Green synthesis of Ag nanoparticles from Argemone mexicana L. leaf extract coated with MOF-5 for the removal of metronidazole antibiotics from aqueous solution.

There are growing concerns about the toxicity of metronidazole (MNZ) antibiotics in wastewater, which must be removed. This study used AgN/MOF-5 (1:3) to investigate the adsorptive removal of MNZ antibiotics from wastewater. Green synthesis of Ag-nanoparticles was from Argemone mexicana leaf aqueous extract blended with the synthesized MOF-5 in 1:3 by proportion. The adsorption materials were characterized by scanning electron microscope (SEM), N2 adsorption-desorption analysis, X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The surface area increased due to the appearance of micropores. Besides, the efficiency of AgN/MOF-5 (1:3) for MNZ removal was evaluated by adsorption properties, including key influential parameters (adsorbent dosage, pH, contact time, etc.) and adsorption mechanism, kinetics/isotherms. The results from the adsorption process conformed to pseudo-second-order kinetics (R2 = 0.998) and well fitted with the Langmuir isotherm having 191.1 mg/g maximum adsorption capacity. The adsorption mechanism of AgN/MOF-5 (1:3) was due to the interactions of π-π stacking, Ag-N-MOF covalent bonding and hydrogen bonding. Thus, AgN/MOF-5 (1:3) is a potential adsorbent for the removal of aqueous MNZ. The adsorption process is endothermic, spontaneous, and feasible based on the obtained thermodynamic parameter of ΔHO and ΔSO having 14.72 and 0.129 kJ/mol respectively.

Technological advancements in the use of ionic liquid- membrane systems for CO2 capture from biogas/flue gas - A review.

Carbon capture has become a very important method for curbing the problems associated with the release of carbon dioxide into the atmosphere, which in turn has detrimental effects on the planet and its inhabitants. Ionic liquids and membrane separation have been explored in this review paper as effective means of capturing carbon dioxide. An innovative approach to CO2 capture is the use of Ionic liquids (ILs) since they exhibit certain significant traits such as good stability (thermal, mechanical and chemical), inflammability and high absorptive capacities. Ionic liquids (ILs) are widely regarded as nontoxic substances. Viscosity and thermal degradation of ILs at temperatures slightly above 100 °C are the major disadvantages of ILs. Membrane separation is a technique used for the effective separation of substances by materials bearing holes in a continuous structure. Membrane technology has gained significant improvements, over the years. Several ILs and membrane systems were considered in this work. Their weaknesses, strengths, permeability, selectivity, operating conditions and carbon capture efficiencies, were all highlighted in order to gain a good perspective on ways by which the individual systems can be improved upon. The study considered several polymer-Ionic liquid hybrid materials as viable options for CO2 capture from a post-combustion process. Different ILs were scrutinized for possible integration in membranes by taking full advantage of their individual properties and harnessing their tune-able characteristics in order to improve the overall carbon capture performance of the system. Several options for improving the mechanical, chemical, and thermal stabilities of the hybrid systems were considered including the use of cellulose acetate membrane, nanoparticles (graphene oxide powder) alongside potential ionic liquids. Doping membranes with ILs and nanoparticulates such as graphene oxide serves as a potential method for enhancing the CO2 capture of membranes and this review provides several evidences that serve as proofs for this concept.

Occurrence of Microplastics in Borehole Drinking Water and Sediments in Lagos, Nigeria.

We investigated the occurrence of microplastics in samples of borehole drinking water and sediments obtained from borehole sites in Lagos Island, Nigeria. The samples were digested with hydrogen peroxide, pretreated, and filtered through a polytetrafluoroethylene membrane. The filtered microplastics were examined/analyzed under an attenuated total reflection Fourier-transformed infrared device, to quantify the microplastics. The results showed the presence of microplastics in drinking water and sediments from the sites, with plastic concentrations ranging from 206 to 1691 items m-3 and 9-47 items kg-1 for drinking water and sediments, respectively; polypropylene was the most common and was approximately 61.9% for borehole drinking water. In terms of shape distribution, plastic fragments were the highest, at 73.02%. The detected microplastics had a size range of 0.02-0.5 mm. In addition, sites with a lower percentage of microplastics had lower population densities and lower industrial activity, whereas areas of high industrial activity had high amounts of microplastics. Environ Toxicol Chem 2022;41:1721-1731. © 2022 SETAC.

