Accumulation of some metals in Morinda lucida from Nigeria

Transfer coefficients of the four metals As, Cd, Hg, and Pb were determined in the leaves and barks of Morinda lucida collected in Nigeria, with the view to quantify relative differences in the bioavailability of the metals to these parts of the plant. Samples were acid digested and the levels of the metals in the digestates were determined using an atomic absorption spectrophotometer. Certain properties of the soils, i.e., pH, clay fraction, electrical conductivity, cation exchange capacity, and organic matter, were also determined. The latter influence the bioavailability of the metals. All parameters correlated with the concentrations of the metals in soils. Transfer coefficient values recorded for Cd and Pb in various tissues of M. lucida Benth were within the expected ranges, while those of As and Hg showed elevated topsoil concentrations of metals. The order of bioavailability of the metals and their bioaccumulation in the tissues of M. lucida Benth was Hg > Cd > As > Pb. Stem barks of the plant showed the least bioaccumulation of all four metals and hence are most suitable for therapeutic purposes. Vegetative parts of M. lucida Benth used for therapeutic purposes should be sourced at sites that will give low transfer coefficient in order to reduce human exposure to toxicity associated with ingestion of heavy metals.     

Valorization of sodium sulfate waste to potassium sulfate fertilizer: experimental studies,process modeling,and optimization

ABSTRACT

Sodium sulfate is a common low-value industrial by-product but can be managed using the Glaserite process to convert it into high-value potassium sulfate. The aim of the study is to investigate the potential for implementing this process in an industrial application. Experimental studies were completed to determine the yield and purity of both glaserite and potassium sulfate. Process simulation using SysCAD was utilized to optimize a two-stage glaserite process to produce potassium sulfate. Comparison of experimental and simulated data was made to validate the simulator’s results, finding the AAD in solid and liquid phase for glaserite production to be 6.9% and 5.7%, respectively, and for potassium sulfate to be 5.7% and 2.3%, respectively. For a process treating seven MT/hr of Na₂SO₄, a KCl feed strategy of 3.0 MT/hr to the glaserite reactor and 4.5 MT/hr to the K₂SO₄ reactor was found to maximize yield and minimize water demand. It was also found that ambient temperatures were preferred for the K₂SO₄ reactor and that K₂SO₄ yield suffered significantly under certain conditions when the glaserite reactor operated at 50°C or above.     

The co-occurrence network patterns and keystone species of microbial communities in cattle manure-corn straw composting

Environmental Science and Pollution Research - Microbes often form complex ecological networks in various habitats. Co-occurrence network analysis allows exploring the complex community...     

Efficient removal of tetracycline by CoO/CuFe2O4 derived from layered double hydroxides

Environmental Chemistry Letters - Health concerns have been raised over the excessive occurrences of antibiotics such as tetracycline in aquatic environments. Adsorption is a simple and cheap...