Anele Mpupa

Microwave assisted solid phase extraction for separation preconcentration sulfamethoxazole in wastewater using tyre based activated carbon as solid phase material prior to spectrophotometric determination

This work was chiefly encouraged by the continuous consumption of antibiotics which eventually pose harmful effects on animals and human beings when present in water systems. In this study, the activated carbon (AC) was used as a solid phase material for the removal of sulfamethoxazole (SMX) in wastewater samples. The microwave assisted solid phase extraction (MASPE) as a sample extraction method was employed to better extract SMX in water samples and finally the analysis of SMX was done by the UV-Vis spectrophotometer. The microwave assisted solid phase extraction method was optimized using a two-level fractional factorial design by evaluating parameters such as pH, mass of adsorbent (MA), extraction time (ET), eluent ratio (ER) and microwave power (MP). Under optimized conditions, the limit of detection (LOD) and limit of quantification (LOQ) were 0.5μgL-1 and 1.7μgL-1, respectively, and intraday and interday precision expressed in terms of relative standard deviation were >6%.The maximum adsorption capacity was 138mgg-1 for SMX and the adsorbent could be reused eight times. Lastly, the MASPE method was applied for the removal of SMX in wastewater samples collected from a domestic wastewater treatment plant (WWTP) and river water.

Adsorptive removal of microcystin-LR from surface and wastewater using tyre-based powdered activated carbon: Kinetics and isotherms

ABSTRACT Microcystin LR (MC‐LR) is a highly toxic compound and it is known for its adverse health effect on both humans and animals. Due to the ineffectiveness of conventional water treatments methods, for the past decades, researchers have been developing cost‐effective ways of removing MC‐LR from water bodies. This study reports the application of powdered activated carbon (PAC) obtained from the waste tyre for the removal of MC‐LR. The choice of the adsorbent was chosen due to its attractive properties. The prepared tyre‐based PAC was found to have the large surface area (1111 m2 g−1). The detection of MC‐LR was achieved using high performance liquid chromatography (HPLC) coupled with a PDA detector. The experimental parameters (such as optimum pH, dosage and contact time) affecting the removal of MC‐LR using tyre based‐powdered activated carbon were optimized using response surface methodology (RSM). Maximum removal of MC‐LR was achieved under the following optimum conditions; sample pH 4, carbon dosage concentration 10,000 mg L−1 and contact time of 34 min. Under optimum conditions, kinetic studies and adsorption isotherms reflected better fit for pseudo‐second‐order rate and Langmuir isotherm model, respectively. The optimized method was applied for the removal of MC‐LR in wastewater sample. The effluent and influent sample contained initial concentrations ranging from 0.52 to 8.54 &mgr;g L−1 and the removal efficiency was 100%. HighlightsQuantitative removal of MC‐LR was achieved using tyre based activated carbon.The removal of MC‐LR followed pseudo‐second‐order kinetics and Langmuir isotherm.The optimized method was applied for the removal of MC‐LR in wastewater samples.

Vortex assisted-supramolecular solvent based microextraction coupled with spectrophotometric determination of triclosan in environmental water samples

Abstract A simple, fast and environmental friendly vortex assisted-supramolecular solvent based microextraction (VA-SSME) method was developed for the preconcetration of triclosan in wastewater prior to UV spectrophotometric determination. To achieve maximum sensitivity and accuracy for the target analyte, the experimental parameters affecting the VA-SSME procedure were optimized using response surface methodology (RSM). Under optimised conditions, the correlation coefficient (R2) and recoveries were 0.9994 and 100.31-118.5%, respectively. The intra-day (repeatability) and inter-day (reproducibility) precisions expressed in terms of relative standard deviation (RSD) were 2-4% and 5.2%, respectively. The preconcentration factor and limits of detection (LOD) and quantification (LOQ) were found to be 90, 0.28 μg L−1 and 0.92 μg L−1, respectively. The developed VA-SSME/UV method was applied for the determination of triclosan in real samples collected over a period of three months. The analytical results obtained showed that triclosan was frequently detected in influent wastewater samples but was not detected in effluent samples.

