Heavy metals removal from wastewater is totally essential to evade water pollution. The present study showed the performance of chitosan coated carbon for the removal of chromium (VI) and Pb (II) from aqueous solution. The following elements; C, K, Ca, Mg, Al, Si, P and Cl were revealed by Energy dispersive X-ray (EDX) as part of the constituent of the adsorbent while Scanning Electron Microscope (SEM) reveal agglomeration of the adsorbent particle. Batch adsorption experiments were performed in order to examine the removal efficiency under the various factors such as the effects of initial concentration, adsorbent dose, agitation time and particle size. The adsorbent possess good adsorption efficiency for chromium (VI) and lead (II) with optimum agitation time of 90 to 120 min even at low concentration. Experimental data were analysed by Langmuir and Freundlich adsorption isotherms. The characteristic parameters and related correlation coefficients were determined. The isotherm study revealed that the adsorption equilibrium is well-fitted to the Original Research ArticleLangmuir and Freundlich isotherm. The selectivity order of the adsorbent (modified and unmodified) towards the ions was found: Pb (II) > Cr (VI). The method could be successfully employed for removal of toxic metals from industrial effluents and could solve the problem of disposal of agricultural waste materials.

The use of chitosan-grafted cocoa husk char (CCH) and unmodified cocoa husk char (CH) as adsorbents for the removal of Cr 6+ and Pb 2+ were studied. The adsorption efficiencies were compared with that of the commercial activated carbon (GAC F-300). Energy Dispersive X-ray spectroscopy (EDS) was used to determine the elemental compositions of the adsorbents while Scanning Electron Microscope (SEM) was used for the surface texture and morphological characteristics of the cocoa husk. The study optimised metal ion concentration, adsorbent dosage, agitation time and adsorbent particle size for the removal of the metals from simulated wastewater using Atomic Absorption spectroscopy (AAS) and removal efficiencies were calculated. Langmuir and Freundlich models were employed to study the adsorption pattern. The equilibrium experimental data results of Pb 2+ fitted well to Langmuir and Freundlich the two adsorption isotherms. The coefficient of correlation (R 2) for both models falls within 0

Trihalomethanes (THMs) are formed when excess chlorine during chlorination of water reacts with organic material in water. They have mutagenic and carcinogenic properties. Moringa oleifera (MO) has found wide acceptance by many people in Nigeria who have used it for food for both humans and fauna, for health purposes, and as a coagulant for water treatment. However, the seed husks are currently discarded as waste and they have not been used as adsorbent to remove THMs from water. The physicochemical properties of both the treated and raw surface water were determined using standard methods, and the concentration of THMs was determined from the water treatment plant at different stages of treatment using gas chromatography with flame ionization detector (GC-FID). Recovery experiments were carried out to validate the procedure. The efficiencies of activated carbon of Moringa oleifera seed husk (MOSH) adsorbent for the removal of THMs in the water and as a coagulant for water treatment were also assessed. Batch adsorption experiments were carried out, and different parameters such as pH (5, 7, and 9), adsorbent dosage (0.2, 0.4, and 0.8 g), contact time (30, 60, and 90 minutes), and initial concentration (0.2, 0.4, and 0.6 mg/l) were optimized for the removal of trichloromethane and tribromomethane using the MOSH activated carbon. Experimental adsorption data from different initial concentrations of trichloromethane and tribromomethane were used to test conformity with Langmuir and Freundlich adsorption isotherms. The percentage recovery from our procedures ranged from 96.0 ± 1.41 to 100.0 ± 0.00 for trichloromethane while for tribromomethane the range was 60 ± 2.82 to 100.0 ± 0.00. The mean percentage adsorption efficiencies for the simulation experiment ranged from 34.365 ± 1.41 to 93.135 ± 0.57 and from 41.870 ± 0.27 to 94.655 ± 0.41 for trichloromethane and tribromomethane, respectively. The optimum conditions for both trichloromethane and tribromomethane were pH 9, 0.8 g adsorbent dosage, 60-minute contact time, and 0.6 mg/l initial concentration. The optimum values of these parameters used for the adsorption of the two THMs in the surface water serving the treatment plant gave an efficiency of 100.00 ± 0.00%. The turbidity values for the coagulation experiment reduced from 9.76 ± 0.03 NTU in the raw water before coagulation to 5.92 ± 0.13 NTU after coagulation while all other physicochemical parameters of the surface water decreased in value except conductivity and total dissolved solid which increased from 104.5 ± 3.54 to 108.0 ± 2.83 μS/cm and 63.00 ± 11.31 to 83.0 ± 8.49 mg/l, respectively. The experimental data best fit into Langmuir than Freundlich adsorption isotherm. The study concluded that MOSH activated carbon could serve as an adsorbent for the removal of THMs, calcium, and sulphur from water samples.

