Alginate-calcium carbonate composite material was prepared in the form of beads and characterized using Fourier transform infra red (FT-IR) spectroscopy and scanning electron microscope (SEM) techniques. The adsorption of Cd 2? ions was studied through batch experiments. The adsorption parameters such as contact time (120 min), adsorbent dose (1.5 g), initial metal ion concentration(10 mg/L), pH (6) and agitation speed (150 rpm) were optimized at room temperature. Langmuir and Freundlich isotherms were applied to the data and it was noted that the adsorption of Cd 2? ions is better explained by Freundlich model. The kinetic studies showed that the adsorption of Cd 2? ions followed pseudo-first order kinetics. Thermodynamic parameters like DG 0 , DH 0 and DS 0 were calculated and on the basis of these values it was established that the adsorption process is feasible and endothermic in nature. It was concluded from the study that the composite material of alginate and calcium carbonate can effectively be used to recover Cd 2? ions from wastewater.

IntroductionPollution of heavy metals is of major concern in developing countries. The discharge of heavy metals into water-courses is a serious pollution problem which may affect the quality of water supply. Increasing concentration of these metals in the water constitute a severe health hazard due to their nondegradability and toxicity. Copper metal considered in this project is a widely used material. Copper metal contamination exists in aqueous waste streams from many industries such as electronic and electrical, metal plating, mining, manufacture of computer heat sinks, Cu plumbing as well as biostatic surface, as a component in ceramic glazing and glass coloring. Copper is persistent, bioaccumulative and toxic metal that does not readily breakdown in the environment and is not easily metabolized. It may accumulate in human ecological food chain through consumption or uptake and may be hazardous to human health. Drinking water that contains higher than normal levels of copper may cause vomiting, diarrhea, stomach cramp and nausea. The chronic effects of consumption of high levels copper are kidney and liver damage. The suggested safe level of copper in drinking water for humans varies depending on the sources, but tends to be pegged at 1.5 to 2.0 mg/L. Hence removal of copper from water and wastewaters assumes important (Nauja et al. 2008). The effects of various parameters, such as pH of the feed solution, contact time, temperature, adsorbate and adsorbent concentrations, and particle size of the adsorbent, were studied for optimization of the process parameters. The adsorption behavior of Cu on three solid waste materials-sea nodule residue (SNR), fly ash (FA), and red mud (RM) was observed (Agrawal et al. 2004). It was noted that adsorption of copper increased with increasing time, temperature, pH, and adsorbate concentration, and decreased with increasing initial copper concentration. The ability of rice husk ash to remove chromium, zinc, copper and cadmium from waste water has been investigated. Several parameters that can affect metals uptake such as particle size, pH and temperature were described. At the optimal conditions, the chromium, zinc, copper and cadmium ions removal from aqueous solution are 79, 85, 80 and 85%, respectively. After the adsorption of metal ions, the analyte retained in the husk could be recovered almost completely by eluting with dilute hydrochloric acid solution (Munaf et al. 1997). Rice husk was studied as a potential scavenger of lead from various aqueous solutions. Physiochemical parameters such as selection of appropriate electrolyte, shaking time, and the concentrations of adsorbent and adsorbate were studied for the decontamination of effluents using a batch technique (Nasir et al. 1998). The utility of rice husk ash as an adsorbent for metal ions such as iron, zinc and copper from acid mine water was assessed. Study of Chockalingam et al. 2006 revealed that about 99% Fe 3+ , 98% of Fe 2+ and Zn 2+ and 95% Cu 2+ uptake was achieved from acid mine water, with increase i...

The presence of toxic metals like lead, mercury, chromium, arsenic, etc. in water is major problem these days. This investigation involves the removal of lead from water by batch adsorption technique using α- alumina (A12O3) as adsorbent. Percentage adsorption was determined for alumina-lead solution system as a function of pH, temperature, contact time and adsorbate dose. The known quantities of lead in solutions have been adsorbed on α-alumina and the concentration of lead in the solution after adsorption was determined by atomic absorption spectrophotometer. Maximum adsorption of lead was observed at pH 10, temp.15°C, 30 minutes and low adsorbate dose. Adsorption data has been interpreted in terms of Freundlich equation. The results suggest that α-alumina is effective adsorbent for lead removal. Key words: Toxic metals; Adsorbent; α-Alumina DOI: 10.3329/bjsir.v44i4.4589 Bangladesh J. Sci. Ind. Res. 44(4), 403-406, 2009

Adsorption for alumina-cobalt (II) ions solution system was investigated as a function of adsorbent dose, contact time, temperature, pH of solution and initial concentration of adsorbate. The optimum conditions for removal of cobalt (II) ions were found as pH 7.5-8.5, adsorbent dose of solution 20 gl-1 , equilibrium time 90 minutes and initial concentration range 5-50 mgl-1. Pseudo-second-order kinetics was observed for adsorption of cobalt while cobalt removal process does not seem to control the intra-particle diffusion. Langmuir, Freundlich and Dubnin-Radushkevich isotherm models were applied to analyze the equilibrium isotherms for adsorption of cobalt (II) ions onto alumina. The experimental results indicated that equilibrium data follows the Langmuir model within used concentration range.

The incessant release of textile effluent comprehending dyes and heavy metals which impacts on aquatic life. Current study used an enzyme to eradicate phenolic compounds and synthetic dyes from textile effluent by an indigenously isolated white rot fungus Pleurotus ostreatus- P1 has been cultured and indicated the utmost laccase activity with synthetic medium; as reacting substrate for dye decolorization. The textile effluent decolorization optimization has been conducted with different concentrations of laccase enzyme, temperature and pH. The 90% effluent decolorization was obtained by applying response surface methodology (RSM) conditions temperature, crude laccase enzyme and pH, 25˚C, 13.5 U/ml and 5 respectively. The predicted values were validated with experimental values, that confirms the steadiness of the model. Bangladesh J. Sci. Ind. Res.56(2), 115-124, 2021