Decaffeination of wastewater using activated carbon produced from velvet tamarind-pericarp (Dialium Guineense).

Adsorption of caffeine from an aqueous solution was carried out using Velvet Tamarind-Pericarp, activated with H3PO4. The adsorbent was characterized using a scanning-electron microscope and the Brunauer-Emmett-Teller. Parameters such as activating agent concentration (80 wt.% in 100 mL solution), initial caffeine concentration of 5-40 g/L, pH of 0-14, and residence time 0-90 minutes, were investigated. Improved adsorptive capacities were seen at increased acid concentrations, with the highest removal rate obtained at a pH of 6. The highest residence time and adsorbent concentrations were obtained at 40 min and 10 g/L. The surface adsorption of the adsorbent obeyed the Langmuir Isotherm, while the regression coefficients conformed to the pseudo-second-order kinetic model for the remediation of caffeine with DG-AC. The highest amount of caffeine removed per gram DG is 72.60 mg.g-1. From the thermodynamic study, the caffeine adsorption was feasible, spontaneous, entropy-driven, and endothermic. These data show that the use of DG-AC can be a good alternative to other expensive methods for caffeine remediation. The Pseudo - first/second-order kinetic results gave R2 values of 0.95 and 0.99, other parameters such as entropy (ΔS°) and enthalpy (ΔH°) are 0.06 (kJmolK) and (19.21) (kJmolK).

A Review on Polymer Nanocomposites and Their Effective Applications in Membranes and Adsorbents for Water Treatment and Gas Separation.

Globally, environmental challenges have been recognised as a matter of concern. Among these challenges are the reduced availability and quality of drinking water, and greenhouse gases that give rise to change in climate by entrapping heat, which result in respirational illness from smog and air pollution. Globally, the rate of demand for the use of freshwater has outgrown the rate of population increase; as the rapid growth in town and cities place a huge pressure on neighbouring water resources. Besides, the rapid growth in anthropogenic activities, such as the generation of energy and its conveyance, release carbon dioxide and other greenhouse gases, warming the planet. Polymer nanocomposite has played a significant role in finding solutions to current environmental problems. It has found interest due to its high potential for the reduction of gas emission, and elimination of pollutants, heavy metals, dyes, and oil in wastewater. The revolution of integrating developed novel nanomaterials such as nanoparticles, carbon nanotubes, nanofibers and activated carbon, in polymers, have instigated revitalizing and favourable inventive nanotechnologies for the treatment of wastewater and gas separation. This review discusses the effective employment of polymer nanocomposites for environmental utilizations. Polymer nanocomposite membranes for wastewater treatment and gas separation were reviewed together with their mechanisms. The use of polymer nanocomposites as an adsorbent for toxic metals ions removal and an adsorbent for dye removal were also discussed, together with the mechanism of the adsorption process. Patents in the utilization of innovative polymeric nanocomposite membranes for environmental utilizations were discussed.

Comparing microplastics contaminants in (dry and raining) seasons for Ox- Bow Lake in Yenagoa, Nigeria.

The occurrence and distribution of microplastics (MPs) for two seasons (dry and raining) were investigated based on 10 sections of OX- Bow Lake Yenagoa, Nigeria for surface water and sediments. MPs were abundant in colour and dominated by fibrous items. For dry season, Polyethylene terephthalate (PET) and Plasticised polyvinyl chloride (Plasticised PVC) were the predominant MPs; they both account for 72.63% and 10.9% of surface water and sediment samples. The raining season accounted for Plasticised (PVC) 81.5% and low-density polyethylene 4.2% respectively. The raining and dry seasons MPs were characterise by µ-FTIR. Beads and pellets were most common MP shapes in both water and sediment samples for the two seasons. The results showed that there is high presence of MPs in OX -Bow Lake.