In this work, the quality of River Benue water at Makurdi was assessed for its heavy metal load alongside seven other physico-chemical parameters using water quality index (WQI) and multivariate statistical tools. A total of 45 samples from three (3) different points along the River course were collected for five months (October 2018–May, 2019) spanning the dry and wet seasons. Samples were analysed in accordance with standard methods. Most of the parameters evaluated were found to fall in the allowable limits of the World Health Organization (WHO) among others, except for colour, turbidity, total suspended solids, nickel, lead and cadmium. WQI analysis using the BISWQI, OWQI and CCMEWQI indicated that all indexing methods were suitable for estimating the WQI of River Benue as they all showed that the water corresponded to the classification as “poor water”. Heavy metal index of the river ranged from13.40–6080.00 and from 47.07–7240.00 for the dry and wet seasons, respectively, and was majorly influenced by high cadmium and lead pollution levels. Principal component analysis (PCA) revealed three rotated factor with respective communality levels for both the dry and wet seasons. Factor 1 was positively loaded with nine parameters which accounted for 32.3% of the total variance during the dry season, while it was positively loaded with 10 parameters in the wet season accounting for 25.9% of total variance. Hierarchical cluster analysis (HCA) revealed that the river was zoned into four clusters each for both dry and wet seasons. Sampling points 2 and 3 were the most polluted during the dry season, while sampling point 1 was found to be the most polluted in the wet season. It was concluded that the increasing and diverse nature of anthropogenic activities on the river course was responsible for the deteriorating quality of the water. The study recommended continuous pollution monitoring and local regulations to reduce the entrance of both diffuse and point source pollution into the river.
This study investigated the optimal synthesis conditions for the production of Raffia Palm Shell Activated Carbon (RPSAC) using phosphoric acid as activation agent. The optimization of the synthesis conditions was achieved using the Central Composite Design (CDD) in Response Surface Methodology (RSM). The influences of impregnation ratio, temperature, time and concentration on the specific surface area and yield of RPSAC were evaluated. Based on the CDD, 2FI and quadratic models were developed for the two responses. Analysis of Variance (ANOVA) was utilized to determine the significant factors and factor interactions for each response. All process variables except impregnation ratio were observed to significantly influence the quality of RPSAC. The optimal synthesis conditions for RPSAC were; 523.68 °C, 76.91%, and 103.83 min for temperature, concentration, and time respectively which provided a specific surface area and yield of 1762.92 m
2
/g and 77.98 % respectively. The Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) analyses proved that RPSAC had a meso-micro-porous morphology with high carbon and oxygen contents. Fourier-transform infrared spectroscopy (FTIR) revealed the abundance of hydroxyl, carbonyl and carboxylic groups on RPSAC. X-ray Powder Diffraction (XRD) analysis showed that RPSAC composed mainly of amorphous and disordered microcrystalline phases ascribed to the high quartz content of the precursor. The Brunauer–Emmett–Teller (BET) surface area, average pore diameter, total pore volume, and pH
pzc
of RPSAC were obtained as 456.10 m
2
/g, 0.25 cm
3
/g, 2.13 nm and 2.10 correspondingly. Thus, RSM was found to be an excellent and desirable tool for optimal synthesis of RPSAC that possess high surface area and porosity suitable for application in the adsorption of both large and small molecular sized pollutants such as dyes and fluoride in real and aqueous solution.
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