Chitosan (CS) and nanocomposite 5%bentonite/chitosan (5%Bt/CS) prepared from the natural biopolymer CS were tested to remove Cu(II) ions using a batch adsorption experiment at various temperatures (25, 35 and 45°C). X-ray diffraction, Fourier transform infrared spectroscopy, and thermogravimetric analysis/differential thermal analysis (TGA/DTA) were used in CS and the nanocomposite characterisation. This confirmed the exfoliation of bentonite (Bt) to form the nanocomposite. The adsorption kinetics of copper on both solids was found to follow a pseudo-second-order law at each studied temperature. The Cu(II) adsorption capacity increased as the temperature increased from 25 to 45°C for nanocomposite adsorbent but slightly increased for CS. The data were confronted to the nonlinear Langmuir, Freundlich and Redlich–Peterson models. It was found that the experimental data fitted very well the Langmuir isotherm over the whole temperature and concentration ranges. The maximum monolayer adsorption capacity for the Cu(II) was 404–422 mg/g for CS and 282–337 mg/g for 5%Bt/CS at 25–45°C. The thermodynamic study showed that the adsorption process was spontaneous and endothermic. The complexation of Cu(II) with NH2 and C = O groups as active sites was found to be the main mechanism in the adsorption processes.
5 Common questions about fluoride in water
Fluoride in water can be both naturally occurring, or artificially added. In the latter case, this is usually with the objective of aiding oral hygiene in populated areas. Because of its controlled addition in many water systems around the world, it has become associated with a number of different controversies, myths and confusion. Whether you are interested in monitoring fluoride in water, or simply want to know more about how the ionic compound affects those who consume it, we have included answers to some...
Inspection that took 5 months now completed in a single day
Pure Technologies completes longest single day pipeline inspection to date using PipeDiver® technology. From the Colorado town of Buena Vista, the views of the distant Rocky Mountains are deceptively stunning. Up close, the terrain is hilly, inhospitable and extremely remote. With no roads and little access, this is helicopter, snowmobile and 4-wheel-drive country. As might be expected, the logistics of inspecting a water pipeline that runs through this unforgiving territory makes the inspection extremely...
5 Key elements to look for in your etch process
High wafer throughput Fast etch rates and low clean overheads mean higher tool uptime. Higher uptime means more wafers through your fab Profile control Vertical facets means higher device efficiency – more light out for power in Smooth surfaces Smooth surfaces means less light scattering – more usable light Accurate depth control Essential with such complex structures, stopping in the right layer can make or break your device Uniformity Uniform etch depth means that more devices can be...
5 Habits that are bad for your indoor air quality
School is starting, but warm weather means we are still spending more time outside and keeping windows open as much as possible. However, it doesn’t mean we are safe from poor indoor air quality at home. In fact, indoor air may be more polluted in the summer months than in the wintertime. The reasons include high humidity, pollutant buildup, pesticides and VOCs. There are certain habits in particular that put our health and well-being at risk in the summer and fall, but awareness and a few tweaks in these...
5 ways to keep asthma in check
Asthma rates have been on the rise for some time - in 2009 nearly 1 in 12 Americans were diagnosed with the long-term inflammatory disease that restricts airways and makes it difficult to breathe. Other symptoms include coughing, wheezing and chest tightness, and these often get worse when the patient is also fighting a common cold or flu. Asthma affects people of all ages, but especially children: Up to 10% of children are diagnosed with childhood asthma. Many will grow out of it, but the disease and treatment...