Assessment of Phaseolus vulgaris L. biomass as low-cost adsorbent for the removal of Congo red dye from aqueous solutions

This research deals with the evaluation of available waste biomass of Phaseolus vulgaris L., as low cost adsorbents, in the removal of organic azo dye Congo red (CR). The effects of operational parameters on the efficiency of dye removal, including contact time, initial pollutant concentration and adsorbent dose have been investigated. The obtained results show that the amount of dye uptake was found to increase with the increase of contact time and initial dye concentration. The maximum sorption capacity was 1.291 mg g-1 for CR at 20°C. The removal efficiency of CR is increasing with the increase on sorbent dose, in the range of studied concentration (10 - 30 mg L-1 ). For evaluating the mechanism involved in the sorption process, the experimental results were analyzed using pseudo-I order kinetic model, pseudo-II order kinetic model, the Ritchie second-order model and intraparticle diffusion model. The pseudo II-order kinetic model agrees very well with the dynamic behavior of the sorption of CR dye onto Phaseolus vulgaris L. hull. The experimental sorption results indicated that agricultural waste - bean hull could be applied as an low-cost sorbent alternative used for azo dye removal from industrial effluents, taking into account that no pretreatment on the solid is carried out

Potenţialul unor microorganisme şi plante indigene de eliminare a metalelor grele din sol

Heavy metals found in soils from different industrial sources or mining activities are persistent inorganic pollutants able to bioaccumulate along the food chain and cause negative effects in theenvironment and for human health. Differentphysical, chemical and biological processes are applied for their removal from soil environments. Biological processes become more and more preferred, since bioremediation strategies have often proved to be more advantageous than the conventional remediation tools, mainly because these processes can be implemented directly onto the contaminated sites (in situ). In this context, the present paper examines the abilityof microorganisms and plants to remove heavy metals from soil, in terms of tolerance and bioaccumulation. A particular interest is given to the bioaccumulation processes of metals by proteobacteria, bacilli and actinobacteria, alone or in synergismwith indigenous plants. Also, some advances in the biosorption of highly toxic heavy metal ions as Cr(VI) and Cd(II) are just discussed,together with various strategies and practices to explore the synergism between microorganisms and plants as valuable biological resource for increasing tolerance against heavy metals and strengthening the bioremediation processes

Sorption of Organic Pollutants onto Soils: Surface Diffusion Mechanism of Congo Red Azo Dye

For the protection of human and ecological receptors from the effects of soil pollution with chemical compounds, we need to know the behavior and transport of pollutants in soil. This work investigated the Congo red (CR) acid dye sorption on three natural soils collected from central and northeastern regions of Romania, symbolized as IS-65, IS-T, and MH-13. To define the mechanism of sorption and identify the rate governing step, various diffusion models such as Weber–Morris intraparticle diffusion, Boyd, film and pores diffusion, and mass transfer analysis have been verified. The intraparticle diffusion analysis of Congo red sorption onto soils has been described by a multi-linear plots, showing that the sorption process takes place by surface sorption and intraparticle diffusion in macro, meso, and micropores. The values of intraparticle diffusion coefficient kid increased with any rise of the initial concentration of pollutant. The results show that the values of pore diffusion coefficient (Dp) and film diffusion coefficient (Df) are found to be from 10−8 to 10−10 cm2 s−1, indicating that film diffusion influences the sorption rate limiting step. The intraparticle diffusion analysis shows that the plots did not pass through the origin and have two distinct parts, confirming that intraparticle diffusion is not the single determining mechanism involved in the sorption of Congo red on soils IS-65, IS-T, and MH-13. The results revealed that the sorption process has a complex nature, since both external diffusion and internal diffusion are involved in the sorption of CR from solution onto the investigated soils