Preparation and characterization of adsorbents derived from bentonite and kaolin clays

Abstract

The comparative study on preparation and characterization of modified bentonite and kaolin clay types is aimed at establishment of the ability of these clay types to adsorb pollutants. Its low cost, availability and recovery of clay give it added advantage of an effective adsorbent. The modified clay types were prepared by impregnation using various concentrations of either H 2 SO 4 or NaOH in w/v ratio of 1:2. The physicochemical and adsorptive properties were investigated using standard physicochemical methods like moisture content, bulk density, pH, iodine and methylene blue numbers. FTIR, XRD and SEM analyses were also conducted on these clay types. Unmodified kaolin clay exhibited lowest moisture content (1.12%) while unmodified bentonite clay type had highest value (3.98%). The peaks at 3435 cm −1 and 3410 cm −1 assigned N-H stretching frequency were obtained for 2 M H 2 SO 4 modified and unmodified bentonite clay types, respectively. The peaks at 912 cm −1 and 914 cm −1 that indicate the presence of Al-Al-OH deformation frequency were obtained for unmodified bentonite clay type and 2 M H 2 SO 4 modified bentonite clay, respectively. The physical surface morphology of the clay types revealed the presence of pores with irregular shapes, while their XRD analysis showed that the clay types are crystalline. The modified clay types exhibited better potential adsorbent for removal of small metallic or gas molecules as well as large organic molecules. Adsorbents could also remove cations or anions of pollutants since their surface charge could be positive or negative depending upon pH condition.

Evaluation of bentonite clay in modified and unmodified forms to remove fluoride from water

“…RB, ATB, and AOMB had pH values of 7.16, 5.8, and 7.6, respectively, suggesting that the substance is more neutral. As per the literature (Nwosu et al 2018), the pretreated clay samples have pH values that are similar to 7.2.…”

Adsorption of atrazine from aqueous solution using unmodified and modified bentonite clays

“…It was shaken vigorously using a Uniscope SM 101 shaker water bath for 24 h at 30 °C and then washed with distilled water to remove the excess acid until its effluent become neutral (pH = 7). (Nwosu et al 2018, Abu-Elella et al 2015. It was then filtered under vacuum and dried in oven at 376 K for 8 h. The dried samples were grounded and stored in airtight sample bottle (Nwosu et al 2018, Gómez-Tamayo et al 2008 to produce 2 M sulphuric acid modified bentonite clay (2-ABC) and 2 M sodium hydroxide modified bentonite clay (2-BBC), respectively.…”

Exploration of Intercalated Kaolinite Clay for the Uptake of Basic Dye by Adsorption − Equilibrium, Kinetics and Thermodynamic Studies

“…This then implied that (1) at pH < pHpzc, the sorbent surface has a net positive charge and the adsorption of Anions becomes more enhance at lower pH than the pHpzc. (2) at pH > pHpzc, the sorbent surface has net negative charges and the adsorption of cations are more enhanced at pH higher than pHpzc [19]. These are electrostatic interaction.…”