This study evaluates the adsorptive capacity of elephant grass (EG) in the removal of Methylene blue (MB) dye from wastewater sourced from two major local dyeing industries in Ogun State, Nigeria. Batch adsorption method was used to determine the optimum conditions, characterization of the adsorbent, equilibrium Isotherm models, kinetics and thermodynamics studies were conducted to evaluate the nature of the adsorption process. The optimum adsorption conditions obtained for the standard solution of MB dye were; pH 7, Temp 40 °C, contact time 180 min and adsorbent dosage 2.0 g. The presence of oxygen containing functional groups and shift or disappearance of bands in the FTIR suggested the suitability of EG for the process. The SEM of EG revealed presence and disappearance of pores before and after the adsorption process. The mechanism of this adsorption is complex, the adsorption data is best fitted to Langmuir isotherm, the mean adsorption energy E (≤6.455 kJ/mol), and activation energy (10.84 kJ/mol) represents physical process but, the thermodynamic studies revealed spontaneity (ΔG° −15.93 to −14.26 kJ mol⁻¹), randomness, and endothermic (ΔH° 40.1 kJ/mol) nature, representing chemisorption. Therefore, local dyers around the study sites can make use of the freely available EG for the remediation of their wastewater. Elephant grass (EG) abundantly thrives on the study sites where dye wastewater is released by local dyers. This serves as the impetus for this research as no other plants thrive on the dye-polluted environment. A favorable adsorption was obtained with EG as adsorbent for the Methylene blue (MB) dye that is a major constituent of the wastewater from the two major local dyeing industries investigated. Therefore, this study provides scientific support for the local dyers around the study sites to make use of the freely available EG for the remediation of their wastewater.

Geophagy clay has been used in tropical regions as gastrointestinal protector for adsorbing toxins in human body, but it was rarely used in adsorbing heavy metals contaminants in water. This study determines elemental concentration of geophagy clay and evaluates its adsorptive capacity in removing Cd²⁺ and Pb²⁺ in water. Fifteen clay samples were randomly collected from three layers in the space of one meter apart from Amawom clay deposit in Ikwuano local government, Southeast Nigeria. Elemental analysis was carried out using the inductively coupled plasma mass spectrophotometer (ICP-MS), and chemical characterization was performed with Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD). The adsorptive capacity of Cd²⁺ and Pb²⁺ on the clay samples was evaluated using standard solutions of the metal ions. The result of the elemental analysis in mg/kg (Pb ≤ 12.4, Zn ≤ 2.75, Co ≤ 1.50, Ni ≤ 1.47, Mn ≤ 15.0, Cd = 0.01, Ca ≤ 300, Al ≤ 3466, Na ≤ 13.3, and Hg = 0.02; P≤40.0) revealed that the concentrations of most of the studied metals in the three layers are statistically similar and fall below the permissible recommended safety levels. The presence of functional groups (hydroxyl, amine, and carboxylic/ester) and minerals (kaolinite, goethite, and quartz) provided evidence of the good adsorptive properties of the clay samples. The adsorption of Cd²⁺ and Pb²⁺ unto the clay samples increased with increase in pH, concentration, time, and temperature, and the equilibrium data for the adsorption fitted well into Langmuir isotherm. The study, therefore, concluded that geophagy clay possesses the capacity to adsorb Cd²⁺ and Pb²⁺ for water treatment.

The production of cheap and eco-friendly graphene material for the removal of contaminants in wastewater is necessary for sustainable water treatment. In this study, the production of graphene oxide from agricultural wastes (rind of orange and palm kernel shell) for the adsorption of paracetamol from aqueous solution was examined. The Graphene Oxides (GO) were produced using modified Hummer method and characterized using XRD and FTIR analyses. The kinetic data were analyzed using the pseudo-first and pseudo-second order equations, while the equilibrium isotherm data were fitted into Langmuir and Freundlich isotherms. FTIR spectral indicated mainly the presence of oxygen containing functional groups such as Hydroxyl group (OH) and Carbonyl group (C=O, C-O) confirming the synthesis of graphene oxide. The highest percentage removal of 76.6 from the aqueous paracetamol solution was established at pH 7, adsorbent dose of 0.4 g and contact time of 80 minutes with graphene oxide from palm kernel shell. The adsorption data was best described by pseudo-second-order model (R2---gt--- 0.900) and Freundlich isotherm. Therefore the rind of orange and palm kernel shell can be suitable cheap alternatives to graphite for the synthesis of GO. Modification and further purification of the GO can be carried out to enhance their adsorption capacities.

This study assessed the level of toxic metals and hydroquinone in skin-lightening-creams commonly use in Ogun State, Nigeria. The pH of all the cream samples was determined and metals quantification was carried out using ICP-OES after acid digestion while that of hydroquinone was done using HPLC. The health risk of dermal exposure to heavy metals via the regular application was done by evaluating the carcinogenic and non-carcinogenic risk. The pH of all the samples are acidic and it follows this trend; Sample 3 > Sample 1 > Sample 4 > Sample 2. All the metals considered in this study were detected in all the analyzed samples except Cd, Co and Cr in sample 1, As, Ba and Pb in sample 2, Ag, As and Hg in sample 3 and Ba in sample 4. Highest levels of Al, Co, Pb and Zn were recorded in Sample 3 (Organic cream). Though the concentrations of most of the toxic metals (Al, Zn and Mn) are above the permissible levels, they pose no non-carcinogenic health risk based on the calculated HQ and HI. The carcinogenic risk of metals in the sampled creams were all within the acceptable limit except that of Cd. Hydroquinone was detected in all the four samples analyzed ranging between 2.58 and 4.17 % which exceeded the permissible limit by WHO. This finding show that long-term use of skin-whitening-creams may pose serious health hazards so, public should be continually enlightening on the hazardous health effects of the use.

Geophagy has been a common practice especially in the Southern part of Nigeria and some parts of the world at large. They are earthy/clay materials eaten as food supplements and also adopted for medical purposes. Hence, they are bound to contain trace metal contents that may be harmful to human health which is a great cause for concern among health workers in this modern age. Therefore, geophagic clays from Amawom- Ikwanoin Abia province, South-eastern Nigeria were examined and evaluated for their heavy metal concentration to deduce their quality and possible health implication that is associated with their consumption. Edible clay from south eastern Nigeria was analysed with X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and Inductively Couple Plasma Mass-Spectrometry (ICP-MS) revealing quartz (SiO2), kaolinite (Al2Si2O5(OH)4, goethite (FeOH) and pyrite (FeS2) as the predominant minerals while SEM revealed clay flaky structure specifying an alumino-silicate with sulfur and carbon as impurities. The clay’s pH ranges between 3.36 and 4.57, E.C from 52-399 μs/cm revealed its high acidity and signified high ionic contents in the edible clays. The soil Organic Carbon 0.1-5.83% may possibly indicate absorption and retention of contaminants. High concentrations ppm for Cu(19.91), Pb(13.15), Zn(18.4), Ni(5.8), As(9.15) and Hg(126.0) in the clay exceeded the WHO and USEPA recommended dietary intake by humans signifying its likely toxicity. Other associated carcinogenic and non-carcinogenic diseases that could be connected to the high concentrations of mercury, chromium, arsenic, lead and nickel in the edible clay structure which may likely camouflage the taunt and healing properties of kaolinite include renal, respiratory, cardiovascular, gastrointestinal, hepatic, immune, reproductive and dermal systems. For this reason, continuous ingestion of edible clay may lead to bio-accumulation of mercury, chromium, arsenic, lead and nickel in the inhabitants of Amawom, hence, posing serious health challenges that may lead to death.