Effective and selective conversion of nitrate from aqueous solutions to nitrogen gas under neutral pH condition using Al/Cu bimetal-sulfamic acid reduction method

•A two-step method was used to remove NO3–-N from aqueous solution under wide pH range.•100% NO3–-N removal efficiency was obtained at pH 7 using Al/Cu bimetal reduction as the first step.•Satisfied NO3–-N reduction performance was achieved by Al/Cu under varies pH condition.•100% N2 conversion rate was further obtained with the second step using sulfamic acid as reductant.