Trends in removal of pharmaceuticals in contaminated water using waste coffee and tea-based materials with their derivatives.

The introduction of large amounts of pharmaceuticals into the environmental waters is well-documented in literature with their occurrence reported in all different water matrices accessible to humans and animals. At the same time, the increasing consumption of coffee and tea-based beverages results in the generation of solid waste, which is mostly disposed-off in the environment. To minimize environmental pollution, coffee and tea-based materials have been proposed as suitable options to remove pharmaceuticals in environmental waters. Therefore, this article provides a critical review on the preparation and applications of coffee and tea-based materials in removing pharmaceuticals from contaminated water. In this context, most studies in literature focused on the applications of these materials as adsorbents, while only limited work on their role in degradation of pharmaceuticals is discussed. The successful application in adsorption studies is attributed to high surface areas of adsorbents and the ability to easily modify the adsorbent surfaces by incorporating functional groups that provide additional oxygen atoms, which promote easy interactions with pharmaceuticals. Hence, the adsorption mechanisms are mostly described by hydrogen bonding, electrostatic and π-π interactions with sample pH playing a dominant role in the adsorption process. Overall, the present article focused on the developments, trends and future research direction on the preparations and applications of coffee and tea-based materials for efficient removal of pharmaceuticals in water. PRACTITIONER POINTS: Review of tea and coffee wastes application for removal of pharmaceuticals in water Key applications in adsorption and degradation of pharmaceuticals in water Removal mostly explained by hydrogen bonding, electrostatic, and π-π interactions Trends, gaps, and future research to be explored are reviewed and highlighted.

Quantification of some ARVs' removal efficiency from wastewater using a moving bed biofilm reactor.

To date, in South Africa alone, there are an estimated 4.5 million people receiving antiretroviral (ARV) therapy. This places South Africa as the country with the largest ARV therapy programme in the world. As a result, there are an increasing number of reports on the occurrence of ARVs in South African waters. Achieving efficient and bio-friendly methods for the removal of these pollutants is considered as a concern for environmental researchers. This study aims at studying the efficiency of a moving bed biofilm reactor (MBBR) system for removing ARVs from wastewater. A continuous-flow laboratory scale system was designed, built, installed, and operated at a carrier filling rate of 30%, an organic loading rate of 0.6 kg COD/m3.d-1 OLR, a hydraulic retention time of 18h, and a 27.8 mL/min flow rate. The systems were monitored over time for the elimination of conventional wastewater parameters i.e., Biological Oxygen Demand, Chemical Oxygen Demand, and nutrients. The results showed that the MBBR system as a bio-friendly method has high efficiency in removing Nevirapine, Tenofovir, Efavirenz, Ritonavir and Emtricitabine from the synthetic influent sample with an average removal of 62%, 74%, 94%, 94% and 95%, respectively, after 10 days of operation.

Synthesis, Characterization and Antimicrobial Activity of Zinc Oxide Nanoparticles against Selected Waterborne Bacterial and Yeast Pathogens.

The disinfection of wastewater using nanoparticles (NPs) has become a focal area of research in water treatment. In this study, zinc oxide (ZnO) NPs were synthesized using the microwave heating crystallization technique and characterized using transmission electron microscopy (TEM), Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction (XRD). Qualitative well diffusion and quantitative minimum inhibitory concentration (MIC) tests were conducted to determine the antimicrobial activity of ZnO NPs against selected waterborne pathogenic microbes. FTIR spectral studies confirmed that the binding of urea with Zn occurs through Zn-O stretching. XRD confirmed the crystallized identity in a hexagonal ZnO wurtzite-type structure. The formation of zones of inhibition and low MIC values in the antimicrobial analysis were indicative of the effective antimicrobial activity of zinc oxide nanoparticles against the test microorganisms. The application of metallic nanoparticles in water treatment could curb the spread of waterborne microbial diseases.

Scavenging of hexavalent chromium from aqueous solution by Macadamia nutshell biomass modified with diethylenetriamine and maleic anhydride.

