Equilibrium, kinetic and thermodynamic studies on the removal of U(VI) by low cost agricultural waste

In this research, biosorption efficiency of different agro-wastes were evaluated with rice husk showing maximum biosorption capacity among the selected biosorbents. Optimization of native, SDS-treated and immobilized rice husk adsorption parameters including pH, biosorbent amount, contact time, initial U(VI) concentration and temperature for maximum U(VI) removal was investigated. Maximum biosorption capacity for native (29.56 mg g-1) and immobilized biomass (17.59 mg g-1) was observed at pH 4 while SDS-treated biomass showed maximum removal (28.08 mg g-1) at pH 5. The Langmuir sorption isotherm model correlated best with the U(IV) biosorption equilibrium data for the 10-100 mg L-1 concentration range. The kinetics of the reaction followed pseudo-second order kinetic model. Thermodynamic parameters like free energy (ΔG°) and enthalpy (ΔH°) confirmed the spontaneous and exothermic nature of the process. Experiments to determine the regeneration capacity of the selected biosorbents and the effect of competing metal ions on biosorption capacity were also conducted. The biomass was characterised using scanning electron microscopy, surface area analysis, Fourier transformed infra-red spectroscopy and thermal gravimetric analysis. The study proved that rice husk has potential to treat uranium in wastewater

Lanthanum biosorption by different Saccharomyces cerevisiae strains

Biosorption can be a promising technology in rare earth metal separation and recovery due to the low costs of waste biomasses (used as biosorbents) and the high selectivity exploiting specific interaction between metals and biological active sites. In this work, Saccharomyces cerevisiae biomass was used to recover lanthanum. Biosorption properties of two S. cerevisiae strains, wild type and rim20. mutant, have been tested. Potentiometric titrations were carried out for rim20. mutant strain and compared with wild type. Nature of the main active sites and their concentration were determined by implementing mechanistic models. Carboxylic, amino and phosphoric sites are the main groups present. Higher concentration of negatively charged sites was found in rim20. (0.0024 mol/g) than in wild type (0.0022 mol/g). The rate of lanthanum biosorption process is very fast requiring only 10-20 minutes to reach equilibrium condition for both strains. Then biosorption equilibrium tests were done for both biomasses by testing two equilibrium pH (4.0 and 6.0). Maximum uptake capacities (qmax) were: 70 mg/g and 40 mg/g at pH 4.0 for rim20. and wild type, respectively, and 67 mg/g and 80 mg/g at pH 6.0 for wild type and rim20., respectively. These data evidenced that: rim20. mutant had a higher maximum biosorption capacity with respect to wild type counterpart, and that pH had a relevant effect on lanthanum removal. S. cerevisiae yeast denoted good lanthanum biosorption properties and, between tested strains, rim20. was found to be the most promising for such aim

Biosorption of chromium (VI) by chitosan-immobilized acinetobacter haemolyticus

In this study, the ability of chitosan-immobilized Acinetobacter haemolyticus as biosorbent for chromium (VI) biosorption in batch system was investigate. Optimized parameter namely pH, contact time, biosorbent dosage and initial metal concentration obtained from the experiment was then applied for electroplating wastewater treatment. Biosorption using chitosan-immobilized Acinetobacter haemolyticus at pH 3, 8 hours contact time, 3% (w/v) of biosorbent dosage with 100 mg L 1 initial metal concentration resulted in maximum chromium (VI) uptake of 0.2 mg g 1. Using electroplating wastewater, the biosorption capacity of the chitosan immobilized Acinetobacter haemolyticus was 0.27 mg g 1 at pH 3 which is higher than unmodified pH

Valorization of keratin biofibers for removing heavy metals from aqueous solutions

Four common waste keratin biofibers (human hair, dog hair, chicken feathers, and degreased wool) have been used as biosorbents for the removal of heavy metal ions from aqueous solutions. Different parameters of the biosorption processes were optimized in batch systems. For multiple-metal systems, consisting of a mixture of eight metal ions [Cr(III), Mn(II), Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II)], the total metal biosorption increased in the order: degreased wool¿>¿chicken feathers¿>¿human hair¿>¿dog hair. From the kinetic models tested, the pseudo-second-order model provided better results. Furthermore, biosorption isotherms of Pb(II) with the different keratin biofibers fitted the Langmuir model. Surface morphology of the biosorbents were analyzed before and after the sorption using Fourier transform infrared spectroscopy and scanning electron microscopy. The keratin biofibers tested are potentially good sorbents of metal ions, with degreased wool and chicken feathers being the more efficient onesPostprint (author's final draft

