No abstract

Daniellia—oliveri sawdust-based adsorbents were employed to remove trimethoprim (TMP) from water. The sawdust was thermally carbonized and activated in-stu with ZnCl2 and H3PO4 separately. The adsorbents surface features were profiled using scanning electron microscopic (SEM) and pH point of zero charge (pHpzc ) analyses. The prospects of the adsorbents for the removal of trimethoprim from water were verified. The adsorption processes were performed under different experimental conditions. The adsorption isotherm, the kinetics, and the thermodynamics were studied; and the data fitting output revealed that both chemisorptions and physisorption occurred. Surface and pore diffusion played active role in the adsorption of TMP by the adsorbents. The optimum conditions for adsorption of TMP by the adsorbents were pH at slightly acidic to neutral medium and temperature at room temperature. The fitting isotherm models were: Langmuir (R2 = 0.993) for the zinc-chloride-activated-carbon, Temkin (R2 = 0.962) for the phosphoric-acid-activated-carbon, and the kinetics: pseudo-second order (R2 = 0.997) for both. The maximum monolayer adsorption capacities of the adsorbents for TMP was 4.115 and 6.495 mg/g, respectively. The thermodynamic parameters determined suggested feasibility, spontaneity, and endothermicity of the adsorption processes. The results reveal that the adsorbents were goodprospects for the removal of TMP from water.

The following were the identified and defined classes of emerging contaminants of concern (ECCs): pharmaceutical and personal care products (PPCPs), perfluorinated compounds (PFCs), plasticizers, agrochemicals, industrial additives and agents (IAAs), flame retardants (FRs), Nanopar-ticles (NPs), steroids and hormones, gasoline additives. From 1983 to 1990, an estimated 15,000 metric tons of pesticides were reported to have been imported annually. In 2016, a yearly application of about 130,000 metric tons of pesticides was reported for Nigeria. Nigeria’s pesticides imports were worth USD128.671 in that year. Of the applied pesticides, about 85% ended in the environment as contaminants/pollutants. While few individuals in the households or neighbourhoods deal with pesticides, almost all human beings deal with PPCPs. PPCPs are taken to prevent or cure diseases and/or to sustain wellbeing. Nigeria produced 30 % of its PPCPs demands while 70% imported. In 2012, 2013 and 2014, Nigeria imported PPCPs worth USD425 million, USD481 million and USD530 million respectively. In 2018, Nigeria imported PPCPs worth USD606.31 million, while the total amount of pharmaceuticals procured was USD866.16 million. Almost all the candidates of ECCs had been detected in the Nigerian environment. Untoward episodes of pesticides abuse ranging from abuse to death, have been profiled. Some of the factors responsible for these were weak regulatory instruments on accessing these pesticides, bad economy, stigmatization and lack of resilience.

Wood sawdust, one the high volume agricultural wastes in Nigeria, occupies space and constitutes environmental nuisance. Burning, it produces green house gases. Converting it to adsorbents is economical and environmental benign. This work assessed the adsorptive capacities of two Danielliaoliveri sawdust-based adsorbents for the removal of ibuprofen from waste stream. The sawdust was carbonized and activated with ZnCl2 and H3PO4 to produce adsorbents code-named ZCAC and PAAC respectively. The physicochemical properties of the adsorbents were determined and batch adsorption experiments performed. The optimum pH for the adsorption of ibuprofen onto the ZCAC and PAAC was 3. The isotherm studies revealed that the Ibuprofen (IBU)-ZCAC system data fitted Redlich-Peterson and Langmuir models. The data also fitted Pseudo-second order and Boyd kinetics, defined intraparticle diffusion of the adsorbate molecules. The process was physical and endothermic. For the adsorption onto PAAC, the data fitted the Freundlich and the Halsey models. The data also fitted the Pseudo-second order and the Elovich kinetics. The process was endothermic. The adsorption capacities of ZCAC and PAAC for IBU were 3.876 and 15.385 mg/g respectively. ZCAC and PAAC were promising adsorbents for remediation of wastewater contaminated with ibuprofen.