Based on the premise that aqueous anions of hexavalent chromium (Cr(VI)) are capable of electrostatic interaction with cationic and polar active sites, acid-washed Madacamia nutshell biomass was sequentially treated with diethylenetriamine (DETA) and maleic anhydride (MA) to graft poly(diethylenetriamine-co-maleic anhydride). By displaying a new peak at 1685 cm-1 ascribed to amide CO stretching vibrations, Fourier transform infrared spectroscopy highlighted the formation of amide groups through reaction of DETA with carboxyl groups on the biomass surface. Scanning electron microscopic images of the MA-modified biomass displayed polymeric growths attributed to copolymerization of DETA with MA. The polar and ionizable amide and amine groups of the grafted copolymer endowed the adsorbent with Cr(VI) removal capabilities over a wide pH range demonstrated by removal efficiencies between 70.9% and 81.7% in the pH 1.6 to pH 10.0 range for the treatment of 20 mL solutions containing 100 mg L-1 Cr(VI) with 200 mg of adsorbent. Conformity of the adsorption isotherm data to the Freundlich model revealed the heterogeneous nature of the adsorbent surface, which comprised a variety of functional groups capable of interaction with Cr(VI) species in solution. The Sips isotherm model provided the best fit to the equilibrium experimental data, and the adsorption capacity was 779.1 mg g-1 at pH 1.6, room temperature and an adsorbent dosage of 5.0 g L-1. The findings indicate that Cr(VI) adsorption onto diethylenetriamine and maleic anhydride modified Madacamia nutshell biomass is a promising option for Cr(VI) removal from aqueous solutions.

Synthesis of molecularly imprinted polymers for extraction of fluoroquinolones in environmental, food and biological samples.

In recent years, fluoroquinolones have been found present in important water resources and food sources which compromises the food quality and availability, thereby, causing risks to the consumer. Despite the recent advancement in the development of analytical instrumentation for routine monitoring of fluoroquinolones in water, food, and biological samples, sample pre-treatment is still a major bottleneck of the analytical methods. Therefore, fast, selective, sensitive, and cost-effective sample preparation methods prior to instrumental analysis for fluoroquinolones residues in environmental, food and biological samples are increasingly important. Solid-phase extraction using different adsorbents is one of the most widely used pre-concentration/clean-up techniques for analysis of fluoroquinolones. Molecularly imprinted polymers (MIPs) serve as excellent effective adsorbent materials for selective extraction, separation, clean-up and preconcentration of various pollutants in different complex matrices. Therefore, synthesis of MIPs remains crucial for their applications in sample preparation as this offers much-needed selectivity in the extraction of compounds in complex samples. In this study, the progress made in the synthesis of MIPs for fluoroquinolones and their applications in water, food and biological samples were reviewed. The present review discusses the selection of all the elements of molecular imprinting for fluoroquinolones, polymerization processes and molecular recognition mechanisms. In conclusion, the related challenges and gaps are given to offer ideas for future research focussing on MIPs for fluoroquinolones.

Application of polymer-coated Macadamia integrifolia nutshell biomass impregnated with palladium for chromium(VI) remediation.

Freely suspended and porous basket restrained granules of palladium nanoparticles supported on polymer-grafted Macadamia nutshell biomass (Pd@Polym-MNS) composite were used for the treatment chromium(VI)-containing water. In the presence of formic acid, the Pd@Polym-MNS demonstrated its activity in the adsorption-reduction-based conversion of noxious chromium(VI) to less toxic chromium(III) with a low activation energy of 13.4 kJ mol-1, ΔH0 (+ 10.8 kJ mol-1), ΔS0 (-270.0 J mol-1 K-1), and ΔG0 (+ 91.3 to + 98.0 kJ mol-1) indicated the exothermic, endergonic and non-spontaneous nature of the catalytic redox reaction. In addition to facilitating easy recovery, rinsing, and reuse, restraining the Pd@Polym-MNS in the basket reactor helped maintain the integrity of the catalysts by preventing violent collisions of suspended granules with the mixing apparatus and the walls of the reaction vessel. Whereas the pseudo-first-order rate constant was recorded as 0.157 min-1 upon initial use, values of the mean and relative standard deviation for the second, third and fourth consecutive uses were found to be 0.219 min-1 and 1.3%, respectively. According to a response surface methodological approach to batch experimentation, the initial concentration of chromium(VI) and catalyst dosage had the greatest impact on the redox reaction rate, accounting for 85.7% and 11.6% of the variability in the value of the pseudo-first-order rate constant, respectively. Mutually beneficial effects of the combinations of high formic acid and low chromium(VI) concentration, high temperature and catalyst dosage as well as high formic acid and catalyst dosage were recorded.

