Utilizations of agricultural waste as adsorbent for the removal of contaminants: A review.

The Department of Environmental Science and Technology (ENST) is The Place for Ecological Discovery and Natural Solutions! Our primary mission is to educate students on the fundamentals of environmental science, while instilling a deep fascination and intellectual capacity to work in their chosen area of specialization, whether its Natural Resources Management, Ecological Design, Soil and Watershed Science or Environmental Health. When our students graduate, we want them to be top-notch environmental stewards with a broad framework from which they can advance professionally, personally and socially.

Environmental Science and Technology

Enhanced phosphate removal by zeolite loaded with Mg–Al–La ternary (hydr)oxides from aqueous solutions: Performance and mechanism

Adsorption for phosphate by crosslinked/non-crosslinked-chitosan-Fe(III) complex sorbents: Characteristic and mechanism

Effect of hexavalent chromium on the environment and removal techniques: A review

In the present work, nanocrystalline Fe-Al-Mn ternary oxide nanosorbent was synthesized via impregnation method. X-ray diffraction (XRD), scanning electron microscope coupled with energy dispersive x-ray spectroscopy (SEM/EDX), Brunauer–Emmett–Teller (BET) technique and Fourier transform infrared spectroscopy (FTIR) were employed to characterize the as-synthesized nanomaterials. The XRD result indicates the crystalline nature of the ternary oxide with BET surface area of 49.53 m 2  g −1 . The optimum operating conditions to carry out sorption study such as pH, adsorbent dose, contact time, speed of agitation and initial phosphate concentration were found to be 3, 0.1 g, 16 h, 100 rpm and 30 ppm, respectively. Both Freundlich and Langmuir isotherm models fit the equilibrium data well with the latter model providing more fit to the experimental data. Kinetic data correlated well with the pseudo-second-order and Elovich models suggesting chemisorptions as the prevailing mechanism of phosphate sorption onto the nanosorbent. Thermodynamic studies resulted negative ΔG values indicating the spontaneity of the sorption process. The Fe-Al-Mn ternary nanocomposite sorbent showed a sorption capacity of 38.46 mg g −1 at pH 3. The sorption efficiency of the nanosorbent was found to be 99.5%. This adsorbent, with large sorption capacity and efficiency, is therefore a promising adsorbent for the removal of phosphate ions from aqueous systems.

https://digital.csic.es/bitstream/10261/162383/1/ternary_oxide_nanosorbent.pdf

Fe-Al-Mn ternary oxide nanosorbent: Synthesis, characterization and phosphate sorption property

In the present study, removal of Cr(VI) from aqueous solutions was investigated utilizing Teff straw, the agricultural solid waste product of Tef [Eragrostis tef (Zucc.) Trotter]. The characteristic surface chemistry of the Teff straw was analyzed by FT-IR analysis and the adsorption efficiency of this novel adsorbent was studied using the batch adsorption technique. Different experimental parameters including pH, contact time, adsorbent dose, initial metal ion concentration, and agitation speed were optimized. Equilibrium and kinetic models for Cr(VI) sorption were studied by considering the effects of concentration and contact time at the optimum pH (pH = 2) and agitation speed of 150 rpm. Results of the sorption equilibria were found to fit better to the Langmuir isotherm (R2 = 0.9739) than the Freundlich isotherm (R2 = 0.9187) and maximum Cr(VI) loading capacity of 3.51 mg/g was determined. On the other hand, kinetics of Cr(VI) sorption on the Teff straw was well defined by the pseudo-second o...

