Lizie D.T. Prola

Microwave-assisted activated carbon from cocoa shell as adsorbent for removal of sodium diclofenac and nimesulide from aqueous effluents

Microwave-induced chemical activation process was used to prepare an activated carbon from cocoa shell for efficient removal of two anti-inflammatories, sodium diclofenac (DFC) and nimesulide (NM), from aqueous solutions. A paste was obtained from a mixture of cocoa shell and inorganic components; with a ratio of inorganic: organic of 1 (CSC-1.0). The mixture was pyrolyzed in a microwave oven in less than 10 min. The CSC-1.0 was acidified with a 6 mol L(-1) HCl under reflux to produce MWCS-1.0. The CSC-1.0 and MWCS-1.0 were characterized using FTIR, SEM, N2 adsorption/desorption curves, X-ray diffraction, and point of zero charge (pHpzc). Experimental variables such as initial pH of the adsorbate solutions and contact time were optimized for adsorptive characteristics of MWCS-1.0. The optimum pH for removal of anti-inflammatories ranged between 7.0 and 8.0. The kinetic of adsorption was investigated using general order, pseudo first-order and pseu do-second order kinetic models. The maximum amounts of DCF and NM adsorbed onto MWCS-1.0 at 25 °C are 63.47 and 74.81 mg g(-1), respectively. The adsorbent was tested on two simulated hospital effluents. MWCS-1.0 is capable of efficient removal of DCF and NM from a medium that contains high sugar and salt concentrations.

Adsorption of Procion Blue MX-R dye from aqueous solutions by lignin chemically modified with aluminium and manganese

A macromolecule, CML, was obtained by purifying and carboxy-methylating the lignin generated from acid hydrolysis of sugarcane bagasse during bioethanol production from biomass. The CMLs complexed with Al(3+) (CML-Al) and Mn(2+) (CML-Mn) were utilised for the removal of a textile dye, Procion Blue MX-R (PB), from aqueous solutions. CML-Al and CML-Mn were characterised using Fourier transform infrared spectroscopy (FTIR), scanning differential calorimetry (SDC), scanning electron microscopy (SEM) and pHPZC. The established optimum pH and contact time were 2.0 and 5h, respectively. The kinetic and equilibrium data fit into the general order kinetic model and Liu isotherm model, respectively. The CML-Al and CML-Mn have respective values of maximum adsorption capacities of 73.52 and 55.16mgg(-1) at 298K. Four cycles of adsorption/desorption experiments were performed attaining regenerations of up to 98.33% (CML-Al) and 98.08% (CML-Mn) from dye-loaded adsorbents, using 50% acetone+50% of 0.05molL(-1) NaOH. The CML-Al removed ca. 93.97% while CML-Mn removed ca. 75.91% of simulated dye house effluents.

New carbon composite adsorbents for the removal of textile dyes from aqueous solutions : Kinetic, equilibrium, and thermodynamic studies

New carbon composite materials were prepared by pyrolysis of mixture of coffee wastes and red mud at 700 °C with the inorganic: organic ratios of 1.9 (CC-1.9) and 2.2 (CC-2.2). These adsorbents were used to remove reactive orange 16 (RO-16) and reactive red 120 (RR-120) textile dyes from aqueous solution. The CC-1.9 and CC-2.2 materials were characterized using Fourier transform infrared spectroscopy, Nitrogen adsorption/desorption curves, scanning electron Microscopy and X-ray diffraction. The kinetic of adsorption data was fitted by general order kinetic model. A three-parameter isotherm model, Liu isotherm model, gave the best fit of the equilibrium data (298 to 323 K). The maximum amounts of dyes removed at 323 K were 144.8 (CC-1.9) and 139.5 mg g−1 (CC-2.2) for RO-16 dye and 95.76 (CC-1.9) and 93.80 mg g−1 (CC-2.2) for RR-120 dye. Two simulated dyehouse effluents were used to investigate the application of the adsorbents for effluent treatment.

