Preparation and Characterization of Chemically Modified Silk Cotton Hull Activated Carbon and Its Effects on Cd(II) Removal from Aqueous Solutions

Abstract

The novel biosorbent silk cotton hull, an agrowaste material, has been successfully utilized for the removal of cadmium(II) from aqueous solutions. The adsorption of cadmium onto three kinds of activated biosorbent has been studied: modified by concentrated sulfuric acid alone (AC), a mixture of concentrated sulfuric acid and hydrogen peroxide (AC1), and a mixture of concentrated sulfuric acid and ammonium persulfate (AC2). The adsorption studies were carried out to optimize the process parameters such as pH, adsorbent dosage, contact time, and initial metal ion concentration. Maximum metal removal was observed at pH 7.0 with a contact time of 90 min at stirring speed of 200 rpm with an adsorbent dosage of 4.0 g L −1 . The sorption isotherms were studied using the Langmuir, Freundlich, and Tempkin isotherm models. The maximum adsorption capacities were 100.00, 142.86, and 142.87 mg g −1 for AC, AC1, and AC2, respectively. Accordingly, the surface modification of the activated carbons AC1 and AC2 enhanced cadmium removal greatly. The experiments demonstrated that the removal of metal ions followed the pseudosecond-order kinetic model. The sorption mechanism is discussed in terms of the activated surface properties. A relationship between the oxygen content and sorption was found in this novel material. Desorption experiments were carried out using hydrochloric acid with a view to generate the spent adsorbent and to recover the adsorbed metal ions.

Magnetically separable CoFe2O4/CoxFey/activated carbon composites for Cd(II) removal from wastewater

“…At pH ≤ 8, Cd(II) is primarily present as Cd 2 + and CdOH + , beyond which Cd(OH) 2 tends to dominate. The principal species of Cd(II) are formed depending on the pH as follows: …”

Competitive sorption of nickel, copper, lead and cadmium on okra leaves (Abelmoschus esculentus)

“…Cadmium is non-essential, nonbeneficial and recognized as an occupational health hazard for many decades and increasing number of studies have shown early adverse health effects on the kidney (Kefela et al, 1999;. Cadmium ions are not biodegradable and easily accumulate in human tissues (Evangelin et al, 2014). The inhalation of nickel and its compounds can lead to serious problems, including respiratory cancer, skin allergies, dermatitis, lung fibrosis, headaches, nausea, vomiting, chest pain, dry cough and shortness of breath .…”