Kinetic Studies of Adsorption Process of Chromium Ions From Aqueous Solution.

Abstract

The adsorption efficiency of granular activated carbon was investigated for removal of Cr(VI) ions in a lab scale fluidised bed reactor. The effect of various parameters like pH, contact time and initial metal ion concentration on adsorption process were investigated. More adsorption was observed at lower pH and optimum pH was found to be 3.0.The equilibrium time was observed at 420 min. With the increase in initial Cr(VI) ion concentration, the percentage adsorption decreases while the adsorption capacity (q e ) increases. Maximum adsorption of 96.02 % and 63.28 % was found at concentration of 10 mg/L and 50 mg/L respectively. The kinetic study was performed using pseudo-first and pseudo-second order kinetic model. The process of adsorption of Cr(VI) ions was found to follow pseudo-second order kinetic model. …………………………………………………………………………………………………….... Introduction:-Environmental pollution in water bodies is due to the enormous quantity and variety of chemical compounds found in the industrial wastewaters. Large amount of effluent laden with toxic heavy metals from industries is discharged into the environment posing threat to public health due to their toxic and persistent nature.High concentrations of chromium are found in wastewater released from the chemical industries especially electroplating and leather tanning industries [1]. Othersources include pigment, paper, paints, steel fabrication, mining and textile dyeing industries. Chromium salts also found their use in wood preservatives and ceramic, fungicides and rubber manufacturing [2]. In aqueous phase chromium exists in two forms: trivalent and hexavalent. Cr(III) is required for nutrition but upto a certain limit only. However, Cr(VI) is toxic and is found to be carcinogenic. The tolerance limit for Cr(VI) in potable water is 0.05 mg/L. For releasing the hexavalent chromium into the inland waters, the tolerance limit is 0.1 mg/L. The safe limit for chromium containing effluent discharge into the surface water is also 0.1 mg/L as set by the Ministry of Environment and Forest [MoEF] [3]. According to EPA, chromium inhalation causes shortening of breath, asthmatic problems, wheezing and nose and throat irritation. Continuous exposure leads to bleeding of stomach and intestine and circulatory, kidney and liver damage. Skin contact causes skin allergy, ulcers and skin irritation [4]. Ion exchange, Reverse osmosis, Chemical reduction, Electrolysis, Precipitation, Flocculation, Coagulation andNano-filtration are the most popular conventional methods used for the removal of chromium ions from the industrial wastewater. Most of the processes have one or more drawbacks and they cannot be used for removing lower concentrations of heavy metal ions. It is challenging task for the environment scientists and engineers to develop new technologies for removing heavy metals which are effective and economic [5]. Adsorption process is efficient in removing very low concentrations of metal ions and is considered more effective

Modeling Date Palm Trunk Fibers (DPTF) Packed Bed Adsorption Performances for Cadmium Removal from Aqueous Wastewater

“…Furthermore, much literature investigated cadmium accumulation's adverse effects on lung tissues and the related respiratory problems, as well as its effect on immunity suppression [15]. Consequently, developing processes for removing cadmium from industrial wastewaters and drinking water becomes essential [16]. According to FAO/WHO permitted pollution levels, the limit of cadmium should be less than 0.005 mg/l.…”

Adsorption Studies of Zinc, Copper, and Lead Ions From Pharmaceutical Wastewater Onto Silver Modified Clay Adsorbent

“…Also, Cu has been reported to have adverse effects on human health. These include mental disorders, anemia, arthritis/rheumatoid arthritis, hypertension, and liver enlargement (Lakherwal, 2014).…”

“…Furthermore, it was reported that nanomaterials have appropriate adsorption surfaces that possess unique characteristics vis-à-vis a very high surface-areato-volume ratio. All of these advantages give a tremendous driving force for diffusion, especially at high temperatures [9] .…”

Adsorptive Potency of Activated Carbonized Avocado Pear Seeds (Persea Americana) and Activated Carbonized orange peels (Citrus Sinensis) in Eliminating Pb2+ ions in Contaminated Water.

“…It was known to cause harm to vital human organs such as the lungs, kidney, liver, reproductive system, brain and basic cellular processes. Soaring knowledge of the ecological effect of lead (Pb 2+ ) ions has provoked calls for decontamination of polluted water preceding release into waters bodies (Lakherwal, 2014;Singh &Gupta, 2016 andAbdel-Raouf &Abdul-Raheim, 2017).…”