Mesoporous Nb2O5/SiO2 material obtained by sol–gel method and applied as adsorbent of crystal violet dye

ABSTRACT In this work, SiO2/Nb2O5 (SiNb) material was prepared using sol–gel method and employed as adsorbent for removal of crystal violet dye (CV). The material was characterized using nitrogen adsorption–desorption isotherms, FTIR spectroscopy, pHpzc, and SEM-EDS. The analysis of N2 isotherms revealed the presence of micro- and mesopores in the SiNb sample with specific surface area as high as 747 m2 g−1. For the CV adsorption process, variations of several parameters such as of pH, temperature, contact time, and concentration of dye of the process were evaluated. The optimum initial pH of the CV dye solution was 7.0. The adsorption kinetic and equilibrium data for CV adsorption were suitably represented by the general-order and Liu models, respectively. The maximum adsorption capacity of the CV dye by SiNb was achieved at 303 K, which attained 116 mg g−1 at this temperaure. Dye effluents were simulated and used to check the applicability of the SiNb material for treatment of effluents – the material showed very good efficiency for decolorization of dye effluents.

Activated Carbon from Sewage Sludge for Preconcentration of Copper

ABSTRACT Sewage sludge was pyrolyzed in an inert atmosphere at 550°C after chemical treatment with ZnCl2 or KOH using an organic precursor to inorganic weight ratio of 1:1. The materials were used as adsorbents for removal of Cu(II) from aqueous solution. The adsorbents were characterized using adsorption/desorption nitrogen isotherms, thermal analysis, scanning electron microscopy, and elemental analysis. The results showed that copper removal was linked to surface pH and compounds present on the surface of the adsorbent. The KOH-treated adsorbent had a smaller surface area (186 m2 g−1) than the ZnCl2-treated adsorbent (192 m2 g−1). However, the KOH-treated adsorbent provided more efficient removal of Cu(II). The performance of the KOH-treated adsorbent may be due to the presence of basic groups on the surface. The Liu isotherm model provided the best description of the equilibrium data: The maximum adsorption capacities at 298 K for KOH-treated, ZnCl2-treated, and untreated sewage sludge were 31.85, 19.79, and 3.513 mg g−1, respectively. The highest desorption was obtained using 1.50 mol L−1 of HNO3 as the eluent. The recoveries of Cu(II) loaded adsorbents were 98.9% for ZnCl2-treated and 95.5% for KOH-treated adsorbents.

Application of aqai stalks as biosorbent for the removal of Evans Blue and Vilmafix Red RR-2B dyes from aqueous solutions

Abstract The aqai palm stalk (Euterpe oleracea) is food residue used in its natural form (AS) as biosorbent for the removal of Evans Blue (EB) and Vilmafix Red RR-2B (VR) textile dyes from aqueous solutions. The effects of pH, biosorbent dosage, and shaking time on biosorption capacities were studied. The maximum adsorption of both dyes occurred at pH 2.0. The Avrami fractional-order kinetic model provided the best fit to experimental data compared with pseudo-first-order and pseudo-second-order kinetic adsorption models. The equilibrium data were fitted to Langmuir, Freundlich, and Sips isotherm models. For both dyes, the equilibrium data were best fitted to the Sips isotherm model. Simulated dyehouse effluents were used to check the applicability of the proposed AS biosorbent for effluent treatment.

REMOVAL OF CIBACRON BRILLIANT YELLOW 3G-P DYE FROM AQUEOUS SOLUTIONS BY BRAZILIAN PEATS AS BIOSORBENTS

Two Brazilian peat samples in different stages of decomposition, fibrous peat (FP) and decomposed peat (DP), were used as biosorbents for the removal of the textile dye Cibacron Brilliant Yellow 3G-P (CBY) from aqueous solutions. These biosorbents were characterized by Fourier transform-infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The effects of initial pH of dye solution and contact time between the dye and the biosorbents on the biosorption capacities were studied. Based on an error function (Ferror ) the general-order kinetic model provided the best fit to the experimental data compared with the pseudo-first-order and pseudo-second-order kinetic biosorption models. The equilibrium data were fitted to Langmuir, Freundlich, and Liu isotherm models. For both biosorbents the equilibrium data were best fitted to the Liu isotherm model. Simulated dye house effluents were used to check the applicability of the proposed biosorbents for effluent treatment.