The Teff straw: a novel low-cost adsorbent for quantitative removal of Cr(VI) from contaminated aqueous samples

Fe-Al-Zr ternary mixed oxides composite was synthesized via co-precipitation method for the removal Pb(II), Cd(II) and Cr(VI) ions from aqueous solutions. The as-synthesized materials were characterized by X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), scanning electron microscope hyphenated with energy dispersive X-ray diffraction (SEM-EDX) and Fourier transform infrared (FTIR) techniques. The pH at the point of zero charge (pHpzc) of the sorbent and effect of ionic strength on sorption were also determined. The batch tests were conducted to optimize the various sorption parameters such as pH, adsorbent dose, contact time, speed of agitation and initial metal concentration. The experimental results showed that the adsorbed amounts of Pb(II), Cd(II) and Cr(VI) tend to decrease with increase in pH. Freundlich isotherm model fits better the equilibrium data for the adsorbent. Kinetic data correlated better with both pseudo first order and pseudo second order kinetic models. The spontaneous nature of the adsorption process was also confirmed from thermodynamic grounds. The nanosized adsorbent exhibited an adsorption efficiency of 96.65%, 96.55% and 97.2% for Cd(II), Cr(VI) and Pb(II), respectively, at optimum condition. Experimental results showed that the nanocomposite was effective for the removal of the title heavy metals from aqueous solution.
 
Bull. Chem. Soc. Ethiop. 2020, 34(1), 105-121.
DOI: https://dx.doi.org/10.4314/bcse.v34i1.10

/pdf/preparation-and-sorption-property-study-of-fe3o4-al2o3-zro2-3r2rfmm4oy.pdf

Preparation and sorption property study of Fe3O4/Al2O3/ZrO2 composite for the removal of cadmium, lead and chromium ions from aqueous solutions

The purpose of this study was to determine the concentration of heavy metals (Cr, Cd and Pb) in vegetables and the soil contaminating levels as a result of irrigation using Flame Atomic Absorption Spectrophotometer (FAAS). The wet digestion and sequential fractionation extraction procedures were employed to solubilize the metals from the collected samples. The results obtained from this study showed overall concentration of heavy metals Cr, Cd and Pb respectively, in the range of (2.90-3.77), (2.20-3.68) and (4.60-5.50) (mg/Kg) in the edible parts of sampled vegetables. Whereas, concentrations (mg/Kg) of the metals in the soil samples were found to be in the ranges of 22.37-66.30, 27.93-45.33 and 18.82-64.87 for Cr, Cd and Pb, respectively. The modified Tessier sequential extraction procedure was used to fractionate the above three metals from the soil samples into five fractions. In this study the heavy metals were predominantly concentrated in residual fraction (F5); since lead was mainly associated with the organic matter bounded fraction (F4) (34.33-43.45%), it was found to be more bioavailable and mobile than the other investigated heavy metals. The concentrations of heavy metals (Cr, Cd and Pb) in the soil and vegetable samples were above the recommended limit of both WHO and FAO. But Pb for the soil samples was smaller than WHO and FAO recommended limit. Based on facts obtained from this study we suggests concerned official body (ies) to take the necessary precaution measures for cleaning the polluted area.

	Key words: Heavy metals, sequential fractionation, eastern industry zone.

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Levels of some toxic heavy metals (Cr, Cd and Pb) in selected vegetables and soil around eastern industry zone, central Ethiopia

Salting˗out-assisted liquid–liquid extraction coupled with high-performance liquid chromatography was developed for selective extraction and preconcentration of five s-triazine herbicides and three...

Salting-out-assisted liquid–liquid extraction for the preconcentration and quantitative determination of eight herbicide residues simultaneously in different water samples with high-performance liquid chromatography

Endale Teju

Papers

Fe-Al-Mn ternary oxide nanosorbent: Synthesis, characterization and phosphate sorption property

The Teff straw: a novel low-cost adsorbent for quantitative removal of Cr(VI) from contaminated aqueous samples

Preparation and sorption property study of Fe3O4/Al2O3/ZrO2 composite for the removal of cadmium, lead and chromium ions from aqueous solutions

Levels of some toxic heavy metals (Cr, Cd and Pb) in selected vegetables and soil around eastern industry zone, central Ethiopia

Salting-out-assisted liquid–liquid extraction for the preconcentration and quantitative determination of eight herbicide residues simultaneously in different water samples with high-performance liquid chromatography