Magnetic Ion Imprinted Polymers (MIIPs) for Selective Extraction and Preconcentration of Sb(III) from Environmental Matrices.

Antimony(III) is a rare element whose chemical and toxicological properties bear a resemblance to those of arsenic. As a result, the presence of Sb(III) in water might have adverse effects on human health and aquatic life. However, Sb(III) exists at very ultra-trace levels which may be difficult for direct quantification. Therefore, there is a need to develop efficient and reliable selective extraction and preconcentration of Sb(III) in water systems. Herein, a selective extraction and preconcentration of trace Sb(III) from environmental samples was achieved using ultrasound assisted magnetic solid-phase extraction (UA-MSPE) based on magnetic Sb(III) ion imprinted polymer-Fe3O4@SiO2@CNFs nanocomposite as an adsorbent. The amount of antimony in samples was determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The UA-MSPE conditions were investigated using fractional factorial design and response surface methodology based on central composite design. The Sb(III)-IIP sorbent displayed excellent selectivity towards Sb(III) as compared to NIIP adsorbent. Under optimised conditions, the enrichment factor, limit of detection (LOD) and limit of quantification (LOQ) of UA-MSPE/ICP-OES for Sb(III) were 71.3, 0.13 µg L-1 and 0.44 µg L-1, respectively. The intra-day and inter-day precision expressed as relative standard deviations (%RSDs, n = 10 and n = 5) were 2.4 and 4.7, respectively. The proposed analytical method was applied in the determination of trace Sb(III) in environmental samples. Furthermore, the accuracy of the method was evaluated using spiked recovery experiments and the percentage recoveries ranged from 95-98.3%.

Application of Hollow Fibre-Liquid Phase Microextraction Technique for Isolation and Pre-Concentration of Pharmaceuticals in Water.

In this article, a comprehensive review of applications of the hollow fibre-liquid phase microextraction (HF-LPME) for the isolation and pre-concentration of pharmaceuticals in water samples is presented. HF-LPME is simple, affordable, selective, and sensitive with high enrichment factors of up to 27,000-fold reported for pharmaceutical analysis. Both configurations (two- and three-phase extraction systems) of HF-LPME have been applied in the extraction of pharmaceuticals from water, with the three-phase system being more prominent. When compared to most common sample preparation techniques such as solid phase extraction, HF-LPME is a greener analytical chemistry process due to reduced solvent consumption, miniaturization, and the ability to automate. However, the automation comes at an added cost related to instrumental set-up, but a reduced cost is associated with lower reagent consumption as well as shortened overall workload and time. Currently, many researchers are investigating ionic liquids and deep eutectic solvents as environmentally friendly chemicals that could lead to full classification of HF-LPME as a green analytical procedure.

Palladium nanoparticles dispersed on functionalized macadamia nutshell biomass for formic acid-mediated removal of chromium(VI) from aqueous solution.

Driven by the need for sustainably sourced catalysts and the use of reaction systems that generate environmentally benign by-products, the present study aimed to deposit stable, dispersed palladium (Pd) nanoparticles on the modified surfaces of granular macadamia nutshell (MNS) biomass for catalytic reduction of hexavalent chromium (Cr(VI)) to trivalent chromium (Cr(III)). Through wet impregnation with Pd(II) ions and subsequent hydrazine-mediated reduction to Pd(0), Pd nanoparticles were embedded in a scaffold of polyethyleneimine grafted on bleached MNS previously coated with a chemically bound layer of polyglycidyl methacrylate. Imagery from scanning electron microscopy showed the formation of different layers of the polymeric coating and dispersed palladium resulting from surface modification and palladium nanoparticle synthesis, respectively. X-ray diffraction analysis confirmed the formation of Pd on the modified MNS surface and suggested an estimated crystallite size of 5.0 nm. The supported nanoparticles exhibited catalytic activity in formic acid-mediated Cr(VI) reduction and showed promising stability with consecutive reuse. These findings set the stage for advanced studies into performance optimization.