## 1 Introduction  
The discharge of industrial effluents with toxic and hazardous materials is an alarming problem because of the serious water pollution that may cause [1]. Among these pollutants, heavy metals are responsible for environmental and public health issues [2]. Cadmium is a heavy transition metal that exists in the aquatic environment through geochemical processes and is increasingly exposed to the air through anthropogenic industrial activities [3], that pollute natural water sources. Principal responsible of this environmental issue are effluents from metal plating industries, Cd-Ni batteries, pesticides, paints, pigments, plastics, metallurgy, fertilizers, alloys, stabilizers and metal plating [4, 5]. Cadmium is a toxic metal that, since it is not biodegradable, accumulates within living organisms. It is considered carcinogenic and inhibits the functioning of the liver, kidneys and lungs. Cadmium also causes bone degradation, cancer, high blood pressure, destruction of testicular tissue and erythrocytes, and Itai-tiai disease, among others [6; 7]. The World Health Organization recommends that drinking water should have a maximum concentration of 0.003 mg/L of Cd\({}^{2+}\) and its concentration in discharges should not exceed 2 mg/L [7]. Different physical and chemical methods have been used in the removal and recovery of heavy metals from contaminated aqueous solutions, such as electrocoagulation, ultrafiltration, membrane technologies and reverse osmosis [8]; however, some of them have limited applications for this type of pollutant due to the high costs, low efficiencies, high energy consumption and large waste generation [9]. Biosorption appears to be the most promising alternative compared to other methods as it is cost-effective, efficient, easy to operate and minimizes the secondary wastes [10]. Different residues have been applied as biosorbents for the removal of heavy metals from wastewater [11], due to the presence of functional groups, such as hydroxyl, carboxyl and amino groups and inorganics such as sulfates and phosphates, which are the binding center for ion exchange and complexation reactions [12; 13; 14; 15; 16]. It is well known that agricultural wastes provide large sources of biomass that can be applied to prepare biosorbents reducing its disposal problems [17]. Different materials have been used for heavy metal ions removal, such as nanofiber-poly (ethylene glycol) chitosan diacrylate hydrogel [18], hydrogel based on residual biomass of soy-poly (acrylic acid) [19], tea residues [20], biochar from poplar sawdust, residues of corn and sewage sludge [21], fungi [22] and algae [23]. They have also removed dyes such as methylene blue using _Syringa vulgaris_ leaf powder [24], insecticides such as neonicotinoids using nanocomposite hydrogels [25], and ammonia on poly (acrylic acid) -grafted chitosan and biochar composite [26]. Similarly, agroindustrial residues have been used, such as the residues of the process of obtaining lactic acid with application to polylactic from _Dioscorea rotundata_[27; 28]. Additionally, several works have been focused on removing heavy metal ions from aqueous solution using low cost biosorbent. [PERSON] et al. [29] evaluated adsorption capacity of Cadmium by calcium alginate/spent coffee grounds composite beads obtaining best results of 56 mg/g at lowest dose of adsorbent, 0.025 g in 100 mL of a solution, and highest initial concentration of 100 mg/g with removal yields efficiencies around 97-98%. [PERSON] & [PERSON] [30] used the tamarind nut seeds to prepared activated carbon by treatment with phosphoric acid. The resulting material was applied for the removal of cadmium ions from aqueous solution reaching an adsorption yield of 98% (9.8 mg/g) under contact time of 4 h. [PERSON] et al. [31] also reported the application of biochars from rice husk at different conditions of pyrolysis (300, 400, 500, 600, and 700 \({}^{\circ}\)C); they found that increasing pyrolysis temperatures, the biochar yield decreased.