Search

New criteria in assessing the quality of drinking water reduced the maximum permissible concentration of arsenic from 50 mu g L-1 to 10 mu g L-1 and set a requirement for the development of new technologies for arsenic removal. In this paper, ethylenediamine functionalized multiwall carbon nanotubes (e-MWCNT) were loaded with iron(III) oxide in the goethite form, by precipitation of adsorbed Fe3+ and oxidized Fe2+ using base, in that way e-MWCNT/Fe3+ and e-MWCNT/Fe2+ adsorbents, respectively, were obtained. The influence of pH on the As(V) and As(III) removal from drinking water was studied in a batch system, of pH range 3-10 and initial arsenic concentration 0.05-4 mg L-1. Time dependent As(V) adsorption and adsorption data can be described by pseudo-second-order kinetic model and by Freundlich isotherm, applying linear and non-linear fitting methods. The maximum adsorption capacities obtained from Langmuir model for As(V) on e-MWCNT/Fe2+ and e-MWCNT/Fe3+ were 23.47 and 13.74 mg g(-1) at 25 degrees C. respectively. Thermodynamic parameters showed that the adsorption of As(V) was spontaneous and endothermic for both e-MWCNT/Fe2+ and e-MWCNT/Fe3+. Influences of the pH, iron(III) oxide loading and interfering ions were modeled by MINTEQ program, and good agreement between experimental and modeling data was obtained.

New criteria in assessing the quality of drinking water reduced the maximum permissible concentration of arsenic from 50 mu g L-1 to 10 mu g L-1 and set a requirement for the development of new technologies for arsenic removal. In this paper, ethylenediamine functionalized multiwall carbon nanotubes (e-MWCNT) were loaded with iron(III) oxide in the goethite form, by precipitation of adsorbed Fe3+ and oxidized Fe2+ using base, in that way e-MWCNT/Fe3+ and e-MWCNT/Fe2+ adsorbents, respectively, were obtained. The influence of pH on the As(V) and As(III) removal from drinking water was studied in a batch system, of pH range 3-10 and initial arsenic concentration 0.05-4 mg L-1. Time dependent As(V) adsorption and adsorption data can be described by pseudo-second-order kinetic model and by Freundlich isotherm, applying linear and non-linear fitting methods. The maximum adsorption capacities obtained from Langmuir model for As(V) on e-MWCNT/Fe2+ and e-MWCNT/Fe3+ were 23.47 and 13.74 mg g(-1) at 25 degrees C. respectively. Thermodynamic parameters showed that the adsorption of As(V) was spontaneous and endothermic for both e-MWCNT/Fe2+ and e-MWCNT/Fe3+. Influences of the pH, iron(III) oxide loading and interfering ions were modeled by MINTEQ program, and good agreement between experimental and modeling data was obtained.

This paper presents an optimisation-based method for the screening and conceptual design of processes with heterogeneous catalytic reactors. The method follows a multi-level approach to process synthesis to establish performance targets and identify high-performance designs. At each level, process superstructures are optimised to explore performance limits of the system and to guide the understanding of the relationships between individual design features and process performance. This enables the design engineer to explore trade-offs between performance and structural complexity in a coordinated manner. The method leads to a number of potential design candidates that provide the design engineers with insight into the performance gains that can be expected by increasing design complexity. The method has been developed and implemented for heterogeneously catalysed gas-phase reaction systems and is illustrated with an example in styrene production.

In this work, novel hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and different poly(alkylene glycol)(meth)acrylates (BIS) were prepared by radiation-induced copolymerization. The influence of different BIS types with variation in chain length, based on ethylene glycol (EG) and/or propylene glycol (PG) pendant units, on the nature and inherent properties of P(HEMA/BIS) copolymeric hydrogels was the main idea of this paper. Swelling studies were conducted for all types of P(HEMA/BIS) copolymeric hydrogels in a wide pH and temperature range. Additional characterization of structure, morphology and thermal behaviour of the obtained hydrogels was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric (TG) analysis. The modelling of drug release and diffusion characteristics was tested using cephalexin (CEX). The results indicate that P(HEMA/BIS) hydrogels' properties are significantly dependent on the type of BIS. The hydrogels with ethylene glycol (EG) pendant chains show a noticeable pH and/or temperature sensitivity and can be considered smart hydrogels. The introduction of propylene glycol (PG) units, pure and mixed with ethylene glycol (EG) pendant chains, can additionally tune the characteristics of such gels. Furthermore, drug release studies indicate that these types of P(HEMA/BIS) copolymeric hydrogels are suitable candidates for controlled drug release systems.

This paper presents an optimisation-based method for the screening and conceptual design of processes with heterogeneous catalytic reactors. The method follows a multi-level approach to process synthesis to establish performance targets and identify high-performance designs. At each level, process superstructures are optimised to explore performance limits of the system and to guide the understanding of the relationships between individual design features and process performance. This enables the design engineer to explore trade-offs between performance and structural complexity in a coordinated manner. The method leads to a number of potential design candidates that provide the design engineers with insight into the performance gains that can be expected by increasing design complexity. The method has been developed and implemented for heterogeneously catalysed gas-phase reaction systems and is illustrated with an example in styrene production.

In this work, novel hydrogels based on 2-hydroxyethyl methacrylate (HEMA) and different poly(alkylene glycol)(meth)acrylates (BIS) were prepared by radiation-induced copolymerization. The influence of different BIS types with variation in chain length, based on ethylene glycol (EG) and/or propylene glycol (PG) pendant units, on the nature and inherent properties of P(HEMA/BIS) copolymeric hydrogels was the main idea of this paper. Swelling studies were conducted for all types of P(HEMA/BIS) copolymeric hydrogels in a wide pH and temperature range. Additional characterization of structure, morphology and thermal behaviour of the obtained hydrogels was conducted by Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric (TG) analysis. The modelling of drug release and diffusion characteristics was tested using cephalexin (CEX). The results indicate that P(HEMA/BIS) hydrogels' properties are significantly dependent on the type of BIS. The hydrogels with ethylene glycol (EG) pendant chains show a noticeable pH and/or temperature sensitivity and can be considered smart hydrogels. The introduction of propylene glycol (PG) units, pure and mixed with ethylene glycol (EG) pendant chains, can additionally tune the characteristics of such gels. Furthermore, drug release studies indicate that these types of P(HEMA/BIS) copolymeric hydrogels are suitable candidates for controlled drug release systems.