Valorization of Wasted Black Tea as a Low-Cost Adsorbent for Nickel and Zinc Removal from Aqueous Solution

Abstract

Characteristics and efficiency of wasted black tea (WBT) were investigated as a low-cost sorbent in removal of Ni 2+ and Zn 2+ ions from aqueous solution. Initial findings showed WBT potential to be applied as an effective sorbent due to high concentrations of carbon and calcium and high porosity and availability of functional groups. Sorption dynamics were studied with varying pH, contact time, and adsorbent dose. Maximum percentages of metal ions removal were recorded at pH 5, contact time 250 min, and 20 g/L of adsorbent concentration. Binary metal sorption studies showed that Ni 2+ and Zn 2+ do not compete with each other for available sorption sites, so the adsorption trend in binary system appears similar to monocomponent metal adsorption. Evaluation of the isotherms confirmed that WBT has high value of adsorption capacity. Sorption data fitted well with both Freundlich and Langmuir models. In the optimum conditions, maximum capacity of WBT could reach up to 90.91 mg-Ni/g adsorbent and 166.67 mg-Zn/g adsorbent. This experiment demonstrated the ability of tea waste as an effective, sustainable, and low-cost adsorbent for removal of the heavy metal ions.

Adsorption capability of brewed tea waste in waters containing toxic lead(II), cadmium (II), nickel (II), and zinc(II) heavy metal ions

“…In another study, walnut shells and the agricultural wastes of sunflowers, potatoes and canola have been used as biosorbents for the removal of heavy metals from aqueous solutions using batch experiments and the maximum adsorption capacity of the walnut shells was as follows: Cd (76.9 mg/g) > Zn (33.3 mg/g) > Ni (29.4 mg/g) 23 . Previous studies have concluded that Zn can be removed at an 80% removal efficiency by using black tea waste (20 g) 39 . The experimental studies conducted within the scope of the present study were in line with the results of relevant studies in the literature 40 , 41 .…”

“…Among the kinetic studies conducted, the Pseudo-second-order (PSO) (R 2 = 0.99) was able to express the adsorption in this study clearly. The PSO model consisted of the external liquid film diffusion, surface adsorption and intra-particle diffusion processes 19,39,45,52 . Therefore, the results of this model can be accepted as a clearer and more reliable description of the adsorption mechanism between the BTW and the Pb, Cd, Zn and Ni ions.…”

“…According to the k 2 constant, the adsorption ratio of the polluting cations onto the BTW occurred in the following sequence: Zn > Cd > Pb > Ni. According to previous studies that focused on the adsorption of heavy metals using various methods, the removal of the Pb, Cd, Zn and Ni ions is suitable for PSO kinetic modelling 19,39,45,52 . The findings of the present study regarding the Pb, Cd, Zn and Ni ions showed distinct correlation with the results of previous studies conducted on the topic.…”

Single-Pot Synthesis of Biodiesel using Efficient Sulfonated-Derived Tea Waste-Heterogeneous Catalyst

“…After preparing tea, the waste is usually disposed of as solid waste. Previously, tea waste was used for different applications such as an adsorbent for industrial wastewater treatment, for preparation of activated carbon (AC) for purification of waste cooking oil esters and for hydrogen production [25,26,27]. However, there is no such study found in literature on tea waste used for the preparation of acidic catalyst and its application for ester conversion.…”

Radioactive Cobalt(II) Removal from Aqueous Solutions Using a Reusable Nanocomposite: Kinetic, Isotherms, and Mechanistic Study

“…Industrial wastewater contains various toxic heavy metals that pose significant health risks if they enter the human food chain [ 1 , 2 ]. Cobalt, a toxic element, exits in the wastewater from nuclear power plants as well as from the mining, metallurgical, electroplating, paints, pigments, and electronic industries.…”