CHEMICAL FUNCTIONALIZATION AND CROSS-LINKING OF BIOCHAR FROM COW DUNG FOR USE AS SUPER ABSORBENT MULCH SUBSTRATE FOR AGRICULTURAL PURPOSE

Abstract

Water scarcity significantly affects agricultural productivity, particularl y in arid and semi-arid areas. There is a pressing need for developing mulching substrates that are sustainable and effective in conserving water and nutrients. In this study, cow dung collected from a farm in Thika, Kiambu County, converted into biochar through pyrolysis (burni ng under limited oxygen supply). It was subsequently functionalized using Ethan1,2 diol, Glycerol, Phosphoric acid that introduced hydroxy ls (hydrophilic group) and phosphates to improve the biochar’s affinity for water. The funtionalized biochar was cross-linked with phosphoric acid, citric acid, and urea to form a polymer-like network (gel-like structure when wet), with improved the swelling capacity and water retention.The functionalization were confirmed with the FTIR spectrum which showed peaks for -OH at 3350.73 cm-1, P-OH at 788.87 cm-1, P=O at 1279.5 cm-1, C-N at 1045.23 cm-1, N-H at 1622.80 cm-1, C-H at 2919.68 cm-1 and C=O at 1602.5 cm-1. This confirmed that the diol, phosphate and amino used for functionalization and cross-linking had been successively anchored. This was recommended as a sustainable modification of biochar to super absorbent mulch.