This study examines the effectiveness of porous silica extracted from rice husk and chitosan modified silica in removing pesticides (Malathion and Atrazine) from wastewater to assess the efficacy and efficiency of natural-source silica in the elimination of pesticide residues. This is with a view to solid waste management and valorisation. Agricultural by-products, rice husk and periwinkle shell, were sun-dried, crushed, and pulverized. The dried rice husk sample was ashed for 6 hours at 700°C in a furnace. The chitosan was extracted from periwinkle shell while rice husk ash was acid reflux treated to produce silica. The porous silica was prepared using sol-gel method, modified with chitosan and stored in a desiccator. FTIR, TEM, SEM/EDX, and XRD were used to examine the properties of the porous silica. During batch adsorptions of pesticides, the following parameters were investigated: sorbent dose, contact time, pesticide concentration, and pH. The pesticide concentrations were determined using Gas Chromatography (Agilent 19091GC). The results obtained were subjected to appropriate isotherm and kinetic models. The study revealed that the extracted silica showed the presence of Si, and O; and the morphology revealed agglomeration of particle and porosity. For Porous Rice Husk Silica (PRHS) and Chitosan Modified Porous Rice Husk Silica (MPRHS), the percentage removal of atrazine decreased from 99.82 to 96.32 % and 100 to 99.97 %, respectively, while the percentage removal of malathion decreased from 99.22 to 96.04 % for PRHS, but the percentage removal of malathion by MPRHS was 100 % as the initial pesticide concentration increased. The modification of the adsorbent (MPRHS) caused an increase in the amount of pesticides (Atrazine and Malathion) adsorbed, over the unmodified adsorbents. Freundlich and pseudo second order models fit the adsorption of both pesticides. The study concluded that porous silica from rice husk was effective at removing pesticides from wastewater, and that its effectiveness improved with the addition of chitosan. This will serve as a waste management strategy and promote circular economy.