A Comparative Study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ Metal Ions Removal from Industrial Wastewaters by Chitosan-Based Composite Cryogels.

Materials coming from renewable resources have drawn recently an increased attention in various applications as an eco-friendly alternative in the synthesis of novel functional materials. Polysaccharides, with their prominent representative - chitosan (CS), are well-known for their sorption properties, being able to remove metal ions from dilute solutions either by electrostatic interactions or chelation. In this context, we proposed here a comparative study on Cu2+, Zn2+, Ni2+, Fe3+, and Cr3+ metal ions removal from industrial wastewaters by CS-based composite cryogels using batch technique. The composite cryogels consisting of CS embedding a natural zeolite, namely clinoptilolite, were synthesized by cryogelation, and their sorption performance were compared to those of CS cryogels and of acid-activated zeolite. A deeper analysis of thermodynamics and kinetics sorption data was performed to get insights into the sorption mechanism of all metal ions onto sorbents. Based on the optimized sorption conditions, the removal of the above-mentioned ions from aqueous solutions by the composite sorbent using dynamic technique was also evaluated.

Dynamic Surface Properties of Fullerenol Solutions.

Application of dilational surface rheology, surface tensiometry, ellipsometry, Brewster angle, and transmission electron and atomic force microscopies allowed the estimation of the structure of the adsorption layer of a fullerenol with a large number of hydroxyl groups, C60(OH) X ( X = 30 ± 2). The surface properties of fullerenol solutions proved to be similar to the properties of dispersions of solid nanoparticles and differ from those of the solutions of conventional surfactants and amphiphilic macromolecules. Although the surface activity of fullerenol is not high, it forms adsorption layers of high surface elasticity up to 170 mN/m. The layer consists of small interconnected surface aggregates with the thickness corresponding to two-three layers of fullerenol molecules. The aggregates are not adsorbed from the bulk phase but formed at the interface. The adsorption kinetics is controlled by an electrostatic adsorption barrier at the interface.

Randomized trial of Roux-en-Y gastric bypass versus sleeve gastrectomy in achieving excess weight loss.

BACKGROUND: Robust data on quality of life (QoL) after different techniques of bariatric surgery are sparse. This RCT compared excess weight loss (EWL) and QoL after sleeve gastrectomy versus Roux-en-Y gastric bypass (RYGB). METHODS: Obese patients were assigned randomly to RYGB or sleeve gastrectomy. The primary outcome measure was EWL. Secondary outcomes included QoL, co-morbidity, adverse events, vitamin and glycolipid status. QoL was assessed before and annually after surgery, using the Moorehead-Ardelt Quality of Life Questionnaire II (M-A-QoLQII) and Gastrointestinal Quality of Life Index (GIQLI). RESULTS: One hundred patients were enrolled, 45 in the RYGB group and 55 in the sleeve gastrectomy group. Mean postoperative EWL at 1, 2, 3 and 5 years was 80·4, 79·8, 83·0 and 74·8 per cent respectively after RYGB, and 83·0, 77·8, 66·3 and 65·1 per cent after sleeve gastrectomy (P = 0·017). Mean M-A-QoLQII score before surgery and at 1, 2, 3 and 5 years after operation was 0·5, 1·6, 1·7, 2·1 and 1·4 respectively after RYGB, and 0·3, 1·7, 1·5, 1·5 and 1·2 after sleeve gastrectomy. Mean GIQLI score before and at 1, 2, 3, 5 years after RYGB was 96·4, 113·8, 113·3, 113·4, 111·7, compared with 90·7, 113·9, 114·5, 113·1 and 113·0 for sleeve gastrectomy. The improvement was significant compared with preoperative values (P < 0·001 for M-A-QoLQII and GIQLI), with no difference between groups (P = 0·418 and P = 0·323 respectively). RYGB resulted in higher readmission rates (P = 0·002) and length of hospital stay (P = 0·006) than sleeve gastrectomy. CONCLUSION: RYGB and sleeve gastrectomy resulted in equivalent, long-standing QoL improvement. RYGB resulted in more stable weight loss but was associated with higher readmission rates. Registration number: NCT02475590.

Agricultural by-products as low-cost sorbents for the removal of heavy metals from dilute wastewaters.

n the last years, much attention has been focused on the use of low-cost adsorbents for the removal of Cu(II) and Zn(II) from contaminated waters. In this context, we studied the sorption performances of two kinds of by-products resulted from the agriculture: soy bran and mustard husk. The effects of contact time, the initial metal ion concentration, pH, sorbent mass, and temperature on the adsorption capacity of the agricultural by-products as sorbents were investigated. The thermodynamic parameters associated with the adsorption process indicated that the process is spontaneous and endothermic. Modeling of experimental adsorption isotherm data showed that non-linear Langmuir isotherm fits better than other isotherms. The obtained values for the separation factor, R L were less than one which supports that the adsorption process was favorable. The obtained results indicated that the soy bran has a higher sorption capacity toward zinc ions (74.02 mg g(-1)) than mustard husk (63.69 mg g(-1)). Therefore, there is a great requirement for the search of biomaterials that are cheap and easily available for the removal of heavy metal ions from wastewater. The studied sorbents have the advantage of very low cost and great availability for simple operational experiments.

Comparison of failure characteristics of a range of cancellous bone-bone cement composites.

Over the past decade, orthopedic surgery has embraced an increase in the depth of cement penetration into the adjacent cancellous bone structure. The resultant interdigitation transforms this zone into a thick layer of continuous interpenetrating composite material. The failure behavior of the composite formed with a number of potential bone cements with different bonding ability was investigated. The cancellous bone-cement composites exhibit considerable resistance to crack extension, and in situ optical observation indicates that the contribution of the cancellous bone is analogous to that of a typical fiber bridging process. The critical stress intensity factor and the work of fracture have been used to quantify the failure characteristics of the cancellous bone-cement composites. The nature of the crack propagation through these cement-bone composites was also captured via optical microscopy, and scanning electron microscopic images were taken of the failure surfaces. The R-curve behavior, or crack extension characteristic, of the cancellous bone-cement composite was also determined. The interesting outcome is that the cancellous bone-PMMA (poly-methylmethacrylate) composite, despite the absence of chemical bonding with bone, required the highest energy to fracture. In addition, the dimensional stability of the cement has a great effect on the interface.

New SnO2/MgAl-layered double hydroxide composites as photocatalysts for cationic dyes bleaching.

A new type of nanocomposite containing SnO(2) has been obtained by wet impregnation of dehydrated Mg/Al-hydrotalcite-type compounds with ethanolic solutions of SnCl(4).2H(2)O. Tin chloride hydrolysis was achieved using NaOH or NH(4)OH aqueous solutions, at pH around 9, followed by the conversion into corresponding hydroxides through calcinations. The powder X-ray diffraction (PXRD) and UV-Vis diffuse reflectance (UV-DR) methods confirmed the structure of as-synthesized solids. The chemical composition and morphology of the synthesized materials were investigated by energy dispersive X-ray analysis (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The as-synthesized materials were used for photocatalytic studies showing a good activity for methylene blue decolourization, which varies with SnO(2) content and used as a hydrolysing agent. The proposed mechanism is based on the shifting of flat band potential of SnO(2) due to the interaction with Mg/Al-LDH, this being energetically favourable to the formation of hydroxyl radicals responsible for methylene blue degradation.