Optimization and activation of renewable durian husk for biosorption of lead (II) from a aqueous medium

Background: Biosorption of lead Pb(II) by durian husk activated carbon (DHAC) was investigated. The main aim of this work is to explore the effect of operating variables such as pH, biosorbent dose, temperature, initial metal ion concentration and contact time on the removal of Pb(II) from synthesized aqueous medium using a response surface methodology (RSM) technique. The experimentation was performed in two sets, namely set 1 and set 2. Results: For experimental set 1, pH was set to 7.0. The optimum conditions for the remaining parameters were determined to be 0.39 g DHAC dose, 60 min contact time and 100 mg L−1 of initial metal ion concentration, which yielded maximum biosorption capacity of 14.6 mg g−1. For experimental set 2, 41.27 °C, 8.95 and 99.96 mg L−1 were the optimum conditions determined for temperature, pH and initial Pb(II) concentration, respectively; which revealed a maximum adsorption capacity of 9.67 mg g−1. Characterization of the adsorbent revealed active functional groups such as hydroxyl, carboxylic, alcohol and hemicellulose. The equilibrium adsorption data obeyed the Langmuir isotherm and pseudo‐second‐order kinetic models with maximum Langmuir uptake of 36.1 mg g−1. Conclusions: The biosorbent was capable of reuse, so that the abundant durian husk could be utilized effectively for the removal of Pb(II) from polluted water

New insights into microwave pyrolysis of biomass: preparation of carbon-based products from pecan nutshells and their application in wastewater treatment

Microwave pyrolysis of pecan nutshell (Carya illinoinensis) biomass was used to produce carbon-based solid products with potential application in contaminated water treatment. A range of analytical techniques were applied to characterize the intermediate products of microwave pyrolysis in order to monitor the physio-chemical effects of the interacting energy on the biomass. The performance of the carbon-based products was tested through evaluation of lead ion removal capacity from solution. Further analyses demonstrated that ion-exchange by calcium ions on the material surface was the main mechanism involved in lead removal. Calcium compound development was directly correlated to the interaction of the electromagnetic waves with the biomass. Through monitoring the physio-chemical effects of biomass-microwave interactions during microwave pyrolysis, we have shown for the first time that the intermediate products differ from those of conventional pyrolysis. We hypothesise that selective heating leads to the (hemi)cellulosic and lignin degradation processes occurring simultaneously, whereas they are largely sequential in conventional pyrolysis. This work provides optimization parameters essential for the large scale design of microwave processes for this application as well as an understanding of how the operating parameters impact on functionality of the resulting carbon-based materials

Application of Agricultural Wastes Activated Carbon for Dye Removal – An Overview

Dyes are an important class of pollutants and can even be identified by the human eyes. Disposal of dyes in precious water resources must be avoided especially those that are not easily biodegradable, however, and for that various treatment technologies are in use. Among various methods adsorption occupies a prominent place in dye removal. The growing demand for efficient and low-cost treatment methods and the importance of adsorption has given rise to agricultural waste. This review highlights and provides an overview of these activated carbons prepared by non-woody and woody materials and their application for dyes removal. From a comprehensive literature review, it was found that many researchers used non-woody material as activated carbons to removal dye contaminants

Production and characterization of activated carbon from palm shell by using microwave heating method / Roozbeh Hoseinzadeh Hesas

Activated carbon (AC) demonstrated significant adsorption of pollutants in gas and liquid phases due to its high micropore volume, large specific surface area, favorable pore size distribution, thermal stability, capability for rapid adsorption and low acid/base reactivity. Palm shell (agricultural waste) is used as a raw material in this study due to its inherent characteristics such as high carbon content, low ash, and almost negligible sulfur content. In the present work, microwave heating was applied instead of conventional heating techniques as a heat source of AC preparation. This method reveals higher sintering temperatures and shorter processing times which result in higher efficiency and more energy saving. The effects of significant parameters such as microwave radiation time and power level, different types of chemical and physical agents, chemical impregnation ratio and particle size in production of ACs were investigated. Accordingly, the effects of these variables on the structural and surface chemical properties of the ACs were explored. Several methods of characterization were utilized to examine the prepared ACs including nitrogen adsorption-desorption at -196 °C, proximate and ultimate analysis, Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). Moreover, CO2 adsorption at different temperatures and methylene blue (MB) adsorption were carried out. The response surface methodology was used to optimize the preparation conditions of palm shell based ACs with microwave heating methods by zinc chloride chemical activation. The influence of variances on MB adsorption capacity and AC yield was investigated. Based on the analysis of variance, microwave power and microwave radiation time were identified as the most influential factors for AC yield and MB adsorption capacity, respectively. In this study, effects of different heating methods of microwave and conventional on textural and surface chemical properties of the ACs were compared. The ZnCl2 chemical activation at different weight ratio of ZnCl2 to precursors were applied. The results indicated that for both the microwave and conventionally prepared samples, the BET surface area (SBET) is enhanced to a maximum value at optimum impregnation ratio and then decreased with further increases in the agent ratio. The total pore volume in the microwave samples increased continuously with increasing zinc chloride, while in the conventional samples, the total pore volume increased up to the optimum impregnation ratio and then decreased. Oil palm shell based ACs were also prepared using KOH as an activation agent under the microwave irradiation. The effects of the activation time, chemical impregnation ratio and microwave power on the AC properties were investigated. To study the effects of the nature of the physical agent, the impregnated precursors were activated under a flow of carbon dioxide or nitrogen. The results demonstrates that the CO2 activation requires a shorter activation time to reach the maximum SBET than the activation under N2 since CO2 reacts with the carbon to develop the porosity

Thermodynamic evaluation of distillation columns using exergy loss profiles:a case study on the crude oil atmospheric distillation column

This paper presents a case study on the crude oil atmospheric distillation column of Tabriz refinery plant to show the applicability of exergy loss profiles in thermodynamic examination of the different retrofit options. The atmospheric distillation column of Tabriz refinery has been revamped as a consequence of increase of the plant capacity to 100,000 bpd. To cover the deficit of feedstock of the revamped unit, a blend of the existing feedstock with imported crude oil is used as a feedstock. However, to investigate how the blend of these two different types of crudes as a feedstock has an influence on the operating conditions, the examination of the column is needed. Exergy as a comprehensive thermodynamic property which translates the temperature, pressure and composition change into a common unit has been chosen to evaluate the distillation column thermodynamically. Furthermore, the exergy loss profile of the base case serves as a scoping tool to pinpoint the source of inefficiencies. Then, the exergy loss profile as a screening tool has found the retrofit options which are likely to yield greatest energy saving from a list of retrofit options proposed by the industrial partner. In the presented case study, the exergy loss profile identifies the best retrofit option with 17.16% reduction in exergy losses, which finally lead to 3.6% reduction of primary fuel demand