally prepared adsorbent materials

The adsorption properties of eggshell membranes (ESM), eggshells (ES) and orange peels (OP) were studied for the removal of arsenic (total As) and selenium (total Se). The effect of chemical treatment of these adsorbents by HNO3 and NaOH was also investigated using Fourier transform infrared spectroscopy (FT-IR). Analysis of the FT-IR spectra showed that treatment with NaOH and HNO3 had an effect on the functional groups present in the materials and also on the adsorption by extension. Thermal analysis showed that ES were more thermally stable than the others with no water molecules in their matrix, which could have caused a substantial weight loss at around 70xa0°C. In terms of adsorption capacities, chemical treatment increased the adsorption capacities of ESM and OP achieving up to 170xa0μgxa0g−1 (As) and 160xa0μgxa0g−1 (Se), and 120xa0μgxa0g−1 (As) and 70xa0μgxa0g−1 (Se), respectively, with not much activity for ES in terms of adsorption. The two adsorbents (NaOH-treated OP and ESM) were then tested in environmental water samples and the results showed that 68.9xa0% of As and 74.8xa0% of Se, and 54.1xa0% of As and 47.3xa0% of Se were removed from domestic wastewater samples investigated using OP and ESM, respectively. Moreover, better selectivities towards the compounds of interest were achieved.

Evaluation of groundwater quality in Madurai City, South India for drinking, irrigation and construction purposes

The present research is contributed on groundwater quality, its deterioration and evaluation based on drinking, irrigation, and construction standards. The study area chosen for investigation on water quality is the Tirunagar (TN) area, located in the south-west of Madurai City. The TN area was formerly an agricultural land but presently a residential area that is at a starvation of drinking water quality. A total of 49 bore well samples from TN and Amaithisolai (AS) were investigated for drinking, irrigation, and construction qualities based on various physicochemical parameters. The chemistry of groundwater samples was reflected from very hard and noncarbonate-dominating species. TN was recorded with higher inorganic species in groundwater sources than AS. The Water Quality Index values indicated that 75xa0% of the samples fall under excellent category and the positive Langelier Saturation Index values of the samples highlighted their tendency to deposit calcium carbonate. The Gibbs plot showed that AS samples were categorized under the domination of rock–water interaction whereas the TN samples under evaporation zone. The US Salinity Laboratory Staff plot depicted that all the groundwater sources at AS with C3S1 type whereas 88xa0% of the TN sources represented C4S1 type. The results from Wilcox diagram for irrigation inferred that the groundwater sources at AS were permissible, but 68xa0% of the samples at TN was registered under unfit type. The suitability of groundwater from the knowledge of residual sodium carbonate, sodium absorption ratio, and sodium percentage was also investigated. The perception based on standards recommended the groundwater sources for construction activities. The contribution of ionic species and inter-relationship among the ions were also interpreted from the knowledge of statistical studies.

Preparation and use of maize tassels’ activated carbon for the adsorption of phenolic compounds in environmental waste water samples

The determination and remediation of three phenolic compounds bisphenol A (BPA), ortho-nitrophenol (o-NTP), parachlorophenol (PCP) in wastewater is reported. The analysis of these molecules in wastewater was done using gas chromatography (GC)u2009×u2009GC time-of-flight mass spectrometry while activated carbon derived from maize tassel was used as an adsorbent. During the experimental procedures, the effect of various parameters such as initial concentration, pH of sample solution, eluent volume, and sample volume on the removal efficiency with respect to the three phenolic compounds was studied. The results showed that maize tassel produced activated carbon (MTAC) cartridge packed solid-phase extraction (SPE) system was able to remove the phenolic compounds effectively (90.84–98.49xa0%, 80.75–97.11xa0%, and 78.27–97.08xa0% for BPA, o-NTP, and PCP, respectively) . The MTAC cartridge packed SPE sorbent performance was compared to commercially produced C18 SPE cartridges and found to be comparable. All the parameters investigated were found to have a notable influence on the adsorption efficiency of the phenolic compounds from wastewaters at different magnitudes.

Polypropylene–zeolite polymer composites for water purification: synthesis, characterisation and application

AbstractThis paper reports on the preparation of polypropylene–zeolite polymer composites using the melt-mixing compounding technique. These polymer composites have shown unique and enhanced properties as compared to their monolithic constituents. All polymer hybrids were formed by solvent-less melt-intercalation and extrusion. The changes in conventional properties of the two mixed constituents were probed using techniques, such as scanning electron microscopy, X-ray diffraction (XRD), Fourier transform infrared spectroscopy and thermogravimetric analysis. XRD analyses showed a co-existence of intercalated and exfoliated zeolite phases. The influence of operational conditions such as exposure time, zeolite loading rate and solution pH were determined. An optimum zeolite loading of 15xa0wt.% was observed. Solution pH had the greatest influence on the removal of both heavy metals and substituted phenols. The polymer composites exhibited both adsorption and ion-exchange properties in the removal of heavy meta...