No abstract

Three commercial membranes (NF70, NF90 and TFC-SR) were firstly characterized in terms of pure water flux and the: rejection of uncharged (alcohols and sugars) compounds. Subsequently, the rejection of monovalent (sodium and chloride) and divalent (calcium and sulphate) ions in single (NaC1, CaC12 and Na2SO4) and binary (NaC1/Na2SO4, CaClJCaSO4, NaC1/CaC12 and Na2SO4/CaSO4) salt mixtures was studied. According to the pure water permeability the TFC-SR membrane is a loosely packed NF membrane (12.3 L.m-2.h-1.bar-1 ), while both NF70 and NF90 are tightly packed (2.6 and 3.6 L.m-2.h" 1.bar-I). According to the uncharged solute rejection, the MWCO~70 = 60, MWCO~9o = 200 and MWCOrFc.sR > 500. NF70 and NF90 were equally efficient in rejecting 1-2, 1-1 and 2-1 salts (>90%), while TFC-SR showed typical negatively charged surface behaviour, i.e., R (1-2) salt > R (1-1) salt > R (2-1). Sulphate rejectkm decreased in the presence of sodium chloride more significantly than in the presence of calcium chloride due to the more efficient retention of the bivalent calcium.

No abstract

No abstract

The sorption of lead(II) onto pine cone powder (PCP) and 0.15 mol/L NaOH treated pine cone powder (PCP 0.15), an abundant agricultural waste from the wood industry, was studied to evaluate the effect of NaOH treatment on the kinetics of lead(II) uptake by performing batch kinetic sorption experiments. Batch biosorption kinetics was performed by varying biosorbent dose and initial lead(II) concentration and the kinetic data modeled using the pseudo-first, pseudo-second intraparticle, and Bangham diffusion models. The results revealed that NaOH treatment changed the pattern of the biosorption kinetics, the biosorption kinetic parameters, and influenced the rate-limiting step. The pseudo-second-order kinetic model gave a better fitting of the kinetic data for both PCP and PCP 0.15. The batch biosorption model, based on the pseudo-second-order mechanism, was applied to predict the rate constant of biosorption, the equilibrium capacity, the initial sorption rate, the effects of biosorbent dose, and initial lead(II) concentration. Equilibrium concentrations were evaluated with the equilibrium capacity obtained from the pseudo-second-order rate equation. In addition, pseudo-isotherms were obtained by changing initial lead(II) concentration using the equilibrium concentration and equilibrium capacity obtained based on the pseudo-second-order constants.

No abstract

Macadamia nutshell powder oxidized by hydrogen peroxide solutions (MHP) was functionalized by immobilizing 1,5′-diphenylcarbazide (DPC) on its surface. The effectiveness of grafting was confirmed by the Fourier transform infrared spectrum due to the presence of NH and C=C stretches at 3361, 1591, and 1486 cm−1, respectively, on the grafted material which were absent in the nongrafted material. Thermogravimetric analysis revealed that the presence of DPC on the surface of Macadamia shells lowered the thermal stability from 300°C to about 180°C owing to the volatile nature of DPC. Surface roughness as a result of grafting was appreciated on the scanning electron microscopy images. Parameters influencing the adsorptive removal of Cr(VI) were examined and found to be optimal at pH 2, 120 min, 150 mg/L, and 2.5 g/L. Grafting MHP with DPC leads to an increase in the Langmuir monolayer capacity from 37.74 to 72.12 mg/g. Grafting MHP with DPC produced adsorbent with improved removal efficiency for Cr(VI).

It can be concluded that the extracts of C. erythrophyllum are safe for medicinal use in folk medicine for treating infectious and stress related diseases.