Removal of antiretroviral drugs from wastewater using activated macadamia nutshells: Adsorption kinetics, adsorption isotherms, and thermodynamic studies.

Antiretroviral drugs (ARVDs) have been extensively employed in health care to improve the quality of life and lifecycle longevity. However, overuse and improper disposal of ARVDs have been recognized as an emerging concern whereby wastewater treatment major recipients. Therefore, in this work, the activated macadamia nutshells (MCNs) were explored as low-cost adsorbents for the removal of ARVDs in wastewater samples. Fourier transform infrared spectroscopy (FTIR), Scanning Electron microscopy (SEM), Brunauer-Emmet-Teller (BET), and Powder X-ray diffraction (PXRD). The highest removal efficiency (R.E) was above 86% for the selected analytes nevirapine, abacavir, and efavirenz. The maximum adsorption capacity of the functionalized MCN adsorbent was 10.79, 27.44, and 38.17 mg/g for nevirapine, abacavir, and efavirenz for HCl-modified adsorbent. In contrast, NaOH modified had adsorption capacities of 13.67, 14.25, and 20.79 mg/g. The FTIR showed distinct functional groups OH and CO, which facilitate the removal of selected ARVDs. From studying kinetics parameters, the pseudo-second-order (R2 = 0.990-0.996) was more dominant than the pseudo-first-order (R2 = 0.872-0.994). The experimental data was most fitted in the Freundlich model with (R2 close to 1). The thermodynamic parameters indicated that the adsorption process was spontaneous and exothermic. The study indicated that MCNs are an eco-friendly, low-cost, and effective adsorbent for the removal of nevirapine, abacavir, and efavirenz. PRACTITIONER POINTS: Modification macadamia nutshell with HCl and NaOH improved physio-chemical properties that yielded high removal efficiency compared with raw macadamia nutshells. Modification of macadamia by HCl showed high removal efficiency, which could be attributed to high interaction such as H-bonding that improves adsorption. The macadamia nutshell as an adsorbent showed so much robustness with regeneration studies yielding to about 69.64% of selected compounds.

Efficiency comparison of extraction methods for the determination of 11 of the 16 USEPA priority polycyclic aromatic hydrocarbons in water matrices: Sources of origin and ecological risk assessment.

As a result of their toxicity, ease of analysis, and environmental occurrence, 16 polycyclic aromatic hydrocarbons (PAHs) were chosen as priority pollutants by the USEPA. Few studies have been conducted to assess the levels of PAHs in South Africa, especially KwaZulu Natal province, and no work has been done in the selected study area. Therefore, this study aimed to evaluate the levels of such PAHs in river water and wastewater samples and evaluate their source and ecological risk. The status of these PAHs in the South African environment has not been investigated fully, which is a gap this study intended to fill. The PAHs were determined using solid-phase extraction (SPE) and dispersive liquid-liquid microextraction (DLLME) methods. The optimization and validation of these methods indicated that both methods can be used for the extraction of PAHs in liquid samples. This is because of the acceptable %recovery of 72.1%-118% for SPE and 70.7%-88.4% for DLLME with a %RSD less than 10% (indicating high precision) that was obtained. The limit of detection and limit of quantification ranged from 5.0 to 18 ng/L and 6.0-20 ng/L for SPE and from 10 to 44 ng/L and 11 to 63 ng/L for DLLME. These results demonstrated that SPE is more accurate and sensitive than DLLME, which was also confirmed by statistical analysis. The PAH concentration levels ranged from not detected (nd) to 1046 ng/L in river water and nd to 778 ng/L in wastewater samples with naphthalene demonstrating dominance over all other PAHs in both water matrices. The PAHs were found to be of petrogenic origin and posed low ecological risk on average. Integr Environ Assess Manag 2024;00:1-13. © 2024 The Authors. Integrated Environmental Assessment and Management published by Wiley Periodicals LLC on behalf of Society of Environmental Toxicology & Chemistry (SETAC).

Methods optimization and application: Solid phase extraction, ultrasonic extraction and Soxhlet extraction for the determination of antiretroviral drugs in river water, wastewater, sludge, soil and sediment.

The continuous release of antiretroviral drugs into the environmental has resulted in the interest to assess their occurrence in various environmental matrices. Their presence has led to antiretroviral drugs being considered the pollutants of concern due to their possible alterations of the ecosystem as well as the antiviral resistance that may develop upon their unintentional consumption. Therefore, in this work, solid phase extraction (SPE), ultrasonic extraction (UE), Soxhlet extration (SE) and liquid chromatography coupled to photodiode array detector (LC-PDA) methods have been optimized and validated. They were then applied for the simultaneous determination of abacavir, nevirapine and efavirenz antiretroviral drugs in wastewater, river water, sludge, soil and sediments. The percentage recoveries ranged from 71% to 112% for SPE, 88 - 108% for SE and 61 - 104% for UE. Good precision with a relative standard deviation less than 20% in all compounds for all methods was obtained. The LODs and LOQs ranged between 0.68 and 0.77 µg/L and 2.1-2.4 µg/L for SPE; 0.8-0.9 µg/kg and 2.3-2.8 µg/kg for SE and 1.6-2.8 µg/kg and 4.9 - 7.0 µg/kg for UE, respectively. The concentrations ranged from

Optimization and application of hollow fiber liquid-phase microextraction and microwave-assisted extraction for the analysis of non-steroidal anti-inflammatory drugs in aqueous and plant samples.

