Characterization of formulated copper chitosan nanoparticles for the controlled release studies of dicamba dimethylamine herbicide

In this study, a dicamba herbicide was encapsulated onto copper nanoparticles (CuNPs) via a green chemical reduction method in order to improve its herbicidal activity, with the intention of reducing its negative impacts on the environment. The synthesised Dicamba-copper chitosan nanoparticles (Dic-CuCtsNPs) was characterised using UV-visible spectroscopy, scanning electron microscopy (SEM), Fourier transform- infrared (FT-IR), powder x-ray diffraction (PXRD), differential scanning calorimetry (DSC), thermo gravimetric analysis/differential thermal analysis (TGA/DTA) and energy-dispersive x-ray spectroscopy (EDX). The maximum absorption peak of the Dic-CuCtsNPs was observed at 556 nm. The encapsulation efficiency of the Dic-CuCtsNPs formulation was 86 %. The average crystalline size of the nanoparticles, from its PXRD pattern, estimated using the Debye- Scherrer’s equation was 45.94 nm. The SEM image obtained indicated particle size distribution of 16 – 64 nm. The DSC curve showed that the formulation exists in the crystalline state while the TGA data indicated that the formulation was thermally stable up to 425.75oC. Aqueous release study of Dic- CuCtsNPs was carried out using three different pH media and two agricultural soils. The leaching profile of the formulated nano-herbicide through the University of Agriculture (UAM) and college of advance and professional studies (CAPS) soil layer index showed a high value for the UAM soil being 43.84 % higher than in the CAPS soil value of 26.92 %. Thus, an eco-friendly herbicide delivery system was formulated using CuCtsNPs, for the successful release of Dicamba in aqueous medium and agricultural soils.Keywords: Controlled release, Dicamba, Encapsulation, Green synthesis, Herbicide, Soi

A Kinetic, Thermodynamic and Stoichiometric Study on the Reductive Detoxification of Cr(VI) in Aqueous Phase by Sodium Metabisulphite

In this study Na2S2O5, was assessed as an inorganic reductant of Cr(VI) in aqueous phase. The absorbance of Cr(VI) was monitored at 349 nm using a Milton  Roy Spectronic 20D UV/Visible spectrophotometer  at different temperatures (298 – 323 K) to study the effect of temperature on reduction while, the effect of pH was studied at pH 3, 5, 7, 9 and 12. The effect of concentration was also considered by varying the concentrations of the reductants (i.e. 4, 6, 8, 10 and 12 mg/L) over a pH of 5, 298 K and 5 minutes with concentration of Cr(VI) set at 10mg/L. The temperature effect showed that the reaction rate increased slightly with increase in temperature. It was found that there was a logarithmic increase in time required to reach a certain percentage reduction of the [Cr(VI)]initial, as the pH was increased. The kinetic results showed that the reaction was first – order with respect to Cr(VI) with the rate equation of . The activation entropy obtained from plots of ln(kobs/T) vs. 1/T was -197.53 J.K-1.mol-1 agreeing with the formation of a condensed compound. The activation enthalpy varied from (-7.5x10-6 - 3.3x10-4 kJmol-1) and most cases it was negative showing that the reaction was rather exothermic. The activation energies obtained were 58.87, 60.84, 62.82, 63.80 and   65.78 kJmol-1 for the respective Kelvin temperatures of 298, 308, 318,323 and 333. This increase in activation energy with increasing temperature implied that bond breakage and product formation was more favourable at lower temperature. The stoichiometry suggests that the Cr(VI) : Na2S2O5 ratio was 1 Cr(VI) : 1.36 Na2S2O5, this value was found to be in agreement with the theoretically obtained result for both acidic and alkaline rigimes.  The findings from the research show that Na2S2O5 could be used for the reductive detoxification of Cr(VI) in polluted areas

Evaluating the Effects of Roofing Materials on Physicochemical Properties of Harvested Rainwater in Warri, Delta State, Nigeria

