title: The effect of pH, temperature, and molecular size on the removal of dyes from textile effluent using manganese oxides-modified diatomite.
abstract: This work is an investigation on the use of manganese oxides-modified diatomite (MOMD) for the removal of color from textile wastewaters. The modification of the diatomite was carried out by treatment with manganese oxides; delta-bimessite type resulted. The surface area, pH(ZPC), Fourier transform infrared (FTIR), and scanning electron microscopy of MOMD were studied. The influence of concentration, pH, particle size, and temperature on the adsorption capacities of methylene blue (MB) and hydrolyzed reactive black (RB) and reactive yellow (RY) was investigated. Key thermodynamic parameters such as deltaH degrees, deltaS degrees, and deltaG degrees were also determined. The deltaH degrees of MB and hydrolyzed RB and RY was +94.64, -143.1, and -38.78 kJ/mol, respectively, whereas the deltaG degrees values of -17.68, -27.93, and -23.26 kJ/mol were obtained, indicating a spontaneous process with low activation-energy requirements. The findings further indicated that coulomb interaction, molecular size, and orientation of the dye and its surface charge played an important role in the adsorption and attachment of the dyes to the bimessite layers of MOMD.
authors.affiliation: Department of Civil and Environmental Engineering, University College, London. m.khraisheh@u-cl.ac.uk
authors.forename: M A M
authors.initials: MA
authors.lastname: Khraisheh
authors.forename: M A
authors.initials: MA
authors.lastname: Al-Ghouti
authors.forename: S J
authors.initials: SJ
authors.lastname: Allen
authors.forename: M N M
authors.initials: MN
authors.lastname: Ahmad
mesh_terms: D000327:Adsorption; D004396:Coloring Agents / Q000737:chemistry*; D007692:Diatomaceous Earth / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017895:Manganese Compounds / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D010087:Oxides / Q000737:chemistry*; D010316:Particle Size; D017550:Spectroscopy, Fourier Transform Infrared; D013696:Temperature; D013816:Thermodynamics; D014865:Waste Disposal, Fluid / Q000379:methods*; D018508:Water Purification / Q000379:methods*
chemical_list: D004396:Coloring Agents; D017895:Manganese Compounds; D010087:Oxides; D007692:Diatomaceous Earth; C027424:manganese oxide; C033787:diatomite