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The effluent from the rubber processing industry usually contains a high concentration of organic compounds, suspended solids, color, nitrogen, and other pollutants. If an excessive amount of ammonia nitrogen is discharged into bodies of water, it may cause eutrophication and the death of various aquatic creatures. The goal of this experimental design was to investigate the effectiveness of zeolite for ammoniacal nitrogen, chemical oxygen demand (COD), and color removal from rubber processing industry effluent. The samples of rubber processing industry effluent for this study were acquired directly from the discharging point of a manufacturer in Kluang, Malaysia. The effects of optimal adsorbent dose, shaken speed, contact time, and pH were determined for ammoniacal nitrogen, COD and color removal. The obtained result reveals that the best batch adsorption experiment of ammoniacal nitrogen, COD, and color removal was attained at pH 7, ZEO dosage 4.0 g, contact time 120 min, and shaken speed 200 rpm respectively. The best efficiency removal of ammoniacal nitrogen, COD, and color was achieved based on dosage generally in the range of 75% for ammoniacal nitrogen, 69% for COD, and 79% for the color of all batch experiments conducted. The kinetic equilibrium model data fitted well with the pseudo-first and second model. The pseudo-second-order better fitted the equilibrium data over the entire concentration range studied. The pseudo-second-order described the best coefficient of determination compared to the pseudo-first-order. The coefficient of determination for pseudo-second-order was generally in the range of 0.9958 for ammoniacal nitrogen, 0.9978 for COD, and 0.9984 for the color of all kinetics studies conducted. [ABSTRACT FROM AUTHOR]

Removal of Cr(VI) from liquid by iron-loaded composite resin was studied. The isothermal adsorption model and the adsorption kinetic model were established. The adsorption thermodynamic parameters were solved. The iron-loaded composite resins before and after adsorption were characterized by scanning electron microscope (SEM) and energy dispersive spectrometer (EDS). It was found that the adsorption capacity of iron-loaded composite resin was higher than others. The results showed that the optimum adsorption condition was performed at 318 K, the pH of 2, and the time of 6 h. Freundlich model and pseudo-first-order kinetic model fitted the experimental data. The main control step of the adsorption was liquid film diffusion process. The value of ΔH was 2–16 kJ mol–1, which showed that the adsorption was an endothermic process. The adsorption of ΔG was less than zero which indicated the adsorption was spontaneous. The value of ΔS was constant positive that revealed the adsorption was the total entropy-increasing process. SEM and EDS analyses indicated that Cr(VI) can adsorb by iron-loaded composite resin effectively. The eluent of 6% NaOH + 5% NaCl had an excellent desorbing performance. [ABSTRACT FROM AUTHOR]

Activated carbon (AC) was prepared from eucalyptus sawdust by microwave-assisted activation with ZnCl2and utilized for removing chromium(VI) from an aqueous solution with a concentration of 10–80 mg L−1and a temperature of 30–60°C. The effects of pH, contact time, initial concentration of Cr(VI) and temperature on adsorption, as well as the thermodynamics and kinetics were investigated. The results were as follows: (1) The adsorption capacity of Cr(VI) was dependent on pH and initial concentration as the equilibrium time increased, but the Cr(VI) removal percentage decreased with an increase in the initial Cr(VI) concentration; (2) The adsorption process was in good agreement with the Langmuir adsorption isotherm model at 30°C and the Freundlich adsorption isotherm model at 45 and 60°C; (3) Adsorption thermodynamic parameters ΔH°, ΔS°, and ΔG°indicated that Cr(VI) adsorption on AC was a spontaneous and endothermic process with increased randomness at the solid–solution interface; (4) Cr(VI) adsorption on AC followed a pseudo-second-order equation at 30, 45, and 60°C fitted into an intraparticle diffusion model at 30 and 45°C, and it followed a pseudo-first-order equation only at 60°C and at Cr(VI) concentrations of 10 and 20 mg L−1. [ABSTRACT FROM PUBLISHER]