Biochar as a soil amendment

master's thesis

• Title (english): Biočar kao poboljšivač tla
• Author: Ivan Niko Botica
• Mentor: Marija Romić (mentor)
• Committee member: Marija Romić (predsjednik povjerenstva)
• Committee member: Marko Vinceković (član povjerenstva)
• Committee member: Željka Zgorelec (član povjerenstva)
• Granter: University of Zagreb; Faculty of Agriculture; (Soil Amelioration); Zagreb
• Defense date and country: 2020-09-17, Croatia
• Scientific / art field, discipline and subdiscipline: BIOTECHNICAL SCIENCES; Agronomy

Abstract

Biochar is a solid by-product of biomass pyrolysis in an oxygen depleted atmosphere. It is reported that the use of biochar as a soil amendment has positive effects on soil chemical, physical and biological properties. A sorption/desorption kinetics experiments were conducted with the aim to study the effects of soil-biochar mixtures on the mobility of zinc (Zn). Sewage sludge and olive pomace-derived biochars as soil amendments were mixed with terra rossa soil, the most widespread soil type in the region of Istria.
The results indicated that the adsorption of Zn in the mixture of studied soil with sewage sludge and olive pomace-derived biochars was not well-described by both Langmuir and Freundlich models. The highest Kd values which were measured at lower initial concentrations of Zn in sorption solution are caused by the presence of sorption sites with great selectivity which have relatively stronger bonding energy. Lower Kd values at higher initial concentrations of Zn in sorption solution may be explained by strong competition between heavy metals. Key soil properties that affect the Zn sorption in the soil are pH, clay mineral content and cation exchange capacity (CEC). Interactions between biochar and metals are complex and several sorption mechanisms are evident for divalent metals such as Zn, including electrostatic attraction with negatively charged biochar surfaces, complexation with biochar surface ligands and precipitation or co-precipitation with other mineral phases.

Abstract (croatian)

Biočar je čvrsti nusproizvod pirolize biomase u okolini osiromašenoj kisikom. Evidentno je da upotreba biočara kao poboljšivača tla ima pozitivne učinke na kemijska, fizikalna i biološka svojstva tla. Provedeni su sorpcijski-desorpcijski kinetički eksperimenti da bi se utvrdili učinci biočara na pokretljivost specifičnog teškog metala cinka (Zn) kada su dodani kao poboljšivači tla. Biočari su proizvedeni od komunalnog mulja i komine masline te pomiješani s crvenicom kao najzastupljenijim tipom tla u Istri.
Rezultati su pokazali da adsorpcija Zn u smjesi crvenice s biočarima komunalnog mulja i komine masline nije dobro opisana ni Langmuir ni Freundlich modelima. Najveće Kd vrijednosti koje su izmjerene u najnižim početnim koncentracijama Zn u sorpcijskoj otopini su rezultat prisutnosti sorpcijskih mjesta s velikom selektivnošću koja imaju jaku energiju vezivanja. Niske Kd vrijednosti u višim početnim koncentracijama Zn u sorpcijskoj otopini mogu se pripisati snažnoj kompeticiji između teških metala. Glavne značajke tla koje su bitne za sorpciju Zn su pH, udjel gline i kapacitet zamjene kationa. Interakcije biočara i metala su kompleksne te je kod dvovalentnih metala kao što je Zn prisutno nekoliko sorpcijskih mehanizama uključujući elektrostatičnu privlačnost prema negativno nabijenoj površini biočara, kompleksaciju s ligandima biočara i precipitaciju ili koprecipitaciju sa ostalim mineralnim fazama.

• Keywords: biochar; heavy metal; sorption and desorption experiment; distribution coefficient
• Keywords (croatian): biočar; teški metali; eksperiment sorpcije i desorpcije; koeficijent distribucije
• Language: english
• URN:NBN: urn:nbn:hr:204:763571
• Study programme: Title: Environment, Agriculture and Resource Management; Study programme type: university; Study level: graduate; Academic / professional title: Master of Engineering in Agriculture (Master of Engineering in Agriculture)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Access restricted to students and staff of home institution
• Created on: 2021-01-13 13:23:06