ECO-FRIENDLY DYEING OF COTTON FABRIC WITH WASTE TEA LEAVES BASED TANNIN NATURAL DYE

<p>Natural products have always been appreciated due to the awareness about environmental standards for global health by using green technologies in their isolation and extraction. Thereupon natural dyes have been used in all fields due to having ecofriendly, therapeutic and aesthetic nature. For the current study, microwave radiations (MW) have been used as a green extraction tool to explore the natural coloring potency of Tea leaves for the dyeing of cotton fabrics. For isolation of natural dye from tea leaves in aqueous and basic media MW irradiation for 1-6 min has been given and used to dye cotton fabric. It has been evaluated that an increase in color yield (K/S) with the use of 6 min of microwave energy when basic extract of tea leaves was used to dye onto cotton fabric. It has been also revealed that in the case of the pre-mordanting method, 6% of Cu and 8% of Fe as a post mordanting method give the best fastness properties and the highest color yields. It is concluded that MW energy has an excellent ability for isolation of colorant from Tea leaves for dyeing of cotton fabric under reduced optimal dyeing conditions.</p>

Waste tea residue adsorption coupled with electrocoagulation for improvement of copper and nickel ions removal from simulated wastewater

The present research deals with the removal of copper and nickel ions from synthesized wastewater by using simple, cheap, cost-effective and sustainable activated green waste tea residue (AGWTR) adsorption coupled with electrocoagulation (ADS/EC) process in presence of iron electrode. Considering previous studies, their adsorbents used for treating their wastewaters firstly activate them by applying either chemicals or activating agents. Our adsorbent was prepared without applying neither chemicals nor any activating agents. The operating parameters of both metals were optimized: pH (4.0), hydraulic retention time (HRT = 30 min), adsorbent dose (1 mg.L− 1), initial concentration (20 mg.L− 1) and Fe-Fe electrode was found to be better with compared to the other electrodes with a current density of 1.19 mA/cm2. In the process of ADS/EC, The removal efficiency was obtained as 100% for copper and 99.99% for nickel ions. After the ADS/EC process, Fourier transform infrared (FT-IR) spectroscopy, Scanning Electron Microscopy (SEM) and EDS analysis were used to characterize the adsorbent green waste tea residue. The results showed seven clear peaks of functional groups that were detected in the range of 1000–4000 cm− 1, the rough-stone-like with various larger holes and higher amounts of carbon containing traces of different elements, respectively. The adsorption isotherm and kinetic model results showed that the Langmuir and the pseudo-second-order were well-fitted to the adsorption experimental data better than the Freundlich and pseudo-first-order models for both Cu2+ and Ni2+ with their maximum adsorption capacity of 15.6 and 15.9 mg.g− 1, respectively. These indicate that the dominant adsorption occurs in a monolayer of homogeneous adsorbent surfaces on AGWTR and its kinetic mechanism belongs to chemical adsorption. Based on the above results, it is well understood that the use of the ADS coupled with EC technique is the cheapest compared with single ADS and EC technique for heavy metal removal due to remarkable low adsorption dose, energy consumption and also it is a suitable technique for developind countries. Therefore, the AGWTR shows the greatest potential to improve the quality of water contaminated with different heavy metals in the environment.