Kun She Low

REMOVAL OF METALS FROM ELECTROPLATING WASTES USING BANANA PITH

Banana pith (Musacea zingiberales) was evaluated for its ability to sorb metal ions from electroplating waste and synthetic solutions under both batch- and continuous-flow conditions. Sorption was both pH and concentration dependent, with pH 4·5 being the optimum value. The equilibrium data followed the Langmuir isotherm model with maximum capacities of 8·55 and 13·46 mg/g for Cu in electroplating waste and synthetic solution respectively. Competitive studies showed that the affinity of metal sorption was in the order Pb(II) > Cu(II) > Ni(II) > Cr(III) > Zn(II). In the continuous-flow studies, breakthrough curves for Cu(II) and Ni(II) in the elctroplating waste were obtained at different bed depths and flow rates. Cu(II) was more satisfactorily sorbed on the banana pith than Ni(II).

Biosorption of basic dyes by water hyacinth roots

Laboratory investigations of the potential of the biomass of non-living, dried, roots of water hyacinth (Eichhornia crassipes) to remove two basic dyes, methylene blue and Victoria blue, from aqueous solutions were conducted. Parameters studied included pH, sorbent dosage, contact time and initial concentrations. The Langmuir isotherm was found to represent the measured sorption data well. Maximum sorption capacities of water hyacinth roots for methylene blue and Victoria blue were 128.9 and 145.4 mg/g respectively. Water hyacinth roots could represent a cheap source of biosorbent for basic dyes as they are readily available in great abundance.

Removal of some organic dyes by acid-treated spent bleaching earth

Acid treated spent bleaching earth was prepared by treating spent bleaching earth, a waste material from the palm oil industry, with 20% sulphuric acid and heated at 350°C for three hours. This material can efficiently sorb a variety of organic dyes especially reactive and acid dyes, with maximum sorption capacity in the order of 2–300 mg g−1. The applicability of both the Langmuir and Freundlich isotherms to the experimental data indicates that both physicosorption and chemisorption were involved in the sorption process.

Sorption of copper by dye-treated oil-palm fibres

Abstract Both dye-treated and natural oil-palm fibres from a palm-oil mill were used to remove copper and related heavy metal cations from solutions. The sorption of copper for both types of fibres was studied under various conditions, the parameters being effect of pH, initial concentrations, presence of other metal cations and chelators. The results showed that dye coating had a pronounced effect on metal sorption. A comparative study on the uptake by the fibres of metal cations from electroplating wastes was also undertaken.

Cadmium uptake by the Moss, Calymperes delessertii, Besch

Studies were conducted to assess the capability of a moss, Calymperes delessertii Besch, in removing cadmium from solutions. In the batch experiments, parameters studied included pH, sorbent dosage, cadmium concentration, ionic strength, presence of other ions, temperature and contact time. In addition, a series of fixed-bed experiments was performed to study the flow system in an attempt to simulate industrial conditions. The bed depth service time (BDST) model proposed by Hutchins was successfully applied to the system. The results show that the moss is an efficient sorbent for cadmium from solution and that the mechanism of sorption is mainly an ion-exchange process.

Removal of chromium from aqueous solution

Abstract Laboratory studies were conducted to assess the ability of natural moss and copper-coated moss to remove Cr(III) and Cr(VI) from aqueous solutions. Parameters investigated included pH, contact time, initial concentration, sorbent dosage and temperature. Application of the Langmuir isotherm to the systems yielded maximum sorption capacities of 18·9 and 7·1 mg/g for Cr(III) and Cr(VI), respectively. In addition, a series of flow studies was carried out using columns containing a mixture of natural and copper-coated moss. Results indicated that the treatment of aqueous solutions containing a mixture of Cr(III) and Cr(VI) using such a column is feasible.

Chrome Sludge as an Adsorbent for Colour Removal

The potential of chrome sludge, a waste product from the electroplating industries, to remove colour from aqueous solutions was investigated. Results indicated that the sludge had better affinity for acid than basic dyes. Equilibrium data can be fitted into the Langmuir isotherm with maximum sorption of 30 – 60 mg g−1 for the range of acid dyes studied. The process followed a first order rate kinetics and the rate of dye removal was influenced by concentration and agitation speed.

Sorption of basic dyes by Hydrilla verticillata

Abstract The potential of an aquatic plant, Hydrilla verticillata, to remove two basic dyes, methylene blue and basic blue, from aqueous solutions was assessed under various experimental conditions. Results showed that dried Hydrilla was able to remove the dyes efficiently and rapidly. Its breakthrough time under flow conditions could be predicted using Hutchins bed depth‐service time (BDST) model. As Hydrilla is readily available, it could represent a cheap source of biosorbent for basic dyes.

Biosorption of copper by water hyacinth roots

Abstract Biomass of non‐living dried water hyacinth roots, Eichhornia crassipes, showed high sorption for copper from aqueous solutions. Maximum sorption was 20.90 mg Cu/g as determined from Langmuir isotherm. Several factors affecting sorption were investigated. They include effect of pH, initial concentrations, presence of chelators and other metals. The feasibility of removing copper from electroplating waste using this material in a packed‐bed system was also discussed.

Carbonized spent bleaching earth as a sorbent for some organic dyes

The potential of carbonized spent bleaching earth (CSBE) to remove/reduce acid and basic dyes in aqueous solution was investigated. Results show that CSBE was more effective in removing basic dyes. Parameters like pH, initial concentration, agitation rate, contact time and temperature which affect the sorption process were studied. As determined from Langmuir isotherms the maximum sorption capacities of CSBE for Basic Blue 3 and Methylene Blue were 102.6 and 94.5 mg/g respectively. Hence CSBE could be a useful sorbent in the treatment of baisc dyes in wastewater.