Human consumption of non-steroidal anti-inflammatory drugs (NSAIDs) is increasing, which poses a great risk of pollution by these pharmaceuticals on the aquatic environment. Therefore, this study reports the optimization of microwave-assisted extraction using water as a green solvent and hollow fiber liquid-phase microextraction (HF-LPME) methods followed by high-performance liquid chromatography-high resolution mass spectrometry analysis of NSAIDs in wastewater and aquatic plant, Eichhornia crassipes. The optimized MAE resulted in efficient transfer of selected NSAIDs from plant samples into the aqueous phase yielding the recoveries ranging from 91 to115%. A multivariate approach based on half fractional factorial and central composite design was used during the optimization of HF-LPME. Under the optimized conditions, the maximum enrichment factors for naproxen, fenoprofen, diclofenac, and ibuprofen were 49, 126, 93 and 156, respectively. The overall analytical method recoveries ranged from 86 to 116% while the limits of quantitation for wastewater and plant samples ranged from 0.09 to 0.59 µg L-1 and from 0.11 to 0.59 µg kg-1, respectively. The precision of the proposed analytical method which was measured in terms of RSD values did not exceed 5%. Naproxen was the most abundant compound in both wastewater and the Eichhornia crassipes plant samples with concentrations of up to 3.30 µg L-1 and 10.97 µg kg-1, respectively. The detection of NSAIDs in Eichhornia crassipes means this plant has the ability to bioaccumulate pharmaceutical load in surface water.

Determination of selected antiretroviral drugs in wastewater, surface water and aquatic plants using hollow fibre liquid phase microextraction and liquid chromatography - tandem mass spectrometry.

This work describes a simple and sensitive method for the simultaneous isolation, enrichment, identification and quantitation of selected antiretroviral drugs; emtricitabine, tenofovir disoproxil and efavirenz in aqueous samples and plants. The analytical method was based on microwave extraction and hollow fibre liquid phase microextraction technique coupled with ultra-high pressure liquid chromatography-high resolution mass spectrometry. A multivariate approach via a half-fractional factorial design was used focusing on six factors; donor phase pH, acceptor phase HCl concentration, extraction time, stirring rate, supported liquid membrane carrier composition and salt content. The optimal enrichment factors for emtricitabine, tenofovir disoproxil and efavirenz from aqueous phase were 78, 111 and 24, respectively. The analytical method yielded recoveries in the range of 86 to 111%, and quantitation limits for emtricitabine, tenofovir disoproxil and efavirenz in wastewater were 0.033, 0.10 and 0.53 µg L-1, respectively. The drugs were detected in most samples with concentrations up to 37.6 µg L-1 recorded for efavirenz in wastewater effluent. Roots of the water hyacinth plant had higher concentrations of the investigated drugs ranging from 7.4 to 29.6 µg kg-1. Overall, hollow fibre liquid phase microextraction proved to be an ideal tool for isolating and pre-concentrating the selected antiretroviral drugs from environmental samples.

Development and application of SPE-LC-PDA method for the determination of triazines in water and liquid sludge samples.

The solid phase extraction method has been developed and applied for the simultaneous analysis of the five most commonly used triazine pesticides. The analysis was conducted using a liquid chromatography-photodiode array detector, which was first optimized to improve the limit of quantification and detection. The extraction parameters (conditioning solvent and sample volume) that affect the recovery of the analytes for solid phase extraction were optimized. The recoveries obtained were between 107 and 111%. The limit of detection ranged between 0.668 and 1.16 µg/L and the limit of quantification ranged between 2.01 and 3.54 µg/L. Good precision with a relative standard deviation of less than 8% in all compounds was achieved. The developed and validated method was then applied to river water, wastewater and sludge samples from around KwaZulu-Natal. The quantified concentrations ranged from 8.35 to 2820 µg/L, 2.41-48.7 µg/L and 3.20-65.0 µg/L in sludge, wastewater, and river water respectively.

Synthesis and application of a molecularly imprinted polymer in selective solid-phase extraction of efavirenz from water.

Efavirenz is one of the antiretroviral drugs widely used to treat the human immunodeficiency virus. Antiretroviral drugs have been found to be present in surface water and wastewater. Due to complexity of environmental samples, solid-phase extraction (SPE) is used for isolation and pre-concentration of antiretroviral drugs prior to their chromatographic analysis. However, the commercially available SPE sorbents lack selectivity, which tends to prolong the analysis time. Therefore, in this study a molecularly imprinted polymer was synthesized for the specific recognition of efavirenz and then applied as the SPE sorbent for its extraction from wastewater and surface water samples. The imprinted and non-imprinted polymers were synthesized using a bulk polymerization technique where efavirenz was used as the template, 2-vinylpyridine as functional monomer, 1,1'-azobis-(cyclohexanecarbonitrile) as initiator, ethylene glycol dimethacrylate as cross-linker and toluene:acetonitrile (9:1, v/v) as the porogenic solvent mixture. The characterization was performed using Fourier transform infrared spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, elemental analysis, and thermogravimetric analysis techniques. Results showed better selectivity of molecularly imprinted polymer to efavirenz than did non-imprinted polymer. The analysis was performed using high performance liquid chromatography equipped with a photo-diode array detector. The analytical method gave a detection limit of 0.41 µg/L and the analyte recovery of 81% in wastewater. The concentrations found in wastewater ranged from 2.79 to 120.7 µg/L, while in surface water they were between 0.975 and 2.88 µg/L. Therefore, the results of this study show a strong need for a detailed screening of efavirenz in major water utilities in the country.