Numerical examination of concentration-dependent wastewater sludge ejected into a drinking water source.

One of the significant water-related health challenges globally is due to pollutant fate. Contaminants endanger the lives of humans, animals, and even plants. The present mathematical analysis explains reactive wastewater sludge ejected into a drinking water source from wastewater treatment plants. The assumption that wastewater sludge follows a power-law constitutive relation leads to nonlinear momentum and concentration equations. The contaminants are assumed to follow a nonlinear irreversible first-order sorption model. The numerical solution of the coupled problem is solved using the Bivariate Spectral Local Linearization Method and validated with the spectral Chebyshev weighted residual method. Profiles are presented for dimensionless flow velocity and concentration. Comprehensive explanations for the obtained results are provided with relevant applications.

Preparation of magnetic, macro-reticulated cross-linked chitosan for tetracycline removal from aquatic systems.

A novel adsorbent, magnetic, macro-reticulated cross-linked chitosan (MRC) was synthesised for the removal of tetracycline (TC) from water using a source of biogenic waste (gastropod shells) as a pore-forming agent. The insertion of crosslinks into the chitosan frame was confirmed by FTIR analysis, while the stability of the MRC was demonstrated via a stability test performed in an acidic solution. The enhanced porosity of the MRC was confirmed by the evaluation of its porosity, a swelling test and the determination of its specific surface area. The time-concentration profile of the sorption of TC onto the MRC demonstrated that equilibrium was attained relatively quickly (120 min), and the data obtained fitted a pseudo second order (r(2)>0.99) kinetic equation better than a pseudo first order or reversible first order kinetic equation. The optimisation of process variables indicated that the sorption of TC onto the MRC was favoured at a low solution pH and that the presence of organics (simulated by the addition of humic acid) negatively impacted the magnitude of TC removal. The area of coverage of TC on the MRC (2.51 m(2)/g) was low compared to the specific surface area of the MRC (47.95 m(2)/g). The value of the calculated energy of adsorption of TC onto the MRC was 100 kJ/mol, which is far above the range of 1-16 kJ/mol stipulated for physical adsorption.

Competitive modeling for the biosorptive removal of copper and lead ions from aqueous solution by Mansonia wood sawdust.

Mansonia wood sawdust is applied as a biosorbent for the removal of copper and lead ions from single and binary aqueous solution. The effect of solution pH, electrolyte, metal ion competition and temperature were examined to obtain insight of its application for industrial waste water treatment. The Langmuir isotherm provided a better fit to experimental data for lead ion sorption with a higher monolayer capacity, while copper ion sorption was best described by the Freundlich and BET isotherms. The combined effect of adsorbing one metal ion in the presence of the other metal ion reduced the adsorption capacity of either metal ion. In a binary solution, removal of lead ions in the presence of copper ions followed the Langmuir isotherm model while the removal of copper ions in presence of lead ions followed both the Langmuir and BET isotherm models.

Comparison of two-stage sorption design models for the removal of lead ions by polyvinyl-modified Kaolinite clay.

Kaolinite clay obtained from Ubulu-Ukwu, Delta State in Nigeria was modified with polyvinyl-alcohol (PVA) reagent to obtained PVA-modified Kaolinite clay. Kinetic and equilibrium data were obtained for the batch adsorption of Pb(2+) onto PVA-modified Kaolinite clay. Time-dependent Langmuir and pseudo-second order kinetic models (TDLM and PSOM) were developed to predict the optimized minimum operating time for the adsorption of Pb(2+) onto PVA-modified Kaolinite clay in a two-stage batch adsorber system. Results obtained suggest that the two-stage batch adsorber process leads to improved contact time and increased percentage Pb(2+) removal. Data from both models (TDLM and PSOM) were compared using t-test and F-test and were found to be precise enough for use in the optimization of kinetic data for a two-stage adsorption of Pb(2+) ions from aqueous solution.

Kinetic and thermodynamic studies of the adsorption of lead (II) ions onto phosphate-modified kaolinite clay.

This study is on the kinetics and thermodynamics of the adsorption of Pb(2+) onto phosphate-modified and unmodified kaolinite clay obtained from Ubulu-Ukwu in Delta State of Nigeria. Increasing initial Pb(2+) concentration increased the rate of Pb(2+) adsorbed with increase in initial Pb(2+) concentration from 300 to 1000 mg/L. Increasing Pb(2+) concentration also increased the initial sorption rate h, from 1.404 to 13.11 mgg(-1)min(-1) for phosphate-modified kaolinite clay and 1.04-3.48 for unmodified kaolinite clay as Pb(2+) concentration. Increase in temperature was found to increase the initial sorption rate of Pb(2+) adsorption onto phosphate-modified adsorbent from 3.940 to 8.85 and 2.55 to 4.16 mgg(-1)min(-1) for the unmodified adsorbent. The overall sorption rate k, increased only slightly from 5.1x10(-2) to 9.7x10(-2)gmg(-1)min(-1) for phosphate-modified adsorbent, 3.8x10(-2) to 5.4x10(-2)gmg(-1)min(-1) for unmodified adsorbent. The adsorption reaction on both adsorbents was found to be chemically activated reaction and endothermic with energy of activation, E, at 500mg/L of Pb(2+) in solution as 19 and 10.68 kJmol(-1) for phosphate-modified and unmodified adsorbents, respectively. The positive values of both DeltaH degrees and DeltaS degrees obtained suggest an endothermic reaction and in increase in randomness at the solid-liquid interface during the adsorption of Pb(2+) onto the adsorbents. DeltaG degrees values obtained were all negative indicating a spontaneous adsorption process. The presence of Cd(2+) decreased both initial sorption rate and the amount of Pb(2+) adsorbed on phosphate-modified and unmodified adsorbents at equilibrium. The adsorption process follows a pseudo-second-order reaction scheme.