A review on performance of waste materials in self compacting concrete (scc)

Self-compacting concrete (SCC) was first developed in late 80’s in Japan. SCC is well known for its self-consolidation and able to occupy spaces in the formwork without any vibration and become new interesting topic in Construction and Building Materials Research. There were various SCC researches that have been carried out in Turkey, Malaysia, Thailand, Iran, United Kingdom, Algeria, and India.The aim of this review is to summaries the alternative material used in the mix design from 2009 to 2015 through available literature. It hascommon materials such as Limestone Powder (LP), Fly Ash (FA), Silica Fume and Granulated Blast Furnace Slag (GBFS). While there are many alternative or recycled material can be used in producing SCC. This review only focus on waste material fromMarble Powder (MP), Dolomite Powder (DP), Crump Rubber (CR), Recycled Aggregate (RA) and Rise Husk Ash (RHA).Each type of materialshassimilarity effect in fresh and hardened state of SCC. Therefore, this paper will provide significant and useful information to those new to SCC and fellow researchers for future studies on SCC

A review on performance of waste materials in self compacting concrete (scc)

Self-compacting concrete (SCC) was first developed in late 80’s in Japan. SCC is well known for its self-consolidation and able to occupy spaces in the formwork without any vibration and become new interesting topic in Construction and Building Materials Research. There were various SCC researches that have been carried out in Turkey, Malaysia, Thailand, Iran, United Kingdom, Algeria, and India.The aim of this review is to summaries the alternative material used in the mix design from 2009 to 2015 through available literature. It hascommon materials such as Limestone Powder (LP), Fly Ash (FA), Silica Fume and Granulated Blast Furnace Slag (GBFS). While there are many alternative or recycled material can be used in producing SCC. This review only focus on waste material fromMarble Powder (MP), Dolomite Powder (DP), Crump Rubber (CR), Recycled Aggregate (RA) and Rise Husk Ash (RHA).Each type of materialshassimilarity effect in fresh and hardened state of SCC. Therefore, this paper will provide significant and useful information to those new to SCC and fellow researchers for future studies on SCC

Determination of biosorption mechanism in biomass of agave, using spectroscopic and microscopic techniques for the purification of contaminated water

[Abstract] Lead (Pb2+) and copper (Cu2+) are polluting metals due to their toxicity; however, the extraction of these metals is essential for economic development, so it is important to look for efficient and low-cost alternatives that can remove heavy metals from the various bodies of water. One of the alternatives used in this work is biosorption, for which an agroindustrial waste (epidermis from Agave atrovirens) was used to evaluate the affinity of removal of lead and copper in aqueous solutions; in addition, spectroscopy and microscopy techniques were used to elucidate and corroborate the removal and affinity capacity of the agave epidermis for both metals studied. The optimal pH value for the removal of both metals was 3. The adsorption isotherms yielded a qmax of 25.7 and 8.6 mg/g for lead and copper, respectively. Adjusting to the Langmuir-Freundlich model, the adsorption kinetics were pseudo-second order, and it was found that the equilibrium time was at 140 min. The spectroscopy and microscopy analyses corroborated the affinity between metals and functional groups of the agave, as well as with the elemental analysis, which reported 17.38% of lead and 4.25% of copper.[Resumen] El plomo (Pb2+) y el cobre (Cu2+) son metales contaminantes debido a su toxicidad; sin embargo, la extracción de estos metales es indispensable para el desarrollo económico, por lo que es importante buscar alternativas eficientes y de bajo costo que puedan remover metales pesados de los diversos cuerpos de agua. Una de las alternativas utilizadas en este trabajo es la biosorción, para la cual se utilizó un residuo agroindustrial (epidermis de Agave atrovirens), para evaluar la afinidad de remoción del plomo y cobre en soluciones acuosas; adicionalmente, se emplearon técnicas de espesctroscopía y microscopía que permitieron elucidar y corroborar la capacidad de remoción y afinidad que tuvo la epidermis de A. atrovirens para ambos metales estudiados. El valor óptimo de pH para la remoción de ambos metales fue 3. Las isotermas de adsorción arrojaron una qmax de 25.7 y 8.6 mg/g para el plomo y cobre, respectivamente. Ajustando al modelo de Langmuir-Freundlich, las cinéticas de adsorción resultaron de pseudo-segundo orden, se encontró que el tiempo de equilibrio es a los 140 min. El análisis espectroscópico y microscópico, corroboró la afinidad entre metales y grupos funcionales del agave, así como con el análisis elemental, el cual reportó 17.38% de plomo y 4.25% de cobre