A study on Pb removal kinetics using modified agricultural wastes from Tanzania
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A study on Pb removal kinetics using modified agricultural wastes from Tanzania Mwemezi Johaiven Rwiza1 · Matthias Kleinke2 · Kyoung‑Woong Kim3 Received: 16 August 2020 / Accepted: 20 October 2020 / Published online: 29 October 2020 © Springer Nature Switzerland AG 2020
Abstract Lignocellulosic materials, abundant and renewable materials, are gaining popularity as metal scavenging agents because of their high sorption capacities, relatively low cost and environmental-friendliness. However, there is not much research to discover how the modification of different lignocellulosic materials can enhance their metal sorption capacities. In the present study, corn hulls and rice husks were pyrolyzed at 500 °C to produce biochars and these biochars were then activated using KOH and ZnCl2 as activating agents. Material characterization was done using Field Emission-Scanning Electron Microscope (FE-SEM), Brunauer–Emmett–Teller (BET) analysis, and Fourier Transform Infrared (FTIR) analysis. Equilibrium concentrations were measured using Inductively Coupled Plasma-Optical Emission Spectrometry (ICP-OES). Results indicated that the modified biosorbents removed Pb2+ more efficiently and faster than the raw hulls and husk. The KOH-treated corn husk biochar (KOH-CHB) achieved a removal capacity of >97 mg/g in the first 15 min compared to a sorption capacity of 15 mg/g achieved by raw corn husk (CH). High Pb2+ removal by activated biochars at a relatively shorter contact time was probably attributable to enhanced structures as indicated in the FT-IR, SEM, and BET results. The results also indicated that, for all eight biosorbents, the removal of P b2+ from water followed a pseudo-second-order kinetic model with R2 values >0.94. This model was able to predict the experimental qe values with greater precision than the pseudo-first-order kinetic model. Low-cost materials used in the current study have the potential to remove toxic Pb2+ from water and this Pb2+ removal can be attained at a relatively low cost. Keywords Agro-industrial wastes · Metal sorption capacities · Biosorption kinetics · Pseudo-first-order kinetic model · Tanzanian lignocellulosic materials
1 Introduction Toxic metal and metalloid ions in the environment are a global challenge to environmental engineers, environmental scientists, water treatment specialists, biologists, life scientists and even soil scientists. Because of their
toxicity, non-biodegradability, and persistence, these ions require strict special monitoring and control measures. The following are some of the negative human and/or ecological health effects of several metal or metalloid ions: P b2+ is known as neurotoxin especially in underage children; Ni2+, Be2+, As3+, Cd2+, and Cr6+ are known as carcinogens;
Supplementary information is available for this paper at https://doi.org/10.1007/s42452-020-03743-6. * Mwemezi Johaiven Rwiza, mwemezi.rwiza@nm‑aist.ac.tz; Matthias Kleinke, matthias.kleinke@hochschule‑rhein‑waal.de; Kyoung‑Woong Kim, [email protected] | 1School of Mate
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