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In this work, CeAland CeAlMnxoxides (x = 0.1, 0.3, 0.5 and 0.7) were prepared using a co-precipitation method and their use for removal of methyl violet dye from an aqueous solution was investigated. The characteristics of the mixed oxides were determined using XRD, FT-IR, UV-vis DRS, SEM and EDX. It was found that cerium, aluminum and manganese ions were homogeneously incorporated into the cubic fluorite structure of CeO2. Moreover, the mixed oxides were found to consist of small grains containing pores, which resulted in a large surface area to volume ratio. Batch adsorption studies were performed to determine the contact time required to achieve equilibrium. The removal of dye by CeAl and CeAlMnx(x = 0.1 and 0.3) attained equilibrium after 60 min, while oxide samples with higher manganese fractions achieved equilibrium in 120 to 150 min. Based on the isotherm data, the adsorption behavior of CeAl was found to follow a Langmuir isotherm (R2= 0.9951) with a maximum adsorptive capacity of 2.35 mg/g. Results show that the Freundlich model best describes the adsorption of MV dye onto all CeAlMnxformulations.

AbstractIn this study, the adsorption efficiency of methyl violet dye onto Ce03Al07, Ce05Al05, and Ce07Al03 mixed oxides was investigated. The properties of Ce/Al oxides were determined by scanning electron microscope, X-ray diffraction, FT-Raman spectrometry, and N2adsorption–desorption isotherms. Characterization tests showed that synthesized Ce/Al oxide with fluorite has pure cubic structure of mesoporous nature and non-uniform in size with rough surface. Moreover, the surface areas of Ce/Al oxides were observed to decrease with increase in cerium content. The batch adsorption experiments were performed at 25°C and various parameters including solution pH, contact time, and initial dye concentration were studied. The dye adsorption of Ce03Al07 mixed oxide attained equilibrium at 15 min, which was faster than that of Ce05Al05 and Ce07Al03. The equilibrium adsorption data were analyzed using Langmuir, Freundlich, and Temkin isotherms. The adsorption behavior of methyl violet onto Ce03Al07 (R2 = 0.9739) was found to follow the Langmuir isotherm, providing maximum monolayer adsorptive capacity of 25 mg/g. On the other hand, the adsorption of methyl violet onto Ce05Al05 (R2 = 0.9581) and Ce07Al03 (R2 = 0.9894) followed the Freundlich isotherm.

ABSTRACTThe removal of Mn2+and Fe2+from synthetic groundwater via oxidation using potassium permanganate was investigated. Batch jar tests were carried out under a constant pH of 8.0, where the effect of parameters such as the oxidant dose, presence of co-ions (Ca2+, Mg2+) and alum addition on the removal of Mn2+and Fe2+was examined. The partial removal of Mn2+using aeration in single and dual metal system was 30.6% and 37.2%, respectively. The oxidant dose of 0.603 mg/L KMnO4was the minimum amount needed to reduce Mn2+below its maximum contaminant level. The presence of Fe2+improved the removal of Mn2+due to the autocatalytic effect of hydrous manganese-iron oxide, where its presence was confirmed by digital microscopy and EDX. The presence of Ca2+and Mg2+as well as the alum addition after oxidation has a negative effect on the removal of Mn2+. The removal mechanism of Mn2+and Fe2+was a combination of oxidation and adsorption or co-precipitation between the hydrous oxide and the dissolved metal ions.

The present work proposes the adsorption of methyl violet (MV) from two solution systems including single MV and binary MV-Cu2+ systems by activated carbon (AC) prepared from tamarind seeds in a batch system. Parameters including contact time, solution pH, adsorbent dose, and initial dye concentration were studied. The morphology of the AC was determined by scanning electron microscopy (SEM). The results showed the maximum adsorption of MV dye onto the AC at a contact time of 60 min, solution pH of 9.0 and adsorbent dose of 0.2 and 0.5 g for the single and binary solution systems, respectively. The presence of copper ions in binary solution system decreased the adsorption efficiency of MV dye onto the AC. The equilibrium adsorption data were analyzed using Langmuir, Freundlich and Temkin isotherms.

The study aimed to investigate the adsorption efficiency of methyl violet (MV) dye on activated carbon (AC) derived from coffee residues. A batch adsorption study was performed to examine various contributory parameters including contact time, solution pH, adsorbent dose and initial dye concentration. The morphology of the AC was studied by means of scanning electron microscopy (SEM). The results showed that maximum adsorption of MV dye on activated carbon occurred with a contact time of 60 min, solution pH of 9.0 and adsorbent dose of 0.3 g. The equilibrium adsorption data were analysed using Freundlich and Temkin isotherms. The adsorption isotherm was found to follow the Freundlich isotherm. Adsorption behavior of MV dye follows mechanism of physical adsorption which is occurred by heterogeneous surface. The results indicate that the AC from coffee residues is a suitable adsorbent for the adsorption of dyes.