Josep Sabaté

Determination of equilibrium distribution constants of phenol between surfactant micelles and water using ultrafiltering centrifuge tubes

Abstract Equilibrium distribution constants, K s , of phenol between surfactant micelles and water have been determined by micellar enhanced ultrafiltration (MEUF) using commercial ultrafiltering centrifuge tubes. Three surfactants: sodium dodecyl sulphate (SDS), polyoxyethylene 20 cetyl ether (C16E20) and cetylpiridinium chloride (CPC) were tested with a 10 000 molecular weight cut off (MWCO) membrane. Additionally, membranes of 5000 and 30 000 MWCO were used for CPC. A phenomenological mathematical model has been proposed for the batch MEUF process and checked with the experimental permeate or retentate composition. The model is based on two assumptions: monomeric molecules are not rejected by the membrane and the rejection of micelles is independent of the retentate concentration. The measured micelles rejections for different surfactants and the equivalent molecular weight of the micelles are correlated and they are not significantly affected by the addition of phenol. The estimates of K s for SDS and CPC agree with previously reported values determined by other methods. K s values for CPC, calculated using 5000, 10 000 and 30 000 MWCO membranes, have not been significantly different. K s estimate has allowed to predict the phenol permeate concentration measured in continuous tangential MEUF experiments.

Two-phases model for calcium removal from aqueous solution by polymer enhanced ultrafiltration

Abstract Water softening has been carried out by polymer enhanced ultrafiltration (PEUF). Poly(acrylic acid–maleic anhydride) sodium salt (PAM-Na), a polyelectrolyte containing COO − groups, attracts Ca 2+ and releases Na + ions. When pH is lowered, H + replaces the bound Ca 2+ . Thus, the polyelectrolyte can be regenerated and reused. A model is proposed to explain the observed calcium and sodium rejections at different experimental conditions. The feed solution is considered to be divided into two phases. One phase is occupied by the macro ions and bound counter ions and the other is the remaining solution. The model only needs to determine two equilibrium constants ( K Na,H and K Ca,Na ) which indicate the relative tendencies of Na + versus H + , and Ca 2+ versus Na + to bind the polymer, respectively. K Na,H value was determined by titration and it is pH dependent. K Ca,Na value was calculated from ultrafiltration runs at neutral pH and its value goes well with other ultrafiltration runs when pH is varied.

Viability of the use of polymer-assisted ultrafiltration for continuous water softening

We examined the viability of a continuous metal-removing process using polymer-assisted ultrafiltration. The proposed system has two connected sections at different pH. Each section has an ultrafiltration membrane that filters the aqueous solution and retains the polymer. In the first section, the metal is attached to the polymer. In the second section, the metal is detached. The polymer is recycled, and then recovered, by pumping from the second section into the first section. Preliminary experiments provided sufficient information for simulations of the continuous removal of Ca2+ from water. A poly(acrylic acid–maleic anhydride) sodium salt was selected as the polymer. Ceramic membranes of 5 kDa cut-off were used to filtrate the aqueous solutions. We show that the proposed system continuously removes Ca2+ from water in a satisfactory way.

Education and research related to organic waste management at agricultural engineering schools

Purpose – The purpose of this paper is to describe the experience of the Agriculture Engineering School of Barcelona (ESAB), where undergraduate students were involved in field research experiments on organic waste use in agricultural systems.Design/methodology/approach – The paper outlines how the formation of professionals oriented to work for OWM companies has been successfully promoted.Findings – Agricultural systems can assimilate self‐produced organic wastes (OW) and others from different sources. Their management for crop production can generate enormous economic and environmental benefits which can contribute to sustainable development. The implementation of an integrated strategy for OW treatment (OWT) and management (OWM) must be adapted to the characteristics of the specific geographical region and must consider the interrelations among diverse subjects such as: soil science, fertilizer management, plant production, animal husbandry, farm machinery, climate and culture.Practical implications – ...

Influence of chemical speciation on the separation of metal ions from chelating agents by nanofiltration membranes

ABSTRACT The simultaneous separation of various metal ions (nickel, copper, calcium, and iron) from chelating agents (EDTA and citric acid) in water streams using Nanofiltration membranes is analyzed. Assuming that multiply-charged species are highly rejected, chemical speciation computations reproduce the observed patterns of metal and ligand rejection at different pH values and concentrations. The separation of metal ions from citric acid is achieved in acidic conditions, where multiply-charged free metal ions and neutral or singly charged free chelating species are abundant. Overall, speciation studies help to evaluate the applicability of Nanofiltration for recycling chelating agents used for metal extraction.