Nigeria is currently the largest rice producing country in Africa. High volumes of waste such as rice husk are inevitable with high production. Also pesticides used to rid of pests, diseases and improve crop yield find their ways into available surface water that serves domestic purpose. This study therefore determined the efficiency of conventional water treatment procedure for pesticide/pesticide residue removal and evaluated the performance of rice husk-based biochar as adsorbent to remove chlorpyrifos from domestic water supply with a view to manage  solid waste (rice husk) for treating pesticide polluted water. Batch adsorption studies were carried out to assess the adsorption efficiency of rice husk biochar (RHB) for chlorpyrifos pesticide removal from surface water. Adsorbent dosage, initial concentration, contact time and dosage were optimized during simulation experiment. RHB and commercial activated carbon (CAC) were used for the removal of chlorpyrifos from surface water sample using the optimum condition from the simulation experiment after which the concentrations were determined using Gas Chromatography with Mass Spectrometry detector. Both Langmuir and Freundlich adsorption isotherms were investigated. RHB gave percentage moisture (5.27±0.94), carbon yield (39.44±0.47), ash (41.96±0.96), fixed carbon (35.24±0.55), volatile matter (35.67±1.01 mg/g), Iodine number (85.57±0.81), surface area (97.20 m2/g), pH (7.90±0.14) and Electrical conductivity (298.8±1.14). Of the elements present in the char, Carbon has the highest percentage of 59.14%. Best adsorption conditions for RHB in this study were 2.8 mg/L initial concentration; 0.8 g of adsorbent dosage; pH of 5 and contact time of 30 min. The data fitted Freundlich than Langmuir model (R2 0.996 and 0.8315 respectively). Percentage removal of chlorpyrifos for CAC and RHB was 93.7±3.96 and 94.5±5.23 respectively for the surface water sample. Results concluded that RHB was efficient for removal of chlorpyrifos present in water and could be used as alternative for CAC in water treatments.

The study assessed the seasonal variations in the physico-chemical properties of surface water and sediments in some villages located around a scrap metal recycling industry in Ile-Ife. This is with a view to monitor the impact of the industry on the quality of surrounding water. The three water bodies (one river, one stream and one pond) identified in the area were sampled every other month for ten months. Water and sediment were sampled from the water bodies and their physico-chemical properties were determined using standard methods. Highest and least pH values: 7.15 ± 0.29 and 6.27 ± 0.26 were recorded in river and pond water sample, respectively during dry season, while the least pH values: 5.64 ± 0.09 were recorded in sediment samples from the river during wet season. Fe in water was highest in pond during dry season with (0.10 ± 0.01) mg/L. Stream sediment recorded higher values of Fe (1.02 ± 0.05) mg/kg, Zn (0.48 ± 0.01) mg/kg and Pb (0.09 ± 0.01) mg/kg than in stream water samples, while the values of pH, Mn, Cd and Cr (6.95 ± 0.03, 0.67 ± 0.11, 0.11 ± 0.02, 0.17 ± 0.03)mg/L respectively in stream water were higher than in stream sediment samples. In River, Fe and Zn values were higher in sediment (0.63 ± 0.04 and 0.52 ± 0.01)mg/kg respectively than in water samples, while in the pond pH, Mn, Cd and Cr were higher in water (6.51 ± 0.12, 0.71 ± 0.07, 0.09 ± 0.01 and 0.22 ± 0.03)mg/L respectively than in sediment samples. The study concluded that the scrap metal recycling industry has impact on the surrounding water bodies as the values of cadmium, lead and iron significantly exceeded the national and international standards.