# Effects of Biochar Production Methods and Biomass Types on Lead Removal from Aqueous Solution  
[PERSON]  
1 School of Earth, Environmental and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; [EMAIL_ADDRESS] (P.G. ); [EMAIL_ADDRESS] (E.P. ); [EMAIL_ADDRESS] (C.-L.C.) 12 Department of Civil Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA 2  
[PERSON]  
3 Division of Environmental Health, Safety & Risk Management, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; [EMAIL_ADDRESS] 3  
[PERSON]  
1 School of Earth, Environmental and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; [EMAIL_ADDRESS] (P.G. ); [EMAIL_ADDRESS] (E.P. ); [EMAIL_ADDRESS] (C.-L.C.) 12 Department of Civil Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA 2  
[PERSON]  
1 School of Earth, Environmental and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; [EMAIL_ADDRESS] (P.G. ); [EMAIL_ADDRESS] (E.P. ); [EMAIL_ADDRESS] (C.-L.C.) 12 Department of Civil Engineering, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA 2  
[PERSON]  
1 School of Earth, Environmental and Marine Sciences, University of Texas Rio Grande Valley, Edinburg, TX 78539, USA; [EMAIL_ADDRESS] (E.  
water system's customers (the 90 th percentile) sample above this level, then further action is needed to diminish Pb exposure. In the USA from 2001 to 2004, hundreds of homes had Pb concentrations of up to 300 ppb in Washington D.C., while a 2015 citizen science effort testing Pb in home water samples in Flint, Michigan determined a 90 th percentile of 27 ppb with samples ranging up to 108 ppb [5,7]. The global average of Pb concentrations in lakes and rivers was reported to be 116 \(\pm\) 29 ppb (mean \(\pm\) standard error) during 2010-2017 [1]. Biochar is a charcoal-like substance derived from agricultural or forestry waste (biomass) under limited or no oxygen conditions (pyrolysis) and it has been used as a soil amendment. By charring the biomass, carbon dioxide (CO\({}_{2}\)) in the biomass material is \"fixed\" into a stable, solid form while reducing the potential release of CO\({}_{2}\) into the atmosphere. The use of biochar as a low-cost adsorbent to remove metallic contaminants from aqueous solutions has been an emerging research topic [8, 9, 10]. In addition, adsorption is regarded as an efficient method of the contaminant removal due to its low operating cost and simple design [11]. A promising opportunity is the conversion agricultural residues from food production into biochar and its subsequent use for water treatment [12]. A biochar-based water treatment system has the potential to be used when biochar production is feasible (e.g., flame curtain kiln for developing countries or biomass gasifier for developed countries) [13]. In this study, biochar materials were produced from locally sourced biomasses and tested for their adsorptive properties of aqueous Pb ion (Pb\({}^{2+}\)). The Pb\({}^{2+}\) was chosen as a model divalent heavy metal cation due to its potential to make its way into drinking water systems. Four biomass sources (avocado seed, avocado peel, brown seaweed, and grapefruit Peel) were used as the biochar feedstock due to the abundancy of these biomasses. For example, worldwide production of avocado is 6.4 million tons per year with a waste proportion of 24% [14]. Citrus waste represents 50-60% of the 100 million tons of fruits produced per year [15]. Seaweed is also an abundant and seasonal marine waste, which is highly undesired by the coastal tourism industry [16]. Biochars were produced through two different methods in this study: (1) through a laboratory tube furnace in which the temperature was controlled, and (2) through a Do-It-Yourself (DIY) biochar maker, \"BioCharlie Log\", in which the pyrolysis temperature is not controlled and represents a household biochar production.