This study was aimed at investigating the effects of roofing materials on water quality, in Warri district. Random sampling technique was used to collect forty two (42) rainwater samples from different roofing materials made from (asbestos, zinc, aluminium and thatch roof) including the control (rainwater collected directly from the sky) in Warri refinery and petrochemical company(WRPC) and military formation area(MLF). The harvested rainwater samples were analyzed using Atomic adsorption spectrophotometer, AAS, TDS meter, heating plates, electrical conductivity meter, retort stand, pH meter, Turbidity meter, Conductivity meter etc. Results obtained revealed that most of physiochemical parameters of rainwater samples analyzed were generally below the WHO threshold. The results also indicate the presence of Pb, Fe and Cr, in the harvested rainwater samples, of which Pb that is a poisonous metal is above the maximum WHO allowable limit of 0.3 mg/L. From the results, scientifically, it is advisable that the first flush from all the rooftops cannot be used because of high levels of dirt, rust etc. Fifth flush and above can be used for domestic chores like washing, mopping, irrigation, cleaning, laundry etc. without further purification, but should be subjected to simple water treatment like boiling and chlorination before it can be consumed. &nbsp

Removal of heavy metals from a contaminated soil using organic chelating acids

Changes in heavy metal speciation and uptake by maize in a soil before and after washing with chelating organic acids, citric acid, tartaric acid and ethylenediaminetetraacetic acid were assessed. A sandy loam was collected from the vicinity of the Benue industrial layout, Makurdi, Nigeria and spiked with a quinternary mixture of nickel, copper, zinc, cadmium and lead nitrates to achieve higher levels of contamination. Batch soil washing experiments performed on 1.0 g portions of the spiked soil using 0.05 M chelating agents at a solid:liquid ratio of 1:25 showed that washing efficiencies varied in the order: ethylenediaminetetraacetic acid> citric acid> tartaric acid with metal extraction yields typically following the sequence, copper> nickel> zinc> cadmium> lead. Sequential extractions proposed by the European Communities Bureau of Reference method used to assess the redistribution of heavy metal forms in the soil showed that apparent metal mobilities were reduced upon soil washing. Citric acid removed most of the metals hitherto associated with the exchangeable and reducible fractions; tartaric acid, the exchangeable metal pools; and ethylenediaminetetraacetic acid, the non-residual metal pools. Heavy metal assay of harvested biomass of maize grown on unwashed and washed soil samples indicated that metal transfer coefficients, decreased in the order of treatment: ethylenediaminetetraacetic acid <citric acid <tartaric acid <unwashed soil. Ethylenediaminetetraacetic acid and citric acid appeared to offer greater potentials as chelating agents to use in remediating the high permeability soil. Tartaric acid, however, is recommended in events of moderate contamination

A review on the use of chelating agents as an alternative to promote photo-Fenton at neutral pH: Current trends, knowledge gap and future studies

In this review, we have critically examined the alternatives to conventional photo-Fenton process such as the strategies to perform it in circumneutral pH in the so-called photo-Fenton like process. They include iron chelation, iron replacement with another metal and use of iron immobilized on surfaces of solid materials, use of iron oxides, among others. The use of such strategies can be employed to overcome the challenges identified in conventional photo-Fenton, moreover, advantages and drawback of each technique must be clarified and the recent achievements should be shared with the scientific community. The use of a chelating agent to make iron soluble at circumneutral pH presents many advantages when compared to other current techniques. However, the correct understanding of the chelating process, complex activity and the complex resistance along with the mechanism of radical production should be taken into account to prepare an effective photo-Fenton with complexed iron. The review also identifies the current trends in chelate assisted photo-Fenton process and the unexplored areas in this field of study. A discussion about the environmental and safety issues in the application of these methods, with emphasis to the Fe chelation strategy, was also considered with detailed review over the past ten years710CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESP308914/2017-1; 424395/2016-92014/17774-