In-Syringe Micro Solid-Phase Extraction Method for the Separation and Preconcentration of Parabens in Environmental Water Samples

In this study, a simple, rapid and effective in-syringe micro-solid phase extraction (MSPE) method was developed for the separation and preconcetration of parabens (methyl, ethyl, propyl and butyl paraben) in environmental water samples. The parabens were determined and quantified using high performance liquid chromatography and a photo diode array detector (HPLC-PDA). Chitosan-coated activated carbon (CAC) was used as the sorbent in the in-syringe MSPE device. A response surface methodology based on central composite design was used for the optimization of factors (eluent solvent type, eluent volume, number of elution cycles, sample volume, sample pH) affecting the extraction efficiency of the preconcentration procedure. The adsorbent used displayed excellent absorption performance and the adsorption capacity ranged from 227–256 mg g−1. Under the optimal conditions the dynamic linear ranges for the parabens were between 0.04 and 380 µg L−1. The limits of detection and quantification ranged from 6–15 ng L−1 and 20–50 ng L−1, respectively. The intraday (repeatability) and interday (reproducibility) precisions expressed as relative standard deviations (%RSD) were below 5%. Furthermore, the in-syringe MSPE/HPLC procedure was validated using spiked wastewater and tap water samples and the recoveries ranged between from 96.7 to 107%. In conclusion, CAC based in-syringe MSPE method demonstrated great potential for preconcentration of parabens in complex environmental water.

Ultrasound-assisted dispersive solid phase nanoextraction of selected personal care products in wastewater followed by their determination using high performance liquid chromatography-diode array detector

This study reports a rapid and simple method based on ultrasound-assisted dispersive solid phase nanoextraction (UA-SPNE) method for the extraction and preconcentration of selected personal care products using MPC@Al2O3-SiO2 nano adsorbent. A high performance liquid chromatograph equipped with a diode array detector (HPLC-DAD) was used to detect the analytes of interest. Experimental parameters affecting the extraction and preconcentration efficiency of the UA-SPNE (such as mass of adsorbent, extraction time, sample pH and eluent volume,) were optimized using fractional factorial design and response surface methodology based on central composite design. Under optimized conditions, the linear range for benzophenone, N,N-diethyl-3-methylbenzamide and trichlorocarbanilide were in the interval of LOQ-1000u2009μg L-1 with correlation coefficients ranged from 0.9907 to 0.9977. The limits of detection and limits of quantification were 0.066-0.096u2009μg L-1 and 0.22-0.32u2009μg L-1, respectively. The accuracy of the UA-SPNE/HPLC-DAD method was evaluated using spike recovery test and the recoveries were in the range of 98-107%. The repeatability and reproducibility of the method 0.8-1.0 % and 2.4-4.4%, respectively.

Near-Infrared Spectroscopy Combined with Multivariate Tools for Analysis of Trace Metals in Environmental Matrices

Environmental contamination by trace elements is becoming increasingly important problem worldwide. Trace metals such as cadmium, copper, lead, chromium, and mercury are major environmental pollutants that are predominantly found in areas with high anthropogenic activities. Therefore, there is a need for rapid and reliable tools to assess and monitor the concentration of heavy metal in environmental matrices. A nondestructive, cost-effective, and environmentally friendly procedure based on near-infrared reflectance spectroscopy (NIRS) and chemometric tools has been used as alternative technique for the simultaneous estimation of various heavy metal concentrations in environmental sample. The metal content is estimated by assigning the absorption features of metals associated with molecular vibrations of organic and inorganic functional groups in organic matter, silicates, carbonates, and water at 780–2500 nm in the near-infrared region. This chapter, reviewed the application of NIRS combined with chemometric tools such as multiple linear regression (MLR), principal component regression (PCR), and partial least squares (PLS) regression. The disadvantages and advantages of each chemometric tool are discussed briefly.

Ultrasonic-Assisted Dispersive Solid Phase Microextraction (UA-DSPME) Using Silica@Multiwalled Carbon Nanotubes Hybrid Nanostructures Sorbent for Preconcentration of Trace Aflatoxin B1 in Liquid Milk Samples

A reliable, simple, rapid and cost-effective extraction method based on ultrasonic-assisted dispersive solid phase microextraction (UA-DSPME) method using silica@multiwalled carbon nanotubes hybrid nanostructures combined with spectrophotometric detection was developed for the first time for preconcentration and determination of aflatoxin B1 (AFB1) in liquid milk samples. Two level factorial design and central composite design in combination with response surface methodology were used to evaluate the factors affecting extraction and preconcentration procedure. The influence of different variables including mass of adsorbent, extraction time, eluent volume and sample volume was investigated in the optimization study. Under the optimal conditions, a dynamic linear range of 0.3–250 μg L−1 with detection limit of 0.1 μg L−1 was obtained. The intraday and interday precisions expressed as relative standard deviations were 3.2% and 4.3% respectively. The developed UA-DSPME/UV-Vis method was applied for extraction and preconcentration of AFB1 in real milk samples. As a result of relatively high enrichment factor (108), satisfactory extraction recoveries (96.8–99.2%) using only 62 mg of an adsorbent were achieved.